In people with autosomal dominant Alzheimer's disease (ADAD), an inherited and rare form of Alzheimer's, engaging in at least 150 minutes of physical activity was associated with better cognition, lower levels of disease biomarkers in cerebrospinal fluid (CSF), and a delay in diagnosis of mild dementia. These are the findings of a cross-sectional analysis published online in Alzheimer's & Dementia on September 21.
To understand how exercise affects people who carry the gene mutation for ADAD, a team of international researchers analyzed data from participants enrolled in the DIAN study, a longitudinal observational study that includes individuals who have a parent or a first-degree relative with a mutation in one of three genes—APP, PSEN1, or PSEN2—that causes Alzheimer’s disease.
Using recommendations from the World Health Organization and American College of Sports Medicine of at least 150 minutes of exercise per week, the researchers classified 224 carriers of the mutated gene, with an average age of 38.4 years, as either high (150 or more minutes of exercise per week) or low (less than 150 minutes) exercisers. The participants reported the type of exercise, including walking, running, cycling, swimming, tennis, aerobics, or weight training. How often participants exercised was corroborated by a family member or friend. Overall, 70 percent of study subjects were considered high exercises and 30 percent low.
The researchers estimated when symptoms would first appear in participants based on the participants’ ages and the age at which their parent or first-degree relative first exhibited symptoms. For example, if a participant was 37 and his mother or sister was 45 when her symptoms first appeared, the researchers predicted he would develop symptoms in eight years.
Researchers measured participants' cognition and function using the Mini-Mental State Examination (MMSE), a 30-point questionnaire. A score of 20 to 24 suggests mild dementia; 13 to 20 suggests moderate dementia, and less than 12 suggests severe dementia. The researchers also used the Clinical Dementia Rating Sum of Boxes (CDR-SOB), which consists of six domains—memory, orientation, judgment and problem-solving, community affairs, home and hobbies, and personal care. Scores range from 0, which signifies an asymptomatic state, to 18, which denotes severe dementia.
The researchers also measured concentrations of Alzheimer’s disease biomarkers such as tau protein in participants’ cerebrospinal fluid.
Participants who were more physically active had significantly better cognitive and functional scores than low exercisers. High exercisers scored 3.4 points higher on the MMSE at the time symptoms appeared and were diagnosed with very mild dementia 15 years later than low exercisers. More physically active participants also had lower levels of tau protein and other Alzheimer's disease biomarkers in their cerebrospinal fluid than their couch potato counterparts.
"Individuals at genetic risk for dementia should be counseled to pursue a physically active lifestyle,” the researchers wrote.
These findings should be interpreted with caution since researchers were unable to assess the status of participants’ cognitive changes over time.
Further research that uses various neuropsychological tests to measure cognition and function throughout the study period is warranted, the researchers concluded.
Currently, the Alzheimer's Association is conducting a two-year clinical trial called the US Study to Protect Brain Health through Lifestyle Intervention to Reduce Risk (U.S. POINTER) to evaluate whether lifestyle interventions, such as exercise, nutrition, and mental stimulation may protect cognitive function in older adults with an increased risk of cognitive decline.