Participating in 150 minutes of exercise a week—just 2.5 hours of walking briskly or another physical activity—could delay an inherited form of Alzheimer’s, according to researchers of a new study.
The cross-sectional study, recently published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, gathered 15 years of data from 459 participants. The participants were selected from the longitudinal Dominantly Inherited Alzheimer Network (DIAN) study, which consists of family members of individuals with a rare form of genetically-inherited autosomal dominant Alzheimer’s Disease (ADAD). This form of Alzheimer’s is inherited when a parent carries a genetic mutation in one of three genes. Children of a parent with this mutation have a 50 percent chance of inheriting ADAD, and nearly 100 percent of those with ADAD will develop Alzheimer’s disease by the age of 60. Of the study’s participants, 275 had been diagnosed with ADAD. The remaining 184 participants were not ADAD carriers. The average age of all participants was 38.4.
Researchers calculated the year in which participants would begin to show signs of Alzheimer’s by looking at the age of onset for participants’ closest family members. Calculating that age helped researchers determine that carriers of the rare form of Alzheimer’s who exercised 150 minutes per week showed improved cognition when they took the Mini Mental State Examination (MMSE) and Clinical Dementia Rating Sum of Boxes (CDR-SOB), two tests used to diagnose dementia patients at the age researchers predicted they would develop Alzheimer’s.
In contrast, ADAD carriers who exercised fewer than 150 minutes a week demonstrated a decline in cognition when taking the tests. There were no changes in cognition in participants who were non-carriers of ADAD.
In addition, participants’ cerebrospinal fluid, a biomarker used to diagnose Alzheimer’s, was measured at the start of the study and again at expected onset of ADAD. Mutation carriers who had a high level of physical activity showed a statistically significant decline in Alzheimer’s disease biomarkers in cerebrospinal fluid, including lower tau, a protein that builds into toxic clumps in the brains of people diagnosed with Alzheimer’s. Those with a low level of physical activity showed an increase in Alzheimer’s disease biomarkers, including a build-up of tau.
An expert not associated with the study says that evidence of biological changes to the brain is encouraging. “Cognitive tests are showing a biological change in the brain. That the biomarkers confirmed the results of the cognitive tests is exciting and it tells us more research is needed,” said James Hendrix, Ph.D., the director of Global Science Initiatives at the Alzheimer’s Association.
The study also supports a potential link between higher amounts of exercise and a later diagnosis of very mild dementia. The results support a “beneficial effect of [physical activity] on cognition and dementia signs and symptoms in individuals with genetically-driven autosomal dominant Alzheimer’s Disease,” the study’s authors report. “A physically active lifestyle seems to play an important role in slowing the development and progression of autosomal dominant Alzheimer’s Disease.”
This new study sheds light on an area of Alzheimer’s research that has been less understood. Dr. Christoph Laske, M.D., and his research team at the University Hospital of Tübingen, Germany add to the is a growing body of research supports the correlation between exercise and improved mental cognition for the more common, late-onset Alzheimer’s disease. One study shows a link between exercise and decreased incidence of dementia in people 65 and over. Other studies suggest that regular exercise can delay Alzheimer’s in APoE4 carriers by 20 years or more. The new study’s findings also align with the findings of a study that show a positive correlation between exercise and improved cognitive function.
“The results of this study are encouraging, and not only for individuals with rare genetically-caused Alzheimer’s disease,” said Maria C. Carrillo, Ph.D., the Alzheimer’s Association chief science officer. “If further research confirms this relationship between physical activity and later onset of dementia symptoms in ADAD, then we need to expand the scope of this work to see if it also is true in the millions of people with more common, late onset Alzheimer’s.”
The study’s findings are good news for people who are able to exercise, but for those who are physically unable to exercise, this news could present a challenge.
“We need to understand what other lifestyle factors could give people benefits,” said Hendrix. “The recent SPRINT MIND study looked at blood pressure and found that people with lower blood pressure had lower rates of dementia and cognitive decline. There are ways to manage blood pressure through drugs and diet, so this could be one approach for people who are unable to exercise.”
In an effort to better understand all the lifestyle factors that influence brain health, the Alzheimer’s Association has initiated a two-year clinical trial called the U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER). The study will evaluate the effects of physical exercise, nutrition counseling and modification, cognitive and social stimulation, and improved self-management of health status, on the cognitive function of 2,500 volunteers between the ages of 60-79 who are at risk for cognitive decline.