EXERCISE AND ALZHEIMER'S

Issue : April / May 2018
 

Although we identified Alzheimer’s disease in 1906, over a century ago, treatment for this terrible disease has hardly progressed. While some medicines are prescribed to treat mild to moderate Alzheimer’s, such as rivastigmine and galantamine, and donepezil has been approved to treat all stages of Alzheimer’s, these only ameliorate symptoms and cannot provide any kind of cure.

It is a dark and debilitating disease, but many clinical trials are looking at ways to slow its progression or protect our brains from symptoms. One interesting positive factor is exercise, which is easy enough for us to pursue. I will discuss the available information so readers can take it into account.

Regular physical activity can lower the risk of Alzheimer's and vascular dementia, or brain deterioration. Because it is well known for cardiovascular benefits, a medically approved exercise programme is a valuable part of any wellness plan. Regular exercise may help prevent Alzheimer’s in a number of ways, by increasing blood and oxygen flow in the brain and thus encouraging the development of new brain cells.

A study released in May 2017 added information on the impact of physical activity on brain physiology and offers hope that it may be possible to re-establish some protective neuronal connections. This study, led by University of Maryland School of Public Health researchers Dr J. Carson Smith, associate professor of kinesiology, and colleagues, explored how a 12-week walking intervention with older adults aged 60-88 affected functionality of a brain region known to show decline in people suffering from mild cognitive impairment (MCI) or Alzheimer's disease.

Dr Smith's research team recruited two groups, one with 16 healthy elders and another with 16 elders with mild cognitive impairment, to participate in an exercise intervention that included walking for 30 minutes four times a week (at 50-60% of heart rate reserve) for three months. Before and after exercise, participants in both groups underwent brain scans to assess functional connectivity between multiple brain regions and the posterior cingulate cortex (PCC), or the area around the midline of the brain and precuneus (the medial area of the brain).

After completing the intervention, both groups showed improved ability to remember a list of words; however, only the MCI group showed increased connectivity to the PCC/precuneus hub, evident in 10 brain regions spanning the frontal, parietal, temporal and insular lobes and the cerebellum.

Dr Smith commented, "These findings suggest the protective effects of exercise training on cognition may be realized by the brain re-establishing communication and connections among the brain's so-called default mode network, which may increase the capacity to compensate for the neural pathology associated with Alzheimer's disease."

While it is still unclear whether exercise can delay cognitive decline in patients diagnosed with MCI, the neural network connectivity changes documented in this study provide hope that exercise may stimulate brain plasticity and restore communication between brain regions that is lost through Alzheimer's disease. The specificity of these effects in the MCI group suggests that exercise may be particularly useful for those who have already experienced mild memory loss.

The best types of exercise are aerobic activities like walking, biking or even gardening. The Alzheimer’s Association suggests 30 minutes of exercise a day to get the body moving and the heart pumping. Surprisingly, we don’t have to do these 30 minutes all at once. Research shows that even breaking this time into three episodes of 10 minutes each (walking the dog, taking a brisk walk, climbing a few flights of stairs at lunchtime or as a work break) can be beneficial. Basically, it doesn’t have to be one specific activity; any activity can help us stay mentally active and we can do whatever we enjoy. The old belief of “use it or lose it” seems to hold true for the brain just as it does for other parts of the body.

The study on the benefits of physical activity on Alzheimer’s is from Dr Steen Hasselbalch and colleagues from the Danish Dementia Research Centre in Copenhagen. In the study, 200 people with Alzheimer’s aged 50-90 (average age 70.9) were randomly assigned either an aerobic exercise programme (60-minute exercise sessions three times a week for 16 weeks supervised by experienced physiotherapists) or a control group (standard care, no extra exercise).

There was a significant difference in neuropsychiatric symptoms in favour of the intervention group. People who participated in the exercise programme had far less anxiety, irritability and depression. Those in the control group had deteriorated psychiatric symptoms while the intervention group improved slightly. Furthermore, those who attended more than 80% of classes and exercised vigorously had significant improvements in mental speed and attention span. In addition, this group improved in physical fitness, physical function, dual-task performance and exercise self-efficacy.

Dr Hasselbalch commented that these neuropsychiatric symptoms that often occur in Alzheimer’s disease are the cause of great distress in both caregivers and people with disease. Therefore, multimodal treatment strategies including mixing exercise and drug therapies may prove to be effective for Alzheimer’s patients.

The third study was conducted on the impact of aerobic exercise on reducing the tau protein in older adults with mild cognitive impairment. Tau protein, when it becomes abnormal, can initiate a variety of biological changes that result in brain cells dying, and higher levels of tau in the brain are associated with faster rates of decline. As such, therapies to prevent cognitive decline and dementia are now beginning to focus on reducing tau.

Researcher Dr Laura Baker and colleagues from the Wake Forest School of Medicine, Winston-Salem, North Carolina, US, had previously shown that in older adults with mild cognitive impairment, regular moderate-to-high intensity aerobic exercise has benefits for cognition and plasma levels of amyloid protein, the other primary component of the hallmark lesions of Alzheimer’s known as plaques.

Her team reported results of a six-month randomized controlled trial of moderate-to-high intensity aerobic exercise in 65 sedentary adults with MCI 55-89 years old to test whether aerobic exercise might also lower tau levels in the brain. What they found was that participants who completed aerobic exercise (most commonly on a treadmill) saw a statistically significant reduction in tau levels in their cerebrospinal fluid (CSF). The effect was most pronounced in adults over the age of 70. Aerobic exercise significantly increased blood flow in the memory and processing centres of participants' brains, with a corresponding improvement in attention, planning and organizing abilities referred to as the “executive function”.

Dr Baker concluded that these findings suggest a potent lifestyle intervention such as aerobic exercise can have greater impact on Alzheimer’s-related changes in the brain than currently approved medications.

The benefits of exercise on dementia were also confirmed in a trial conducted by Dr Teresa Liu-Ambrose from the University of British Columbia, Vancouver, Canada. This study started with the fact that cerebrovascular disease is the second most common cause of dementia in older adults, behind Alzheimer’s. Research showed that reducing heart health risk factors, such as high blood pressure and high cholesterol, may reduce dementia risk and slow the progression of cognitive decline due to mini-strokes, known as vascular cognitive impairment (VCI). This indicated that aerobic exercise such as running and brisk walking may be a very promising strategy against vascular cognitive impairment. Activity not only decreases heart health risk factors but may improve brain structure and function.

Dr Liu-Ambrose reported results from a six-month study of 71 adults 56-96 years old with confirmed cases of mild VCI. These adults were assigned to two groups, one with aerobic exercise three times per week, while the other received the usual care plus an educational seminar on nutrition. These two groups received a standard test of memory and thought process at the beginning and end of the study. Participants who took aerobics classes significantly improved cognitive function, including memory and selective attention, compared to people receiving the usual care.

In addition, functional brain scans acquired before and after the six-month study showed that the brains of study participants became more efficient with aerobic exercise.

Dr Liu-Ambrose commented that aerobic exercise can improve cognitive function in VCI, meaning there may soon be a tool that can prolong independence and improve the quality of life of people with the condition. Exercise is a strategy that can be inexpensively delivered at the population level.

Besides the benefits of exercise shown in these four studies, there are other recommendations thought to hinder Alzheimer’s, including using the brain to analyse and be challenged, to have friends and a nice surrounding environment, to refrain from stress where possible, to eat properly and take good care of your heath and have good quality sleep. As such, try your best to adopt these habits and your advanced years can be a golden period in your life.

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