In addition, the study also evaluated the impact of cardiovascular and mental health, as well as carrying the APOE-ε4 gene, which are all known to increase the risk of cognitive decline.
A long-term study published online in the Journal of Neurology Neurosurgery & Psychiatry indicates that any regular leisure-time physical activity at any age is associated with improved brain function in old age, but maintaining an exercise routine throughout adulthood appears to be optimal for preserving mental acuity and memory.
Adjusting for factors including childhood intelligence, family wealth, and parental education did reduce the observed relationships, but they were still statistically significant.
Several studies have shown a link between physical activity and a lower risk of dementia, cognitive decline, and loss of mental sharpness in old age. Yet, it is unknown whether the timing, frequency, or maintenance of leisure-time physical exercise over the life span may be important for developing cognitive abilities in later years.
The researchers were especially curious as to whether the benefits of physical exercise would be maximized in a single “sensitive” phase over the life cycle or would be spread out across multiple periods.
To try and answer this question, researchers analyzed the strength of associations between a variety of cognitive tests administered at age 69 and reported leisure time physical activity at ages 36, 43, 53, 60-64, and 69 in 1417 people (53% women) who participated in the 1946 British birth cohort study.
There were three categories for physical activity levels: inactive, moderately active (1-4 times per month), and most active (5 or more times per month). The five evaluations were added together to get a final score that ranged from 0 (inactive at all ages) to 5 (active at all ages).
In each of the five time periods, 11% of participants were physically inactive, compared to 17% at the first, 20% at the second and third, 17% at the fourth, and 15% at all five.
The validated ACE-111, which measures verbal fluency, verbal memory, visuospatial function, attention and orientation, as well as processing speed (visual search speed) and verbal memory (word learning test), was used to evaluate cognitive functioning at age 69.
In addition, factors that are linked to an increased risk of cognitive decline, such as cardiovascular and mental health as well as the carriage of the APOE-ε4 gene, were investigated to see whether or not these factors impacted any of the observed relationships.
After analyzing the data, they found that a correlation existed between greater levels of cognitive ability, verbal memory, and processing speed in those who had been physically active over all five time periods.
Researchers concluded that “being physically active at any time in adulthood, even if participating as little as once per month, is linked with higher cognition,” and that the impact sizes were consistent across all adult ages and for those who were moderately and most active.
But the strongest link was found between long-term physical activity and brain function in old age, and among people who were the most active at all ages.
Childhood cognition, socioeconomic status, and level of schooling helped to explain the beneficial correlation between cumulative physical exercise and adult cognitive function.
But the effect was still there when these things were taken into account, and the links couldn’t be explained by differences in cardiovascular or mental health in later life.
“Together, these results suggest that the initiation and maintenance of physical activity across adulthood may be more important than the timing….or the frequency of physical activity at a specific period,” they write.
Since this is an observational study, it can’t prove a cause, and the researchers admit that their findings have some weak points.
Only White people participated in the research, and those who were socially disadvantaged attrition rates were disproportionately high. There was also no information on exercise frequency, duration, or adherence.
But they still came to this conclusion: the findings “support guidelines to recommend participation in any physical activity across adulthood and provide evidence that encouraging inactive adults to be more active at any time, and encouraging already active adults to maintain activity, could confer benefits on later life cognition.”
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