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 o f lithium and valproate and associated serum levels in the treatment of man ia in elderly patients. Method: Records of 59 patients aged 55 years and older with minimal or no n eurologic 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 improve ment in each case with Clinical Global Impress ions (CGI) scores based on abstracted notes. Results: Overall, the percentage of patients improved was significantly gre ater in the lithium group than in the valproate group (67% vs. 38%, chi(2) = 4.88, p = .027). Patients taking lithium with serum levels greater than o r equal to 0.8 mmol/L were more improved at discharge than those outside th is range (greater than or equal to 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 b etween 65-90 mu g/mL were more improved at discharge than those outside thi s 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 (7 5%). The difference in efficacy between drugs was maintained in classic man ia, 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 valpr oate overall, but response rates for the 2 drugs were similar when "therape utic" serum levels were achieved. For lithium, levels similar to those repo rted for younger adults were associated with response. For valproate, a "th erapeutic window" different from that in younger adults was found. While th e retrospective and naturalistic design of this study has limitations, thes e data may help direct further studies and treatment of mania in the elderl y.