Can Maintained Exercise Lead to Better Brain Function in Later Life?

A new study has found that regular physical activity at any age is associated with better brain function later in life. However, the most benefits for mental acuity and memory are gained from a regular exercise routine throughout adulthood, suggests the study, published in the Journal of Neurology, Neurosurgery & Psychiatry.

Activity levels over time

Keeping physically active has many health benefits, including a reduced risk of dementia and cognitive decline as we age. However, there are still several unknowns surrounding the advantages of regular exercise on our brain health – how exactly does the timing, frequency or maintenance of physical activity during our leisure time affect cognition in later life?

In the current study, researchers investigated whether there may be periods across our lifespan during which we are particularly “sensitive” to exercise and its benefits, or if there may be multiple time periods.

The researchers examined data from 1417 participants of the British 1946 National Birth Cohort study, a project that followed people born in the same week of March 1946. The project is now an important source of information on the biological and social processes of aging.

The reported leisure time activity of the participants at ages 36, 43, 60–64 and 69 years were compared to the results of cognitive tests performed at age 69 to look at the strength of any associations. Physical activity was characterized as either:

• Inactive
• Moderately active (one to four times per month)
• Most active (five or more times per month)

These categories were summed across the ages that were examined, giving participants a total score from zero  to five depending on their activity levels over time.

Working out the effects on cognition

Assessments of cognitive performance – which included tests of attention, verbal fluency, memory and language – showed that maintenance of physical activity across all 5 time-points was associated with better cognitive performance, verbal memory and processing speed at 69 years of age.

The study authors suggest “that being physically active at any time in adulthood, even if participating as little as once per month, is linked with higher cognition.”

In fact, those who were the most physically active across all ages had the strongest association with cognitive ability at 69 years of age.

These effects remained statistically significant even after accounting for other factors such as cognitive ability in childhood, household income and education (though these did decrease the strength of the associations). Additionally, the results were not due to cardiovascular or mental health in later life.

Is routine more important than timing?

“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,” the researchers explain.

Importantly, the results of this observational study do not establish causation, and there are several limitations associated with it. For example, only white participants were included in the study, socially disadvantaged participants had a much higher attrition rate than others and there was no information provided on the intensity or duration of exercise.

Reference: James S-N, Chiou Y-J, Fatih N, Needham LP, Schott JM, Richards M. Timing of physical activity across adulthood on later life cognition: 30 years follow-up in the 1946 British birth cohort. 2023. J. Neurol. Neurosurg. Psychiatry. doi: 10.1136/jnnp-2022-329955

This article is a rework of a press release issued by the British Medical Journal. Material has been edited for length and content.