Effect of valproic acid on dementia onset in patients with bipolar disorder.

BACKGROUND: Valproic acid (VPA) is widely used for treating patients with bipolar disorder; however, it has adverse effects on cognitive function. This study investigated the effect of VPA on the risk of dementia in patients with bipolar disorder.

METHODS: We analyzed data from Taiwan's Longitudinal Health Insurance Database 2010. Patients with bipolar disorder who were prescribed VPA for 28 days or at least once per month for 3 consecutive months after the index date were classified as the VPA-treated group, whereas those who did not receive VPA were classified as the VPA-untreated group. Both groups were tracked until the end of 2013 or until loss to follow-up to identify new-onset dementia events. Multivariable Cox proportional hazards models were used to estimate the hazard ratio (HR) of subsequent dementia associated with VPA treatment after adjustment for confounding variables.

RESULTS: The study comprised 5158 patients with bipolar disorder. The multivariable-adjusted HR for newly diagnosed dementia was 1.73 (95% confidence interval [CI], 1.24-2.41, P=0.001) for the VPA-treated group compared with the VPA-untreated group after adjustment for potential confounders. The VPA-treated group had a higher risk than did the VPA-untreated group after propensity score adjustment (HR=1.95, 95% CI=1.42-2.67, P<0.001).

LIMITATION: Certain variables that may affect the incidence of dementia were unavailable in the claims database and thus could not be considered.

CONCLUSION: Treating bipolar disorder with VPA increases the risk of dementia by 73-95%.