In a recent study published in JAMA Network Open, researchers investigated whether anti-inflammatory diets support cognitive functions among cardiometabolic disease (CMD) patients.
Study: Anti-Inflammatory Diet and Dementia in Older Adults With Cardiometabolic Diseases. Image Credit: Elena Eryomenko/Shutterstock.com
Background
CMDs like insulin-independent diabetes, heart disease, and stroke are associated with an elevated dementia risk, particularly when they coexist. Studies associate inflammation with the pathophysiologic features of CMDs and dementia, and dietary habits can modulate systemic inflammation.
Increased levels of inflammatory biomarkers are associated with Western diets heavy on eggs, high-fat dairy, red meat, processed foods, and refined grains.
In contrast, diets rich in fruits, vegetables, whole grains, seafood, and legumes lower inflammatory biomarker levels.
Studies associate lower dietary inflammation with a lower risk of cognitive decline and favorable MRI brain aging indicators. However, the efficacy of anti-inflammatory diets in improving cognition in CMD patients is uncertain.
About the study
The present study researchers explored the potential cognitive benefits of anti-inflammatory diets among older adults with cardiometabolic diseases.
The researchers included 84,342 adult United Kingdom Biobank participants aged 60 years or above, with baseline evaluations conducted between 13 March 2006 and 1 October 2010.
They excluded individuals with dementia, insulin-dependent diabetes, and those with missing CMD data. The primary study outcome was new-onset dementia, identified through medical records and self-reported.
The researchers performed joint effects analysis to assess cardiometabolic disease status and diet-related inflammation concerning the risk of dementia and magnetic resonance imaging (MRI) markers of neurodegeneration and vascular injury in the brain.
In total, 8,917 participants without chronic neurological diseases underwent MRI between 2 May 2014 and 13 March 2020 to provide their gray matter volumes (GMV), total brain volume (TBV), hippocampal volumes (HV), white matter volumes (WMV), and white matter hyperintensity volumes (WMHV).
Researchers ascertained baseline CMDs such as heart disease, stroke, and insulin-independent diabetes from health records.
They calculated Dietary Inflammatory Index (DII) scores based on 31 food nutrients consumed between 8 February 2011 and 15 June 2012, evaluated using the 24-hour Oxford WebQ dietary assessment.
Points up to -1.5 indicated anti-inflammatory, above -1.5 but less than 0.5 indicated neutral, and 0.5 or above indicated pro-inflammatory potential.
Researchers followed the participants through 20 January 2022. They used Cox proportional hazard regressions to calculate the hazard ratios (HR) for analysis. Study covariates included race, education, body mass index (BMI), smoking status, calorie intake, physical activity, socioeconomic status, hypertension, antihypertensive medication use, and apolipoprotein E (APOE) status.
MRI covariates included time between scans, assessment centers, and table and head positions within MRI scanners.
Researchers performed sensitivity analyses applying Fine and Gray's regressions to non-imputed information and limiting participants to those completing at least two dietary evaluations, excluding individuals diagnosed with dementia within five years.
They also determined the association of DII scores with systemic inflammation biomarkers such as serological C-reactive protein (CRP) levels and assessed DII score stability across dietary evaluations.
Results
The mean participant age was 64 years; 51% were female, and 37% had attained at least a college-level education. At baseline, 14,079 (17%) had one or more cardiometabolic diseases.
CMD patients tended to be less educated, older, physically inactive, and more socioeconomically deprived male Asian black smokers with elevated BMI and hypertension. Individuals undergoing MRI had lower age, less socioeconomic deprivation, and better vascular injury risk profiles.
Over 12 years (median) of follow-up, 1,559 individuals (1.90%) received dementia diagnosis. The joint effects analysis yielded an HR of 2.4 for dementia for CMD patients following pro-inflammatory diets and 1.7 for individuals with CMDs consuming foods with anti-inflammatory potential.
Individuals with CMDs consuming anti-inflammatory diets rather than pro-inflammatory diets showed a 31% lower dementia risk (HR, 0.7) among CMD patients consuming anti-inflammatory foods.
Brain MRI scans of individuals consuming anti-inflammatory diets showed significantly higher GMV and lower WMHV values. Using Laplace regressions, CMD patients eating anti-inflammatory foods developed dementia two years after those with CMDs who ate pro-inflammatory foods.
Sensitivity analyses yielded similar results with stable DII scores across dietary evaluations. However, Fine and Gray's regressions yielded attenuated all-cause dementia HR values, indicating that the competing risk of death could influence the results.
Conclusions
The study found that cardiometabolic disease patients consuming anti-inflammatory foods had a decreased incidence of dementia, higher GMV, and lower WMHV values, indicating less neurodegeneration and vascular damage.
The findings suggest that anti-inflammatory diets improve cognitive function in those with cardiometabolic illnesses. Anti-inflammatory foods may reduce systemic inflammation, delaying dementia onset.
Longitudinal brain MRI studies may enhance knowledge of the links between dietary inflammation and brain illness, particularly concerning risk factors like cardiometabolic disorders.
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