Aerobic Exercise Improves Brain Function for People with Prediabetes
Having prediabetes or type 2 diabetes is the second biggest risk factor for developing Alzheimer's disease, following only advanced age. In fact, diabetes increases a person's risk of Alzheimer's by 65 percent. American Diabetes Association-funded researcher Laura D. Baker, Ph.D., has spent much of her career trying to understand how to reduce this risk. She has recently found that aerobic exercise may be one of the answers.
Dr. Baker began her research career as a graduate student at Washington University in St. Louis. There, she met Dr. Suzanne Craft and began working under Dr. Craft's mentorship on a project investigating whether a glucose drink could improve memory. Dr. Baker fell in love with working one-on-one with patients and families, and was intrigued by the study's findings that changing metabolism for just a short period of time could improve cognition. Some 20 years later, Dr. Baker is still working with Dr. Craft – now as a colleague at Wake Forest School of Medicine in Winston-Salem, NC – where both women are continuing down the path arising from this initial fascinating finding.
With funding from the American Diabetes Association, Dr. Baker has conducted a series of studies on how exercise affects cognition in people at higher risk for developing Alzheimer's disease due to prediabetes. Her first Association-funded project began in 2004 and allowed her to develop and fine-tune the exercise protocol that she continues to use in her studies today. It also showed that changing insulin sensitivity changed cognition. Her second Association grant was funded in 2011 to study people with a "double-hit" risk for Alzheimer's disease: people with both mild cognitive impairment and prediabetes. The results of this study were recently presented at the Alzheimer's Association International Conference in Washington, DC.
The study enrolled older adults who considered themselves sedentary and were found to have prediabetes and mild cognitive impairment. The participants were randomly assigned to either a high-intensity supervised aerobic exercise group or an active control group that underwent supervised low-intensity stretching and balance exercises. The two groups met in the same environment four times a week for six months, and exercised 45-60 minutes each time.
At the end of the study, there was significant improvement in cognition among the participants assigned to the aerobic exercise group. Not only did they perform better on tests of multitasking and of organizing and planning, but they also had reductions in the levels of a protein in the cerebrospinal fluid, called tau protein, that is typically increased in older people with Alzheimer's disease. Most interestingly, people who performed aerobic exercise showed improvements in blood flow to regions of the brain that are important for memory and cognition, which includes one area that typically shows reduced flow with aging AND one area that typically show reduced flow with advancing Alzheimer's disease. The aerobic exercise routine reversed the aging clock in these high-risk individuals.
Based on these exciting results and the early investment of American Diabetes Association research funding, Dr. Baker has received funding from the National Institute of Aging to start a multi-site national Phase III trial that will follow participants for 18 months of exercise and help determine what "dose" of exercise is required for the most benefit.
The bottom line from this work is that any physical activity is better than none in terms of providing beneficial effects on cognition, and it's never too late to start. In fact, the study participant who was the oldest (89 years old) showed some of the biggest improvements as a result of aerobic exercise. Exercise acts like medicine for the brain – it gives the brain what it needs, and Dr. Baker expects that any amount of exercise will benefit not only the body, but also the brain.
The researchers are currently writing the study results for publication in a scientific journal. The study was recently featured on the US News & World Report website as a highlight of the Alzheimer's Association International Conference 2015.