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Cognitive and Language Skills in Adults with Autism: A 40-Year Follow-Up

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Title: Cognitive and Language Skills in Adults with Autism: A 40-Year Follow-Up
Language: English
Authors: Howlin, Patricia, Savage, Sarah, Moss, Philippa, Tempier, Althea, Rutter, Michael
Source: Journal of Child Psychology and Psychiatry. Jan 2013 55(1):49-58.
Availability: Wiley-Blackwell. 350 Main Street, Malden, MA 02148. Tel: 800-835-6770; Tel: 781-388-8598; Fax: 781-388-8232; e-mail: cs-journals@wiley.com; Web site: http://www.wiley.com/WileyCDA
Peer Reviewed: Y
Page Count: 10
Publication Date: 2013
Document Type: Journal Articles
Reports - Research
Descriptors: Autism, Pervasive Developmental Disorders, Intelligence Quotient, Language Skills, Cognitive Ability, Adults, Children, Standardized Tests, Developmental Stages, Aggression, Self Destructive Behavior, Injuries, Language Impairments, Neurological Impairments, Epilepsy, Behavior Disorders, Intervention
Assessment and Survey Identifiers: Vineland Adaptive Behavior Scales
DOI: 10.1111/jcpp.12115
ISSN: 0021-9630
Abstract: Background: It is well established that very few individuals with autism spectrum disorders (ASD) and an IQ below 70 are able to live independently as adults. However, even amongst children with an IQ in the normal range, outcome is very variable. Childhood factors that predict later stability, improvement or decline in cognitive functioning remain uncertain and, in particular, very little is known about trajectories in later adulthood. Method: Changes in cognitive and language ability from childhood to adulthood were assessed in 60 individuals with autism, all of whom had an IQ in the average range as children. Mean age in childhood = 6 years (range 2-13 years); mean age in adulthood = 44 years (range 29-64 years). Trajectories of change and factors related to current cognitive abilities were explored. Results: For the majority of participants (N = 45, 75%), who were testable both as children and adults, IQ remained very stable and language also improved over time. However, 15 individuals could not be assessed on standard tests as adults and their developmental level could be estimated only on the Vineland Adaptive Behavior Scales. Almost all these adults (apart from one who had suffered a major stroke) showed severe aggressive or self-injurious behaviours; none had ever developed language above a 3-year level, and seven had developed epilepsy. Conclusions: For most individuals with autism who had an IQ in the average range (i.e. =70) as children, childhood IQ proved a reliable predictor of cognitive functioning well into mid- to- later adulthood. However, a significant minority was no longer testable on standard tests as adults. Their current very low levels of functional ability were generally associated with severe behavioural disturbance and persisting and severe language impairment; 50% of these individuals had also developed epilepsy, pointing to the role of organic brain dysfunction. Implications for early intervention are discussed.
Abstractor: As Provided
Number of References: 69
Entry Date: 2014
Accession Number: EJ1032144
Database: ERIC
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  Value: <anid>AN0092967498;jyy01jan.14;2024Jun04.07:33;v2.2.500</anid> <title id="AN0092967498-1">Cognitive and language skills in adults with autism: a 40-year follow-up. </title> <p>Background: It is well established that very few individuals with autism spectrum disorders (ASD) and an IQ below 70 are able to live independently as adults. However, even amongst children with an IQ in the normal range, outcome is very variable. Childhood factors that predict later stability, improvement or decline in cognitive functioning remain uncertain and, in particular, very little is known about trajectories in later adulthood. Method: Changes in cognitive and language ability from childhood to adulthood were assessed in 60 individuals with autism, all of whom had an IQ in the average range as children. Mean age in childhood = 6 years (range 2–13 years); mean age in adulthood = 44 years (range 29–64 years). Trajectories of change and factors related to current cognitive abilities were explored. Results: For the majority of participants (N = 45, 75%), who were testable both as children and adults, IQ remained very stable and language also improved over time. However, 15 individuals could not be assessed on standard tests as adults and their developmental level could be estimated only on the Vineland Adaptive Behavior Scales. Almost all these adults (apart from one who had suffered a major stroke) showed severe aggressive or self‐injurious behaviours; none had ever developed language above a 3‐year level, and seven had developed epilepsy. Conclusions: For most individuals with autism who had an IQ in the average range (i.e. ≥70) as children, childhood IQ proved a reliable predictor of cognitive functioning well into mid‐ to‐ later adulthood. However, a significant minority was no longer testable on standard tests as adults. Their current very low levels of functional ability were generally associated with severe behavioural disturbance and persisting and severe language impairment; 50% of these individuals had also developed epilepsy, pointing to the role of organic brain dysfunction. Implications for early intervention are discussed.</p> <p>adulthood; Autism spectrum disorders</p> <p>Since the earliest follow‐up studies of individuals with autism spectrum disorders (ASD; Lockyer & Rutter, [<reflink idref="bib37" id="ref1">37</reflink>] ), it has been evident that two factors ‐ childhood IQ and the development of functional language ‐ are amongst the strongest predictors of later outcome (see Howlin & Moss, [<reflink idref="bib23" id="ref2">23</reflink>] for review). However, although most longitudinal studies, especially those involving individuals of normal intelligence, suggest that IQ is relatively stable from childhood to adulthood, this finding is far from consistent (Eaves & Ho, [<reflink idref="bib12" id="ref3">12</reflink>] ; Freeman et al., [<reflink idref="bib17" id="ref4">17</reflink>] ). Moreover, the specific factors that predict stability, improvement, or decline in functioning in this group remain uncertain (Howlin, Goode, Hutton, & Rutter, [<reflink idref="bib22" id="ref5">22</reflink>] ) although prognosis tends to be poorer among females (Joseph, Tager‐Flusberg, & Lord, [<reflink idref="bib28" id="ref6">28</reflink>] ; Szatmari & Jones, [<reflink idref="bib61" id="ref7">61</reflink>] ; Volkmar, Szatmari, & Sparrow, [<reflink idref="bib62" id="ref8">62</reflink>] ), those who develop epilepsy (Miller & Tuchman, [<reflink idref="bib46" id="ref9">46</reflink>] ) and those with very limited language (Howlin et al., [<reflink idref="bib22" id="ref10">22</reflink>] ).</p> <hd id="AN0092967498-2">Change in IQ profiles over time</hd> <p>Cognitive studies of young children with ASD have generally indicated a significant deficit in verbal compared with nonverbal IQ (Mayes & Calhoun, [<reflink idref="bib44" id="ref11">44</reflink>] ). However, in older, higher IQ samples, scores for verbal and performance IQ are less discrepant (e.g. Ambery, Russell, Perry, Morris, & Murphy, [<reflink idref="bib1" id="ref12">1</reflink>] ; Charman et al., [<reflink idref="bib9" id="ref13">9</reflink>] ; Farley et al., [<reflink idref="bib15" id="ref14">15</reflink>] ; Koyama, Tachimori, Osada, Takeda, & Kurita, [<reflink idref="bib32" id="ref15">32</reflink>] ; Manjiviona & Prior, [<reflink idref="bib40" id="ref16">40</reflink>] ). Other studies have reported significantly higher verbal IQ in this group (e.g. Ehlers et al., [<reflink idref="bib13" id="ref17">13</reflink>] ; Ozonoff, South, & Miller, [<reflink idref="bib47" id="ref18">47</reflink>] ), especially among individuals with a full scale IQ >100 (Siegel, Minshew, & Goldstein, [<reflink idref="bib57" id="ref19">57</reflink>] ). There is also marked individual variability. For example, among 35 adolescents (mean IQ 111) studied by Ozonoff et al. ([<reflink idref="bib47" id="ref20">47</reflink>] ), 42% had a significant VIQ > PIQ discrepancy; in 12% PIQ > VIQ and 46% showed no significant difference (see also Black, Wallace, Sokoloff, & Kenworthy, [<reflink idref="bib5" id="ref21">5</reflink>] ).</p> <hd id="AN0092967498-3">Language changes over time</hd> <p>Many studies have found that the development of at least some useful speech by the age of 5 or 6 years is a significant prognostic indicator in autism (Howlin & Moss, [<reflink idref="bib23" id="ref22">23</reflink>] ). Language difficulties are also correlated with impairments in intellectual functioning and educational achievement (Johnson, Beitchman, & Brownlie, [<reflink idref="bib27" id="ref23">27</reflink>] ). If speech does develop, language often continues to improve into later childhood (Ballaban‐Gil, Rapin, Tuchman, & Shinnar, [<reflink idref="bib3" id="ref24">3</reflink>] ; Eaves & Ho, [<reflink idref="bib12" id="ref25">12</reflink>] ; Howlin et al., [<reflink idref="bib22" id="ref26">22</reflink>] ; Mawhood, Howlin, & Rutter, [<reflink idref="bib43" id="ref27">43</reflink>] ; Seltzer et al., [<reflink idref="bib55" id="ref28">55</reflink>] ; Sigman & McGovern, [<reflink idref="bib58" id="ref29">58</reflink>] ) but little is known about subsequent development.</p> <p>Children with ASD typically show greater impairments in receptive than expressive language (Bartak, Rutter, & Cox, [<reflink idref="bib4" id="ref30">4</reflink>] ; Ellis, Lord, & Esler, [<reflink idref="bib14" id="ref31">14</reflink>] ; Hudry et al., [<reflink idref="bib25" id="ref32">25</reflink>] ), but the disparity tends to diminish (Kjelgaard & Tager‐Flusberg, [<reflink idref="bib29" id="ref33">29</reflink>] ) or disappear by early adulthood (Howlin, [<reflink idref="bib21" id="ref34">21</reflink>] ; Koning & Magill‐Evans, [<reflink idref="bib31" id="ref35">31</reflink>] ; Mawhood et al., [<reflink idref="bib43" id="ref36">43</reflink>] ).</p> <p>Around 20%–30% of individuals with autism have a history of language regression (i.e. loss of existing language abilities around the age of 30–36 months; Kurita, [<reflink idref="bib33" id="ref37">33</reflink>] ). Some studies report that early language regression is subsequently associated with lower IQ, poorer social skills and higher levels of autism symptomatology (Baird et al., [<reflink idref="bib2" id="ref38">2</reflink>] ; Kobayashi & Murata, [<reflink idref="bib30" id="ref39">30</reflink>] ; Richler et al., [<reflink idref="bib52" id="ref40">52</reflink>] ; Rogers & DiLalla, [<reflink idref="bib53" id="ref41">53</reflink>] ; Wilson, Djukic, Shinnar, Dharmani, & Rapin, [<reflink idref="bib69" id="ref42">69</reflink>] ), but this relationship is inconsistent and complex (Brown & Prelock, [<reflink idref="bib6" id="ref43">6</reflink>] ; Lord, Shulman, & DiLavore, [<reflink idref="bib38" id="ref44">38</reflink>] ; Meilleur & Fombonne, [<reflink idref="bib45" id="ref45">45</reflink>] ).</p> <hd id="AN0092967498-4">Purpose of present study</hd> <p>Although early language and IQ are significantly related to development in childhood and adolescence, most follow‐up studies of individuals with autism only extend to early adulthood (Howlin & Moss, [<reflink idref="bib23" id="ref46">23</reflink>] ); little is known about later trajectories or the factors that influence these. The aim of this study was to assess cognitive and language change in a cohort of individuals first diagnosed as children and followed up to mid‐later adulthood. The principal research questions explored were:</p> <p>IQ:</p> <p>What is the pattern of change in IQ from childhood to adulthood?</p> <p>What are the main childhood correlates of adult IQ?</p> <p>What are the factors most predictive of IQ decline over time?</p> <p>Language:</p> <p>Does language continue to improve from childhood to adulthood?</p> <p>Are expressive skills in advance of receptive skills in adulthood?</p> <p>What is the impact of early language regression on later outcome?</p> <hd id="AN0092967498-5">Methods</hd> <hd id="AN0092967498-6">Study background</hd> <p>This research stems from a follow‐up study of individuals diagnosed with autism as children at the Institute of Psychiatry/Maudsley Hospital, London, between 1950 and 1979. This study focuses on those with a nonverbal childhood IQ in the normal range (i.e. ≥70). Ethical approval was obtained from the Joint South London and Maudsley/Institute of Psychiatry NHS Research Ethics Committee (reference: 07/H0807/65; 19/12/07). All participants gave their consent (either verbally or nonverbally) to participate.</p> <hd id="AN0092967498-7">Participants</hd> <p>All participants met the following criteria:</p> <p>Current age ≥21 years.</p> <p>Initial clinical diagnosis of autism made between 2 and 13 years of age.</p> <p>Diagnosis confirmed using the Autism Diagnostic Interview (ADI; Le Couteur et al., [<reflink idref="bib34" id="ref47">34</reflink>] ) or the Autism Diagnostic Interview – Revised (ADI‐R; Rutter, Le Couteur, & Lord, [<reflink idref="bib54" id="ref48">54</reflink>] ).</p> <p>Childhood nonverbal IQ ≥70.</p> <p>Ninety‐one individuals from the original child cohort (see Howlin et al., [<reflink idref="bib22" id="ref49">22</reflink>] ) met criteria but one had died (cause unknown). Of these, 82 were traced and contacted, 12 did not respond and 10 (two of whom considered they no longer had autism) declined to participate. In total, 60 individuals (49 males, 11 females; 67% of the eligible sample still alive) agreed to participate. There were no significant differences between non/participants with respect to childhood nonverbal IQ or language level, or ADI total scores at diagnostic confirmation (see Howlin, Moss, Savage and Rutter, [<reflink idref="bib24" id="ref50">24</reflink>] ).</p> <p>When assessed in childhood, the mean age of the cohort was 6 years 9 months (SD 2 year 9 months; range 2–13 years); their mean age as adults was 44 years 2 months (SD 9 year 4 months; range 29–64 years). The mean time between initial assessment and follow‐up was 37 years 6 months (SD 9 year 2 months; range 23–59 years). Among the total group, 44 participants (37 males, 7 females) had also been previously assessed when aged 16 years or older (average age 26 year 1 month, SD 8 year 2 months, range 16–46 years) allowing for further analysis of change from childhood through later adolescence/early adulthood to mid/later adulthood. In describing our findings, we report overall changes from childhood to adulthood in the total sample (Child‐Adult cohort, N = 60). Data on the subgroup of 44 individuals who were additionally assessed in later adolescence/early adulthood are used to explore patterns of change in IQ over three time points [T1 (childhood) through T2 (late adolescence early adulthood) to T3 (mid/later adulthood)].</p> <hd id="AN0092967498-8">Measures</hd> <p>For full details see Howlin et al. ([<reflink idref="bib24" id="ref51">24</reflink>] ).</p> <hd id="AN0092967498-9">Diagnosis</hd> <p>In all cases, initial clinical diagnoses (made/confirmed by M.Rutter using ICD‐9 or ICD‐10 criteria) were reconfirmed using the ADI (Le Couteur et al., [<reflink idref="bib34" id="ref52">34</reflink>] ) when this became available. Diagnostic status at current follow‐up was reconfirmed on the ADI‐R (Rutter et al., [<reflink idref="bib54" id="ref53">54</reflink>] ). (Details of ADI & ADI‐R data can be found in Howlin et al., [<reflink idref="bib24" id="ref54">24</reflink>] ).</p> <hd id="AN0092967498-10">IQ</hd> <p>Because of the variable abilities of the participants and differences in IQ tests for children and adults, assessment measures varied over time. A ‘Best Estimate’ IQ score was derived for each participant based on the best quality, age‐appropriate test completed. As the term suggests, this was designed to give the best estimate, from all the assessments available, of an individual's general level of cognitive ability. For the sample as a whole, best estimate scores in childhood were based on the WISC/WISC‐R or WPPSI (Wechsler, [<reflink idref="bib63" id="ref55">63</reflink>] , [<reflink idref="bib64" id="ref56">64</reflink>] , [<reflink idref="bib65" id="ref57">65</reflink>] ; Full scale n = 19; Performance scale only n = 8); Merrill Palmer (Stutsman, [<reflink idref="bib60" id="ref58">60</reflink>] ; n = 31), or Leiter scales (Levine & Leiter, [<reflink idref="bib35" id="ref59">35</reflink>] ; n = 2). At final adult assessment, best estimate IQ was based mainly on the WAIS‐III (Wechsler, [<reflink idref="bib67" id="ref60">67</reflink>] ; Full scale n = 23; Performance scale only n = 2); the WASI (Full scale; Wechsler, [<reflink idref="bib68" id="ref61">68</reflink>] ) was used for 9 individuals who were reported to have difficulties with longer assessments. As there was no significant difference between mean WAIS‐III and WASI FSIQ (t = −.13, p = .89); PIQ (t = −1.22, p = .23) or VIQ scores (t = .74, p = .46) at follow‐up, the adult Wechsler scores reported are based on either test. Raven's Coloured Matrices scores (Raven, [<reflink idref="bib50" id="ref62">50</reflink>] ) were used as a proxy for best estimate IQ for 10 adults with very limited speech. Fifteen adults did not complete any direct assessments, either because they clearly could not understand test instructions or requirements and/or because of behavioural problems such as aggression or self‐injury which their carers feared would be exacerbated by attempts to test them formally (see Appendix S4 for individual details). For them, a ‘Best Estimate’ score was based on their developmental level as assessed by the Vineland Adaptive Behavior Scales (VABS; Sparrow, Balla, & Cicchetti, [<reflink idref="bib59" id="ref63">59</reflink>] ). One other participant refused any psychometric testing at follow‐up because of disapproval of normed assessments.</p> <p>Separate verbal and nonverbal IQ scores in adulthood were generally based on the Wechsler tests, although the Raven's was used to estimate nonverbal IQ for ten individuals with very limited verbal ability. As numbers completing PIQ or VIQ scales varied, sample size for each analysis is indicated on the relevant tables. (For details of IQ assessments at each time point see Appendix S1[A]).</p> <hd id="AN0092967498-11">Language</hd> <p>Language ratings at each time point were based on ADI‐R scores for ‘Overall level of Language’ (Rutter et al., [<reflink idref="bib54" id="ref64">54</reflink>] ; details in Tables [NaN] and [NaN] ). At final follow‐up, expressive language was additionally assessed by the Expressive One Word Picture Vocabulary Test (EOWPVT; Brownell, [<reflink idref="bib7" id="ref65">7</reflink>] ), and receptive language by the British Picture Vocabulary Scale (BPVS; Dunn, Dunn, Whetton, & Burley, [<reflink idref="bib11" id="ref66">11</reflink>] ). The group seen in earlier adulthood had also completed the BPVS at that assessment.</p> <p>(Note: Detailed analysis of social outcomes can be found in Howlin et al. ([<reflink idref="bib24" id="ref67">24</reflink>] ), but a brief summary of current living and occupational status is provided in Table S1).</p> <hd id="AN0092967498-12">Reliability</hd> <p>Independent rater agreement on 20 randomly selected ADI‐R interviews ranged from moderate to excellent on the diagnostic algorithm score (κ = 0.57–1.00); 89% of item ratings had good to excellent agreement (κ ≥ .73); ICC's for domain scores = 0.98–0.99. All current IQ test scores were double‐checked (by SS & PM) and past IQ data were rechecked by PH. The mean difference between initial and rechecked scores was <1 IQ point.</p> <hd id="AN0092967498-13">Statistics</hd> <p>Non/parametric analyses were used as appropriate and statistical tests used are indicated in the tables below (See Appendix S1[B] for details of decisions re statistical analyses). Alpha level was set at p < .01 to compensate for multiple comparisons although p < .05 variables are noted. Analysis of change in Wechsler IQ scores from early to later adulthood took account of the possible influence of the Flynn effect (increases in IQ scores from WAIS‐R (Wechsler, [<reflink idref="bib66" id="ref68">66</reflink>] ) to WAIS‐III (Wechsler, [<reflink idref="bib67" id="ref69">67</reflink>] ) over time; Flynn, [<reflink idref="bib16" id="ref70">16</reflink>] ; see Appendix S1[C]). As the results did not differ whether actual or adjusted scores were used, only actual scores are presented here. In the analysis of individual IQ change, data were also explored using the formula used by Remington et al. ([<reflink idref="bib51" id="ref71">51</reflink>] ) to determine ‘clinically significant change’ (Full details in Appendix S1[D] and Table S3).</p> <hd id="AN0092967498-14">Results</hd> <hd id="AN0092967498-15">IQ</hd> <hd id="AN0092967498-16">Child – Adult cohort</hd> <hd id="AN0092967498-17">IQ change over time</hd> <p>Although there was a decline in IQ scores for the group as a whole (Best‐estimate Child IQ = 86.2; SD = 13.94; Adult IQ = 70.24, SD = 33.90; r = .12 (ns), t = 3.5; p = .001), this apparent decrease was attributable to 15 individuals who were unable to be tested directly in adulthood and for whom follow‐up assessments were based on the Vineland only. For the remainder of the cohort, there was little change in average IQ scores and correlations between test scores over time were moderate to high (Table [NaN] ). When first seen as children, only around one third of the group was able to score on the Wechsler tests or to obtain a verbal IQ score on any formal measure. However, as adults, the number able to complete these assessments had increased and group means in adulthood were very similar to those in childhood (see Table [NaN] ). The mean scores of individuals who were assessed on these measures both as children and adults had actually increased, with marginally significant improvements in Verbal IQ and Wechsler FIQ and PIQ scores (see Table S2).</p> <p>Changes in IQ scores from childhood to adulthood</p> <p> <ephtml> <table><tr><th align="left">IQ</th><th align="center">Childhood</th><th align="center">Adulthood</th><th align="center" /><th align="center">Sig. of change</th></tr><tr><th align="center">Mean (SD) [n]</th><th align="center">Mean (SD) [n]</th><th align="center">r</th><th align="center">t</th></tr><tr><td align="left">BEIQ</td><td align="char" char=" ">85.5 (14.2) [45]</td><td align="char" char=" ">87.2 (19.8) [44]</td><td align="char" char=".">.45</td><td align="char" char=".">.47</td></tr><tr><td align="left">NON‐V IQ</td><td align="char" char=" ">88.5 (14.4) [44]</td><td align="char" char=" ">89.9 (21.8) [44]</td><td align="char" char=".">.54</td><td align="char" char=".">.53</td></tr><tr><td align="left">VIQ</td><td align="char" char=" ">84.32 (21.24) [19]</td><td align="char" char=" ">85.6 (22.4) [33]</td><td align="char" char=".">.81</td><td align="char" char=".">.97</td></tr><tr><td align="left">Wechsler FSIQ</td><td align="char" char=" ">86.7 (19.4) [20]</td><td align="char" char=" ">88.1 (21.9) [33]</td><td align="char" char=".">.81</td><td align="char" char=".">.24</td></tr><tr><td align="left">Wechsler PIQ</td><td align="char" char=" ">88.9 (15.1) [27]</td><td align="char" char=" ">93.1 (22.7) [35]</td><td align="char" char=".">.61</td><td align="char" char=".">.83</td></tr><tr><td align="left">Wechsler VIQ</td><td align="char" char=" ">84.05 (24.4) [20]</td><td align="char" char=" ">85.6 (22.4) [33]</td><td align="char" char=".">.84</td><td align="char" char=".">.23</td></tr></table> </ephtml> </p> <p>1 N completing test at each time point in parenthesis.</p> <ulist> <item>2 Excludes 15 individuals unable to complete direct testing in adulthood.</item> <item>3 Comparison using independent t‐tests as numbers vary at each time point.</item> <item>4 Significance levels: **p ≤ .01;***p < .001.</item> </ulist> <p>Figure [NaN] summarises individual changes in best estimate IQ over time. The majority of participants remained within 1 standard deviation of their original score or showed an increase in IQ. The lowest estimated scores in adulthood were for those individuals who could be tested only on the Vineland, with 14 out of the 15 obtaining a standard score of 20 or below on this measure. However, as adaptive behaviour scores are typically much lower than IQ scores in people with ASD, this apparent decline is likely due to a change in measurement, rather than a real decline in cognitive ability. Factors related to the problems of assessment in these adults are discussed below.</p> <hd id="AN0092967498-18">Wechsler PIQ‐VIQ discrepancy in childhood and adulthood</hd> <p>The difference between performance and verbal IQ scores was explored in those individuals who were able to complete both Wechsler Performance and Verbal IQ scales as children or adults. In childhood (n = 20), the median PIQ > VIQ difference was 11 points and in adulthood (n = 33) the median difference was 4 points. However, at both ages, there was great individual variation in the size of the discrepancy [range in childhood = +46 (i.e. P > VIQ) to −30 (i.e. V > PIQ); range in adulthood +50 (P > VIQ) to −38 (V > PIQ)] and the size of the discrepancy was not significantly smaller in adulthood than in childhood (Mann–Whitney z = −.569; p = .57).</p> <hd id="AN0092967498-19">Childhood variables related to adult IQ</hd> <p>As indicated in Table [NaN] , for the majority of participants (i.e. those who were testable as adults), there was a significant association between child and adult IQ (r = .45; p < .01). Within the total cohort, adult best estimate IQ was not related to a history of language regression (rho = −.04) or ADI diagnostic total (r = −0.26). Age at initial diagnosis (r = .39), childhood language level (rho = −.41), epilepsy (rho = −.37) and gender (rho = .32) were all significantly (p < .01) associated with IQ at follow‐up, but a multiple regression analysis including these variables failed to identify any overall significant predictor.</p> <hd id="AN0092967498-20">T1‐T2‐T3 cohort</hd> <hd id="AN0092967498-21">IQ change over time</hd> <p>Data on the subgroup of 44 individuals seen at three time points followed the same pattern as for the total cohort. Thus, although for this subgroup as a whole there was a decline in mean best estimate IQ [T1: 86.1 (SD = 12.1); T2: 80.0 (SD = 19.2); T3: 72.6 (SD = 33.1); F = 4.9], the decrease was due to those participants who could no longer be directly tested. Mean IQ scores for the remainder of this subgroup were generally unchanged (Table [NaN] ), although Verbal IQ did show a small but steady increase.</p> <p>T1‐2‐3 cohort: change in IQ scores from childhood to early adulthood and mid/later adulthood</p> <p> <ephtml> <table><tr><th align="left">IQ</th><th align="center">T1</th><th align="center">T2</th><th align="center">T3</th><th align="center">F</th></tr><tr><th align="center">Mean (SD) [N]</th><th align="center">Mean (SD) [N]</th><th align="center">Mean (SD) [N]</th></tr><tr><td align="left">Best estimate IQ</td><td align="char" char=" ">85.0 (12.2) [33]</td><td align="char" char=" ">83.3 (19.0) [33]</td><td align="char" char=" ">88.2 (18.5) [33]</td><td align="char" char=".">1.4</td></tr><tr><td align="left">Non‐V IQ</td><td align="char" char=" ">88.8 (11.5) [44]</td><td align="char" char=" ">82.0 (19.5) [44]</td><td align="char" char=" ">92.0 (20.8) [33]</td><td align="char" char=".">1.6</td></tr><tr><td align="left">VIQ</td><td align="char" char=" ">75.8 (20.7) [19]</td><td align="char" char=" ">81.6 (19.5) [32]</td><td align="char" char=" ">86.1 (21.7) [24]</td><td align="char" char="."><p>5.4</p><p>T1 < T2 = T3</p></td></tr><tr><td align="left">Wechsler</td></tr><tr><td align="left">FSIQ</td><td align="char" char=" ">82.9 (11.3) [16]</td><td align="char" char=" ">82.7 (16.5) [32]</td><td align="char" char=" ">89.8 (19.5) [24]</td><td align="char" char=".">2.9</td></tr><tr><td align="left">PIQ</td><td align="char" char=" ">87.4 (10.5) [22]</td><td align="char" char=" ">84.4 (16.6) [34]</td><td align="char" char=" ">95.5 (21.1) [26]</td><td align="char" char=".">1.4</td></tr><tr><td align="left">VIQ</td><td align="char" char=" ">79.1 (17.8) [16]</td><td align="char" char=" ">81.6 (19.5) [32]</td><td align="char" char=" ">86.1 (21.7) [24]</td><td align="char" char="."><p>4.0</p><p>T1 < T2 = T3</p></td></tr></table> </ephtml> </p> <ulist> <item>5 Excludes 10 individuals unable to complete direct testing at T3.</item> <item>6 Significance level: *p ≤ .05; **p ≤ .01.</item> </ulist> <p>However, as indicated in Figure [NaN] , there was also considerable variability in individual patterns of change. Some participants showed a steady decrease in best estimate IQ; others showed a period of stability followed by change, or vice versa, but for the majority best estimate scores remained within 1 standard deviation or improved from T1 to T3. The individuals with the lowest estimated scores were those who could be assessed on the Vineland only at T3.</p> <hd id="AN0092967498-22">Language</hd> <hd id="AN0092967498-23">Changes over time</hd> <p>Language had improved significantly by adulthood with only 5% of the cohort remaining without useful speech (Table [NaN] ). Data from the T1‐T2‐T3 subgroup suggest that most change took place between T1 and T2, when the proportion without speech declined from 27% to 3%. Only four individuals showed deterioration in language over time: two who had been using very few words at T2 were predominantly nonverbal at T3; of two other individuals using spontaneous phrase speech at T2, one was now using mainly brief echoed phrases and the other single words. Three of these four individuals had also shown clinically meaningful decline in IQ from T2 to T3.</p> <p>Change in ADI‐R language ratings</p> <p> <ephtml> <table><tr><th align="left" /><th align="center" /><th align="center" /><th align="center" /><th align="center">Sig. of change</th></tr><tr><td align="left">Child–adult cohort (n = 60)</td><td align="center">Child</td><td align="center" /><td align="center">Adult</td><td align="center" /></tr><tr><td align="left">0</td><td align="char" char=" ">34 (57%)</td><td align="char" /><td align="char" char=" ">48 (80%)</td><td align="char" char=" ">Wilcoxon z = −3.6</td></tr><tr><td align="left">1</td><td align="char" char=" ">11 (18%)</td><td align="char" /><td align="char" char=" ">9 (15%)</td></tr><tr><td align="left">2</td><td align="char" char=" ">15 (25%)</td><td align="char" /><td align="char" char=" ">3 (5%)</td></tr><tr><td align="left">T1‐2‐3 cohort (n = 44)</td><td align="char" char=" ">T1</td><td align="char">T2</td><td align="char">T3</td><td align="char" /></tr><tr><td align="left">0</td><td align="char" char=" ">23 (52%)</td><td align="char" char=" ">31 (70%)</td><td align="char" char=" ">37 (84%)</td><td align="char"><p>Χ<sup>2</sup> = 10.83</p><p>T1 < T2 = T3</p></td></tr><tr><td align="left">1</td><td align="char" char=" ">9 (21%)</td><td align="char" char=" ">12 (27%)</td><td align="char" char=" ">5 (11%)</td></tr><tr><td align="left">2</td><td align="char" char=" ">12 (27%)</td><td align="char" char=" ">1 (3%)</td><td align="char" char=" ">2 (5%)</td></tr></table> </ephtml> </p> <ulist> <item>7 ADI‐R coding.</item> <item>8 0 = Functional use of spontaneous/echoed phrases (of ≥3 words) on daily basis.</item> <item>9 1 = No phrase speech ≥3words but single words used daily; ≥5 word vocabulary.</item> <item>10 2 = No speech used on daily basis; <5 word vocabulary.</item> <item>11 Significance level: **p ≤ .01.</item> </ulist> <hd id="AN0092967498-24">Impact of early language regression</hd> <p>ADI information on early language regression was available for 49 participants (there was no informant for two participants and the remaining informants could not remember whether regression had occurred). Comparisons between those individuals who did (n = 9) or did not (n = 40) show language regression indicated no group difference in current adult language ratings (Mann–Whitney z = −1.77, p = .08); current IQ (z = −.91, p = .36), or decrease in IQ scores over time (z = .85, p = .39).</p> <hd id="AN0092967498-25">Receptive and expressive language</hd> <p>The BPVS was not systematically given in childhood, so change was assessed from early to later adulthood only; the EOWVT was completed at adult follow‐up only (Table [NaN] ). As participants' ages were above the test ceiling, it was not possible to calculate standard scores and hence language levels were categorised according to age bands. Between early and later adulthood (T2 to T3), there was a small but nonsignificant increase in the number of individuals scoring at the ceiling of the BPVS, and at the current assessment the proportion of participants scoring at ceiling on both receptive and expressive tests was similar. Although analysis based on age bands, rather than actual scores, clearly has limitations, the small improvement in BPVS scores from early to later adulthood appears to reflect the language changes reported on the ADI‐R over the same period. It is more difficult to interpret the relationship between expressive and receptive language in adulthood as this finding could be due to factors such as differences in test ceiling levels or differences in test format. However, the data suggest that, in adults, the discrepancy between expressive and receptive language may be less marked than is typical in childhood.</p> <p>Expressive and receptive language scores in adulthood</p> <p> <ephtml> <table><tr><th align="left">Age equivalent bands</th><th align="center">Early adult BPVS N = 29</th><th align="center">Later adult BPVS N = 39</th><th align="center">Later adult EOWPVT N = 35</th></tr><tr><td align="left"><Basal</td><td align="char" char=" ">3 (10%)</td><td align="char" char=" ">2 (5%)</td><td align="char" char=" ">4 (11%)</td></tr><tr><td align="left">3–5 years 11 months</td><td align="char" char=" ">9 (31%)</td><td align="char" char=" ">5 (13%)</td><td align="char" char=" ">3 (9%)</td></tr><tr><td align="left">6–11 years 11 months</td><td align="char" char=" ">7 (24%)</td><td align="char" char=" ">14 (36%)</td><td align="char" char=" ">11 (31%)</td></tr><tr><td align="left">12‐Ceiling</td><td align="char" char=" ">6 (21%)</td><td align="char" char=" ">11 (28%)</td><td align="char" char=" ">10 (29%)</td></tr><tr><td align="left">>Ceiling</td><td align="char" char=" ">4 (14%)</td><td align="char" char=" ">7 (18%)</td><td align="char" char=" ">7 (20%)</td></tr></table> </ephtml> </p> <p>12 BPVS Ceiling = 18 years, EOWVT Ceiling = 19 years.</p> <hd id="AN0092967498-26">Factors related to severely impaired functioning in adulthood</hd> <p>The characteristics of the subgroup of individuals who could not be assessed directly in adulthood, all of whom were severely functionally impaired, are summarised in Table [NaN] . Vineland standard scores for all but one individual in this group were 20 or below; the man who could not be tested due to a stroke had a standard score of 75. Two variables were significantly associated with severe impairment in adulthood: ADI‐R language rating when participants were first diagnosed (rho = .39, p = .002) and ADI‐R current language rating (rho = .48, p < .001; poorer language = higher probability of no formal adult IQ assessment). Age, when first diagnosed, was also marginally associated with inability to complete adult testing (rho = −.27, p = .03), perhaps because children who receive an early diagnosis are more likely to have higher levels of disturbance or impairment. There was no significant correlation between testability and other variables: i.e. with IQ in childhood (rho = .10); diagnostic ADI score (rho = .19); current age (rho = −.02); history of epilepsy (rho = .19), or gender (rho = .12); (all ps > .15). Nevertheless, five (45%) of the 11 females in the cohort could be assessed on the Vineland only in adulthood compared with 10 (20%) of males. Females also showed a marginally significant greater decrease in IQ over time (median decrease = −32.0; males 1.0; Mann–Whitney z = −2.00, p = .05) and their IQ at follow‐up was lower (median IQ 43.5 vs. 78.0; z = −2.49, p = .02). Compared with the remainder of the cohort, participants with a history of epilepsy (n = 12) also showed a greater decline in IQ from childhood to adulthood (median decrease in best estimate IQ −36.0 vs. 1.0; z = −2.07, p = .03) and they had significantly lower best estimate IQ scores in adulthood (median IQ = 39.5 vs. 81.0, z = −2.88, p < .01). History of epilepsy was also more common in females than males (χ<sups>2</sups>(<reflink idref="bib1" id="ref72">1</reflink>) = 11.7, p < .01).</p> <p>Group differences: individuals who were/were not testable on standard IQ measures at follow‐up</p> <p> <ephtml> <table><tr><th align="left">Variables</th><th align="left">Not testable (N = 15) Mean (SD)</th><th align="left">Testable (N = 45) Mean (SD)</th><th align="left">Significance t</th></tr><tr><td align="left">Current age (years)</td><td align="left">44.3 (10.3)</td><td align="left">44.1 (8.5)</td><td align="left">0.10</td></tr><tr><td align="left">Age initial testing (years)</td><td align="left">5.7 (1.7)</td><td align="left">7.0 (2.3)</td><td align="left">1.98</td></tr><tr><td align="left">Childhood best estimate IQ</td><td align="left">88.6(14.4)</td><td align="left">88.4 (146)</td><td align="left">0.05</td></tr><tr><td align="left">ADI diagnostic algorithm (total score)</td><td align="left">42.9 (7.2)</td><td align="left">38.4 (8.5)</td><td align="left">1.81</td></tr><tr><td align="left" /><td align="left">N (%)</td><td align="left">N (%)</td><td align="left">Fisher p</td></tr><tr><td align="left">Female gender</td><td align="left">4(27%)</td><td align="left">7 (16%)</td><td align="left">0.44</td></tr><tr><td align="left">History of epilepsy</td><td align="left">5 (33%)</td><td align="left">7 (16%)</td><td align="left">0.15</td></tr><tr><td align="left">History of language regression</td><td align="left">3 (20%)</td><td align="left">6 (13%)</td><td align="left">0.69</td></tr><tr><td align="left">ADI‐R language childhood</td></tr><tr><td align="left">0</td><td align="left">4 (27%)</td><td align="left">30 (67%)</td><td align="left">Mann–Whitney z = −2.99</td></tr><tr><td align="left">1</td><td align="left">3 (20%)</td><td align="left">8 (18%)</td></tr><tr><td align="left">2</td><td align="left">8 (53%]</td><td align="left">7 (16%)</td></tr><tr><td align="left">Adulthood</td></tr><tr><td align="left">0</td><td align="left">7 (12%)</td><td align="left">41 (68%)</td><td align="left">Mann–Whitney z = −3.68</td></tr><tr><td align="left">1</td><td align="left">6 (10%)</td><td align="left">3 (5%)</td></tr><tr><td align="left">2</td><td align="left">2 (3%)</td><td align="left">1 (2%)</td></tr></table> </ephtml> </p> <ulist> <item>13 Data available on 49 participants.</item> <item>14 ADI‐R language coding.</item> <item>15 0 = Functional use of spontaneous/echoed phrases (of ≥3 words) on daily basis.</item> <item>16 1 = No phrase speech ≥3words but single words used daily; ≥5 word vocabulary.</item> <item>17 2 = No speech used on daily basis; <5 word vocabulary.</item> <item>18 Significance level: **p ≤ .01; ***p ≤ .001.</item> </ulist> <hd id="AN0092967498-27">Did the inability to complete IQ assessments in adult life reflect a true reduction in ...</hd> <p>Previous cognitive data (many individuals had been assessed several times as children/adolescents) and clinical case records of participants who could no longer be directly assessed were examined in order to explore possible reasons for the inability to complete formal IQ tests in adulthood. In the case of one man, his current level of impairment was due to a severe stroke in his mid‐50s. Of the remaining 14, five individuals had shown no evidence of IQ decline in childhood, but in their teens they had developed severe and persisting behaviour problems that subsequently affected their ability to complete IQ assessments as adults. In four individuals, early IQ results had been inconsistent, so it was not possible to determine if there had been cognitive decline during childhood. However, five individuals had shown clear evidence of a decline in IQ scores during the childhood years, and all but one of these had developed epilepsy. Decline in IQ scores in childhood was also associated with the presence of severe behavioural problems and significant language impairment that made cognitive testing impractical (see Table S4 for characteristics of these individuals).</p> <hd id="AN0092967498-28">Discussion</hd> <p>This study is the largest long‐term follow‐up study of cognitive development in a cohort of individuals with autism who, as children, had a nonverbal IQ in the normal range. Although there was some attrition over time, the 67% response rate is exceptional for a follow‐up of around 40 years. Overall, our data support recent findings by Farley et al. ([<reflink idref="bib15" id="ref73">15</reflink>] ) who also found that, in the majority of cases, IQ remains relatively stable over time. As in many other follow‐up studies (see Howlin & Moss, [<reflink idref="bib23" id="ref74">23</reflink>] ; for review), the findings highlight the importance of the development of functional language skills for later outcome. The data also add to evidence that language abilities tend to improve from childhood to adulthood (e.g. Ballaban‐Gil et al., [<reflink idref="bib3" id="ref75">3</reflink>] ; Mawhood et al., [<reflink idref="bib43" id="ref76">43</reflink>] ; Seltzer et al., [<reflink idref="bib55" id="ref77">55</reflink>] ; Shattuck et al., [<reflink idref="bib56" id="ref78">56</reflink>] ; Sigman & McGovern, [<reflink idref="bib58" id="ref79">58</reflink>] ), although there appear to be fewer major improvements over the adult years. Comparison between receptive and expressive language skills was compromised by the lack of tests suitable, when the study began, for older adults (parallel forms of comprehension and expressive tests for adults up to 80+ years of age have since become available; Martin & Brownell, [<reflink idref="bib41" id="ref80">41</reflink>] ,[<reflink idref="bib42" id="ref81">42</reflink>] ). However, there is some indication that the expressive > receptive skills profile typical of children with ASD may become less marked with age.</p> <p>As in other adult follow‐up studies (see Henninger & Taylor, [<reflink idref="bib20" id="ref82">20</reflink>] ; Levy & Perry, [<reflink idref="bib36" id="ref83">36</reflink>] ; Perkins & Berkman, [<reflink idref="bib49" id="ref84">49</reflink>] , for reviews), at a group level the findings were generally positive with IQ for most individuals remaining relatively stable over time, and language skills improving. However, a minority was functionally extremely impaired in adulthood. Apart from one man who had suffered a stroke, none of these individuals had ever developed language above a 3‐year level, and almost all showed severe behavioural disturbance (aggression and/or self‐injury, often requiring medication), which meant that a systematic cognitive assessment could not be undertaken. In most cases, it was not possible to determine if this reflected a true decline in intellectual capacity, but five individuals had shown a clear decline in IQ scores in childhood. All but one of these participants had developed epilepsy and although onset of epilepsy did not always precede the decline, it is highly likely that the epilepsy indexed an organic dysfunction that had played a causal role.</p> <p>Although one of the largest studies of its kind, sample size placed limitations on our ability to reach definitive conclusions on other issues. For example, as in several other studies (Carter et al., [<reflink idref="bib8" id="ref85">8</reflink>] ; Joseph et al., [<reflink idref="bib28" id="ref86">28</reflink>] ; Szatmari & Jones, [<reflink idref="bib61" id="ref87">61</reflink>] ; Volkmar et al., [<reflink idref="bib62" id="ref88">62</reflink>] ) females tended to be more cognitively impaired but gender differences were only marginally significant, possibly because of the small number of women involved. The variety of measures used for deriving the best estimate IQ also raises issues when comparing cognitive differences between individuals, or assessing change between childhood and adulthood. Thus, while in childhood, some participants could complete a Wechsler Full scale IQ, others were testable only on nonverbal measures such as the Ravens or Merrill Palmer or the Leiter (1982 version). These two latter tests, in particular, tend to assess very different skills from the WISC or WPPSI and how far one can compare IQ estimates based on these different measures is questionable. In adulthood, too, the need to use the Vineland scales to estimate level of functioning in some participants was a major methodological issue. The Vineland is not intended as a measure of IQ, and its focus on social and communication skills means that people with autism may score relatively low on this compared with standard IQ tests. Nevertheless, it was the only way in which we could obtain some measure of functioning on those individuals who were more severely impaired and/or disturbed.</p> <p>Although severely impaired language, both current and in childhood, was one of the variables most significantly associated with low functioning in adulthood, our measures of language ability were limited. Childhood language assessments were based on retrospective parental reports, and although there was no apparent effect of language regression on later outcome, parental reports of early language development may be less accurate than their reports of other developmental milestones (Hus, Taylor, & Lord, [<reflink idref="bib26" id="ref89">26</reflink>] ). Current assessments of expressive and receptive abilities were based mainly on use and understanding of single words although in individuals with autism of higher IQ, their main problems tend to be in discourse and language pragmatics, not single word vocabulary. In contrast to some previous research (see Gillespie‐Lynch et al., [<reflink idref="bib18" id="ref90">18</reflink>] ), early IQ did not significantly predict later cognitive ability in the cohort as a whole; however, this sample was relatively more homogeneous with respect to childhood IQ than in many other studies. Moreover, when the group of individuals who were severely impaired in adulthood was excluded from the analysis, the relationship between child and adult IQ was significant.</p> <p>There are also other limitations to consider. Firstly, there is the question of how representative this cohort is of young people with autism now reaching adulthood. Many of our participants were diagnosed when clinical services for children with autism were very limited. The average age of diagnosis was over 6 years whereas children today tend to be diagnosed at considerably younger ages (e.g. Mandell, Novak, & Zubritsky, [<reflink idref="bib39" id="ref91">39</reflink>] ; Parner, Schendell, & Thorsen, [<reflink idref="bib48" id="ref92">48</reflink>] ). Although many attended specialist autism schools as children (Howlin et al., [<reflink idref="bib24" id="ref93">24</reflink>] ) none had access to the intensive, early behavioural programmes that are available today, and which are claimed, by some, to have a significant impact on IQ and long‐term outcome (e.g. Chasson, Harris, & Neely, [<reflink idref="bib10" id="ref94">10</reflink>] ). Secondly, although all participants were adults, combining outcome data for individuals in their late 20s with those in their mid‐60s is clearly an issue. Nevertheless, age in adulthood was not associated with current IQ or IQ decline. Thirdly, although the cohort is older than in other studies, the average age was around mid‐40 and later trajectories of development remain unexplored. Finally, the standardised measures employed to assess language and IQ provide only a global picture of functioning; research into more complex aspects of cognitive and linguistic functioning is required in order to highlight specific areas of deficit in older individuals (c.f. Guerts & Vissers, [<reflink idref="bib19" id="ref95">19</reflink>] ).</p> <hd id="AN0092967498-29">Conclusions and implications of findings</hd> <p>Research examining the predictive validity and stability of IQ across the life span is important in planning more effective services and intervention for individuals with autism in later life. Our findings indicate that most individuals with an IQ in the average range as children maintain this level of functioning at least until the middle adult years. Thus, cognitive assessments of young children with ASD can provide valuable information, not only with regard to current functioning but also with respect to later abilities and potential skill development. It is also evident that individuals who fail to progress in early language are at significant risk of more severe impairments in adulthood. A focus on improving communication skills throughout the school years could have a longer term effect on general cognitive functioning. Behavioural disturbance, too, can have a significant impact on cognitive performance and early interventions to reduce disruptive, aggressive and self‐injurious behaviours may have a major impact on cognitive functioning in adulthood.</p> <p>Finally, although this study provides valuable information into general trajectories of cognitive development over the years, research is needed on more complex aspects of cognition during adulthood. In particular, the question of whether individuals with autism show similar patterns of cognitive decline to typically developing older people remains unexplored.</p> <hd id="AN0092967498-30">Acknowledgements</hd> <p>We thank the Nuffield Foundation for funding this research. We are most grateful to the individuals with autism and their families or carers who gave so generously of their time during the course of the study. We are also grateful to the National Autistic Society, and in particular Mr. Richard Mills, Research.</p> <ref id="AN0092967498-31"> <title>Footnotes</title> <blist> <bibl id="bib1" idref="ref12" type="bt">1</bibl> <bibtext>Conflicts of interest statement: No conflicts declared. </bibtext> </blist> </ref> <ref id="AN0092967498-32"> <title>References</title> <blist> <bibtext>Ambery, F.Z., Russell, A.J., Perry, K., Morris, R., & Murphy, D.G. ( 2006 ). Neuropsychological functioning in adults with Asperger syndrome. Autism, 10, 551 – 564. </bibtext> </blist> <blist> <bibl id="bib2" idref="ref38" type="bt">2</bibl> <bibtext>Baird, G., Charman, T., Pickles, A., Chandler, S., Loucas, T., Meldrum, D., … & Simonoff, E. ( 2008 ). Regression, developmental trajectory and associated problems in disorders in the autism spectrum: The SNAP study. 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( 2003 ). Clinical characteristics of language regression in children. Developmental Medicine and Child Neurology, 45, 508 – 514. </bibtext> </blist> </ref> <p>Graph: Change in ‘Best Estimate’ IQ from childhood to adulthood ( N  = 59) 1.</p> <p>Graph: Change in ‘Best Estimate’ IQ from child through early to later adulthood ( N  = 43) 1.</p> <p>Graph: Appendix S1 Study Procedures (A) IQ Assessments Determining IQ scores‐ earlier assessments. (B) Adjusting for the Flynn effect. (C) Exploring clinically significant change. (D) Decisions reuse of non/parametric analyses Table S1 Educational Background and Current Social Status (n = 60) Table S2 Changes in IQ scores from childhood to adulthood Table S3 Determining Clinically Significant Change in IQ Over Time Table S4 Characteristics of Individuals who were unable to be tested at follow‐up. (A) No definite evidence of early decline. (B) IQ results inconsistent in early years. (C) Strong evidence of earlier decline.</p> <aug> <p>By Patricia Howlin; Sarah Savage; Philippa Moss; Althea Tempier and Michael Rutter</p> </aug>
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  Data: Cognitive and Language Skills in Adults with Autism: A 40-Year Follow-Up
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  Data: <searchLink fieldCode="AR" term="%22Howlin%2C+Patricia%22">Howlin, Patricia</searchLink><br /><searchLink fieldCode="AR" term="%22Savage%2C+Sarah%22">Savage, Sarah</searchLink><br /><searchLink fieldCode="AR" term="%22Moss%2C+Philippa%22">Moss, Philippa</searchLink><br /><searchLink fieldCode="AR" term="%22Tempier%2C+Althea%22">Tempier, Althea</searchLink><br /><searchLink fieldCode="AR" term="%22Rutter%2C+Michael%22">Rutter, Michael</searchLink>
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  Data: <searchLink fieldCode="SO" term="%22Journal+of+Child+Psychology+and+Psychiatry%22"><i>Journal of Child Psychology and Psychiatry</i></searchLink>. Jan 2013 55(1):49-58.
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  Data: Wiley-Blackwell. 350 Main Street, Malden, MA 02148. Tel: 800-835-6770; Tel: 781-388-8598; Fax: 781-388-8232; e-mail: cs-journals@wiley.com; Web site: http://www.wiley.com/WileyCDA
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  Data: 10
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  Data: 2013
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  Data: Journal Articles<br />Reports - Research
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  Data: <searchLink fieldCode="DE" term="%22Autism%22">Autism</searchLink><br /><searchLink fieldCode="DE" term="%22Pervasive+Developmental+Disorders%22">Pervasive Developmental Disorders</searchLink><br /><searchLink fieldCode="DE" term="%22Intelligence+Quotient%22">Intelligence Quotient</searchLink><br /><searchLink fieldCode="DE" term="%22Language+Skills%22">Language Skills</searchLink><br /><searchLink fieldCode="DE" term="%22Cognitive+Ability%22">Cognitive Ability</searchLink><br /><searchLink fieldCode="DE" term="%22Adults%22">Adults</searchLink><br /><searchLink fieldCode="DE" term="%22Children%22">Children</searchLink><br /><searchLink fieldCode="DE" term="%22Standardized+Tests%22">Standardized Tests</searchLink><br /><searchLink fieldCode="DE" term="%22Developmental+Stages%22">Developmental Stages</searchLink><br /><searchLink fieldCode="DE" term="%22Aggression%22">Aggression</searchLink><br /><searchLink fieldCode="DE" term="%22Self+Destructive+Behavior%22">Self Destructive Behavior</searchLink><br /><searchLink fieldCode="DE" term="%22Injuries%22">Injuries</searchLink><br /><searchLink fieldCode="DE" term="%22Language+Impairments%22">Language Impairments</searchLink><br /><searchLink fieldCode="DE" term="%22Neurological+Impairments%22">Neurological Impairments</searchLink><br /><searchLink fieldCode="DE" term="%22Epilepsy%22">Epilepsy</searchLink><br /><searchLink fieldCode="DE" term="%22Behavior+Disorders%22">Behavior Disorders</searchLink><br /><searchLink fieldCode="DE" term="%22Intervention%22">Intervention</searchLink>
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  Data: 10.1111/jcpp.12115
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  Data: 0021-9630
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  Data: Background: It is well established that very few individuals with autism spectrum disorders (ASD) and an IQ below 70 are able to live independently as adults. However, even amongst children with an IQ in the normal range, outcome is very variable. Childhood factors that predict later stability, improvement or decline in cognitive functioning remain uncertain and, in particular, very little is known about trajectories in later adulthood. Method: Changes in cognitive and language ability from childhood to adulthood were assessed in 60 individuals with autism, all of whom had an IQ in the average range as children. Mean age in childhood = 6 years (range 2-13 years); mean age in adulthood = 44 years (range 29-64 years). Trajectories of change and factors related to current cognitive abilities were explored. Results: For the majority of participants (N = 45, 75%), who were testable both as children and adults, IQ remained very stable and language also improved over time. However, 15 individuals could not be assessed on standard tests as adults and their developmental level could be estimated only on the Vineland Adaptive Behavior Scales. Almost all these adults (apart from one who had suffered a major stroke) showed severe aggressive or self-injurious behaviours; none had ever developed language above a 3-year level, and seven had developed epilepsy. Conclusions: For most individuals with autism who had an IQ in the average range (i.e. =70) as children, childhood IQ proved a reliable predictor of cognitive functioning well into mid- to- later adulthood. However, a significant minority was no longer testable on standard tests as adults. Their current very low levels of functional ability were generally associated with severe behavioural disturbance and persisting and severe language impairment; 50% of these individuals had also developed epilepsy, pointing to the role of organic brain dysfunction. Implications for early intervention are discussed.
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  Data: 69
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  Data: 2014
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  Data: EJ1032144
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  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1111/jcpp.12115
    Languages:
      – Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 10
        StartPage: 49
    Subjects:
      – SubjectFull: Autism
        Type: general
      – SubjectFull: Pervasive Developmental Disorders
        Type: general
      – SubjectFull: Intelligence Quotient
        Type: general
      – SubjectFull: Language Skills
        Type: general
      – SubjectFull: Cognitive Ability
        Type: general
      – SubjectFull: Adults
        Type: general
      – SubjectFull: Children
        Type: general
      – SubjectFull: Standardized Tests
        Type: general
      – SubjectFull: Developmental Stages
        Type: general
      – SubjectFull: Aggression
        Type: general
      – SubjectFull: Self Destructive Behavior
        Type: general
      – SubjectFull: Injuries
        Type: general
      – SubjectFull: Language Impairments
        Type: general
      – SubjectFull: Neurological Impairments
        Type: general
      – SubjectFull: Epilepsy
        Type: general
      – SubjectFull: Behavior Disorders
        Type: general
      – SubjectFull: Intervention
        Type: general
      – SubjectFull: Vineland Adaptive Behavior Scales
        Type: general
    Titles:
      – TitleFull: Cognitive and Language Skills in Adults with Autism: A 40-Year Follow-Up
        Type: main
  BibRelationships:
    HasContributorRelationships:
      – PersonEntity:
          Name:
            NameFull: Howlin, Patricia
      – PersonEntity:
          Name:
            NameFull: Savage, Sarah
      – PersonEntity:
          Name:
            NameFull: Moss, Philippa
      – PersonEntity:
          Name:
            NameFull: Tempier, Althea
      – PersonEntity:
          Name:
            NameFull: Rutter, Michael
    IsPartOfRelationships:
      – BibEntity:
          Dates:
            – D: 01
              M: 01
              Type: published
              Y: 2013
          Identifiers:
            – Type: issn-print
              Value: 0021-9630
          Numbering:
            – Type: volume
              Value: 55
            – Type: issue
              Value: 1
          Titles:
            – TitleFull: Journal of Child Psychology and Psychiatry
              Type: main
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