The Mediterranean diet is inspired by the dietary habits of Greece, Southern Italy, and Spain, and consists of high amounts of vegetables, fruits, whole grains, fish, poultry, legumes, and nuts, low-to-moderate alcohol and monounsaturated fat (e.g., olive oil). The diet limits red meat and full-fat dairy products. Numerous studies have shown that the Mediterranean diet may be associated with better cognitive health [1; 2]. But can it protect against Alzheimer’s disease? A recent study reported that higher adherence to the Mediterranean diet is associated with better memory, larger volumes of brain regions important for memory functions, and lower levels of biological markers of Alzheimer’s disease [3].
Findings come from a study of 512 people from Germany, of whom 169 participants had normal cognition without increased risk for Alzheimer’s disease, 53 had first-degree relatives with Alzheimer’s disease, 209 had subjective cognitive decline but preserved performance on cognitive tests, and 81 had mild cognitive impairment?. All participants underwent cognitive assessments covering a broad range of cognitive domains and answered detailed questionnaires on their dietary habits. The Mediterranean diet score was calculated based on the sum of the following nine habits with the total score ranging from 0 to 9 and higher values indicating higher adherence.
Researchers discovered that higher adherence to the Mediterranean diet was associated with larger volumes of two related brain regions important for memory functions: the parahippocampal gyrus and the hippocampus. A one-point higher Mediterranean diet score corresponded to a larger brain volume associated with being 10 months younger in age. They also reported that higher adherence to the Mediterranean diet was associated with better memory function. Here, a one-point increase in the Mediterranean diet score corresponded to better memory function associated with being one year younger in age. And finally, participants who closely followed the Mediterranean diet had lower levels of biological markers of Alzheimer’s disease (abnormal forms of beta-amyloid and tau). Notably, a one-point higher Mediterranean diet score corresponded to a lower pathologic burden associated with being 3.3-3.5 years younger. Importantly, these associations between the diet score and brain volume, memory function, and Alzheimer’s markers remained significant even after controlling for different biological variables such as caloric intake, body mass index, and physical activity.
Because this was an observational study and not a randomized controlled clinical trial, it was not designed to prove that the Mediterranean diet can prevent Alzheimer’s disease. However, the study identified strong associations between the Mediterranean diet and better brain health. And these findings are in line with data from randomized controlled trials showing that the Mediterranean diet improves cognitive functions [4] and lowers the incidence of mild cognitive impairment [1]. Previous observational studies have also shown that closely following the Mediterranean diet is associated with preserved brain volume [5] and less amyloid pathology [6; 7]. With the increasing body of literature on the Mediterranean diet, following a diet rich in fruits, vegetables, fish, whole grains, legumes, and nuts, while limiting red meat and full-fat dairy, appears to be most beneficial for brain health.
Yuko Hara, PhD, is Director of Aging and Alzheimer's Prevention at the Alzheimer's Drug Discovery Foundation. Dr. Hara was previously an Assistant Professor in Neuroscience at the Icahn School of Medicine at Mount Sinai, where she remains an adjunct faculty member. Her research focused on brain aging, specifically how estrogens and reproductive aging influence the aging brain's synapses and mitochondria. She earned a doctorate in neurology and neuroscience at Weill Graduate School of Medical Sciences of Cornell University and a bachelor's degree in biology from Cornell University, with additional study at Keio University in Japan. Dr. Hara has authored numerous peer-reviewed publications, including articles in PNAS and Journal of Neuroscience.
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