1. Modifiable factors that can improve brain health

“There are many factors that we can change to improve our brain health,” began Álvaro Pascual Leone, professor of Neurology at Harvard Medical School and leader of this B·Debate. “Some are quite well known, like nutrition, exercise and sleep, but there are others we don’t talk about as much, like environmental, psychological and social factors.”

Several studies have shown beneficial associations between eating certain foods and cognitive function. In general, the candidates are rich in omega-3 fatty acids and antioxidants like polyphenols. Some of these are fruit, legumes, fish, and nuts. However, “the evidence is weak,” recognizes Emili Ros, researcher at Hospital Clinic Barcelona. Clinical trials have not always confirmed these associations, especially with nutritional supplements. One example is taking the typical capsules with omega-3 fatty acids from fish, which didn’t show any overall cognitive benefits when information from 25 different trials was compiled.

Instead of isolated foods, the evidence currently points to the benefits of a well-rounded Mediterranean diet. A review of 17 studies showed an improvement in older people, and data from the PREDIMED clinical trial coordinated by Emili Ros also pointed in that direction: a Mediterranean diet (enriched in this case with olive oil or nuts) delays onset or even stabilizes age-related cognitive decline.

“Even though there is a lot still to learn, there are many mechanisms that indicate physical exercise is good for the brain,” noted Arthur Kramer, director of the Center for Cognitive and Brain Health and professor of psychology at Northeastern University in Boston. Studies show that exercise improves brain function, and that “the benefits are global, mainly related to executive functions.”

“Walking regularly is enough to see the structural changes in the brain’s gray and white matter,” said Kramer. These changes, which appear in areas like the hippocampus, which is closely tied to memory, seem to favor connectivity, making older people’s brains “look more like those of a young person.”

Lack of sleep, in quantity or quality, has been associated with numerous illnesses, and poor memory, concentration and cognitive performance. According to Alex Iranzo, a neurologist at Hospital Clinic Barcelona, “we need to sleep well and enough to be healthy, to be more productive (at work, socially and in the family) and, in short, to be happier.” 

Sleep alterations can also be a harbinger of some neurological diseases. Iranzo’s group studies REM sleep behavior disorder, which can appear several years before a patient develops Parkinson and could help test the effects of neuroprotective drugs.

Other factors that seem to be important in brain health are environmental, specifically those related to air pollution. “Brain development in the early stages of life is also important to the later stages, and even to the risk of developing dementia, we believe,” explained Jordi Sunyer, head of the ISGlobal Childhood Health Program in Barcelona. In recent years, his research group has been studying the relationship between particles that mainly come from traffic and the neurological development of children of various ages. Their studies show that brain development is slower in more polluted areas, and that pollution has both chronic and acute effects on working memory.

“One thing I’ve learned,” noted Sunyer, “is that scientists can’t focus solely on research and our labs, we also have to work to transfer our results. I’m proud that our research has led to urban planning measures around schools in several cities.”

As Professor of Neurology at Harvard Medical School Amar Dhand noted, the definition of health isn’t just the absence of disease, but also alludes to “full physical, mental and social wellbeing.” This final pillar of health is also crucial, although many times completely overlooked. “Social isolation is detrimental to the brain, both directly and indirectly,” said Dhand. In terms of mortality, the effects of loneliness are comparable to smoking three or four packs of cigarettes a day. 

Another factor that impacts brain health and the risk of cognitive deterioration is personality, which can make a person more likely to suffer from depression or anxiety. According to Nathalie Marchant, a researcher at University College London, both have been associated with an increased risk of dementia in the elderly. Although they could be an initial symptom of the disease, it also seems there is a causal relationship, as with anxiety the risk has been observed even ten years before dementia is diagnosed.

“In general, it is personality traits with a certain degree of neuroticism that increase risk,” said Marchant. “And they all have something in common, which is that they lead to repetitive negative thoughts.” They involve brooding and worrying that has more to do with the process than the content of the thoughts. 

The studies carried out by Marchant’s group show that people with these traits tend to show more build-up of the amyloid plaques typical of Alzheimer and greater age-related cognitive decline. This doesn’t seem like good news because “personality traits are fairly stable,” she explained. “The good thing is that repetitive negative thoughts can be controlled. For example, using practices like mindfulness. Our next studies will focus on finding out whether these psychological interventions decrease the risk of dementia,” she concluded.