Nutrients in blood linked to better brain connectivity, cognition in older adults

Higher levels of several key nutrients in the blood are linked to more efficient brain connectivity and performance on cognitive tests in older adults, a new study has found.

The study was published in the journal 'NeuroImage'. The researchers looked at 32 key nutrients in the Mediterranean diet, which previous research has shown is associated with better brain function in aging. It included 116 healthy adults aged 65 to 75 years.

"We wanted to investigate whether diet and nutrition predict cognitive performance in healthy older adults," said study author Christopher Zwilling.

The analysis linked specific patterns of a handful of nutrient biomarkers in the blood to better brain health and cognition. The nutrient patterns included omega-3 fatty acids, which are abundant in fish, walnuts and Brussels sprouts, omega-6 fatty acids, found in flaxseed, pumpkin seeds, pine nuts and pistachios, lycopene, a vivid red pigment in tomatoes, watermelon and a few other fruits and vegetables, alpha- and beta-carotenoids, which give sweet potatoes and carrots their characteristic orange color and vitamins B and D.

The researchers relied on some of the most rigorous methods available for examining nutrient intake and brain health. Rather than asking participants to answer food-intake surveys, which require the accurate recall of what and how much participants ate, the team looked for patterns of nutrient "biomarkers" in the blood. The team also used functional magnetic resonance imaging to carefully evaluate the efficiency with which various brain networks performed.

"The basic question we were asking was whether diet and nutrition are associated with healthy brain aging. And instead of inferring brain health from a cognitive test, we directly examined the brain using high-resolution brain imaging," said study co-author Aron Barbey.

Functional MRIs can indicate the efficiency of individual brain networks, he stated.

"Efficiency has to do with how information is communicated within the network. We looked at 'local efficiency' - how well information is shared within a spatially confined set of brain regions - and also 'global efficiency,' which reflects how many steps are required to transfer information from any one region to any other region in the network," said Barbey.

"If your network is more efficiently configured, then it should be easier, on average, to access relevant information and the task should take you less time," he added.

Participants also completed several cognitive tests.

The analysis found a robust link between higher levels of several nutrient biomarkers in the blood and enhanced performance on specific cognitive tests. These nutrients, which appeared to work synergistically, included omega-3 and omega-6 fatty acids, carotenoids, lycopene, riboflavin, folate, vitamin B12 and vitamin D.

The analysis also revealed that a pattern of omega-3s, omega-6s and carotene was linked to better functional brain network efficiency.

Different nutrient patterns appeared to moderate the efficiency in different brain networks. For example, higher levels of omega-3 fatty acids paralleled the positive relationship between a healthy frontoparietal network and general intelligence. The frontoparietal network supports the ability to focus attention and engage in goal-directed behavior.

To test the stability of the nutrient-biomarker patterns over time, the researchers invited 40 participants back for a second analysis roughly two years after the first tests. Similar nutrient patterns persisted in this subset of the original group.