Exercise increases brain size, stops glaucoma, studies show
Aerobic exercise can improve memory function and maintain brain health as we age, a new Australian-led study has found.In a first of its kind international collaboration, researchers from Australia’s National Institute of Complementary Medicine at Western Sydney University and the Division of Psychology and Mental Health at the University of Manchester in the United Kingdom (U.K.) examined the effects of aerobic exercise on a region of the brain called the hippocampus, which is critical for memory and other brain functions.
Brain health decreases with age, with the average brain shrinking by approximately five per cent per decade after the age of 40.Studies in mice and rats have consistently shown that physical exercise increases the size of the hippocampus but until now evidence in humans has been inconsistent.
The researchers systematically reviewed 14 clinical trials, which examined the brain scans of 737 people before and after aerobic exercise programs or in control conditions.
The participants included a mix of healthy adults, people with mild cognitive impairment such as Alzheimer’s and people with a clinical diagnosis of mental illness including depression and schizophrenia. Ages ranged from 24 to 76 years with an average age of 66.
The researchers examined effects of aerobic exercise, including stationary cycling, walking, and treadmill running. The length of the interventions ranged from three to 24 months with a range of 2-5 sessions per week.
Overall, the results — published in the journal NeuroImage — showed that, while exercise had no effect on total hippocampal volume, it did significantly increase the size of the left region of the hippocampus in humans.
Also, people who engage in moderate to vigorous physical activity may be able to significantly lower their risk of glaucoma, according to research presented Monday at AAO 2017, the 121st Annual Meeting of the American Academy of Ophthalmology. Researchers from the University of California, Los Angeles reported a 73 percent decline in the risk of developing the disease among the most physically active study participants, compared with those who were the least active.
Glaucoma is one of the leading causes of blindness in the United States. It is most common in people over 40. Treatment can slow its progression, but there is no cure. It has long been thought that lifestyle choices do not play a role in glaucoma, but several recent studies show that lifestyle factors can influence eye pressure, which is a major risk factor for the disease.
To examine the correlation between exercise intensity and glaucoma, the researchers looked at data from the National Health and Nutrition Examination Survey, a large study that has tracked the health and nutritional status of adults in the United States since the 1960s. They defined moderate to vigorous activity in terms of walking speed and the number of steps taken per minute as measured by a pedometer. Taking 7,000 steps a day, every day of the week is considered equivalent to 30 minutes a day of moderate-to-vigorous physical activity at least five days a week.
The researchers found that for each 10-unit increase in walking speed and number of steps taken per minute, glaucoma risk decreased by 6 percent. For each 10-minute increase in moderate-to-vigorous activity per week, glaucoma risk decreased 25 percent.
“Our research suggests that it is not only the act of exercising that may be associated with decreased glaucoma risk, but that people who exercise with higher speed and more steps of walking or running may even further decrease their glaucoma risk compared to people who exercise at lower speeds with less steps,” said Victoria L. Tseng, M.D., Ph.D., of the University of California, Los Angeles.
Some studies have demonstrated that blood flow and pressure inside the eye may change with exercise, which may affect glaucoma risk, Dr. Tseng noted. However, more research directly examining the relationship between exercise and glaucoma is required before physicians can make specific recommendations on exercise and glaucoma.In the meantime, she advises exercise for her patients as a beneficial activity for all aspects of health, including the eyes.
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