Background
It is unknown whether patients diagnosed with brain abscess have an increased risk of psychiatric disorders.

Methods
In this nationwide, population-based matched cohort study from Denmark, we compared the incidence of psychiatric disorders, use of psychiatric hospitals, and receipt of psychiatric medications between patients diagnosed with brain abscess and individuals from the general population, matched on date of birth, sex, and residential area.

Results
We included 435 patients diagnosed with brain abscess and 3909 individuals in the comparison cohort: 61% were male and median age was 54 years. Patients diagnosed with brain abscess were more likely to suffer from comorbidity. The risk of a hospital diagnosis of psychiatric disorders was increased the first 5 years of observation. In the subpopulation, who had never been in contact with psychiatric hospitals or received psychiatric medication before study inclusion, the risk of developing psychiatric disorders was close to that of the background population, especially when we excluded dementia from this outcome. There was a substantial increase in the receipt of anxiolytics and antidepressants. The difference in the proportion of individuals who received anxiolytics and antidepressants increased from 4% (95% confidence interval [CI], 0%–7%) and 2% (95% CI, −1% to 5%) 2 years before study inclusion to 17% (95% CI, 12%–21%) and 11% (95% CI, 7%–16%) in the year after study inclusion.

Conclusions
Patients with brain abscess without prior psychiatric disorders or receipt of psychiatric medicine are not at increased risk psychiatric disorders diagnosed in psychiatric hospitals, but they have an increased receipt of psychiatric medication.