Recent research has found that one hour of vigorous exercise a week is enough to cut your chance of dementia by half – but if you exercise while pregnant, you may be able to boost your unborn child’s memory too.
We all know that exercise is good for our bodies but current research is revealing that it’s also good for our brains. Exercise has been shown to boost executive functions such as planning, working memory and multi-tasking – and people who take part in aerobic exercise in particular, such as running, swimming or cycling, show increased performance on tests of general neuropsychological function. Now, researchers in Cambridge have reported that people who take part in intense exercise for an hour or more every week are far less likely to develop dementia – their risk is reduced by 45 per cent.
So how does exercise affect our brains? Physical activity is known to increase levels of genes such as BDNF and IGF-1 in the brain – genes which are associated with neuronal survival and plasticity. In animal studies, the growth of the branches that connect neurons has been shown to increase with physical exercise. This growth was correlated with the total distance the animal had run – those who ran longer had more wiring in their brains. Exercise also promotes increased neurogenesis – the creation of new brain cells in adulthood – in a part of the brain called the hippocampus. Humans who exercise also show increased grey matter in the hippocampus, and in the prefrontal and cingulate cortices, all areas that are associated with memory. Exercise not only sculpts our bodies, it physically shapes our brains as well.
Surprisingly, these benefits of exercise may not be limited to your own brain. Current research is revealing that the pups of rats that exercise while pregnant appear to inherit brains that are hotwired for better learning. Both adult rats who exercise and the pups of active mothers not only show increased neurogenesis and neuronal growth in the hippocampus, they also haveimproved spatial memory, a function that the hippocampus is known to be crucial for.
In the most recent study in this area, researchers wanted to test whether these benefits extend to other forms of memory that are known to rely on other brain areas. One group of pregnant rats was given access to a running wheel while another group was not, in order to manipulate the amount of exercise they engaged in. After the rats gave birth, the researchers waited for the offspring to mature and then tested their ability to remember certain objects.
It’s easy to test if a human remembers an object – you just ask them. But how can you possibly know whether a rat remembers something? The researchers overcame this problem by exploiting a fundamental principle of animal behaviour. Like all mammals, rats are more interested in novel objects than familiar ones. If you let them spend time with a new object and a previously seen one, it will spend more time exploring the new object – but only if it remembers the other one.
The researchers usedthis phenomenon to measure the memory of the rat offspring. They found that rats whose mothers had exercised regularly while they were pregnant could reliably remember which of the objects they had seen before. Rats in the other group, however, found it impossible to tell novel objects apart from familiarones. Maternal exercise during pregnancy had endowed their pups with a vastly superior memory – an effect that lasted well into adulthood.
In the brain, curled up next to the hippocampus lies the perirhinal cortex, an area that is thought to be specialised for object recognition memory in both rats and humans. The researchers measured how active the cells in this part of the brain had been during the task by tagging the expression of a gene called c-FOS that is switched on when neurons become active. They found that the offspring with improved memory (as a result of their mother’s exercise) had far more neurons active in the peririnhinal cortex during the task, which may account for their increased recognition abilities. So it seems that as well as extending beyond the brain of the individual taking part in the exercise, the benefits also extend into multiple brain areas and improve multiple forms of amemory.
It is still early days for research into the effect of exercise on the brain. In fact, a large-scale study is currently underway at Oxford University which hopes to more fully elucidate the effects of physical activity on cognitive health at we age. While more research needs to be done on the inheritance of exercise related brain benefits in humans, the similarity of our brains to a rat’s makes it likely that similar effects of maternal exercise may be observed in human offspring. Even though you can’t currently bet on a few jogs improving your child’s future school grades, you can rely on exercise benefiting your own brain. Given the specific benefit for memory, remembering to run today may just make you less likely to forget in the future.
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