Depressive subfactors and cognitive function in midlife

Background: This study aimed to evaluate the heterogeneous association of depressive subtypes with cognitive function, according to age and sex. Methods: This cross-sectional study utilized the baseline data from the Cardiovascular and Metabolic Disease Etiology Research Center cohort and included 5271 midlife participants. For identifying depressive subtypes of the Beck Depression Inventory Ⅱ items, factor analyses were utilized and yielded two factors —melancholic- and somatic-depressive subtypes. The information of Mini-Mental State Examination was used for screening cognitive function. The association between depressive subtypes and cognitive function was analysed using multiple regression after adjusting for all covariates. Results: We observed heterogeneous association between depressive subtypes and cognitive dysfunction in midlife participants. The results of sex- and age- stratified analyses indicated that the somatic subtype was associated with dysfunction in cognitive ability. Among women, especially those aged over 60 years, MMSE scores decreased as the somatic depression scores increased. These results might suggest that the somatic subtype, rather than the melancholic subtype, has a greater association with cognitive assessment in a general midlife population, particularly older women. Limitations: Although a confirmatory factor analysis was performed, depressive subtypes need validation and reliability tests. Conclusions: Given this heterogeneity, characterisation of depressive subtypes according to sex and age may improve our understanding of how each depressive symptom is associated differently with cognitive dysfunction in midlife.