Role of Lifestyle Factors in Alzheimer’s Risk and Disparities

Summary: Adopting a healthy lifestyle or adopting minor lifestyle changes helps reduce the risks of developing Alzheimer’s disease, especially for those from a lower socioeconomic background.

Source: American Society for Nutrition

As rates of Alzheimer’s disease and other forms of dementia continue to rise in the U.S., new evidence suggests that lifestyle factors such as diet, exercise and sleep play an important role in reducing the risk of developing dementia.

Researchers say two new studies offer particular insights into the factors that may contribute to the disproportionate burden of dementia in non-White and low-income U.S. populations.

“Our findings support the beneficial role of healthy lifestyles in the prevention of Alzheimer’s disease and related dementias among senior Americans, including those with socioeconomic disadvantages and a high risk of dementia,” said Danxia Yu, Ph.D., assistant professor in the Division of Epidemiology at Vanderbilt University Medical Center, the study’s lead author.

“We should recognize that it is challenging for people facing systemic and structural disadvantages to maintain healthy lifestyles or make lifestyle changes. It is critical to establish public health strategies to make lifestyle modifications achievable for all, especially disadvantaged populations.”

Yu and her team will present the findings from two studies online at Nutrition 2022 Live Online, the flagship annual meeting of the American Society for Nutrition held June 14-16.

The research was published online June 13, 2022, in Neurology, the medical journal of the American Academy of Neurology.

The research is from the Southern Community Cohort Study, a long-term research study launched in 2001 to investigate the root causes of various diseases and health disparities.

Around 85,000 participants were recruited from community health centers in the southeastern U.S. and two-thirds of participants are Black, giving the study among the highest representation of African-Americans of any large U.S. research cohort. Researchers used Medicare claims data to track Alzheimer’s diagnoses among participants over age 65.

For the first study, researchers drew data from 17,209 older study participants, 1,694 of whom were diagnosed with Alzheimer’s or related dementias during a median follow-up of 4 years. They assessed five lifestyle factors—smoking, alcohol use, leisure-time physical activity, sleep hours and diet quality—both individually and in combination.

The results showed that healthy choices (no smoking, high leisure-time exercise, low-to-moderate alcohol consumption, adequate sleep and a high-quality diet) were individually associated with an 11-25% reduced risk of Alzheimer’s disease and related dementias.

When combined, a composite score of those five lifestyle factors was associated with a 36% reduced risk in the highest versus lowest quartile. These associations were independent of participants’ age, sex, race, education, income and underlying chronic diseases.

For the second study, researchers drew data from 14,500 older study participants, of whom 1,402 developed Alzheimer’s or related dementias. In this group, they analyzed intakes of four major classes of dietary polyphenols—flavonoids, phenolic acids, stilbenes and lignans—and their subclasses, using a validated food frequency questionnaire and polyphenol databases.

Polyphenols are a large class of compounds commonly found in tea, red wine, chocolate, berries and other foods and have been associated with a variety of health benefits.

This shows an older man
The results showed that healthy choices (no smoking, high leisure-time exercise, low-to-moderate alcohol consumption, adequate sleep and a high-quality diet) were individually associated with an 11-25% reduced risk of Alzheimer’s disease and related dementias. Image is in the public domain

In this study, researchers found a significant difference in intake of polyphenols among racial groups, with White participants consuming a median of about twice the amount of total polyphenols as Black participants daily.

Overall there was no significant association between total dietary polyphenol intake and incidence of Alzheimer’s disease and related dementias in either race; however, certain flavonoids were associated with a reduced risk among Black participants but not White participants.

The findings showed Black participants in the top quartile for tea consumption had a 28% lower incidence of Alzheimer’s than Black participants in the lowest quartile for tea consumption.

While both studies are observational and did not assess the mechanisms behind the associations, researchers said that healthy lifestyles, including healthy eating, may help protect brain health by improving glucose and lipid metabolism and reducing inflammation and psychological stress.

Yu said more research is needed to further elucidate the relationship between lifestyle factors and Alzheimer’s disease among diverse populations.

“Black Americans and people with low socioeconomic status are disproportionately affected by the disease but have been largely underrepresented in epidemiologic studies,” Yu said.

“Identifying modifiable factors for the prevention of Alzheimer’s disease and related dementias among low-income people of different races and ethnicities is a critical public health issue.”

About this Alzheimer’s disease research news

Author: Press Office
Source: American Society for Nutrition
Contact: Press Office – American Society for Nutrition
Image: The image is in the public domain

Original Research: Closed access.
Association of Healthy Lifestyles with Risk of Alzheimer Disease and Related Dementias in Low-Income Black and White Americans” by Jae Jeong Yang et al. Neurology

Closed access.
Association of Diabetes and Hypertension With Brain Structural Integrity and Cognition in the Boston Puerto Rican Health Study Cohort” by Yi Guan et al. Neurology


Association of Healthy Lifestyles with Risk of Alzheimer Disease and Related Dementias in Low-Income Black and White Americans

Objective: While the importance of healthy lifestyles for preventing Alzheimer’s disease and related dementias (ADRD) has been recognized, epidemiologic evidence remains limited for non-White or low-income individuals who bear disproportionate burdens of ADRD.

This population-based cohort study aims to investigate associations of lifestyle factors, individually and together, with the risk of ADRD among socioeconomically disadvantaged Americans.

Methods: In the Southern Community Cohort Study, comprising two-thirds self-reported Black and primarily low-income Americans, we identified incident ADRD using claims data among participants enrolled in Medicare for at least 12 consecutive months after age 65.

Five lifestyle factors—tobacco smoking, alcohol consumption, leisure-time physical activity (LTPA), sleep hours, and diet quality— were each scored 0 (unhealthy), 1 (intermediate), or 2 (healthy) based on health guidelines.

A composite lifestyle score was created by summing all scores. Cox regression was used to estimate hazard ratios (HRs, 95% CIs) for incident ADRD, treating death as a competing risk.

Results: We identified 1,694 patients with newly diagnosed ADRD among 17,209 participants during a median follow-up of 4.0 years in claims data; the mean age at ADRD diagnosis was 74.0 years.

Healthy lifestyles were individually associated with 11%-25% reduced risk of ADRD: multivariable-adjusted HR (95% CI) was 0.87 (0.76-0.99) for never vs. current smoking, 0.81 (0.72-0.92) for low-to-moderate vs. no alcohol consumption, 0.89 (0.77-1.03) for ≥150 minutes of moderate or ≥75 minutes of vigorous LTPA each week vs. none, 0.75 (0.64-0.87) for 7-9 hours vs. >9 hours of sleep, and 0.85 (0.75-0.96) for the highest vs. lowest tertiles of Healthy Eating Index.

The composite lifestyle score showed a dose-response association with up to 36% reduced risk of ADRD: multivariable-adjusted HRs (95% CIs) across quartiles were 1 (ref), 0.88 (0.77-0.99), 0.79 (0.70-0.90), and 0.64 (0.55-0.74); p-trend<0.001. The beneficial associations were observed regardless of participants’ sociodemographics (e.g., race, education, and income) and health conditions (e.g., history of cardiometabolic diseases and depression).

Conclusion: Our findings support significant benefits of healthy lifestyles for ADRD prevention among socioeconomically disadvantaged Americans, suggesting that promoting healthy lifestyles and reducing barriers to lifestyle changes are crucial to tackling the growing burden and disparities posed by ADRD.


Association of Diabetes and Hypertension With Brain Structural Integrity and Cognition in the Boston Puerto Rican Health Study Cohort

Background and Objectives The Boston Puerto Rican Health Study (BPRHS) is a longitudinal study following self-identified Puerto Rican older adults living in the Greater Boston area. Studies have shown higher prevalence of hypertension (HTN) and type 2 diabetes (T2D) within this ethnic group compared to age-matched non-Hispanic White adults.

In this study, we investigated the associations of HTN and T2D comorbidity on brain structural integrity and cognitive capacity in community-dwelling Puerto Rican adults and compared these measures with older adult participants (non-Hispanic White and Hispanic) from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) and National Alzheimer’s Coordinating Center (NACC) databases.

Methods BPRHS participants who underwent brain MRI and cognitive testing were divided into 4 groups based on their HTN and T2D status: HTN−/T2D−, HTN+/T2D−, HTN−/T2D+, and HTN+/T2D+.

We assessed microstructural integrity of white matter (WM) pathways using diffusion MRI, brain macrostructural integrity using hippocampal volumes, and brain age using T1-weighted MRI and cognitive test scores. BPRHS results were then compared with results from non-Hispanic White and Hispanic participants from the ADNI and NACC databases.

Results The prevalence of HTN was almost 2 times (66.7% vs 38.7%) and of T2D was 5 times (31.8% vs 6.6.%) higher in BPRHS than in ADNI non-Hispanic White participants. Diffusion MRI showed clear deterioration patterns in major WM tracts in the HTN+/T2D+ group and, to a lesser extent, in the HTN+/T2D− group compared to the HTN−/T2D− group. HTN+/T2D+ participants also had the smallest hippocampal volume and larger brain aging deviations.

Trends toward lower executive function and global cognitive scores were observed in HTN+/T2D+ relative to HTN−/T2D− individuals. MRI measures and the Mini-Mental State Examination (MMSE) scores from the HTN+/T2D+ BPRHS group resembled those of ADNI White participants with progressive mild cognitive impairment (MCI), while the BPRHS HTN−/T2D− participants resembled participants with stable MCI.

The BPRHS was not significantly different from the ADNI + NACC Hispanic cohort on imaging or MMSE measures.

Discussion The effects of T2D and HTN comorbidity led to greater brain structural disruptions than HTN alone. The high prevalence of HTN and T2D in the Puerto Rican population may be a key factor contributing to health disparities in cognitive impairment in this group compared to non-Hispanic White adults in the same age range.

Trial Registration Information identifier: NCT01231958.

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