Physical Activity Improves Cognitive and Vascular Health in Older People with Diabetes.

People with diabetes are at increased risk of cardiovascular disease and dementia. Previous research has shown that people with diabetes who get more exercise are less likely to develop these complications, but the reason for this has remained unclear.

Now, a new study co-authored by School of Public Health researchers finds that physical activity in older adults with diabetes increases the circulation of substances that repair vascular and neuronal damage.

The study, published in the Journal of Diabetes Research, shows an association between more physical activity and higher circulating levels of insulin-like growth factor (IGF-1) and brain-derived neurotrophic factor (BDNF).

“Physical activity could be a key factor in lowering the risk of cardiovascular disease and dementia in people with diabetes,” says study co-author and doctoral candidate Kendra Davis-Plourde. “This new evidence adds to the list of reasons people with diabetes should try to stay active as they age.”

IGF-1, BDNF, and vascular endothelial growth factor (VEGF) are substances involved in the creation of blood cells and neurons, and also help repair vascular and neurological damage. People with diabetes tend to have lower levels of these substances circulating in their blood, and previous research has suggested that this may be part of the reason for their higher risk of cardiovascular disease and dementia. Exercise intervention studies have shown that physical activity can increase circulating levels of IGF-1, BDNF, and VEGF in a general population, but it has been unclear whether exercise could have the same effect for people with diabetes.

For this study, the researchers used data on participants of the Framingham Offspring Study, a cohort made up of the children and children-in-law of the participants of the original, BU-based Framingham Heart Study. The researchers looked at data from participants who completed examinations and questionnaires between 1998 and 2001, eliminating participants with prevalent cardiovascular disease, stroke, or dementia, and those taking hormone replacement therapy and those who were unsure of whether or not they had diabetes. This left 179 participants with diabetes and 1,551 participants without diabetes.

The IGF-1, BDNF, and VEGF levels in the stored blood samples from these examinations were measured in 2010 and 2011. The researchers then matched the blood samples to questionnaire information on physical activity and analyzed the relationship between self-reported activity and the levels of these substances in the participants’ blood. They also analyzed this relationship broken down by age, between those who were under 60 years old and those who were 60 or older.

The researchers did not see any association between physical activity and IGF-1, BDNF, and VEGF levels in participants who did not have diabetes. However, among participants with diabetes, they found an association between more physical activity and higher BDNF levels. They also found an association in people with diabetes between higher levels of IGF-1 and more physical activity, particularly walking, although this association only held for those who were 60 years old or older. They did not find a significant association between physical activity and VEGF levels in participants with diabetes.

The study was co-authored by Jayandra Himali, assistant professor of biostatistics; Vasan Ramachandran, professor of epidemiology; and Alexa Beiser, professor of biostatistics. The study’s lead author was Nicole Spartano of the School of Medicine, and the study was also co-authored by Joanne Murabito and Sudha Seshadri of MED.

—Michelle Samuels