Hospitalization for psychiatric disorders before and after onset of unprovoked seizures/epilepsy

OBJECTIVE: To study hospitalization for psychiatric disorders before and after onset of unprovoked epileptic seizures/epilepsy. METHOD: In this population-based case-control study, the cases were 1,885 persons from Stockholm with new onset of unprovoked seizures from September 1, 2000, through August 31, 2008, identified in the Stockholm Epilepsy Register. Controls, in total 15,080, were randomly selected from the register of the Stockholm County population. Odds ratios (ORs) were calculated to assess the risk of developing unprovoked epileptic seizures before and after hospitalization for a psychiatric diagnosis defined as a psychiatric hospital discharge diagnosis using International Classification of Disease codes from the Swedish Hospital Discharge Registry. RESULTS: The age-adjusted OR (95% confidence interval) for unprovoked seizures was 2.5 (1.7-3.7) after a hospital discharge diagnosis for depression, 2.7 (1.4-5.3) for bipolar disorder, 2.3 (1.5-3.5) for psychosis, 2.7 (1.6-4.8) for anxiety disorders, and 2.6 (1.7-4.1) for suicide attempts. The risk of developing unprovoked epileptic seizures was highest less than 2 years before and up to 2 years after a first psychiatric diagnosis. CONCLUSION: The increased rate of psychiatric comorbidity predating and succeeding seizure onset indicates a bidirectional relationship and common underlying mechanisms for psychiatric disorders and epilepsy.