Study under review: Mediterranean and Western diet effects on Alzheimer’s disease biomarkers, cerebral perfusion, and cognition in mid-life: A randomized trial
Alzheimer’s disease (AD) is a slow and progressive neurodegenerative disease that is a major cause of dementia (impaired reasoning and memory). As shown in Figure 1, it is characterized by plaques and tangles in brain tissue that are made up of the mysterious amyloid-beta (Aβ) and tau proteins, respectively. Although there are a number of hypotheses that may explain the pathogenesis of AD, the overproduction, reduced clearance, and aggregation of these proteins is thought to be a major contributor to neurotoxicity and reduced neural connectivity. Moreover, their presence in cerebrospinal fluid (CSF) serve as prominent biomarkers of AD.
The “Western diet,” characterized by high saturated fat, simple carbohydrates, and sodium, is associated with various cardiometabolic diseases (e.g., obesity, diabetes, cardiovascular disease) that may accelerate brain aging. Cerebral perfusion, a measure of the passage of blood through the brain, has been inversely associated with obesity, diabetes, and cardiovascular risk factors, as well as AD and accelerated cognitive decline. When the supply of energy and blood throughout the body is disrupted, the brain is bound to suffer some consequences.
Nutrition can seemingly have a substantial effect on the progression of neurodegenerative diseases. A handful of intervention trials have demonstrated an inverse association between diets low in saturated fat and simple carbohydrates, such as the Mediterranean diet, and AD risk in elderly participants (older than 65). However, the effects of such diets on AD risk has been less explored in middle-aged people. This led the authors of the study under review to conduct a randomized controlled trial to determine whether changes in diet during midlife (45–65 years old) can influence biomarkers of AD risk and metabolic health.
Dietary interventions low in saturated fat, simple carbohydrates, and sodium, such as the Mediterranean diet, are inversely associated with cardiometabolic diseases and prominent biomarkers of AD in elderly participants. The authors of the study under review conducted a randomized controlled trial to determine whether changes in diet during midlife can influence biomarkers of AD risk and metabolic health.
Other Articles in Issue #83 (September 2021)
Mini: Reliable associations between dietary factors and different kinds of cancer
In this Mini, we briefly describe the most reliable associations between dietary factors and cancers at various anatomical sites according to a recent umbrella review.
Deeper Dive: Another possible strike against the relationship between TMAO and heart disease
This secondary analysis of two trials found that TMAO levels go up even when consuming heart-healthy foods, raising questions about whether TMAO actually harms the heart.
Deeper Dive: An inspirational approach to lowering blood pressure
Using a device to create resistance while inhaling could help lower the blood pressure of older adults with hypertension.
Creatine dosing strategies for lean mass and strength gains in older adults
According to this meta-analysis, people over 50 who lift get a slight boost by supplementing creatine, with loading dosing and maybe pre-workout dosing providing better benefits.
Nulls: July-August 2021
A quick roundup of recent studies that found no clear evidence of an effect.
Digital self-monitoring improves adherence to habits associated with weight loss
Monitoring healthy habits using digital tools improves outcomes, according to this recent meta-analysis. However, the authors didn’t find studies lasting more than a year, leaving the longer-term impact unclear.
Is dieting with meal replacements better than just dieting?
Meal replacements held a slight but statistically significant advantage over low-calorie diets for weight loss, but the results weren’t different compared to very-low-calorie diets. Replacing more food-based meals tended to yield better weight loss outcomes.