Vegetarian Dietary Patterns and Cognitive Function among Older Adults: The Adventist Health Study-2

Impact of vegetarianism on cognition and neuropsychological status among urban community-dwelling adults in Telangana, South India: a cross-sectional study

PURPOSE

The potential benefits of vegetarian diets in reducing cognitive impairment have garnered attention due to existing mixed results; hence, our study aims to examine the impact of vegetarianism on cognitive function and neuropsychological status among urban community-dwelling adults from Telangana.

METHODS

The dietary patterns were self-reported and dietary data collected using a Food Frequency Questionnaire while cognitive function was assessed using Mini-Mental State Examination (MMSE) and depression, anxiety, and stress (DASS-21) questionnaire for psychological measures. Adults (N = 304) aged 40 years and above, who followed either a vegetarian or non-vegetarian diet for at least 6 months prior to data collection, scored MMSE ≥ 19 indicating mild cognitive impairment, and were recruited using convenience sampling.

RESULTS

Among the participants, vegetarians (n = 155) exhibited significantly better mood states compared to non-vegetarians (n = 149), as indicated by lower scores on the DASS subscales for depression (10.0 ± 0.06 vs. 17.0 ± 0.07, p =  < 0.001), anxiety (4.0 ± 0.05 vs. 6.0 ± 0.07, p = 0.005), and stress (8.0 ± 0.02 vs. 10.0 ± 0.05, p = 0.007). Vegetarians also demonstrated superior cognitive functioning compared to non-vegetarians, as indicated by higher MMSE scores (26.0 ± 0.04 vs. 24.0 ± 0.03, p =  < 0.001). MMSE scores were inversely correlated with depression, anxiety, and stress for vegetarians (ρ = - 0.371, p = 0.000; ρ = - 0.027, p = 0.734; and ρ = - 0.105, p = 0.914), respectively. Similar to the vegetarians group, MMSE scores were negatively correlated with depression (ρ = - 0.059), but the correlation is not significant.

CONCLUSION

Vegetarianism exerted a positive influence on the cognitive and neuropsychological status of the investigated population. Nevertheless, additional research is required to comprehend the underlying mechanisms that elucidate the long-term effects of vegetarianism and plant-based nutritional interventions on brain health.

The impact of sustainable diets οn cognitive function in an ageing society: A mini-review

The increasing number of older people raises important health concerns because, in part, of the associated cognitive and functional impairment. The United Nations is taking action with its Decade of Healthy Ageing (2021-2030) campaign, by promoting Sustainable Development Goals and shifting our focus towards more sustainable diets. In this mini-review, sustainable dietary patterns are evaluated, with a focus on healthy plant-based diets, the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, and the Mediterranean-DASH Intervention for Neurodegenerative Delay diet. The review analyzes and describes whether older people's cognitive performance can benefit from the adoption of these sustainable diets. The results of primary studies indicate that the Mediterranean diet and healthy plant-based diets can prevent cognitive impairment by improving cognitive function, language and memory. Plant-based dietary patterns with incorporated Mediterranean foods (high consumption of fruit, vegetables, and fish) are associated with delayed cognitive ageing. Additionally, adherence to the Mediterranean-DASH Intervention for Neurodegenerative Delay diet is associated with improved cognitive resilience and lower risk of dementia after 16 years of follow-up. Although consumption of red meat and elevated body mass index are both associated with cognitive dysfunction, some studies have had contradictory findings. Concerns exist regarding the development of chronic diseases, cognitive and functional impairment, as well as disability as age advances. Thus, the policies of the United Nations should ensure healthy ageing for all older individuals. Nonetheless, more research is required to evaluate older people's willingness and readiness to adopt a more sustainable way of eating.

Omega-3 Fatty Acids, Cognition, and Brain Volume in Older Adults

The elderly population is growing at increased rates and is expected to double in size by 2050 in the United States and worldwide. The consumption of healthy foods and enriched diets have been associated with improved cognition and brain health. The key nutrients common to many healthy foods and diets are the omega-3 polyunsaturated fatty acids (omega-3 FAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). We explored whether omega-3 FA levels are associated with brain volume and cognition. Forty healthy, cognitively normal, Seventh-day Adventist older adults (mean age 76.3 years at MRI scan, 22 females) completed neurocognitive testing, a blood draw, and structural neuroimaging from 2016 to 2018. EPA and an overall omega-3 index were associated with individual measures of delayed recall (RAVLT-DR) and processing speed (Stroop Color) as well as entorhinal cortex thickness. EPA, DHA, and the omega-3 index were significantly correlated with the total white matter volume. The entorhinal cortex, frontal pole, and total white matter were associated with higher scores on delayed memory recall. This exploratory study found that among healthy, cognitively older adults, increased levels of omega-3 FAs are associated with better memory, processing speed, and structural brain measures.

Dietary Patterns and Alzheimer's Disease: An Updated Review Linking Nutrition to Neuroscience

Alzheimer's disease (AD) is a growing concern for the aging population worldwide. With no current cure or reliable treatments available for AD, prevention is an important and growing area of research. A range of lifestyle and dietary patterns have been studied to identify the most effective preventive lifestyle changes against AD and related dementia (ADRD) pathology. Of these, the most studied dietary patterns are the Mediterranean, DASH, MIND, ketogenic, and modified Mediterranean-ketogenic diets. However, there are discrepancies in the reported benefits among studies examining these dietary patterns. We herein compile a narrative/literature review of existing clinical evidence on the association of these patterns with ADRD symptomology and contemplate their preventive/ameliorative effects on ADRD neuropathology in various clinical milieus. By and large, plant-based dietary patterns have been found to be relatively consistently and positively correlated with preventing and reducing the odds of ADRD. These impacts stem not only from the direct impact of specific dietary components within these patterns on the brain but also from indirect effects through decreasing the deleterious effects of ADRD risk factors, such as diabetes, obesity, and cardiovascular diseases. Importantly, other psychosocial factors influence dietary intake, such as the social connection, which may directly influence diet and lifestyle, thereby also impacting ADRD risk. To this end, prospective research on ADRD should include a holistic approach, including psychosocial considerations.

The association between adherence to a plant-based diet and cognitive ageing

PURPOSE

While the benefits of adopting a more plant-based diet for sustainability and animal welfare are clear, its long-term health impacts, including the impact on cognitive ageing, are limited studied. Therefore, we investigated the associations between plant-based diet adherence and cognitive ageing.

METHODS

Data from a previous intervention study involving community-dwelling adults aged ≥ 65 years were analysed at baseline (n = 658) and after 2-year follow-up (n = 314). Global and domain-specific cognitive functioning were assessed at both timepoints. Overall, healthful and unhealthful plant-based dietary indices were calculated from a 190-item food frequency questionnaire. Multivariate-adjusted linear regression models were applied to test for associations.

RESULTS

After full-adjustment, higher overall adherence to a plant-based diet was not associated with global cognitive function (difference in Z-score, tertile 1 versus 3 [95% CI]: 0.04 [- 0.05, 0.13] p = 0.40) or cognitive change (- 0.04 [- 0.11, 0.04], p = 0.35). Similarly, healthful and unhealthful plant-based diet indices were not associated with cognitive functioning (respectively p = 0.48; p = 0.87) or change (respectively p = 0.21, p = 0.33). Interestingly, we observed fish consumption to influence the association between plant-based diet adherence and cognitive functioning (p-interaction = 0.01), with only individuals with a fish consumption of ≥ 0.93 portion/week benefitting from better overall plant-based diet adherence (β per 10-point increment [95% CI]: 0.12 [0.03, 0.21] p = 0.01).

CONCLUSION

We did not demonstrate associations of a more plant-based diet with cognitive ageing. However, possibly such association exists in a subpopulation with higher fish intake. This would be in line with earlier observations that diets rich in plant foods and fish, such as the Mediterranean diet, may be beneficial for cognitive ageing.

TRIAL REGISTRATION

Registered at clinicaltrials.gov (NCT00696514) on June 12, 2008.

Plants, Plants, and More Plants: Plant-Derived Nutrients and Their Protective Roles in Cognitive Function, Alzheimer’s Disease, and Other Dementias

Background and Objectives: Alzheimer’s disease (AD) is the most common form of dementia, with the risk of developing it attributed to non-modifiable and modifiable factors. Currently, there is no cure for AD. A plant-based diet may protect against cognitive decline, due to the effects of plant-based nutrients such as vitamins, antioxidants, and fiber. The aim of the review is to summarize current literature on plant-based nutrients and their impact on cognition. Materials and Methods: A search was conducted on PubMed for clinical and murine studies, using combinations of the following words: “Alzheimer’s disease”, “dementia”, “cognition”, “plant-based diet”, “mild cognitive impairment”, “vitamin B”, “vitamin C”, “vitamin E, “beta carotene”, “antioxidants”, “fiber”, “vitamin K”, “Mediterranean diet”, “vitamin D”, and “mushrooms”. Results and Conclusions: A diet rich in vitamin B and antioxidants can benefit the cognitive functions of individuals as shown in randomized clinical trials. Vitamin K is associated with improved cognition, although large randomized controlled trials need to be done. Fiber has been shown to prevent cognitive decline in animal studies. Vitamin D may contribute to cognitive health via anti-inflammatory processes. Several medical organizations have recommended a plant-based diet for optimizing cognitive health and potentially helping to prevent dementia.