Lower your Alzheimer's risk with antioxidants and exercise

By Lauren Davis
Thursday, 06 February, 2020

Lower your Alzheimer's risk with antioxidants and exercise

Fruits, vegetables and cardio may help lower risk of Alzheimer’s disease (AD) — the latter even having an impact in those with genetic predisposition to the disease.

At a time when both the human and monetary costs of AD are projected to rise dramatically in the coming decades, there is a critical need to provide individuals with readily deployable strategies that can decrease the likelihood of acquiring the disease or slow its progression. This is particularly important given that drugs currently available to treat the disease have limited therapeutic capacity.

The first of the two new studies, published in the journal Neurology by Rush University researchers, found that people who eat or drink more foods with the antioxidant flavonol may be less likely to develop AD years later. Flavonol is a type of flavonoid, a group of phytochemicals found in plant pigments known for its beneficial effects on health. It is found in nearly all fruits and vegetables as well as tea; the average flavonol intake in US adults is about 16–20 mg/day.

The study involved 921 people with an average age of 81 who initially did not have AD. Participants filled out a questionnaire each year on how often they ate certain foods and were also asked about other factors, such as their level of education, how much time they spent doing physical activities and how much time they spent doing mentally engaging activities such as reading and playing games. They were followed for an average of six years and tested yearly for AD; it was determined that 220 people developed the disease during the study.

The study found that those with the highest flavonol intake (~15.3 mg/day) were 48% less likely to later develop AD than those with the lowest intake (5.3 mg/day) after adjusting for genetic predisposition as well as demographic and lifestyle factors. Of the 186 people in the highest group, 28 people, or 15%, developed AD, compared to 54 people, or 30%, of the 182 people in the lowest group. The results were the same after researchers adjusted for other factors that could affect the risk of AD, such as diabetes, previous heart attack, stroke and high blood pressure.

The study also broke the flavonols down into four types: isorhamnetin, kaempferol, myricetin and quercetin. The top food contributors for each category were: pears, olive oil, wine and tomato sauce for isorhamnetin; kale, beans, tea, spinach and broccoli for kaempferol; tea, wine, kale, oranges and tomatoes for myricetin; and tomatoes, kale, apples and tea for quercetin.

People with high intake of kaempferol were 51% less likely to develop the disease. Those who had high intake of isorhamnetin were 38% less likely to develop AD, as were those with high intake of myricetin. Quercetin was not tied to a lower risk of AD.

“More research is needed to confirm these results, but these are promising findings,” said study author Dr Thomas M Holland. “Eating more fruits and vegetables and drinking more tea could be a fairly inexpensive and easy way for people to help stave off Alzheimer’s dementia. With the elderly population increasing worldwide, any decrease in the number of people with this devastating disease, or even delaying it for a few years, could have an enormous benefit on public health.”

But how easy is it to prevent AD when you have family history or genetic predisposition to the disease? That’s what researchers from the University of Wisconsin–Madison sought to find out, investigating whether exercise training in asymptomatic individuals harbouring risk for AD improves markers associated with AD.

The team’s study, published in the journal Brain Plasticity, found that those who engaged in six months of aerobic exercise training improved their brain glucose metabolism and executive function — an aspect of cognition that comprises the mental processes enabling individuals to plan, focus attention, remember instructions and juggle multiple tasks successfully, and is known to decline with the progression of AD. These improvements occurred in conjunction with increased cardiorespiratory fitness.

The study investigated 23 cognitively normal, relatively young older adults with a family history or genetic risk for AD. All patients had a sedentary lifestyle. They underwent a battery of assessments, including cardiorespiratory fitness testing, measurement of daily physical activity, brain glucose metabolism imaging (a measure of neuronal health) and cognitive function tests.

Half of the participants were randomly assigned to receive information about maintaining an active lifestyle but no further intervention. The other half participated in a moderate intensity treadmill training program, with a personal trainer, three times per week for 26 weeks.

Compared to the participants maintaining their usual level of physical activity, individuals assigned to the active training program improved their cardiorespiratory fitness, spent less time sedentary after the training program ended and performed better on cognitive tests of executive functioning (but not episodic memory). The participants’ improved cardiorespiratory fitness was associated with increased brain glucose metabolism in the posterior cingulate cortex, an area of the brain linked to AD.

“This research shows that a lifestyle behaviour — regular aerobic exercise — can potentially enhance brain and cognitive functions that are particularly sensitive to the disease,” said lead investigator Dr Ozioma C Okonkwo. “The findings are especially relevant to individuals who are at a higher risk due to family history or genetic predisposition.

“This study is a significant step toward developing an exercise prescription that protects the brain against AD, even among people who were previously sedentary.”

The lead author on the study, Max Gaitán, added that “an important next step would be to conduct a larger, more definitive study. If these findings are replicated, they would have a tremendous impact on quality of later life, providing individuals with more years of independent living, active engagement with loved ones and building memories”.

Image credit: ©stock.adobe.com/au/pressmaster

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