Adults with Autism Spectrum Disorder and the Criminal Justice System: An Investigation of Prevalence of Offending, Risk Factors and Gender Differences.

Background:  The behavioural and cognitive difficulties of some adults with autism spectrum disorder (ASD) may increase their risk of contact with the Criminal Justice System (CJS) either as offenders or victims of crime. There has been limited investigation of ASD and offending. However, available evidence is mixed; some studies report an increased prevalence of ASD in offending populations, an increased risk of committing specific crimes (assault and arson) or that people with ASD are no more likely to commit offences than non-ASD people.

Objectives:  To compare prevalence of offending between adults with ASD and adults without ASD and to investigate between-group differences in types of offences. Further, to investigate gender differences and identify potential risk factors for offending in adults with ASD.

Methods: A retrospective review was completed of the medical records of 1275 adults who attended the Behavioural Genetics Clinic Adult Autism Service, the Maudsley Hospital, for assessment of possible ASD between April 2003 and January 2016. Participants ranged in age from 17 – 75 years of age (M = 32 years, SD = 12); 960 males and 305 females. 880 adults were diagnosed with ASD (660 males, 200 females) and 395 adults were not diagnosed with ASD (non-ASD group; 290 males, 105 females). The presence or absence of ASD and psychiatric co-morbidity was determined by consultant led multidisciplinary expert consensus, according to ICD-10 research criteria and confirmed with either an ADI-R and/or ADOS where possible. The presence of offending behaviour and type of offence (violence, sexual crime, arson, criminal damage, stalking/harassment, theft/burglary, substance misuse and other offences) was identified from medical reports. Forensic history was defined as contact with the CJS; this could include contact with the CJS both as offenders or victims of crime. Qualitative data from medical reports was transformed into nominal data in SPSS and between-group comparisons were made using chi-square tests.

Results: Non-ASD adults were significantly more likely to have a forensic history than adults with ASD (32% vs. 26%; χ²=5.27, p=.02; figure 1). Non-ASD adults were more likely to have committed theft/burglary (9% vs. 5%; χ²=6.05, p=.01) and substance offences (6% vs. 3%; χ²=6.19, p=.01) than adults with ASD. Regarding risk factors, adults with ASD and comorbid ADHD were significantly more likely to have a forensic history than adults with ASD who did not have ADHD (32% vs. 24%; χ²=4.16, p=.04). Adult males with ASD were significantly more likely to have a forensic history than adult females with ASD (30% vs. 13%; χ²=23.56, p<.001).

Conclusions: Adults with ASD were less likely to offend and no more likely to commit any offence than non-ASD adults referred for clinical assessment of ASD. However, 26% of adults with ASD had a forensic history (either as perpetrators or victims of crime). Comorbid ADHD and male gender were risk factors for offending in adults with ASD. Health services research for adults with ASD is warranted, including liaison between CJS and mental health services to reduce the risk of adults with ASD becoming offenders or victims of crime.