Are cholesterol and depression inversely related? A meta-analysis of the association between two cardiac risk factors

Background Cholesterol and depression are both cardiac risk factors, but the direction and magnitude of the association between these risk factors is unclear. Purpose Meta-analytic techniques were used to evaluate the associations among total, high-, and low-density cholesterol (TC, HDL, LDL, respectively) and depression in empirical studies. Methods PubMed, CINAHL, PsycINFO, and manual search strategies were used to identify descriptive studies reporting associations among TC, HDL, LDL, and depression; 30 reports were found for TC, 16 for HDL, and 11 for LDL. Effect sizes were computed and aggregated in accord with Hedges and Olkin's (Statistical methods for meta-analysis. New York: Academic Press; 1985) procedures. Results Higher TC was associated with lower levels of depression, d=-0.29; this association was substantially larger among medication-free samples (d=-0.51). An inverse, non-significant association was observed between LDL and depression (d=-0.17). High HDL was related to higher levels of depression, especially in women (d=0.20). Conclusions TC and depression were inversely related, with the strongest associations in medically naive samples, which is noteworthy because such samples should involve fewer confounds. One clinical implication is that the lipids of patients treated for depression should be monitored.