Expanding clinical strategies to identify high risk groups for psychotic and bipolar disorders is a research priority. Considering that individuals diagnosed with psychotic and bipolar disorder are at high risk of self-harm, we hypothesised the reverse order relationship would also be true (ie, self-harm would predict psychotic/bipolar disorder). Specifically, we hypothesised that hospital presentation for self-harm would be a marker of high risk for subsequent development of psychotic/bipolar disorder and sought to test this hypothesis in a large population sample. This prospective register-based study included everyone born in Finland in 1987, followed until age 28 years (N = 59 476). We identified all hospital records of self-harm presentations, as well as all ICD-10 healthcare registrations of first diagnoses of psychotic and bipolar disorders. Cox proportional hazards models were used to assess the relationship between self-harm and psychotic/bipolar disorders. Of all individuals who presented to hospital with self-harm (n = 481), 12.8% went on to receive a diagnosis of psychosis (hazard ratio [HR] = 6.03, 95% confidence interval [CI] 4.56-7.98) and 9.4% a diagnosis of bipolar disorder (HR = 7.85, 95% CI 5.73-10.76) by age 28 years. Younger age of first self-harm presentation was associated with higher risk-for individuals who presented before age 18 years, 29.1% developed a psychotic or bipolar disorder by age 28 years. Young people who present to hospital with self-harm are at high risk of future psychotic and bipolar disorders. They represent an important cohort for the prevention of serious mental illness.
Keywords: bidirectional; mania/epidemiology; register; schizophrenia; suicide.
© The Author(s) 2021. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.