Original study
Physical Activity Participation May Offset Some of the Negative Impact of Diabetes on Cognitive Function

https://doi.org/10.1016/j.jamda.2008.03.014Get rights and content

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.

Section snippets

Methods

A total of 145 subjects, ages 36 to 86 years, 74 with T2 DM (DM) and 71 nondiabetic controls (CON), participated in this study after giving their written consent. Prior to their enrollment, the study was approved by the Institutional Review Board at Old Dominion University. All subjects reported to the laboratory in the morning where they underwent a fasting blood draw and were given a battery of tests. The testing included 2 cognitive ones (Mini-Mental State Exam [MMSE] and the Saint Louis

Results

The characteristics of the subjects are listed in Table 1. As expected, the DM group had higher blood glucose and insulin levels, as well as elevated HbA1c. The groups differed by physical activity and exercise patterns (Table 2), with a greater percentage of CON subjects (71.8%) classified as “regular exercisers” compared with DM (55.4%; P < .01). CON subjects also walked significantly more city blocks per day, climbed more flights of stairs, and differed from DM in activity levels on weekday

Discussion

The primary goal of this study was to determine whether regular exercisers have a better cognitive status compared with nonexercisers and, more importantly, if subjects with diabetes who are regular exercisers have better cognitive function than sedentary diabetic (and even possibly control) subjects. The results demonstrated that diabetes has a negative impact on cognitive function measured with one measure of cognitive function, the MMSE, even when it is fairly intact in the groups being

Conclusion

Certain types of physical activity appear to be beneficial in the maintenance of cognitive function given that both MMSE and SLUMS scores were positively associated with a greater duration of weekday light exercise and SLUMS scores correlated with longer moderate exercise on weekends. Longer weekend sitting also was associated with higher blood glucose levels and greater depression, and a number of physical activity behaviors were inversely associated with depression, which by itself is a risk

Acknowledgments

The authors are most appreciative of the efforts of Lauren Piccillo, Khededra Lewis, and Margaret Larsen in assisting with the collection of these data. In addition, we would like to acknowledge the skill and expertise of Kimberly Baskette and Rebecca Warren in obtaining fasting blood work and to thank them for their excellent technical support.

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    This research was fully supported by funding from the Commonwealth of Virginia Alzheimer's and Related Diseases Research Award Fund.

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    Copyright © 2008 American Medical Directors Association. Published by Elsevier Inc. All rights reserved.