The benefits of exercise on physical health are no secret, but there is also an increasing amount of evidence to suggest that it can help emotional and mental well-being as well. For example, studies have suggested that it can enhance mood states, boost self-esteem and even help those with anxiety and mild depression. It’s thought that physical activity can trigger changes in brain chemistry, which can in turn have positive effects on our mood. But that might not be where exercise’s effects on the brain end, as a new study suggests exercise could be associated with changes in brain structure.
After studying pairs of identical twins in Finland whose physical activity habits were similar as they grew up but diverged in adulthood, the researchers found that not only were their bodies quite different, but there was also a disparity in the amount of brain tissue in certain regions. Of course, it is difficult to prove cause and effect, but since they have the same DNA and shared an upbringing, the results present a strong case that exercise could be at least playing a role. The study has been published in Medicine and Science in Sports and Exercise.
When scientists try to establish the long-term effects of something on the body, they have to consider many potentially confounding variables, such as genetics or background. As the New York Times points out, that’s why identical twins are so useful in studies such as these. They share 100% of their DNA, and if they grew up together then their upbringing is also likely to be very similar.
It is for these reasons that scientists in Finland took advantage of the country’s FinnTwin16 database to find out more about the effects of different physical activity routines on the body. This archive contained self-reported information about the individual’s health and lifestyle, which they used to narrow down their search. Specifically, they were interested in identical twins whose exercise habits had remained similar throughout their childhood but diverged significantly during adulthood. Just 10 pairs fitted the bill, in which one regularly exercised and the other did not, so they were enrolled into the study.
For the investigation, the scientists looked for differences in body composition, metabolic health in terms of blood sugar regulation, and brain structure. These examinations revealed that, unsurprisingly, the active twins had lower body fat percentages, but they were also found to be better at maintaining balances in blood sugar levels. While these could both be indicative of different food choices, the twins actually had very similar diets, making this an unlikely contributing factor. But perhaps the most interesting finding was that the active twins had more tissue, called grey matter, in two regions, one of which is involved in the coordination of body movements.
Of course, since this was not a randomized controlled trial, the researchers cannot definitively prove that it is the exercise that is causing these effects. However, the fact that the participants were identical twins does strongly suggest that exercise was at least partly responsible.