Researchers in the United States have conducted two clinical trials to assess the benefit of nutritional supplements and exercise on memory and thinking skills. The studies were published in the Journal of the American Medical Association on 25 August 2015.
In one study, a US team followed over 3,500 people with an average age of 72, who were at high risk of developing age-related macular degeneration. Study volunteers received different forms of omega-3 fatty acids (docosahexaenoic acid [DHA], eicosapentaenoic acid [EPA]), lutein/zeaxanthin (antioxidants) or a placebo tablet. As the study volunteers were also taking part in a larger trial for age-related macular degeneration, they also received other supplements such as beta-carotene and zinc. The researchers involved in the trial did not know whether study volunteers were receiving supplements or placebo. The researchers carried out a series of tests to assess memory and thinking skills in volunteers at the start of the study and then every two years. After a five year period, the research team found that neither form of omega-3 supplement or antioxidants improved memory and thinking skills in study participants.
A second US study explored the impact of exercise on memory and thinking skills in 1,635 people aged 70 to 89. The team compared moderate intensity physical exercise with health education. The exercise programme included 30 minutes of walking, 10 minutes of lower-extremity strength training and 10 minutes of balance training three to four times a week. Health education involved weekly sessions, including talks on nutrition and financial issues as well as some flexibility exercises. These classes dropped to a frequency of once a month after the first 26 weeks of the study. The research team found that after two years there were small improvements in working memory and problem solving in the over 80s who took part in physical activity, compared to those on the health education programme. However, there were no differences in the numbers of people who went on to receive a diagnosis of mild cognitive impairment or dementia.
Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, said:
“Dementia is a huge global challenge and while the search for effective therapies intensifies, it is also important to look at more readily available tools that may stave off the onset of memory and thinking difficulties.
“Oily fish, which contains omega-3 fatty acids, is thought to be an important part of a healthy diet. Some studies have linked higher omega-3 intake with a lower risk of dementia, but current evidence does not suggest any benefit of taking omega-3 supplements on cognition. Similarly, this clinical trial suggests there is no benefit to taking omega-3 in later life when it comes to memory and thinking skills, although this study didn’t go on to look at a dementia diagnosis. As volunteers in this study had age-related macular degeneration and were being treated for this condition, it is difficult to know how these results apply to the wider population.
“We know that keeping physically active may reduce dementia risk, so it is interesting to see in this trial that there was no impact of exercise in later life when it came to a diagnosis of dementia. As the changes that occur in the brain diseases that cause dementia start 15-20 years before the onset of symptoms, it may be that a similar trial repeated in middle-aged people may have more of an impact on modifying dementia risk. Finding out when different lifestyle changes will have most impact forms a critical component of dementia prevention research.
“The best current evidence suggests that what’s good for your heart is good for your head and that keeping weight and blood pressure in check, quitting smoking and eating a healthy balanced diet can help reduce dementia risk.”