Efficacy of lithium vs. valproate in the treatment of mania in the elderly: A retrospective study

Background: This retrospective study was conducted to assess the efficacy of lithium and valproate and associated serum levels in the treatment of mania in elderly patients. Method: Records of 59 patients aged 55 years and older with minimal or no neurologic impairment, hospitalized for mania, and discharged on lithium (N = 30) or valproate (N = 29) therapy were reviewed. Data on mood stabilizer choice, serum levels, and type of mania were recorded. A clinician blinded to medications rated improvement in each case with Clinical Global Impressions (CGI) scores based on abstracted notes. Results: Overall, the percentage of patients improved was significantly greater in the lithium group than in the valproate group (67% vs. 38%, χ² = 4.88, p = .027). Patients taking lithium with serum levels ≥ 0.8 mmol/L were more improved at discharge than those outside this range (≥ 0.8, CGI 2.0 ± 0.6 vs. < 0.8, CGI 2.6 ± 0.8, t = 2.15, p = .043). Patients taking valproate with serum levels between 65-90 μg/mL were more improved at discharge than those outside this range (65-90, CGI 2.1 ± 0.6 vs. < 65, > 90, CGI 3.3 ± 0.8, t = 3.73, p=.002). When response rates among only patients with these 'therapeutic' levels were assessed, they were similar for lithium (82%) and valproate (75%). The difference in efficacy between drugs was maintained in classic mania, but the 2 drug groups were similar when only mixed mania was analyzed (lithium 63% vs. valproate 67% improved). Conclusion: Results suggest that lithium may be more efficacious than valproate overall, but response rates for the 2 drugs were similar when 'therapeutic' serum levels were achieved. For lithium, levels similar to those reported for younger adults were associated with response. For valproate, a 'therapeutic window' different from that in younger adults was found. While the retrospective and naturalistic design of this study has limitations, these data may help direct further studies and treatment of mania in the elderly.