A couch potato lifestyle may reduce brain size in later life.
Physical fitness can be challenging to achieve and maintain, but we all know it is something we must strive to do.
The benefits of fitness are well known, and the physiology behind those benefits is, for the most part, well understood.
A new study, published in Neurology, adds further evidence of yet another helth benefit of fitness - maintaining brain size in older age.
The research, carried out by Nicole Spartano, used data from the Framingham Heart Study. In total, 1,583 participants, with an average age of 40 and without dementia or heart disease, took a treadmill test to rate their fitness.
Twenty years down the line, the same individuals were once again examined for fitness, and MRI scans were taken. Fitness was assessed by measuring the length of time it took their heart rate to increase to a certain level.
Lower fitness, smaller brain
The team found that for every eight-unit decrease in performance on the fitness trial, brain volumes dropped in size equivalent to 2 years' additional aging. When people with heart disease and those taking beta blockers were removed from the equation, a similar drop in fitness equated to 1 year's additional aging.
Spartano spells out the findings:
"We found a direct correlation in our study between poor fitness and brain volume decades later, which indicates accelerated brain aging."
The study is observational, so only associations can be drawn, but the results make interesting reading.
The next question is, of course, how a lack of fitness could impact brain volume. Medical News Today asked Spartano what mechanisms she believes might influence this type of neurological change, and she said:
"From other studies, we know that exercise training programs that improve fitness may increase blood flow and oxygen delivery to the brain and improve neuroplasticity over the short term.
Over the course of a lifetime, these mechanisms may have an impact on brain aging and prevent cognitive decline in older age."
She goes on to say that "it is likely that many lifestyle factors have an effect on brain aging, not just fitness." The brain and its relationship with the body is complex; anything that changes its gross anatomy is likely to be equally complex.
Exercise and the aging brain
Although this study examines the effects of fitness in middle age and the implications for brain size in older age, other research has shown that it is never too late for your brain to benefit from exercise.
A small study, published in 2006, using 60-79-year-olds, looked at the effect of 6 months of aerobic exercise on brain size. The researchers found that, compared with a control group who did non-aerobic stretching exercises, both white and gray matter increased in volume.
Another study in 2013 found that a 12-week fitness program for sedentary 57-75-year-olds improved resting cerebral blood flow and performance in memory tasks. It seems that just a small amount of exercise can make significant positive changes in your brain.
Larger studies in the future will undoubtedly unpick the mechanisms at play. In that regard, Spartano told MNT that she is currently working on further trials investigating how "changes in activity over the lifespan impact brain health."
As Americans live longer lives and the average age of the population increases, the science of keeping healthier and brighter for longer becomes ever more important. MNT recently covered research into a treatment that reversed aging in the brain of rats.