by Lewis Chang, PhD
The Mediterranean diet (MED), characterized by a high consumption of plant-based foods, less red meat, and using olive oil as the main source of fat, is one of the healthiest diets. A study found that MED might also prolong brain health and function in cognitively healthy middle-aged individuals.1
According to an earlier systematic review of cohort studies and randomized controlled trials, adherence to MED was associated with a lower risk of cognitive decline and Alzheimer’s disease (AD).2 A new study conducted at NYU School of Medicine/Weill Cornell Medical College (New York, NY) went one step further by investigating whether adherence to MED affected well-established AD biomarkers longitudinally.1
This study included 70 cognitively normal individuals (ages 30-60) who underwent dietary examinations and brain imaging-based biomarker assessments at baseline and again 2-3 years later.1 Dietary data obtained from the food frequency questionnaire were used to determine adherence to MED, and participants were divided into higher adherence group (n=34) and lower adherence group (n=36). The main outcomes include changes in glucose metabolism in temporal cortex (an indicator of neuronal dysfunction), β-amyloid deposition (a marker strongly implicated in AD), and gray matter volume.
The study investigators found that:1
- At baseline, the low MED adherence group exhibited reduced metabolic rates of glucose and increased β-amyloid deposition in AD-affected areas compared with the high MED adherence group
- Longitudinally, greater reductions in glucose metabolism and greater increases in β-amyloid deposition were seen in low MED adherence group compared with the high MED adherence group
- Using mathematical prediction models based on the longitudinal data, the investigators estimated that abnormalities in AD biomarkers originated at least 1.5 years before the baseline assessment in the low MED adherence group, and higher adherence to MED might provide up to 3.5 years of protection against brain aging and AD
This study complements findings from previous association studies by providing biomarker-based insights into the MED’s neuroprotective mechanisms. However, the authors cautioned that self-reported dietary data might be limited in accuracy, and data from their relatively homogeneous population are less generalizable. The study did not investigate how many years of MED adherence would be needed to exert neuroprotective effects. Also, other important risk factors such as smoking status were not assessed. Nevertheless, this study paves the way for future dietary intervention studies.
Why is this Clinically Relevant?
- Some AD risk factors such as age, family history, and genetic predisposition cannot be changed. But other factors like lifestyle and diet can be modified to help lower the risk of AD2
- Accumulating evidence indicates that the Mediterranean diet is beneficial in lowering the risk of cognitive decline1-2
- Berti V, Walters M, Sterling J, et al. Mediterranean diet and 3-year Alzheimer brain biomarker changes in middle-aged adults. Neurology. 2018;90(20):e1789-e1798.
- Aridi YS, Walker JL, Wright ORL. The association between the Mediterranean dietary pattern and cognitive health: A systematic review. Nutrients. 2017;9(7).