Mental Health Outcomes Amongst Higher Ability Adults with Autism and Adult Siblings of People with Autism

Background:  There is a lack of systematic research into the mental health of higher ability adults with a childhood diagnosis of autism who are in mid- to late-adulthood. Although reviews of clinical studies indicate that rates of mental health difficulties from childhood onwards are greater than in the general population, data on the prevalence of such difficulties, or the factors associated with them are inconsistent. Additionally, very little is known about the mental health of siblings of adults with autism spectrum disorders (ASD) thought to be ‘unaffected’ by ASD and its broader phenotype.

Objectives:  (i) To explore the mental health difficulties experienced by higher ability adults with autism in mid- to late-adulthood and to consider what factors affect the rates of such difficulties; (ii) To examine the rates of mental health difficulties experienced by ‘unaffected’ siblings of individuals with ASD in adulthood.

Methods:  Standardised measures were used to establish rates of mental health difficulties in 60 adults with autism who had all been assessed as having a normal non-verbal IQ (PIQ>70) when diagnosed in childhood (current average age = 44 years, range = 29 – 64 years). The same measures were used with 69 siblings of an adult brother or sister with autism (average age of = 40 years, range = 21 - 57 years). A range of cognitive and social assessments was used to examine the factors associated with rates of mental health difficulties in these two groups.

Results: The majority of the adults with autism did not have significant mental health difficulties and only 20% were rated as having ‘poor’ or ‘very poor’ mental health outcomes. In contrast, ‘unaffected’ adult siblings of individuals with ASD reported high rates of mental health difficulties. In both groups, depression and anxiety were the most commonly reported difficulties. Gender was significantly associated with rates of difficulties amongst siblings, with females more likely to experience mental health difficulties than males. However, no other specific factors were associated with rates of mental health difficulties in adulthood in either group.

 Conclusions:  This study is the first systematic investigation into the prevalence of mental health difficulties amongst adults with a childhood diagnosis of autism and a childhood non-verbal IQ in the normal range. Whilst rates of mental health difficulties in this sample were lower than expected, they were still higher than in the general population. The findings have significant service implications; there is a need to develop specialist mental health services for this population and / or for clinicians in general adult mental health services to be appropriately educated on how to engage with this population and recognise their unique presentations in relation to mental health difficulties. The high rates of mental health difficulties amongst ‘unaffected’ siblings, particularly females, of individuals with ASD are particularly pertinent given their potential care-giving role with regard to their adult sibling with ASD.