Exercise May Protect People with Increased Genetic Alzheimers Risk

There are numerous benefits to being physically active, such as losing weight, lowering blood pressure, preventing depression, and reducing the odds of developing heart disease, stroke, and diabetes. Also, exercise changes the brain in ways that protect memory and thinking skills.1 Researchers have even found that simply avoiding a sedentary lifestyle can have dramatic effects on your brain health by maintaining the integrity of your white matter throughout a lifespan.2 Researchers are trying to figure out what physiological changes within the brain may be attributed to these health benefits.

 

The study assessed changes in hippocampal volume over time in older individuals at either low risk or high risk for Alzheimer’s disease who had either low or high physical activity levels (the hippocampus is a part of the brain that is important for making new memories, and is one of the main parts affected by Alzheimer’s disease).3  Low risk and high risk was defined by the individuals’ ApoE gene variants.  The results suggested that the protective effects of physical activity on hippocampal atrophy were not observed in individuals at low risk for Alzheimer’s disease, but that physical activity may help to preserve the hippocampal volume in individuals at an increased genetic risk for Alzheimer’s disease. They recommend targeting individuals at higher genetic risk for Alzheimer’s disease for increased levels of physical activity as a means of reducing atrophy in the brain region critical for the formation of memories.

 

A group of researchers have used magnetic resonance imaging (MRI) to evaluate the impact of physical activity on the hippocampal volume of cognitively intact older adults who were at varying genetic risk for the sporadic form of Alzheimer’s disease. MRI scans of the brain were conducted at baseline and at an 18-month follow-up visit for 97 cognitively intact, healthy older adults. The participants were classified into high or low physical activity based on self-report questionnaire for frequency and intensity. Risk status for Alzheimer’s disease was determined by the presence or absence of the apolipoprotein E-epsilon 4 (APOE-ε4) allele. The researchers broke the patients into four sub-groups for study: low risk/high physical activity (n=24), low risk/low physical activity (n=34), high risk/high physical activity (n=22), and high risk/low physical activity (n=17).

MRI measurements at 18-months indicated a hippocampal volume decrease of 3% in the high risk/low physical activity group, but stable volume in the remaining three groups. The researchers evaluated several control brain regions, including the caudate, amygdala, thalamus, pre-central gyrus, caudal middle frontal gyrus, cortical white matter, and total gray matter. They observed no main effects or interactions between genetic risk and physical activity in these control brain regions.

 

  1. Harvard Health Publications. Regular exercise changes the brain to improve memory, thinking skills. http://www.health.harvard.edu/blog/regular-exercise-changes-brain-improve-memory-thinking-skills-201404097110. Accessed September 12, 2016.
  2. Burzynska AZ, Chaddock-Heyman L, Voss MW, Wong CN, Gothe NP, Olson EA, et al. (2014) Physical Activity and Cardiorespiratory Fitness Are Beneficial for White Matter in Low-Fit Older Adults. PLoS ONE 9(9): e107413. doi:10.1371/journal.pone.0107413
  3. Smith JC, Nielson KA, Woodard JL, et al. Physical activity reduces hippocampal atrophy in elders at genetic risk for Alzheimer’s disease. Frontiers in Aging Neuroscience. 2014; 6:61