New drug candidates for bipolar disorder—A nation‐wide population‐based study

Objective Drug repurposing is an increasingly promising idea in many fields of medicine. We systematically used Danish nation‐wide population‐based registers to investigate whether continued use of non‐aspirin non‐steroidal anti‐inflammatory drugs (NSAIDs), low‐dose aspirin, high‐dose aspirin, statins, allopurinol, and angiotensin agents decrease the rate of incident mania/bipolar disorder. Methods A nation‐wide population‐based longitudinal study using Poisson regression analyses including all persons in Denmark who purchased the exposure medication of interest and a random sample of 30% of the Danish population. The follow‐up period comprised a 10 years period from 2005 to 2015. Two different outcome measures were included, (1) a diagnosis of mania/bipolar disorder at a psychiatric hospital contact as inpatient or outpatient and (2) a combined measure of a diagnosis of mania/bipolar disorder or initiation of lithium use. Results A total of 1,605,365 subjects were exposed to one of the six drugs of interest during the exposure period from 2005 to 2015, median age 57 years [quartiles: 43;69], and female proportion of 53.1%. Continued use of low‐dose aspirin, statins, and angiotensin agents were associated with decreased rates of incident mania/bipolar disorder on both outcome measures. Continued uses of non‐aspirin NSAIDs as well as high‐dose aspirin were associated with an increased rate of incident bipolar disorder. There were no statistically significant associations for allopurinol. Conclusions The study supports the potential of agents acting on inflammation and the stress response system in bipolar disorder and illustrates that population‐based registers can be used to systematically identify drugs with repurposing potentials.