Exercising at least once a month linked to better brain function in later life
Exercising at least once a month at any time in adulthood is linked to better cognitive functioning in later life, a new study led by UCL researchers has found.
The study, published in the Journal of Neurology, Neurosurgery, and Psychiatry looked at data from 1,417 people who filled in surveys about their leisure-time physical activity (sports and exercise) over three decades and took cognitive tests at the age of 69.
The research team found that people who reported being physically active at least one to four times a month in five separate surveys, at the ages of 36, 43, 53, 60-64, and 69, had the biggest cognitive effect. This effect was greater than for those who reported exercising frequently (more than five times a month) during at least one survey period, but who did not necessarily keep this up across multiple surveys.
Lead author Dr Sarah-Naomi James (MRC Unit for Lifelong Health & Ageing at UCL) said: "Our study suggests that engaging in any leisure-time physical activity, at any point in adult life, has a positive effect on cognition. This seems to be the case even at light levels of activity, between once to four times a month. What's more, people who have never been active before, and then start to be active in their 60s, also appear to have better cognitive function than those who were never active.
"The greatest cognitive effect was seen for those who stayed physically active throughout their life. The effect is accumulative, so the longer an individual is active, the more likely they are to have higher later-life cognitive function."
The study participants were from the 1946 British Birth Cohort, the UK's longest-running population-based cohort who were all born in the same week in 1946 and whose health has been tracked throughout their life.
The researchers aimed to investigate if there was a period of life when physical activity was particularly important for later-life cognitive function, in the same way that cardiovascular health in middle age appears to be more important for later cognitive health than during other times of life.
But, rather than finding that one period of life was more important than others, they concluded that starting some form of physical activity and maintaining it over a long time may be more important than the timing of this activity.
At each survey, participants were asked how often they took part in leisure-time physical activity in the last month. Possible activities included jogging, dancing, gardening and hiking as well as a range of sports. The research team grouped respondents as either not active (no physical activity in the last month), moderately active (one to four times a month) and most active (more than five times a month).
At age 69, study participants took several cognitive tests, including the Addenbrooke's Cognitive Examination, which assesses overall cognitive state and is used to screen people for cognitive impairment. They also did a word learning test (having to recall as many of a list of 15 words as they can) and a visual processing speed test, where they were asked to cross out all instances of a particular letter in a page of text.
The researchers also looked at other factors that might explain the link between exercise and cognitive functioning. (The exact mechanism that links the two is still unclear.)
They found that, while a link remained after accounting for a number of other factors including mental health and cardiovascular health, half to two thirds of the association could be explained by three factors: education level, childhood cognition and socioeconomic background.
That is, people who engaged more in physical activity were also more likely to have taken A-levels and gone to university, had parents from a more privileged background, and done better in tests at the age of eight, and these factors may separately contribute to better cognitive function in later life. However, a separate link remained between exercise and cognitive function and the researchers said more work was needed to understand this link better.
Limitations of the study were that the study cohort were exclusively white Caucasian and that participants were more likely to drop out of the cohort if they were socially disadvantaged and less healthy. Strengths were the long follow-up period over decades and its investigation of other potential causes of better late-life cognitive function.
The research was supported by Alzheimer's Research UK (ARUK) and the Medical Research Council, and involved researchers from the MRC Unit for Lifelong Health & Ageing at UCL and the UCL Queen Square Institute of Neurology.
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