Autism spectrum disorder: outcomes in adulthood

Howlin, Patricia; Magiati, Iliana

Current Opinion in Psychiatry: March 2017 - Volume 30 - Issue 2 - p 69–76
doi: 10.1097/YCO.0000000000000308
NEURODEVELOPMENTAL DISORDERS: Edited by James C. Harris

Purpose of review: Until recently, there has been little systematic study of adult life among individuals with autism spectrum disorder (ASD) but recognition of the high psychological and social costs of ASD has led to an increase in adult-focused research over the past decade. The aim of this review is to summarize recent empirical findings on outcomes for adults with ASD.

Recent findings: Most research on adult outcomes in ASD indicates very limited social integration, poor job prospects and high rates of mental health problems. However, studies vary widely in their methodology, choice of measures and selection of participants. Thus, estimates of how many adults have significant social and mental health problems are often conflicting. There is little consistent information on the individual, familial or wider social factors that may facilitate more positive social and psychological outcomes. There is a particular dearth of research on older individuals with ASD.

Summary: The very variable findings reported in this review reflect the problems of conducting research into lifetime outcomes for individuals with a condition as heterogeneous as ASD. Much more systematic research is needed to delineate different patterns of development in adulthood and to determine the factors influencing these trajectories.

aDepartment of Psychology, Institute of Psychiatry, Psychology and Neuroscience, King's College, London, UK

bFaculty of Health Sciences, University of Sydney, Sydney, New South Wales, Australia

cDepartment of Psychology, National University of Singapore, Singapore

Correspondence to Patricia Howlin, PhD, MSc, BA, Department of Psychology, Institute of Psychiatry, Psychology and Neuroscience, King's College, London SE58AF, UK. E-mail: patricia.howlin@kcl.ac.uk

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INTRODUCTION

The estimated prevalence of autism spectrum disorder (ASD) in adults is high (11/1000 [1▪]), and there are increasing concerns about the poor long-term outcome for so many individuals with this condition. Health economists [2▪] also highlight the high financial costs, predicting that annual medical and nonmedical costs of ASD in the United States will be $268 billion for 2015 and $461 billion for 2025 [2▪]. Much of this expenditure is for adults, largely because of the costs of medical care, residential or supported living accommodation and productivity loss, both by caregivers and by individuals themselves.

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AIMS

The aim of the present article is to review data from recent studies on adults with ASD with respect to:

1. Social outcomes

2. Trajectories of change over time

3. Factors related to outcome

4. Mental health

5. Mortality and aging

Articles were selected from a literature search (conducted in October 2016) of PsycINfo, Medline and Google Scholar. The search was limited to peer reviewed articles published in English from 1 January 2015 to 30 September 2016. (See references for details of search strategy.) Articles were included in the review if: the focus was on broader social/lifetime outcomes in ASD (i.e. individuals with autism, Asperger syndrome/disorder and autism spectrum disorder); samples were of adequate size (n >20); average cohort age was 18+ (any IQ level). The search identified 1525 articles relating to adults with ASD; of these, 43 met inclusion criteria for the present review. Additional references outside the specified date range are included in order to place current research in context.

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SOCIAL OUTCOMES IN ADULTHOOD

Assessments based on ‘normative’ measures of social functioning

Previous systematic reviews, focusing on ‘normative’ measures of social outcomes in ASD (i.e. objective measures of employment, independence, social participation and relationships) [3] have concluded that, even among cohorts of average intelligence, most individuals remain highly dependent on others for their care, social contacts are limited and employment rates are extremely low. Moreover, adults with ASD are more economically, educationally and socially disadvantaged than adults with other developmental or intellectual disabilities [4].

A recent systematic review [5▪▪] (12 studies published from 1967 to 2013; n = 828) indicates little change in these conclusions. Outcomes were rated as in previous reviews [3] (i.e. ‘very good’ = high independence and social functioning; ‘good’ = some level of employment, some friends, largely independent; ‘fair’ = requires some support in daily living; ‘poor’ = requires substantial support/residential care; and ‘very poor’ = long-stay secure care). Forty-eight per cent of participants were rated as having a ‘poor’/‘very poor’ outcome, and only 20% were deemed to have a ‘good’ or ‘very good’ outcome. However, the authors also highlight the wide variability in findings. Thus, the mean estimated percentage of individuals with a ‘good outcome’ was 20% but with 95% confidence intervals (CIs) varying from 14 to 27% across studies; similarly, the 95% CIs for ‘poor outcome’ ranged from 37 to 59%.

This variability is evident in subsequent studies. Within a French cohort [6▪] of adults of mixed IQ and autism severity (n = 76; age 18–54 years), two thirds had a ‘poor’ or ‘very poor’ outcome and even among those rated as having a ‘good outcome’, none was living independently. A US-based, online survey [7▪] completed by parents/carers of 143 individuals with ASD (mean age 25 years) revealed that only 22% were in work, 7% lived independently, whereas 87% were on benefits.

Cohorts involving more cognitively and verbally able adults generally report more positive results, although, again figures vary. Among 50 adults with Asperger syndrome (mean childhood IQ 100+; mean current age 30 years) living in Sweden [8▪], 40% were in full time education or independent work, 62% were living independently, 48% had two or more friends and 52% either currently or in the past had a partner (14% of these were married/cohabiting). In a German cohort of 50 adults with Asperger syndrome [9▪] (mean age 36 years), 46% were currently employed, and 28% had a partner; however, 50% depended on their families or state benefits for support and 28% were still living with their parents. The US survey [7▪] also collected data from 255 adults with ASD (mean age 38 years) who were able to report on their own status. They recorded relatively high levels of education (42% batchelors degree or higher), employment (47%) and independent living/living with a spouse or partner (67%). Employment figures in this study are considerably higher than reported for another US cohort [10▪] of individuals with ASD of average IQ (n = 73, mean age 24 years), among whom only one quarter was consistently employed. Nevertheless, even within the former sample [7▪], over half were unemployed and many (36%) were dependent on federal or state benefits.

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Subjective assessments of social outcomes and quality of life

The wide variability in outcomes across studies has led to concerns that standard concepts of what constitutes a ‘good’ social outcome may not always be relevant for people with ASD. For example, higher social achievements for some individuals may come at the cost of higher stress and poorer mental health [11▪▪]. It has been suggested [11▪▪] that when subjective factors such as satisfaction with life, good physical and mental health, adequate living conditions, supportive and fulfilling social and family relationships are taken into account, adult outcomes may be more positive than usually reported. Thus, within a US cohort studied over several decades [12▪▪] (n = 60; mean age 32 years), many participants experienced relatively good subjective Quality of Life (QoL) and their mean scores on the World Health Organization Quality of Life measure [13] were comparable with those of the general population. In the Swedish cohort of individuals with Asperger syndrome [8▪], scores on a subjective quality of life measure [14] were also within the average normative range (albeit at the lower end of that range). Nevertheless, despite these more positive findings, a recent meta-analysis of studies of QoL across the lifespan [15▪▪] concluded that individuals with ASD, including those of higher intellectual and verbal ability, have a poorer QoL than their non-ASD peers.

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TRAJECTORIES OF CHANGE OVER TIME

Research on trajectories of development in ASD generally indicates improvements over time [8▪,16▪,17▪,18▪▪] but, again, there is considerable variability. An 8–10 year follow-up [16▪,17▪] in the United States of over 300 individuals (mean age at follow-up 22 years; 70% with IQ < 70) found that one-third (35%) showed improvements in nonverbal communication, 58% in verbal communication, 40% in social interaction and 61% in repetitive/stereotyped behaviors and interests. Maladaptive behaviors improved in 42%. Only 12% showed a worsening in total autism symptoms and 11% in maladaptive behaviors.

Another longitudinal study in the United States [18▪▪] examined progress in 85 individuals first seen as children. In early adulthood (mean age 19 years), most (77, 91%) continued to meet ASD criteria; of these, 53 had an IQ below 70 and 24 had an IQ of at least 70. Eight individuals (all IQ>70) who no longer met criteria were described as having a ‘Very Positive Outcome’ (VPO). Trajectories of change (IQ, communication, social functioning and repetitive behaviors) among the VPO group were significantly more positive than for participants with IQ below 70. There were also some significant differences between the VPO group and participants of average IQ who still met diagnostic criteria. The authors suggest that further research focusing on different patterns of developmental trajectories may be important for identifying different genetic causes as well as having implications for more individually tailored interventions.

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Is there ‘recovery’ from autism spectrum disorder?

The identification of individuals with ‘Very Positive Outcomes’ [18▪▪] raises the question of whether there can be ‘recovery’ from ASD. The Swedish follow-up [8▪,19▪] also identified a small group of adults (11 out of 50) who no longer met diagnostic criteria for ASD. All had an IQ in the average range, had friends and were living independently, and all but one was employed. Nevertheless, although eight, either currently or in the past, had a partner or were married, romantic relationships were lower than in the general population; three also had some current psychiatric comorbidity. An earlier study [20] described 34 children (mean age 12 years; mean IQ 111) who, although initially meeting ASD criteria, were currently functioning ‘within normal limits’. Recent, more detailed data analyses, however, [21–23] indicate persisting subtle difficulties in social understanding, pragmatic communication, attention, self-control and emotional maturity and in psychiatric morbidity. As yet, there are no data on this cohort in adulthood and it is uncertain whether these remaining differences will abate or become more evident with age.

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FACTORS RELATED TO SOCIAL OUTCOMES IN ADULTHOOD

Intellectual and verbal functioning

Intellectual and verbal functioning in childhood are among the strongest prognostic indicators in ASD [3]. Few individuals with a childhood IQ below 70, or who fail to develop functional speech, live independently as adults and job prospects and social integation are particularly poor. In addition, they show less improvement in cognitive or social skills, and greater increases in ritualistic behaviors over time than individuals with an average IQ in childhood [16▪,17▪,18▪▪]. Nonverbal mental age at 2 years is also predictive of independence in daily living skills at age 21 [24▪]. Unsurprisingly, too, persisting communication and intellectual impairments in adulthood (especially if associated with epilepsy) are associated with low levels of social attainments and independence [6▪]. Nevertheless, even among individuals with a childhood IQ at least 70, outcomes can vary widely. Some show very few autism symptoms or cognitive difficulties as young adults, whereas others continue to experience significant problems [18▪▪]. The relationship between IQ and outcome in higher functioning samples also depends on the variables studied. Thus, among the Swedish Asperger syndrome cohort [8▪,19▪], current IQ correlated highly with academic success, but not with independent living, friendships or marital status.

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Autism symptom severity

Another established predictor of adult outcome is autism severity [3]. In the Swedish study [8▪,19▪], higher levels of autism symptomatology, both in childhood and adulthood, were associated with reduced independence, lower rates of employment and more limited social relationships. Similarly, within the French cohort [6▪], no adults with a childhood diagnosis of ‘severe autism’ were judged to have a ‘good’ outcome; in contrast, 40% of those with ‘moderate autism’ and all those with a childhood diagnosis of Asperger syndrome were rated as having a ‘good’ outcome.

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Gender

The role of gender remains uncertain as most studies involve so few women [25▪]. There are some suggestions that women with ASD have poorer social outcomes, especially with respect to employment [10▪] and quality of life [11▪▪] than men. However, other studies [16▪,26▪▪] report no significant impact of gender on autism symptoms, behavior problems or social outcomes.

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Family/environmental factors

In the community sample followed up over 8–10 years in the United States [16▪,17▪], higher levels of inclusion in social and academic activities in school were associated with more positive outcomes, over and above individual characteristics such as age, IQ and sex. Greater maternal praise/positivity in childhood also predicted higher levels of nonverbal communication and social reciprocity in adulthood; increases in maternal praise over time were associated with decreases in externalizing behaviors. In addition, quality of mother–child relationship was significantly associated with fewer maladaptive behaviors at follow-up; improvements in mother–child relationships were related to a decline in behavioral and social problems. Other research [11▪▪,12▪▪] has also highlighted the positive impact of maternal warmth on adult quality of life, along with factors such as physical health, greater independence in daily living skills and better executive function.

More recently, the specific impact of stress has received attention. Among 25 Swedish adults (mean age 34 years) [27▪], greater perceived stress was associated with more severe autism symptoms and poorer coping in adulthood. A US study [28▪,29▪] has also explored the effects of stress in two groups of adults with ASD (n = 38, 40; mean ages 23–24 years; rates of employment 37–47%; and living independently 17–21%). These adults experienced significantly more stressful life events and stress than community controls, and levels of global stress significantly predicted overall social functioning and social disability. In a long-term follow-up in the United States [12▪▪], current levels of perceived stress, together with frequency of bullying in childhood, were the two factors consistently linked with poorer adult self-reported quality of life. In turn, good quality of life was positively correlated with better-developed daily living skills and good physical health.

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Mental health

Data on rates of psychiatric disorders in ASD are highly variable. In a UK longitudinal study [30▪] of 58 adults originally diagnosed as children (mean IQ 69; mean age 44 years), 28% had at some time experienced mild-to-moderate mental health problems and 28% had severe or very severe difficulties. A retrospective case review [31▪] of 474 adults attending an ASD diagnostic clinic in the UK found that around half (57%) had a comorbid psychiatric disorder. A similar figure (54%) was reported in a large US database study [32▪▪] (n = 1507 adults with ASD). In the Swedish cohort with Asperger syndrome [19▪], 54% had a current diagnosis but almost all (94%) met lifetime criteria for a comorbid psychiatric/neurodevelopmental disorder. In a Dutch cohort [33▪▪] including older adults (n = 172, age 19–79 years, IQ > 80), 79% met criteria for a psychiatric disorder at least once in their lives. Among participants with Asperger syndrome in the German cohort [8▪], 70% had at one or more psychiatric comorbidities. In the online US survey [7▪], 86% of the self-report group and 73% of the proxy-report group had at least one mental/behavioral comorbidity.

The majority of diagnoses/symptoms identified in these studies relate to anxiety and/or depression, but again there are many inconsistencies. Estimates of depressive disorders range from 20 to 58% and anxiety disorders from 22 to 39%; other commonly reported difficulties include Attention Deficit Hyperactivity Disorder (ADHD) (10–28%); tic disorders (1–50%); Obsessive Compulsive Disorder (OCD) (8–28%) and somatoform and eating disorders (6–17%). Two studies [34,35▪] report high rates of social anxiety (50–52%). Estimates of psychotic disorders tend to be relatively low (usually around 2–4%), but again there is wide variability, with a recent review recording figures from 0 to 35% [36▪].

Conflicting data on rates of mental health problems in ASD are due to many factors, including differences in sampling, the range of conditions selected for study and the diagnostic procedures and measures used. Although, overall, the data indicate that psychiatric morbidity is higher in ASD that in the general population [32▪▪], until there is greater methodological consistency across studies, it remains impossible accurately to estimate the true risk.

Estimates of substance abuse disorders are also contradictory. A Swedish epidemiological study [37▪] (n = 26 986 individuals with ASD and 96 557 controls) reported a substantially increased risk of drug [odds ratio (OR) 8.5] and alcohol abuse/dependence (OR 4.0); risks of substance-related crime (OR 1.4), or deaths linked to abuse were also high (OR 3.0). A German study [8▪] recorded similarly high rates of drug abuse (12%) or alcohol-related problems (18%). In contrast, in the US database [32▪▪], alcohol abuse/dependency was identified in 3% and drug abuse/dependency in 4%. Combined rates of these problems in the UK [31▪] and Swedish [19▪] samples were also low (2 and 4%, respectively). This inconsistency is highlighted in a recent systematic review of substance abuse in ASD [38▪▪] (n = 18 studies; 11 epidemiological). Although estimates were generally low, figures ranged from 0.7 to 36%, making it impossible to establish a reliable prevalence figure. The only consistent finding noted in the review was the lack of knowledge among professionals on how to treat this group of patients, and the dearth of intervention research.

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Variables associated with adult mental health

Although there has been little systematic exploration of factors related to mental health in adults with ASD, there is some evidence of an association between poor mental health and poorer social functioning [30▪], lower life satisfaction [39▪] and higher levels of autism symptoms [7▪,19▪,30▪,33▪▪,40].

The relation between mental health and gender is inconsistent, probably because of the small numbers of women in most studies. Most research suggests that, compared with men, women are at greater risk of anxiety and mood disorders [32▪▪,33▪▪] and of conditions such as dementia, schizophrenia and bipolar disorder [32▪▪]; men tend to have higher rates of OCD and ADHD [32▪▪]. However, two studies [30▪,31▪] identified no significant sex differences in overall rates or types of mental health problems and in the German cohort [8▪], whereas there were no differences in rates of major depression, men had more anxiety symptoms (53 vs. 12%) and more mood disorders than women (32 vs. 6%).

Data on substance abuse are, yet again, contradictory. In the German cohort [8▪], more women than men had drug abuse problems (19 vs. 9%) but fewer had alcohol abuse/dependence (12 vs. 20%). In contrast, in the US sample [32▪▪], drug/alcohol problems were more frequent in men (drugs 5 vs. 3%; alcohol 4 vs. 2%).

Findings on the relationship between mental health and age are equally confusing. The German study [8▪] found that young adults (<40 years) showed less psychopathology than those over 40. In the US longitudinal study [39▪], women were more likely to show greater increases in anxiety and depressive symptoms over time, whereas adolescent males had more depressive symptoms that were maintained into young adulthood. In contrast, a study including a much wider age range [33▪▪] (n = 344, age 19–79 years) concluded that psychopathology declined with age, with fewer adults in the older age group (55–79 years) meeting criteria for any psychiatric diagnosis and particularly social phobia. Discrepancies here are likely because of the very small number of older adults in the two former samples.

Findings concerning the relationship with other variables that are frequently associated with mental health in the general population (i.e. cognitive functioning, social economic status and living situations, as well as life events and family factors) remain inconclusive and inconsistent.

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MORTALITY AND SUICIDE IN ADULTHOOD

Many major chronic medical conditions occur significantly more frequently in adults with ASD than in the general population [32▪▪], and mortality risks are also higher. In a Danish epidemiological study [41▪] (total n = 1,912 904; n ASD = 20 492), mortality rates for young adults with ASD were double those in the general population, and similar to the risk for individuals with neurological or mental/behavioral disorders. Comparable rates were identified in Sweden [42] (27 122 individuals with ASD; 2,672 185 matched general population controls). Mortality was over twice as high in the ASD group (OR 2.56) and mean age of death was much lower [controls 70.2 years; ASD 53.9 years (39.5 years in those with intellectual disability (ID); 58.4 years in those without ID)]. The most frequent causes of death were nervous, circulatory, respiratory or digestive disorders and congenital malformations.

Overall, death rates in men and women were similar, but women were more likely to die from endocrine disease, congenital malformations or suicide, and men from diseases of the nervous and circulatory systems. The most common cause of death in individuals with ID and ASD was epilepsy.

This study [40] also found that death by suicide was significantly elevated among cognitively able individuals with ASD (OR 9.4). However, there is little consistent information on suicidal behaviors or ideation, or how frequently these result in serious or fatal suicide attempts, and reported rates of suicide in ASD vary widely (from <10 to >50%) [41▪]. For example, suicide attempts occurred in only 2% of the US database cohort [32▪▪]. In the Swedish Asperger study [19▪] (n = 50), 13 individuals (26%) exhibited ongoing suicidal behavior, but only one was considered to be at high risk. This conflicts with an earlier study [42] in which 66% of 367 individuals with a diagnosis of Asperger syndrome reported suicidal ideation; 35% reported plans or attempts at suicide. Recent studies in this area [43▪▪,44] note the importance of more research into the factors associated with suicide, especially in more able individuals, and the need for more reliable ways of identifying at-risk adults with ASD.

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AGING

Although there has been very little investigation of the impact of aging in ASD, current research [45▪,46▪▪] suggests that many cognitive skills (processing speed, attention, verbal memory, cognitive flexibility and planning, and theory of mind) show similar patterns of decline as in typical aging. Conversely, individuals with ASD may be less prone to decline in visual and working memory than elderly in the general population [46▪▪]. Quality of life in ASD also seems to be less affected by age than in the general population, but to date studies on aging in ASD are small scale, mainly cross-sectional and contain few participants aged over 60. More extensive research in this area is crucially needed.

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CONCLUSION

It is evident from this review that individuals with ASD continue to face many challenges throughout adulthood. Current social and health services for adults [47,48▪,49▪▪,50–52] are often inadequate, resulting in high levels of stress for both individuals themselves and their families [53▪]. To date, however, methodological issues particularly related to wide heterogeneity in the cohorts studied and variability in the measures used, have resulted in inconsistent and sometimes contradictory research findings. We still do not know with any certainly what proportion of individuals manage to attain adequate levels of social integration as adults or how many experience a good psychological and physical quality of life. More importantly, we are a long way from identifying the individual, family or environmental factors that enhance resilience and ensure social and psychological well being in adulthood. High-quality adult outcome research must be a priority if we are to meet the needs of current and future generations of adults with ASD.

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Acknowledgements

None.

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Financial support and sponsorship

None.

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Conflicts of interest

There are no conflicts of interest.

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REFERENCES AND RECOMMENDED READING

Papers of particular interest, published within the annual period of review, have been highlighted as:

▪ of special interest

▪▪ of outstanding interest

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See note to 29

29▪. Bishop-Fitzpatrick L, Minshew NJ, Mazefsky CA, Eack SM. Perception of life as stressful, not biological response to stress, is associated with greater social disability in adults with autism spectrum disorder. J Autism Dev Disord 2016; DOI: 10.1007/s10803-016-2910-6.

This and reference [28] report on high levels of stress in adults with ASD and their greater exposure to stressful events. In turn, these are significantly associated with social disability. The authors highlight the need for more interventions targeting stress management.

30▪. Moss P, Howlin P, Savage S, et al. Self and informant reports of mental health difficulties among adults with autism findings from a long-term follow-up study. Autism 2015; 19:832–841.

Self and informant reports of psychiatric comorbidities in adults with ASD in their mid-40s indicate that around half have some mental health problems. However, over 40% had experienced no psychiatric problems in adulthood.

31▪. Russell AJ, Murphy CM, Wilson E, et al. The mental health of individuals referred for assessment of autism spectrum disorder in adulthood: a clinic report. Autism 2016; 20:623–627.

Clinical case note study of 474 adults with ASD. Just over half (57%) had a history of psychiatric problems. As in the previous study [30], this rate is higher than in the general population, but considerably less than reported in some other studies.

32▪▪. Croen LA, Zerbo O, Qian Y, et al. The health status of adults on the autism spectrum. Autism 2015; 19:814–823.

Very informative article on physical and mental health problems in a large cohort of adults with ASD identified via an insurance database. Although such sampling is prone to a number of biases, the large size of the sample and the detailed information included provide valuable insight into the frequency and range of problems experienced by individuals with ASD.

33▪▪. Lever AG, Geurts HM. Psychiatric co-occurring symptoms and disorders in young, middle-aged, and older adults with autism spectrum disorder. J Autism Dev Dis 2016; 46:1916–1930.

In this study of 344 adults with ASD aged 19–79 years, 79% had a history of psychiatric disorder (mainly depression and anxiety). However, older adults were less likely to experience mental health problems than younger individuals. The discrepancies in reported rates of psychiatric difficulties across studies (e.g. 19, 30, 31, 32 and 37), and disagreements concerning the association with age, highlight the need for more systematic research in this area.

34. Maddox BB, White SW. Comorbid social anxiety disorder in adults with autism spectrum disorder. J Autism Dev Disord 2015; 45:3949–3960.
35▪. Spain D, Happé F, Johnston P, et al. Social anxiety in adult males with autism spectrum disorders. Res Autism Spect Disord 2016; 32:13–23.

As in reference [33], the authors report high rates of social anxiety (52%) in adults with ASD. The article concludes that more research is needed to ascertain the prevalence social anxiety in ASD and to identify triggers and maintaining factors.

36▪. Chisholm K, Lin A, Abu-Akel A, Wood SJ. The association between autism and schizophrenia spectrum disorders: a review of eight alternate models of co-occurrence. Neurosci Biobehav Rev 2015; 55:173–183.

Very useful review of studies on the association between autism and schizophrenia. The article highlights the large discrepancies between many studies in this area and explores possible reasons for these inconsistencies.

37▪. Butwicka A, Långström N, Larsson H, et al. Increased risk for substance use-related problems in autism spectrum disorders: a population-based cohort study. J Autism Dev Disord 2016; doi:10.1007/s10803-016-2914-2.

These authors identify very high rates of substance abuse in ASD and in their siblings and parents. They conclude that ASD is a risk factor for substance abuse-related problems. However, other studies (e.g. [36]) have not identified this as a significant problem in ASD; reasons for these conflicting findings remain unclear.

38▪▪. Arnevik EA, Helverschou SB. Autism spectrum disorder and co-occurring substance use disorder: a systematic review. Substance Abuse: Res Treat 2016; 10:69–75.

A systematic review (18 articles) of substance abuse in ASD. The authors conclude that overall comorbidity rates appear to be low, but lack of agreement across studies makes difficult to establish a general prevalence rate. The authors highlight the lack of high-quality research in this area.

39▪. Gotham K, Brunwasser SM, Lord C. Depressive and anxiety symptom trajectories from school age through young adulthood in samples with autism spectrum disorder and developmental delay. J Am Acad Child Adolesc Psychiatry 2015; 54:369–376.

Study of trajectories of psychiatric disorders in 109 individuals with ASD. Rates of affective and anxiety disorders were high, but men and women showed different patterns of change over time.

40. García-Villamisar D, Rojahn J. Comorbid psychopathology and stress mediate the relationship between autistic traits and repetitive behaviours in adults with autism. J Intell Disabil Res 2015; 59:116–124.
41▪. Schendel DE, Overgaard M, Christensen J, et al. Association of psychiatric and neurologic comorbidity with mortality among persons with autism spectrum disorder in a Danish population. JAMA Pediatr 2016; 170:243–250.

Large epidemiological study identified high risks of early mortality in individuals with ASD. The presence of comorbid mental/behavioral or neurologic conditions significantly increased the risk of early death (2.6-fold to 7.6-fold) compared with individuals without ASD.

42. Cassidy S, Bradley P, Robinson J, et al. Suicidal ideation and suicide plans or attempts in adults with Asperger's syndrome attending a specialist diagnostic clinic: a clinical cohort study. Lancet Psychiatry 2014; 1:142–147.
43▪▪. Hirvikoski T, Mittendorfer-Rutz E, Boman M, et al. Premature mortality in autism spectrum disorder. Br J Psychiatry 2016; 208:232–238.

Important epidemiological study highlighting greatly increased risks of premature mortality in ASD. The study also identifies factors that appear to be associated with a greater risk of early death. The presence of a range of different comorbid medical/neurological conditions was associated with a higher risk of death, especially among women with intellectual disability. Individuals of average intellectual ability had a high risk of suicide. The authors stress the need for more research into factors related to early death in ASD.

44. Salvatore T, Brown J, Hastings B, et al. Suicide risk in adults with autism spectrum disorder: an exploratory discussion. J Special Popul 2016; 1:1–11.
45▪. Lever AG, Werkle-Bergner M, Brandmaier AM, et al. Atypical working memory decline across the adult lifespan in autism spectrum disorder? J Abnormal Psychol 2015; 124:1014.

See note to [46].

46▪▪. Lever AG, Geurts HM. Age-related differences in cognition across the adult lifespan in autism spectrum disorder. Autism Res 2016; 9:666–676.

These authors [44], [45] are among the very few who have explored cognitive and psychological changes in ASD in later adulthood. They have identified certain areas of cognitive difficulty (e.g. in Theory of Mind) that seem to become less apparent in old age in ASD; other skills (e.g. visual memory) show less decline with age than in the general population. The authors conclude that age-related cognitive difficulties in ASD are mainly parallel to those found in typical aging, although deterioration in some areas may actually be reduced. They suggest that ASD could partially protect against an age-related decrease in cognitive functioning.

47. Havlicek J, Bilaver L, Beldon M. Barriers and facilitators of the transition to adulthood for foster youth with autism spectrum disorder: perspectives of service providers in Illinois. Child Youth Serv Rev 2016; 60:119–128.
48▪. Turcotte P, Mathew M, Shea LL, et al. Service needs across the lifespan for individuals with autism. J Autism Dev Disord 2016; 46:2480–2489.

US study indicating that adults with ASD were in greater need of services but had less access to a range of different services than individuals in the general population.

49▪▪. Murphy CM, Wilson CE, Robertson DM, et al. Autism spectrum disorder in adults: diagnosis, management, and health services development. Neuropsychiatric Dis Treat 2016; 12:1669.

This article highlights the lack of health services research for adults with ASD. The authors focus on the need for more rigorous pharmacological and pharmacological trials, and the importance of taking into account the views of individuals with ASD themselves.

50. Vohra R, Madhavan S, Sambamoorthi U. Comorbidity prevalence, healthcare utilization, and expenditures of Medicaid enrolled adults with autism spectrum disorders. Autism 2016; pii: 1362361316665222. [Epub ahead of print].
51. Vohra R, Madhavan S, Sambamoorthi U. Emergency department use among adults with autism spectrum disorders (ASD). J Autism Dev Disord 2016; 46:1441–1454. 50.
52. Raymaker DM, McDonald KE, Ashkenazy E, et al. Barriers to healthcare: instrument development and comparison between autistic adults and adults with and without other disabilities. Autism 2016; pii: 1362361316661261. [Epub ahead of print].
53▪. McKenzie K, Ouellette-Kuntz H, Blinkhorn A, Démoré A. Out of school and into distress: families of young adults with intellectual and developmental disabilities in transition. J Appl Res Intell Disabil 2016; doi: 10.1111/jar.12264. [Epub ahead of print].

This study describes the high levels of stress experienced by many families during their sons’/daughters’ transition from school.

Keywords:

adulthood; aging; autism; autism spectrum disorder; developmental trajectories; outcome

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