Metabolic syndrome and risk of death in older adults with major psychiatric disorders: Results from a 5-year prospective multicenter study

Objectives: No study has explored the association of individual components of metabolic syndrome with mortality in older patients with psychiatric disorders. In this report, we examined whether metabolic syndrome or any of its components predicted mortality in a cohort of older adults with psychiatric disorders. Methods: We used data from a multicenter 5-year prospective cohort, including 634 in- and out-patients with schizophrenia, bipolar or major depressive disorder. Metabolic syndrome was assessed at baseline following NCEP-ATPIII criteria. Cause of death was categorized as cardiovascular disorder (CVD) mortality, non-CVD disease-related mortality (e.g., infections), suicide and accident. Results: 122 participants (44.0%) were diagnosed with metabolic syndrome at baseline. In the full sample, there was no significant association between metabolic syndrome or any of its components with all-cause, CVD and non-CVD mortality. However, for the subpopulation of older adults with major depressive disorder, metabolic syndrome was significantly associated with increased all-cause and disease-related mortality after adjustment for age, sex and smoking status (p = 0.032 and p = 0.036, respectively). There was a significant interaction between metabolic syndrome and psychiatric diagnoses indicating that in participants with major depressive disorder, metabolic syndrome had a significantly greater effect on all-cause mortality (p = 0.025) and on disease-related mortality (p = 0.008) than in participants with either bipolar disorder or schizophrenia. Conclusions: Our findings do not support an association between metabolic syndrome and increased mortality in older patients with major psychiatric disorders. Several explanations are discussed, including a survival bias, a lack of sensitivity of the used cut-offs and a ceiling effect of metabolic syndrome on mortality in this very high-risk population. The latter hypothesis could also explain the significant association between metabolic syndrome and mortality in the depressive subgroup, where a ceiling effect is yet to be reached, given the less marked premature mortality in depressive patients compared to those with bipolar disorder or schizophrenia.