Objective: Diabetes increases an individual's risk of developing dementias (eg, vascular), whereas regular physical activity has been shown to lower this risk. The purpose of this study, therefore, was to examine the relationships among cognitive function, exercise status, and type 2 diabetes (T2 DM) to determine whether physical activity participation offsets any of the increased risk of cognitive dysfunction frequently associated with diabetes.
Measurements: A total of 145 subjects, 71 controls (Con) and 74 with T2 DM (DM), were studied using 2 cognitive tests (Mini-Mental State Exam [MMSE], and the Saint Louis University Mental Status exam [SLUMS]); the Even Briefer Assessment Scale for Depression (EBAS-DEP); the Harvard Alumni Physical Activity Questionnaire (HAPAQ); the Modified Barthel Index (MBI); and fasting insulin, glucose, glycated hemoglobin, and lipid levels.
Results: The presence of diabetes had a negative impact on at least one measure of cognitive function (MMSE), even though such function was fairly intact in most subjects (29.3 +/- 0.1 Con, 28.7 +/- 0.2 DM, P < .05). MMSE scores were significantly inversely associated with fasting insulin levels and insulin resistance (HOMA-IR), and longer duration sitting was associated with elevated blood glucose levels. Although "regular exerciser" status per se was not indicative of higher mental function, MMSE and SLUMS cognitive function scores were significantly associated with specific physical activity submeasures, including a positive association with hours spent doing light exercise on weekdays and an inverse relationship with weekend sitting (SLUMS only). SLUMS scores were also positively associated with a greater duration of weekend moderate exercise, while hours of weekend sitting were associated with higher blood glucose levels and depression.
Conclusions: Certain types of physical activity, including light and moderate exercise, appear to be beneficial to mental function in individuals with T2 DM. Having diabetes, particularly when less well controlled, is associated with lower cognitive function scores, and physical activity participation may prevent some of the potential decline in cognition.