Average ages of onset and time to transition between self-injurious thoughts and behaviors: Retrospective evidence from two developmentally distinct samples

Suicidal thoughts and behaviors often emerge in a predictable sequence, with suicidal ideation (SI) preceding planning, and planning preceding actions. Few studies, however, have considered the timing and duration of non-suicidal self-injury (NSSI) in these transitions. Accordingly, this study examined: 1) the developmental sequencing of NSSI, SI and suicide attempts, and 2) whether age of onset or duration predict transitions from NSSI to other SITB, and from SI to NSSI. 704 first-year students from a mid-sized Canadian university (Sample 1) and 2095 adults from an online research volunteer panel (Sample 2) completed the Self-Injurious Thoughts and Behaviors Interview self-report, which assessed the presence, age of onset, and recency of SITB. NSSI and SI typically onset before age 15, while suicide planning and attempt usually began at or after age 15. Transition from NSSI to SI was likeliest in the first year after NSSI onset. Transition from NSSI to suicide attempt was likeliest in the second and third year after NSSI onset in Sample 1, and up to four years after NSSI onset in Sample 2. Early (before age 13) and late (after age 16) onsets of NSSI predicted higher odds of transitioning from NSSI to SI or attempt. Transition from SI to NSSI was likeliest in the first two years after SI onset and when SI began before age 13. The first year after NSSI or SI onset are critical for transitions to other SITB. Targeted prevention and monitoring should be considered for people who recently initiated NSSI.