“The afternoon knows what the morning never suspected.”
― Robert Frost
A consequence of living is aging, which spares no one. There are no exemptions. However, how we age may be, at least potentially and partially, a variable we can control.
Alzheimer’s disease (AD) and related dementia (ADRD) are chronic diseases that currently affect more than 55 million people worldwide and impose an estimated economic burden of more than $800 billion annually. The cost is projected to increase as the global population ages, as the prevalence of AD/ADRD is expected to triple over the next 30 years. At present, there is no cure and no treatment to stop the disease’s inevitable march of cognitive decline. However, current estimates suggest that roughly 40 percent of worldwide dementia can be theoretically prevented through engaging in healthier lifestyles.
This week’s study examines the role of lifestyle – including dietary approaches – in improving cognitive function as we age.
- The study sought to determine the correlation between lifestyle and dementia.
- The study involved the examination of postmortem brain pathology, lifestyle, and level of cognitive functioning proximate to death.
- The participants and data came from a cohort that participated in the RUSH University Memory and Aging Project from 1997 to 2022 and passed away.
- Lifestyle data came from self-reported factors, and a healthy lifestyle score was derived, ranging from 0 to 5, with higher scores reflecting healthier lifestyles in terms of smoking, alcohol use, diet, and physical activity.
- The data on cognition was derived from the results of 19 standardized tests.
- Brain pathology analysis included measures of beta-amyloid load, phosphorylated tau tangles, global Alzheimer’s disease pathology, vascular brain pathologies, quantitation of Lewy bodies, hippocampal sclerosis, and TAR DNA-binding protein 43.
The Take-Away:
- The study included the results from a total of 586 deceased individuals.
- Roughly 71 percent of the examined group was female and the average age at death was approximately 91 years.
- Dietary composition was assessed using a self-reported 144-item food frequency questionnaire (FFQ).
- The diet quality was determined by calculating the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet score, excluding alcohol intake.
The Caveat:
This study is a correlative, observational study, and as such it is critical to remember the correlation is not causation. Having said that, correlation can be valuable in developing hypotheses and setting the stage for further investigation.
As we age, in certain individuals, there is a progressive accumulation of dementia-related brain pathologies (e.g., beta-amyloid) that starts occurring many years before the onset of cognitive impairment. This provides a window of opportunity during which engaging in healthier lifestyles may delay or even prevent cognitive decline.
In this study, “healthier” lifestyle factors included a higher adherence to the MIND Diet (a MIND diet score greater than 7.5), engagement in cognitive activities, not smoking, at least 150 minutes of exercise or vigorous activity per week, and moderate alcohol consumption (one or two alcoholic drinks per day). For each healthy lifestyle factor present, a study participant was awarded one point, for a maximum score of five and a minimum of 0, with the higher scores representing healthier lifestyles. The mean lifestyle score was 2.7.
The result was that, across various measures, a healthier lifestyle as reflected by a higher lifestyle score, was associated with better cognitive function proximate to death. The most fascinating result of the study was that the association between a healthier lifestyle and better cognition was independent of Alzheimer’s disease pathology burden.
This is intriguing. It suggests that even in the face of developing known markers associated with cognitive decline, engaging in healthy lifestyle choices may result in a blunting of their effect and act to preserve cognitive function. Thus, at least according to this study, the association of lifestyle with cognition is largely independent of brain pathology (a small part, approximately 12 percent, was mediated through the presence of beta-amyloid). This is in agreement with prior studies that have also suggested positive changes in diet and physical activity are associated with preserved cognition, independent of a vascular disease burden.
Such findings reinforce the potential for self-intervention. We are not slaves to a predetermined genetic fate, but neither are we untethered from it. As the novelist Isaac Bashevis Singer opined, “We must believe in free will, we have no choice.”
