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What is the Effectiveness of Psychological Therapy for Anxiety and Depression in Adults with Autism??

Published: 30/11/2023

Autism spectrum disorder (autism) is a neurodevelopmental condition, caused by differences in the brain and characterised by differences in social communication and interaction, and restrictive or repetitive behaviours or interests. It is estimated that around 1-2% of the population in England have autism.

While autism is not an illness or disease with treatments or a “cure”, many people with the condition may benefit from support and therapies. Evidence shows that people with autism are more likely to experience mental health problems, including anxiety and depression, which are leading causes of disability and health-related burden. Some estimates suggest that anxiety and depression may respectively be around four and seven times more prevalent among adults with autism in comparison to the general population. Despite this, adults with autism report more unmet mental health service needs than adults without autism. Addressing this mental health need has been deemed a priority concern by the World Health Organisation and the autism community.

Past studies have found that evidence-based psychological therapy, such as cognitive behavioural therapy (CBT) and mindfulness therapy may be useful for adults with autism experiencing depression or anxiety, especially when such treatments are adapted to specific needs. However, no previous studies have examined the outcomes of routinely delivered psychological therapy for common mental health problems in adults with autism in primary or community care settings.

To address this, the authors of a recent study aimed to evaluate the effectiveness of mental health interventions in a large cohort of adults with autism in a routine clinical setting.

Design and Methods of the Study

The study adopted a naturalistic design to assess outcomes using routinely collected data from 8,761 adults with autism who completed a course of psychological therapy in Improving Access to Psychological Therapies (IAPT) services in England between 2012–19. Adults aged between 18 and 100, who completed at least two sessions of IAPT between 2012 and 2018, as per NHS established evaluation criteria and previous research, and had evidence-based psychological therapies in Hospital Episode Statistics (HES) and the Mental Health Services Dataset (MHSDS), were eligible.

Therapy within IAPT included evidence-based psychological therapies as recommended in national guidelines from the National Institute for Health and Care Excellence (NICE). These guidelines recommended autism-specific adaptations for interventions targeting co-occurring mental health difficulties. Some IAPT therapists reported adapting their practice when working with adults with autism; however, the actual proportion of individuals who received adaptations is unknown.

The aims of the study were to (1) examine the change in symptoms of depression and anxiety after a course of psychological therapy (i.e., IAPT) in a large sample of adults with autism; (2) investigate how therapy outcomes differ for adults with autism compared with adults without autism; and (3) evaluate whether therapy outcomes differ across subgroups according to sociodemographic factors.

Outcomes of the Study

Data were available for 8,761 adults with an autism diagnosis code compared with 1,918,504 who did not. IAPT treatment-related factors were similar between the groups in terms of presenting problem, year of treatment, number of sessions, and waiting times between referral, assessment, and treatment. However, adults with autism were less likely to complete treatment and more likely to receive high-intensity sessions, be referred on to further services, and for IAPT services to be considered unsuitable than were adults without identified autism. The researchers used propensity score matching to match 8,593 individuals with autism with other individuals with similar characteristics, but not recorded as having autism.

The proportion of individuals with autism in the cohort (0.45%) was compared with the proportion of adults with autism expected in IAPT services (1.1 -2.4%). They found that individuals with autism were under-represented by approximately 2.4-5.3 times. They also found that men, older adults, and adults with intellectual disabilities were under-represented.

Differences in Depression and Anxiety Scores

Symptoms of depression and generalised anxiety disorder improved for adults with autism during IAPT therapy. For depression symptoms, pre–post therapy effect sizes were slightly smaller than the effect sizes observed in randomised controlled trials of interventions adapted for adults with autism. For anxiety symptoms, IAPT effect sizes were similar to or higher than effect sizes for adapted mindfulness therapy and guided self-help. However, for anxiety and depression, the effect sizes were higher than those observed in treatment as usual in the NHS, and similar to or higher than effect sizes observed in waiting list controls.

Adults with autism were less likely to meet improvement and recovery criteria and were more likely to show a deterioration in their symptoms than adults without identified autism. For primary outcomes, the researchers observed that adults with autism had a reduced likelihood of reliable improvement and reliable recovery, and an increased likelihood of deterioration compared with adults without identified autism. Similar results were also observed across secondary outcomes with smaller symptom scores in the group with autism than in the comparison group for the PHQ-9 score for depression, the GAD-7 score for anxiety, and the Work and Social Adjustment Scale score.

For tertiary outcomes, the researchers noted that employment and low social deprivation were associated with improved outcomes in the comparison group. However, this was not the case in the group with autism, who generally had similar outcomes regardless of sociodemographic factors.


The results of this study support existing evidence that adults with autism face barriers to accessing psychological therapy services in England. Adults with autism were significantly under-represented in the assessed cohort, with a disproportionate under-representation of groups who are already known to be under-represented in IAPT or are underdiagnosed with autism, such as older adults, adults from minority groups, and adults with intellectual disability. It may, therefore, be theorised that a disproportionate number of adults with autism experiencing anxiety or depression symptoms do not access services.

The authors of the present study note that this under-representation of people with both autism and intellectual disabilities may be due to individuals not having a diagnosis in their record, not completing questionnaires, or not being referred to services.

These findings suggest that, while psychological therapies offered in primary and community care mental health services might help to alleviate symptoms of anxiety and depression in adults with autism who can access these services, they have poorer outcomes than individuals who do not have autism. Further elucidation of the real-world efficacy of adapted psychological therapies for individuals with autism would be helpful in understanding whether the disparity in outcomes is due to inability to access the most appropriate treatments once referred to IAPT, or if the success of these treatments is lower than indicated in randomised controlled trials.

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