Intensive Exercise May Delay Cognitive Decline by 10 Years

March 24, 2016

Two new analyses from a study in a diverse racial US population have added to evidence that good cardiovascular health and physical exercise can slow cognitive decline in later years.

The latest findings come from new analyses of the Northern Manhattan Study (NOMAS), a population-based prospective study originally designed to evaluate the effects of various risk factors on the incidence of stroke in a racially/ethnically diverse community cohort.

For the two new analyses, published as two separate papers, researchers from the University of Miami, Florida, and Columbia University, New York, re-examined the data on various risk factors and how they relate to later cognitive function.

In the study of physical activity, published online in Neurology on March 23, individuals who reported low levels of leisure time physical activity in their mid-60s showed greater cognitive decline when assessed several years later compared with those who exercised to a moderate or intense level. The difference in cognitive decline between the two groups was equal to 10 years of aging.

"Our results suggest that for older people, getting regular quite intensive exercise may help them keep their cognitive abilities longer," senior author, Clinton B. Wright, MD, University of Miami, commented to Medscape Medical News.

He emphasized that they showed a difference between intensive exercise, such as running or swimming, and low level activity such as walking. "To be included in the moderate to intensive group, individuals had to exert themselves — ie, undergo a form of activity that raised their heart rate for more than just a few minutes several times a week."

He noted that similar findings have been reported before but mostly in mainly white populations. "Our study involved a cohort from Manhattan, which is a real melting pot in terms of race and ethnicity. It is reassuring that we have now found supporting evidence for a positive effect of exercise on later cognitive health in such a diverse population."

AHA's "Simple Seven"

For the second analysis, published online in the Journal of the American Heart Association on March 16, the researchers focused on the American Heart Association's (AHA's) "Life's Simple Seven" cardiovascular health indicators: tobacco avoidance; ideal levels of weight; physical activity; healthy diet; and healthy levels of blood pressure, cholesterol, and glucose.

Results suggested that individuals with more of these good cardiovascular health indicators had less cognitive decline later on, specifically in the domains of processing speed, executive function, and episodic memory. Of the seven indicators, nonsmoking and low glucose levels seemed to be particularly important in driving the association with better future cognitive function.

On this study, Dr Wright said, "These findings suggest that a lower burden of vascular risk factors may translate into better cognition and slower cognitive decline several years later. While this has been suggested before this is the first time it has been demonstrated in the context of the AHA's targets for cardiovascular health. And it adds to the accumulating evidence that looking after our cardiovascular health will benefit our cognitive health too."

But he pointed out that most people participating in this study did not have good cardiovascular risk profiles. "Not even one participant had all 7 ideal cardiovascular health factors, and only 5% had 5 or 6 of these indicators, with 60% only having 2 or 3. There is obviously a lot of room for improvement here," he noted. "The AHA's goal of achieving a 20% improvement in cardiovascular health by 2020 may also have the potential of having a significant beneficial effect on cognitive decline."

For the physical activity analysis, cognition was assessed by using a standard neuropsychological examination in 1228 individuals, and a repeat examination was performed 5 years later in 876 individuals. MRI was also conducted to quantify subclinical cerebrovascular disease.

Data on leisure time physical activity was accessed from enrollment records collected 7 years earlier. Questionnaires were correlated with metabolic equivalents (METs), with a MET value of 6 or above classified as moderate–heavy activity and a MET value below 6 as light activity. Light activity and no activity were combined as the control group. Moderate to heavy activity was reported by 10% of participants compared with 90% reporting light or no activity.

Results showed that after adjustment for sociodemographics, cardiovascular disease risk factors, and MRI findings (white matter hyperintensity volume, silent brain infarcts, cerebral volume), no or low levels of physical activity were associated with worse executive function, semantic memory, and processing speed scores on the first cognitive examination. The associations were slightly attenuated and no longer significant after adjustment for vascular risk factors.

However, among those individuals who were cognitively normal at the first examination, those reporting no/low physical activity declined more over time in processing speed and episodic memory than those reporting high levels of activity, and these differences remained after adjustment for sociodemographic and vascular risk factors.

The researchers conclude that increasing physical activity is a likely therapeutic target for cognitive decline with aging, and it is an especially attractive target for lessening the public health burden of cognitive impairment because of its low cost, lack of interaction with medications, and other health benefits.

Vascular Damage and Cognitive Aging

The cardiovascular risk factor analysis followed the same procedures, with 1033 participants from the Northern Manhattan Study who had data recorded on the seven cardiovascular health factors who underwent neuropsychological testing and 722 of these who had repeat testing 6 years later.

Results showed that an increasing number of ideal cardiovascular health factors was associated with better processing speed at initial cognitive assessment and less decline. The association was driven by nonsmoking and glucose levels. Among those with better cognitive performance at initial assessment, positive associations were observed between the number of ideal cardiovascular health factors and less decline in the domains of executive function and episodic memory.

"The relationship between ideal cardiovascular health factors and cognitive domains in our study, as well as in others, supports the role of vascular damage and metabolic processes in the etiology of cognitive aging and dementia," the researchers write.

They conclude: "Achievement of the AHA's ideal cardiovascular health metrics may have benefits for brain health in addition to preventing strokes and myocardial infarctions, even among elderly individuals, underscoring the importance of public health initiatives aimed to better control these 7 factors."

They add that as the population ages and the number of people at risk for cognitive impairment grows, "the public health implications of targeting these modifiable risk factors will be substantial."

These studies were supported by the National Institutes of Health and National Institute of Neurological Disorders and Stroke. Dr Wright is supported by a related grant from the National Heart, Lung, and Blood Institute.

Neurology. Published online March 23, 2016. Abstract

J Am Heart Assoc. Published online March 16, 2016. Full text

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