Exercise may delay cognitive decline in people with rare Alzheimer's disease (AD), suggests a study.

For individuals carrying a genetic mutation that causes AD, engaging in at least 2.5 hours of physical activity per week may have beneficial effects on markers of Alzheimer's disease brain changes and may delay cognitive decline.

According to the authors, these results support the benefit of physical activity on cognition and dementia progression, even in individuals with autosomal dominant Alzheimer's disease (ADAD), a rare genetically-driven form of the disease in which the development of dementia at a relatively young age is inevitable.

The authors said their results "show a significant relationship between physical activity, cognition, functional status and Alzheimer's disease pathology even in individuals with genetically-driven ADAD. The officially recommended physical activity duration of 150 minutes per week was associated with significantly better cognition and less Alzheimer's disease pathology in ADAD. From a public health perspective, this amount of physical activity was achieved by 70 percent of all ADAD individuals participating at the DIAN study. Therefore, a physically active lifestyle is achievable and may play an important role in delaying the development and progression of ADAD."

"The results of this study are encouraging, and not only for individuals with rare genetically-caused Alzheimer's disease," said Maria C. Carrillo of Alzheimer's Association. "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 has been published in Alzheimer's & Dementia.