Women at Risk: A Comparative Study on Socioeconomic Status, Lifestyle, Brain, and Cognition Among Older Females in Japan and Sweden

Abstract

Abstract Objective Determine and compare lifestyle risks addressing the effects of socioeconomic status (SES) on brain and cognitive variations among females in two community-dwelling cohorts across Japan and Sweden. Method We included 576 (73.7 ± 6.0 years) and 195 (63.9 ± 13.4 years) cognitively healthy females from the Arao (AC, Japan) and Betula (BC, Sweden) cohorts, respectively. SES was defined by educational and occupational categories. Lifestyle-related diseases included obesity, diabetes, hypertension, and depressive disorder; habits including exercise, social activity, sleep, alcohol habits, and smoking status. Brain structural outcomes were derived from T1 weighted magnetic resonance imaging scans. A priori regions of interest included volumes of the hippocampus, amygdala, thalamus, and caudate; thickness of the superior frontal gyrus, inferior temporal gyrus, and middle temporal gyrus. General cognitive performance was evaluated by the Mini-Mental State Examination score. The relationships between SES-lifestyle with the brain and cognition were assessed by structural equation models. Results Positive associations were found between SES and volumetric brain measures and cognition (MMSE) in both cohorts, but not between SES and cortical thickness. Lifestyle-related diseases (including obesity, diabetes, hypertension, and depressive disorder), but not habits such as exercise or sleep, partially explained the positive association between SES and brain volumes (up to 18.6% in the AC). A similar, but non-significant trend, was seen in the SES-cognition association that could be explained by lifestyle-related diseases. Discussion Although statements of causality cannot be made from the current work, our findings suggest management of the lifestyle-related disease is particularly important for females for compensating the maladaptive effects of SES on brain atrophy.