By Bahar Gholipour, Staff Writer
Published: 09/04/2013 04:08 PM EDT on LiveScience
People who exercise vigorously as young adults may reduce their risk of developing epilepsy later in life, a new study from Sweden suggests.
The researchers looked at 1.17 million Swedish men born between 1950 and 1987 who had completed cardiovascular fitness tests when they enlisted for military service at the age of 18. The participants were followed for up to 40 years, during which 6,796 men were diagnosed with epilepsy.
The results showed that men who had a high level of fitness were about 80 percent less likely to develop epilepsy, compared with men with low fitness levels, and 35 percent less likely to develop epilepsy than those with medium fitness levels, according to the study published today (Sept. 4) in the journal Neurology.
"There's a lot of relationships between fitness and neurological functions, especially in the developing brain," said study researcher Dr. Elinor Ben-Menachem, professor of neurology and epilepsy at University of Gothenburg in Sweden.
"People who are very fit at the age of 18 have been training the body over the years to reach that level of fitness. So these are children who've been active during the growth of their brain, when all of the synapses are being laid down, and the new connections are made," Ben-Menachemsaid.
How exercise affects epilepsy
Epilepsy is a group of related conditions characterized by repeated seizures. In the United States, an estimated 2.3 million adults and 470,000 children have epilepsy, and nearly 150,000 Americans develop the condition each year, according to the Centers for Disease Control and Prevention (CDC).
There are several risk factors and causes for epilepsy, some of which can be prevented. The CDC recommends proper prenatal care to avoid problems during pregnancy and childbirth that could lead to epilepsy, and vaccinations against infectious diseases that can affect the brain and contribute to epilepsy.
One frequent cause of epilepsy is traumatic brain injuries, such as those due to car crashes or falls. In the study, the researchers looked at the type of epilepsy thought to be caused by accidents in childhood, for which symptoms do not appear until adulthood.
For example, an adult's epilepsy might have been caused by falling off a swing when they were a child, Ben-Menachemsaid.
The new results suggest that exercise during childhood may prevent such injuries from having a lasting effect on the brain, the researchers said. However, the exact mechanisms are still unclear.
"We don't know how [physical activity protects the brain]. But we think that it increases resistance to attacks" on the nervous system, Ben-Menachem said.
'Amazing things' in the brain
In the study, participants' fitness levels were ranked on a scale of 1 to 9, based on how well they did on cycling tests. The men rode stationary bicycles with increasing resistance until they couldn't cycle anymore. The men who had the lowest scores were still healthy enough to have been enlisted in the military, Ben-Menachem noted.
Among men classified as having high fitness, about 2,380 out of about 500,000 developed epilepsy later (0.48 percent). Among men with medium fitness, about 4,000 out of 630,000, or 0.62 percent, developed epilepsy. The number of men with low fitness who developed epilepsy was 502 out of about 46,000 men, or 1.09 percent.
The results held after considering genetic factors, diabetes, previous incidents of traumatic brain injury and stroke.
Positive effects of exercise on the brain have been seen in other areas as well. Previous studies, some in humans and some in animals, have shown that exercise protects the brain against depression and Parkinson's disease, and improves neurogenesis and memory, Ben-Menachem said.
"We think fitness does amazing things in the brain," she said. "It's easy enough to do, and it's not a fancy medicine that costs you a lot of money."