BACKGROUND AND AIMS: Previous studies report cross-sectional associations between harmful gambling and suicidality. Longitudinal evidence is less common, but among young adults in the United Kingdom (UK), current longitudinal evidence highlights the specific association between increases in harmful gambling and subsequent suicidality. In a young UK adult cohort, we aimed to investigate whether harmful gambling, as measured by the Problem Gambling Severity Index (PGSI), would be associated with concurrent and future suicide attempts (at intervals of one, four and five years). Furthermore, the four-year window was used to observe whether PGSI increases were a unique risk factor for suicidality, as has been observed before. In all instances, hierarchical logistic regression models explored whether associations were robust to controls for adolescent suicidality and relevant confounders.

DESIGN: A birth cohort study of the UK general population.

SETTING: Avon, UK.

PARTICIPANTS: n = 2801 (62.4% female) participants with data for suicidality at 24 years from the Avon Longitudinal Study of Parents and Children (ALSPAC).

MEASUREMENTS: Past-year non-fatal suicide attempt prevalence was self-reported at 24 and 25 years (in 2017-2018). PGSI was measured at 20 and 24 years. Measured confounders were sex, maternal education, economic activity (employment/education status), hyperactivity, alcohol disorder likelihood and adolescent suicidality.

FINDINGS: Past-year suicide attempt prevalence was 2.57% at 24 years, and 1.86% at 25 years. Confounder-adjusted models found that PGSI predicted suicide attempts at 24 years [odds ratio (OR) = 1.13, 95% confidence interval (CI) = 1.05-1.21, P = 0.001], and predicted future suicide attempts over one-year (OR = 1.15, 95% CI = 1.06-1.25, P = 0.001) and four-year timespans (OR = 1.20, 95% CI = 1.08-1.34, P < 0.001), but there was inconclusive evidence of this association over five years (OR = 1.14, 95% CI = 0.995-1.31, P = 0.058). There was inconclusive evidence that increases in PGSI scores between 20 and 24 years predict suicide attempts at 24 years (OR = 1.69, 95% CI = 0.72-3.99, P = 0.230).

CONCLUSIONS: Among young adults in the United Kingdom, harmful gambling appears to be associated with suicide attempts; however, this association may be more complex long-term, and increases in harmful gambling during adulthood may not be an important factor.