Elevated Suicidal Thoughts and Behaviors and Nonsuicidal Self-Injury in Autistic Youth and Adults: A Multinational Study

Abstract

Background:

Autistic people are at significant risk for suicidal thoughts and behaviors (STBs) and nonsuicidal self-injury (NSSI). We examined STB and NSSI in different age-groups, considering sex- and age-based effects, in a pooled multinational sample of English-speaking autistic children and adults.

Methods:

We administered the Columbia-Suicide Severity Rating Scale to 245 autistic people without intellectual disability (139 youth and 106 adults; 46.1% female sex; M_age = 24.8, SD_age = 16.3 years, range = 7–70) or their caregivers in Australia, Canada, and the United States. The study samples were enriched with autistic people experiencing depression and suicidality.

Results:

Most participants (87.8%) reported suicidal ideation and NSSI (56.3%). Nearly one-third of autistic people (31.0%) reported a lifetime suicide attempt (M = 2.9 attempts; range = 1–26); overdosing was the most common method of suicide attempt. Sex was not a significant risk factor for suicidal ideation, behavior, or NSSI. Increases in lifetime suicidal ideation were observed across older age-groups, with those aged over 18 years reporting more severe and longer-lasting ideation than in children or adolescents. The youngest age of suicide attempt was 7 years in this sample, and the average ages of first/initial, most lethal, and most recent suicide attempts in youth (n = 24) and adults (n = 42) were 16.6, 19.2, and 20.8 years old, respectively.

Conclusion:

Regardless of age-group, autistic people across the lifespan constitute a high-priority group for suicide prevention strategies, development of appropriate assessments, and evaluation of system-level programs that effectively address the problem of preventable death by suicide.

Community Brief

Why is this an important issue?

Suicide is a leading cause of death among autistic people and a top research and clinical priority among autistic communities. To our knowledge, most research on suicide in autistic people has been limited to one research site and a single time in development (e.g., childhood, adolescence), without consideration of suicide across different age-groups.

What was the purpose of this study?

Our international teams (i.e., Australia, Canada, and the United States) wanted to understand suicidal thoughts and behaviors (STBs) and nonsuicidal self-injury (NSSI) in verbally fluent autistic people without intellectual disability across several age-groups. We studied the most common methods of suicide attempts in this sample and how old a person was at their first, most lethal (i.e., most severe), and most recent suicide attempts. We also tested potential differences in STBs and NSSI in autistic people by sex assigned at birth and age-groups (i.e., childhood, adolescence, early adulthood, and late adulthood). By studying STBs and NSSI in a larger sample at different ages, we hope to improve assessments and interventions for suicide and self-harm risk in autistic people.

What did the researchers do?

Across our three sites, we reviewed responses from 245 autistic people and some of their caregivers about lifetime experiences of STBs and NSSI in a semi-structured clinical interview, the Columbia-Suicide Severity Rating Scale (C-SSRS; Posner et al. ²⁹ ). Autistic people who participated in the study were from the community and those with depression and/or STB who were seeking support for their mental health. Using information from the C-SSRS, we studied the number of autistic people who reported lifetime STBs and NSSI and then checked if there were any differences based on a person’s sex assigned at birth and age-group.

What were the results of the study?

Most participants (87.8%) reported lifetime suicidal ideation/thoughts and NSSI (56.3%). Nearly one-third of autistic people (31.0%) reported a suicide attempt in their lifetime, with an average of three lifetime attempts reported by participants. Overdosing was the most common method of suicide attempt in this sample. Sex only seemed to impact the number of suicide attempts, with females reporting a slightly higher number of attempts than males. We observed some increases in lifetime suicidal thoughts across older age-groups; those aged over 18 years reported more severe and longer-lasting thoughts than children or adolescents. We found that the youngest age of suicide attempt was 7 years old, and the average ages of the first/initial, most lethal, and most recent suicide attempts in youth (n = 24) and adults (n = 42) were 16.6, 19.2, and 20.8 years old, respectively.

What do these findings add to what was already known?

Our findings show that STBs and NSSI are common among autistic people across all age-groups, beginning as early as 7 years of age. Autistic people of both male and female sexes are likely to experience STBs. We found that females may be slightly more likely to attempt suicide than males. Across age-groups, the frequency and severity of STBs and NSSI seem to increase among autistic people, with autistic people reporting overdosing as the most common method of suicide attempt.

What are potential weaknesses in the study?

Although our study examines suicide in different age-groups, our study relies on data that were collected at one timepoint versus following someone over time. By using this type of data, it may not capture the dynamic and changing nature of STBs and NSSI. Across the three sites, autistic people were recruited from different areas, such as the community or from people seeking mental health support (i.e., clinical samples), which leads to sampling differences. As a result, it is important to consider our findings with a level of caution. Furthermore, our sample of verbally fluent autistic people without intellectual disability is not representative of the suicidal experiences of all autistic people.

How will these findings help autistic adults now or in the future?

Our findings add to the existing knowledge of how common and severe STBs as well as nonsuicidal self-injurious behavior are for autistic people of both sexes and across age-groups, particularly among autistic adults. Findings also point to key areas for tailoring suicide assessment and prevention approaches to the needs of autistic people.