December 2, 2021

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‘MIND’ diet may protect against cognitive decline

5 min read

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In people with Alzheimer’s disease, following the MIND diet can help slow cognitive decline. WP Simon/Getty Images
  • Alzheimer’s disease and other age-related conditions that cause cognitive decline are associated with pathological changes in the brain, including unusual accumulation of protein deposits.
  • Although the levels of these brain pathologies are associated with cognitive impairment, some individuals with brain pathologies maintain healthy cognitive function.
  • A recent study suggests that adherence to the MIND diet, which is a diet designed for improving brain health, can slow cognitive decline in individuals with Alzheimer’s disease.
  • The study found that the association between adherence to the MIND diet and better cognitive health was independent of brain pathology levels.

Alzheimer’s disease is the most common form of dementia. Around 1 in 9 adults over the age of 65 years in the United States currently have this condition.

Alzheimer’s disease is associated with the unusual accumulation of protein deposits called beta-amyloid plaques and neurofibrillary tangles in the brain.

These protein deposits are considered to be responsible for damage to brain cells and, consequently, impairment of cognitive function observed in Alzheimer’s disease.

Interestingly, not everyone with high levels of these brain pathologies or markers for Alzheimer’s disease experiences cognitive decline. This ability to maintain normal cognitive function in the presence of brain pathologies is known as cognitive resilience.

In addition, older adults aged 65 years and over who engage in physical activity and activities that provide mental stimulation are likely to have better cognitive performance independent of their levels of Alzheimer’s disease-related brain pathologies.

Even though some recently studied Alzheimer’s disease drugs can reduce the levels of beta-amyloid plaques and neurofibrillary tangles in the brain, the interventions that scientists have studied so far have shown limited success in slowing down the decline in cognitive function.

This highlights the importance of identifying lifestyle factors that can slow down the progression of cognitive decline independent of changes in Alzheimer’s disease-related brain pathologies.

Some studies suggest that the Dietary Approaches to Stop Hypertension (DASH) diet and the Mediterranean diet can improve cognitive function. Based on those studies, the two diets have been combined to create a hybrid MIND diet that is specifically designed to improve brain health.

The MIND diet emphasizes the consumption of leafy green vegetables, other vegetables, berries, legumes, fish, nuts, and whole grains while limiting the consumption of butter, cheese, and red meat.

Previous studies have suggested that the MIND diet can slow down age-related cognitive decline and reduce the risk of Alzheimer’s disease.

Recently, researchers at the Rush University Medical Center in Chicago investigated the ability of the MIND diet to improve cognitive function in older adults independent of brain pathology levels.

Summarizing the research’s findings, first study author Dr. Klodian Dhana, Ph.D., told Medical News Today, “We found that a higher MIND diet score was associated with better cognitive function independently of Alzheimer’s disease pathology and other common age-related brain pathologies, suggesting that adherence to the MIND diet may build cognitive resilience in older adults.”

Understanding the mechanisms underlying the effects of diet and other lifestyle factors on cognitive function could help researchers develop new treatments to slow cognitive decline.

Given the presence of brain pathologies in a significant number of older adults and the absence of treatments that can slow cognitive decline, such treatments could be immensely beneficial.

The study findings appear in the Journal of Alzheimer’s Disease.

The new study analyzed data collected by the Rush Memory and Aging Project (MAP) on 569 deceased individuals. The Rush MAP is a longitudinal study involving adults over 65 years of age with an objective to identify environmental and genetic factors associated with the development of Alzheimer’s disease.

The Rush MAP conducts annual assessments to evaluate cognitive health, lifestyle, and risk factors associated with Alzheimer’s disease. The study also conducts postmortem analyses on brains donated by participants to assess changes associated with Alzheimer’s disease.

In the new study, the researchers used a questionnaire to calculate the MIND diet score based on how frequently the study participants consumed foods deemed to be healthy or unhealthy according to the MIND diet.

The researchers had access to data from comprehensive cognitive tests conducted at a time close to the participants’ deaths. After a participant’s death, the team conducted a postmortem analysis to identify brain changes associated with Alzheimer’s disease and other conditions known to result in age-related cognitive decline.

About one-third of the participants in the study had a clinical diagnosis of Alzheimer’s disease before their death. However, the researchers were able to identify two-thirds of the participants as having Alzheimer’s disease based on high levels of brain pathologies revealed by the postmortem analyses.

The researchers found a positive correlation between the MIND diet score and cognitive function before the participants’ deaths. Moreover, the MIND diet score was associated with a slower rate of decline in cognitive function with aging.

Notably, the association between the MIND diet score and cognitive function was independent of the level of Alzheimer’s disease-related brain pathologies.

Similarly, the levels of brain pathologies associated with other conditions did not influence the association between the MIND diet score and cognitive function.

These results were based on the participants’ self-reports of their dietary patterns during the annual assessments. To minimize the possibility of these reports being inaccurate due to cognitive impairment, the researchers re-analyzed the data after excluding individuals with mild cognitive impairment at the onset of data collection.

The association between the MIND diet and cognitive function remained even after restricting the analysis to individuals without mild cognitive impairment.

The researchers observed similar results when the analysis only included people with high levels of Alzheimer’s disease-related brain pathologies. This further suggests that the association between the MIND diet score and cognitive function was independent of the levels of Alzheimer’s disease-related brain pathologies.

In sum, these results indicate that the potential effects of diet on cognitive function are unlikely to be mediated by influencing the levels of brain pathologies associated with Alzheimer’s disease and other brain conditions.

“The [strengths] of the study [include] high quality assessment of diet and cognition and availability of neuropathologic data,” said Dr. Dhana.

Similarly, Dr. Nikolaos Scarmeas, an associate professor of clinical neurology at Columbia University in New York City, noted:

“This is a quite important study because associations between nutrition and brain neuropathology have not been investigated. Very few, if any, studies have information on both ends: dietary habits and cognition during life and measures of brain changes from autopsy.”

Dr. Scarmeas was not involved with the recent study.

The study authors also note that the investigation had a few limitations. For example, they acknowledge the possibility of the dietary information being inaccurate since it was based on self-reports. To address the potential inaccuracies in the dietary reports, the researchers averaged the MIND diet score obtained from assessments conducted over multiple years.

“The limitation is the generalizability of the findings because that study was conducted among older white volunteers,” added Dr. Dhana.

Speaking about future research directions, Dr. Dhana said, “I think it is of great scientific interest to identify other modifiable lifestyle factors that have protective effects on cognitive functioning independent of [Alzheimer’s disease] pathology and other common brain pathologies.”

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