Causes and consequences of mental health challenges in autistic individuals during the transition to adulthood

Research Questions Autistic individuals1 face profound challenges across their lives, including high rates of mental health problems.

Many of these mental health problems emerge during the transition to adulthood, as illustrated in Figure 1, highlighting the critical need to understand mental health problems faced by autistic individuals during this period.

The purpose of this project is to investigate causes and consequences of educational, occupational, and health challenges mental health problems in autistic individuals during the transition to adulthood. As shown in Figure 2, I will: 1.

Identify risk factors for mental health problems in transitional-aged autistic adults: a) genetics; b) comorbidity; c) trajectories of childhood autistic traits. 2. Assess sex-specific mental health problems 3. Investigate long-term impacts of mental health problems during the transition to adulthood.

Methods Cohorts: I will leverage three richly phenotyped cohorts, with follow-up spanning childhood and adulthood. Their coverage is shown in Figure 2. Swedish registers record healthcare, education, and welfare for the entire Swedish population. I have identified 26,538 autistic individuals from these registers, born 1973-1998, followed-up to ages 18-43.

The Child and Adolescent Twin Study in Sweden (CATSS) includes 18,250 participants (10,848 genotyped), followed-up from ages 9-24. The Twins Early Development Study (TEDS) includes 7,124 participants, followed from birth to age 21. Risk factors, mental health problems, and outcomes are all assessed using questionnaires and registry data.

All data are collected and have ethical approval.

Study Designs: I will define genetic factors linked with autism using polygenic scores, and test their association with mental health problems from ages 18-24 in CATSS.

The utility of genetic factors in predicting these outcomes will be compared with more conventional indicators, such as symptoms (aim 1a).

I will test whether the association between autism and mental health problems is mediated by comorbidity in CATSS and Swedish registers (aim 1b).

I will compare mental health problems at ages 16-21 across trajectories of autistic traits in TEDS, identified using latent growth curve models (aim 1c).

Sex-specific mental health problems at ages 18-24 in CATSS and Swedish registers will be assessed using a stratified cohort design (aim 2).

I will compare long-term outcomes from ages 25-43 between autistic individuals showing different numbers of mental health problems during the transition to adulthood, utilizing the extended follow-up of Swedish registers (aim 3).

Regression models will be the chief analytic approach in all aims, with models varying by outcome (linear, logistic, or time-to-event).

Expected Outcomes This truly interdisciplinary project unites contemporary methods and concepts from epidemiology, behavioural genetics, and lifespan psychology to address three novel aims of crucial priority in autism research.

This project will move the field beyond establishing that autistic adults face challenges, towards assessing why this is so.

This will subsequently inform strategies to identify and support particularly vulnerable autistic adults in navigating adult life, with the goal of improving their mental health and wellbeing by lifting barriers to their participation in society. 1'Autistic individuals' is the preferred terminology of many stakeholders when referring to autism