Mediterranean diet supportive in Alzheimer’s disease prevention

A regular Mediterranean-like dietary pattern with relatively more intake of vegetables, legumes, fruit, cereals, fish, and monounsaturated fatty acids, such as from olive oil, may protect against protein deposits in the brain and brain atrophy, according to new research published in the journal Neurology. This diet has a low intake of dairy products, red meat, and saturated fatty acids.

In Alzheimer's disease, neurons in the brain die. Largely responsible for the death of neurons are certain protein deposits in the brains of affected individuals, so-called beta-amyloid proteins, which form clumps or plaques between neurons, and tau proteins, which stick together the inside of neurons. The causes of these deposits are unclear. In addition, a rapidly progressive atrophy, a shrinking of the brain volume, can be observed. Alzheimer's symptoms such as memory loss, disorientation, agitation, and challenging behavior are the consequences, the researchers said.

For the study, a total of 512 subjects with an average age of around 70 years old took part in the study. According to Michael Wagner, PhD, lead researcher of the study, 169 of them were cognitively healthy, while 343 were identified as having a higher risk of developing Alzheimer's disease, due to subjective memory impairment, mild cognitive impairment that is the precursor to dementia, or first-degree relationship with patients diagnosed with Alzheimer's disease.

The nutrition study was funded by the Diet-Body-Brain competence cluster of the German Federal Ministry of Education and Research (BMBF) and took place as part of the so-called DELCODE study of the DZNE, which does nationwide research on the early phase of Alzheimer's disease, the period before pronounced symptoms appear.

Additionally, the researchers performed brain scans with magnetic resonance imaging (MRI) scanners to determine brain volume. All subjects underwent various neuropsychological tests in which cognitive abilities such as memory functions were examined. The research team also looked at biomarker levels for amyloid beta proteins and tau proteins in the so-called cerebrospinal fluid (CSF) of 226 subjects.

The researchers found that those who ate an unhealthy diet had more pathological levels of these biomarkers in the cerebrospinal fluid than those who regularly ate a Mediterranean-like diet. In the memory tests, the participants who did not adhere to the Mediterranean diet also performed worse than those who regularly ate fish and vegetables.

"It is possible that the Mediterranean diet protects the brain from protein deposits and brain atrophy that can cause memory loss and dementia,” said Tommaso Ballarini, PhD, lead author of the study and postdoctoral fellow in Wagner's research group, in a statement. "But the biological mechanism underlying this will have to be clarified in future studies."

As a next step, Ballarini and Wagner said they now plan to re-examine the same study participants in four to five years to explore how their nutrition, Mediterranean-like or unhealthy, affects brain aging over time.