New findings from a long-term diet trial demonstrate a positive effect on brain health.
A positive impact on brain health has been observed in individuals who switch to a Green Mediterranean Diet, as indicated by recent research conducted by Ben-Gurion University of the Negev. Brain aging was mitigated through weight loss in a sub-study of the DIRECT-PLUS trial.
A large-scale, long-term clinical trial was conducted over 18 months, involving 300 participants, known as DIRECT PLUS.
The sub-study was carried out by Prof. Galia Avidan of the Department of Psychology and Dr. Gidon Levakov, a former graduate student at the Department of Cognitive and Brain Sciences.
Recently, their findings were published in the scientific journal eLife.
The larger study was conducted by Prof. Iris Shai of Ben-Gurion University of the Negev, in collaboration with her former graduate student Dr. Alon Kaplan, and colleagues from Harvard and Leipzig Universities. Prof. Iris Shai is an adjunct Professor from the Harvard School of Public Health and an honorary professor at the University of Leipzig, Germany.
The link between obesity and accelerated brain aging has been identified, surpassing the expected rate. The process of determining a person’s “brain age” through detailed scans, regardless of their chronological age, enables researchers to measure this phenomenon. This approach also allows us to assess the impact of various factors, including lifestyle choices, on brain aging within relatively short timeframes.
In the study conducted by Levakov, Kaplan, Shai, and Avidan, 102 individuals meeting the criteria for obesity were examined. At the beginning and end of the program, participants underwent brain scans, along with additional tests and measurements to monitor other obesity-related biological processes like liver health.
The brain scans obtained at the study’s onset and conclusion were analyzed to evaluate the influence of the lifestyle intervention on the aging trajectory. The findings demonstrated that a mere 1% reduction in body weight resulted in the participants’ brain age appearing nearly 9 months younger than expected after 18 months. This reduction in aging was accompanied by changes in other biological indicators, such as decreased liver fat and liver enzymes. Previous research has shown that increased liver fat and the production of specific liver enzymes have detrimental effects on brain health in Alzheimer’s disease.
“The importance of a healthy lifestyle, including reduced consumption of processed food, sweets, and beverages, in maintaining brain health is highlighted by our study,” – states Dr. Levakov.
“We were pleased to discover that even a 1% weight loss had a significant impact on brain health, resulting in a 9-month decrease in brain age,” – explains Prof. Avidan.
The findings indicate that lifestyle interventions promoting weight loss can positively influence the aging trajectory of the brain in individuals with obesity. The next steps will involve investigating whether slowing down obesity-driven brain aging leads to improved clinical outcomes for patients. Additionally, the study demonstrates a potential approach to evaluating the effectiveness of lifestyle changes on brain health. With the global rates of obesity on the rise, identifying interventions that have a positive impact on brain health can have significant clinical, educational, and social implications.
The concept of the green-Mediterranean, high polyphenols diet was introduced by the research team of the DIRECT-PLUS trial. This modified Mediterranean diet differs from the traditional one by emphasizing a higher intake of dietary polyphenols, which are phytochemicals and secondary metabolites of plant compounds that offer various health benefits, and a lower consumption of red/processed meat. In addition to a daily consumption of walnuts (28 grams), the participants following the green-Mediterranean diet consumed 3-4 cups of green tea and 1 cup of Wolffia-globosa (Mankai) plant green shake made from duckweed per day over the course of 18 months. The aquatic green plant Mankai is rich in bioavailable iron, B12, 200 types of polyphenols, and protein, making it a suitable substitute for meat.
Obesity negatively impacts multiple bodily systems, including the central nervous system. Retrospective studies that estimated chronological age from neuroimaging have found accelerated brain aging in obesity, but it is unclear how this estimation would be affected by weight loss following a lifestyle intervention.
In a sub-study of 102 participants of the Dietary Intervention Randomized Controlled Trial Polyphenols Unprocessed Study (DIRECT-PLUS) trial, we tested the effect of weight loss following 18 months of lifestyle intervention on predicted brain age based on magnetic resonance imaging (MRI)-assessed resting-state functional connectivity (RSFC). We further examined how dynamics in multiple health factors, including anthropometric measurements, blood biomarkers, and fat deposition, can account for changes in brain age.
To establish our method, we first demonstrated that our model could successfully predict chronological age from RSFC in three cohorts (n=291;358;102). We then found that among the DIRECT-PLUS participants, 1% of body weight loss resulted in an 8.9 months’ attenuation of brain age. Attenuation of brain age was significantly associated with improved liver biomarkers, decreased liver fat, and visceral and deep subcutaneous adipose tissues after 18 months of intervention. Finally, we showed that lower consumption of processed food, sweets and beverages were associated with attenuated brain age.
Successful weight loss following lifestyle intervention might have a beneficial effect on the trajectory of brain aging.
The German Research Foundation (DFG), German Research Foundation – project number 209933838 – SFB 1052; B11, Israel Ministry of Health grant 87472511 (to I Shai); Israel Ministry of Science and Technology grant 3-13604 (to I Shai); and the California Walnuts Commission 09933838 SFB 105 (to I Shai).