Exercise – it’s not just good for the heart

Earlier this year, the CDC released a report that only one-quarter of Americans met the federally-recommended exercise guidelines – 2 ½-5 hours/week of moderate aerobic or 1 ¼-2 ½ hours/week of vigorous aerobic exercise and at least two days/week of muscle strengthening exercises. It is well known that exercise may reduce the risk of dementia by reducing cardiovascular risk factors associated with Alzheimer’s disease, such as diabetes, blood pressure, or stroke. However, a new study suggests that physical activity may reduce the risk of cognitive decline independent and beyond its effects on cardiovascular risk factors [1].

The Harvard Aging Brain Study follows older individuals by recording levels of their physical activity, risk of cardiovascular disease, brain volume, and levels of brain amyloid plaques – the toxic protein found in patients with Alzheimer’s disease. The individuals enrolled in the study do not have dementia. Instead of traditional tests used for diagnosis of Alzheimer’s, their cognition is measured with the Preclinical Alzheimer Cognitive Composite (PACC), a test that is sensitive to cognitive problems before dementia.

Although amyloid plaques are found in all patients with Alzheimer’s, not everyone with amyloid plaques will get dementia. The investigators wanted to see whether physical activity could prevent cognitive decline in individuals with amyloid plaques, independent of its effects on traditional cardiovascular risk factors.

In the study, 182 participants with an average age of 73 received a scan to measure brain amyloid, a scan to measure brain volume, and were assessed for cardiovascular disease risk (using the Framingham Heart Study cardiovascular disease risk score, or FHS-CVD). Then they wore a pedometer on their waist for seven days to measure their physical activity. Not surprisingly, more physical activity was associated with lower cardiovascular risk score, meaning that people who exercised more had better cardiovascular health. Additionally, there was no association between physical activity and the presence of amyloid plaques.

The researchers followed the study participants for several years. They found that higher physical activity at the first visit was associated with less cognitive decline and less brain volume loss even in individuals with amyloid plaques. In addition, after taking into account a participant’s cardiovascular risk scores, physical activity was still associated with less cognitive decline in these individuals, suggesting that both physical activity and lowering cardiovascular risk could protect cognition.

We know that improving the function of your brain’s blood vessels through exercise may reduce your risk for Alzheimer’s disease. This study suggests that exercise can improve brain health in other ways beyond improved cardiovascular fitness. There is some evidence to suggest that exercise can increase the levels of neuroprotective growth factors, increase the generation of new brain cells, or reduce inflammation in the brain [2]. Lifestyle factors are an important component to reduce your risk of Alzheimer’s disease. Whether you join a local community center or gym, or you challenge family members and friends in a health app competition, integrating exercise into your daily routine is an important first step for brain health.

1. Rabin JS, Klein H, Kirn DR et al. (2019) Associations of Physical Activity and beta-Amyloid With Longitudinal Cognition and Neurodegeneration in Clinically Normal Older Adults. JAMA Neurol.
2. Ryan SM, Kelly AM (2016) Exercise as a pro-cognitive, pro-neurogenic and anti-inflammatory intervention in transgenic mouse models of Alzheimer's disease. Ageing Res Rev 27, 77-92.

Get the latest brain health news: