Affective symptoms and cognitive reserve in older primary care patients with type 2 diabetes: A cross-sectional case-control study

Population aging and type 2 diabetes mellitus (T2DM) have raised concerns regarding late-life cognition and mental health. Cognitive reserve (CR; education, work, and leisure) may buffer vulnerability; however, evidence in older outpatients is limited. We compared CR, cognition, depressive symptoms, and anxiety in older adults with and without T2DM and examined the CR-outcome associations within T2DM. This single-center, cross-sectional, case-control study included 89 adults aged ≥65 years (43 patients with T2DM and 46 controls). CR was assessed using the Cognitive Reserve Index questionnaire (CRIq). The outcomes were the Turkish Standardized Mini-Mental State Examination (SMMSE-TR), 15-item Geriatric Depression Scale (GDS-15), and Beck Anxiety Inventory (BAI) scores. The groups were compared using nonparametric tests. Within the T2DM group, CR-outcome associations were examined using Spearman correlations. Anxiety was further evaluated using multivariable linear regression adjusted for age, sex, education level, marital status, and hypertension. Participants with T2DM had lower education levels and higher glycated hemoglobin A1c levels. They also had lower CRIq-Education, CRIq-Leisure, and total Cognitive Reserve Index scores than controls, whereas CRIq-Working activity scores were similar. The SMMSE-TR and GDS-15 scores did not differ between groups. BAI scores were higher in the controls in the unadjusted analyses, but T2DM status was not associated with BAI after adjustment. Within the T2DM group, higher CR, particularly education and total Cognitive Reserve Index, was associated with higher SMMSE-TR scores and lower GDS-15 and BAI scores. T2DM was associated with lower CR in older Turkish outpatients. Within T2DM, higher reserve was linked to better global cognitive performance and fewer affective symptoms.