Sports and health: physical activity prevents dementia in women

Middle-aged women with good physical fitness are nearly 90 percent less likely to develop dementia after a few decades than less exercised women. Physical activity, therefore, not only acts on cardiovascular health, but can protect against cognitive decline typical of old age. In addition, if women who do a lot of aerobic sports develop dementia, the symptoms of the condition occur on average 11 years later than others.

This is reported in a study led by Helena Hörder, of the University of Gothenburg, Sweden, and published in Neurology, the medical journal of the American Academy of Neurology.

Sports help prevent dementia by several mechanisms 

Numerous studies have shown that exercise is useful in the prevention of cognitive disorders and dementia in old age. Potential mechanisms underlying the protective effects of physical activity on cognitive function are presumed to be several: Sports are associated with a reduced risk of cardiovascular disease, which in turn are predisposing factors for dementia.

• Exercise improves blood circulation.
• Physical activity is associated with increasing substances needed for neuron growth and survival.
• Physical activity reduces substances responsible for oxidative stress.
• Physical activity correlates with more proper nutrition, which positively improves cognitive performance.
• Physical activity facilitates sociability and good mood.

At the brain level, it would appear that aerobic exercise can make the brain more efficient, plastic and adaptive, which leads to improved memory and executive function. Indeed, some research using animal models has shown that aerobic training increases the number of capillaries, the number of connections between brain cells, and the development of new neurons. In short: the mechanisms stimulated by regular physical activity include all those changes that affect the proliferation of neuronal cells, especially newly formed neurons that "connect" with others. 

A recent German study, for example, explored how exercise is able to influence brain metabolism by preventing the excessive increase of choline, a substance very important for the functioning of the nervous system. The results showed that exercise leads to stable brain choline concentrations in the "exercise" group, while choline levels are altered in the "control" group. According to the researchers, high levels of choline can cause nerve cell loss, a damage that commonly occurs in Alzheimer's disease. Alzheimer's is the most common form of dementia, and is caused by altered brain function with very serious consequences for the patient, who finds it difficult even to conduct normal daily activities. The disease affects areas of the brain involved in the processing of thought, memory, and language, causing amnesia, states of confusion, personality changes, loss of control of bodily functions, mood changes, and spatiotemporal disorientation. 

Women who play sports are less likely to develop dementia  

The new study investigated the role that physical fitness plays in protecting middle-aged women from cognitive decline, revealing that females who had done more aerobic physical activity showed up to 88 percent less likelihood of developing dementia, compared to those who were moderately fit. In addition, highly trained participants who had manifested cognitive deficits over the years had shown the first symptoms much later in life than the others, about 11 years later; at age 90 instead of age 79. "These results are exciting because it is possible that improved cardiovascular function in people in middle age may delay or even prevent them from developing dementia," said Professor Hörder. "This indicates that adverse cardiovascular processes that may occur around age 50 may increase the risk of dementia later in life," she continued.

Some details of the research 

To carry out the research, 191 women, with an average age of 50 years, who were classified by their peak cardiovascular capacity, were involved. The women were subjected to a physical exercise test, using a bicycle. The average workload was measured at 103 watts. A total of 40 women met the criteria of a high fitness level, equivalent to 120 watts or higher, 92 women were in the medium fitness category, while 59 women were classified in the low fitness level, represented a peak workload of 80 watts or less. Participants in the latter category had discontinued the exercise test because of high blood pressure, chest pain or other cardiovascular problems. The study continued over the next 44 years, during which the women were tested for dementia six times. After that period, a total of 44 women had developed dementia, 32% of whom were those who had shown low levels of fitness, at the beginning of the study, compared with 25% of the moderately fit women. Incredibly, only 5 percent of the ladies with dementia belonged to the highest physical activity level group.

More studies will be needed to understand the beneficial role of sports over the years. 

The reported study has some limitations, the main one being that it only examined women from Sweden, with results, therefore, applicable to a limited number of people. In addition, the participants' fitness levels were measured only once, so any changes in performance over time were not recorded. According to the researchers who conducted the research, although the results show an association between fitness, cardiovascular health and dementia, further studies will be needed to show a concrete cause and effect relationship, and to better determine whether increased exercise can have a positive effect on dementia risk and at what time of life it is most effective.

Source: Helena Hörder, Lena Johansson, XinXin Guo, Gunnar Grimby, Silke Kern,Ingmar Skoog.October 16, 2018; 91(16).Midlife cardiovascular fitness and dementia: A 44-year longitudinal population study in women.