The Phenomenology of Non-Suicidal Self-Injury in Autistic Adults.
Non-suicidal self-injury (NSSI) is defined as socially unsanctioned harming of the body without suicidal intent. Two studies have shown increased rates of NSSI in autistic (50-65%) compared to non-autistic adults (5-30%), and similar phenomenology of NSSI in a small sample of autistic and non-autistic adults (n=42). Larger scale studies are needed to confirm similarities and differences in NSSI behaviour between autistic and non-autistic adults, to inform new assessment and treatment strategies for autistic people. As many autistic adults are currently undiagnosed, and mental health problems are the most common presenting concern prior to being diagnosed autistic, it is important to include adults who self-identify as autistic but have not yet been formally diagnosed.
To compare the phenomenology (methods, frequency, severity, functions, and initial motivations) of NSSI between autistic, self-identified autistic, and non-autistic adults.
An online cross-sectional survey in the UK and USA, measuring NSSI (Non-Suicidal Self-Injury – Assessment Tool; NSSI-AT), in: 1) n=132 autistic adults (UK), 2) n=56 self-identified autistic adults (UK), 3) n=57 non-autistic adults (general population) (UK), and 4) n=257 non-autistic adults (undergraduate students) (US).
Rates of NSSI differed across the samples, with more autistic adults (66.5%) and self-identified autistic adults (70.4%) endorsing NSSI than UK (29.6%) and US (20.5%) non-autistic adults. Autistic adults reported significantly more episodes of NSSI across their lifetime than non-autistic UK [t(187) = 4.87, p<.001] and non-autistic US adults [t(288.1) = 11.28, p<.001], but not self-identified autistic adults. There were also significant differences in certain self-reported forms, functions, motivations and wound locations of NSSI in autistic compared to non-autistic adults. Conversely, there were no significant differences – with the exception of one item – between autistic and self-identified autistic adults. Autistic adults also reported being significantly more likely to injure themselves in the future than non-autistic adults [UK: t(186) = 5.27, p<.001; US: t(387) = 8.82, p<.001], but not self-identified autistic adults. Overall, the endorsement of NSSI-AT items was very similar between autistic and self-identified autistic adults (Table 1).
We compared the phenomenology of NSSI behaviour in a large sample of autistic, self-identified autistic, and non-autistic adults. Autistic adults reported a wider range of forms and functions of NSSI, different initial motivations for NSSI, reported injuring more parts of their body, a higher number of NSSI episodes in their lifetime, and increased likelihood of future self-injury, compared to two samples of non-autistic adults. Interestingly, the phenomenology of NSSI was very similar between the autistic and self-identified autistic group. Our results have important implications for clinical practice, as there is very little awareness of NSSI in autistic people, as traditionally defined in the general population. Self-identified autistic adults (i.e. those who identify as autistic but do not have a diagnosis) are also a high-risk group for NSSI, and further research is needed to explore their specific needs.