Given the vast number of individuals in america who’re approaching 65 years of age, there’s a necessity for interdisciplinary research on aspects influencing the trajectory of cognition and brain aging in older adults. In a recent review published in Nutrients, researchers examine the collective effect of weight loss program and exercise interventions on age-related cognition and brain health changes. 

Study: Impact of Eating regimen and Exercise Interventions on Cognition and Brain Health in Older Adults: A Narrative Review. Image Credit: Isarat / Shutterstock.com

Age-related cognitive decline

Reduced processing speed is one in all the key cognitive deficits observed in older adults, along with impaired semantic and episodic memory. Likewise, working memory that actively maintains information within the short term to enable goal-directed decision-making also declines due to aging.

Reduced working memory ends in a corresponding reduction in executive functions in advanced age. Attributable to structural and functional changes within the brain, aging also affects a person’s crystallized and fluid intelligence.

Structural changes within the brain related to aging include reduced gray matter volume and cortical thickness. Gray matter volume, a measure of neuronal and glial cell bodies, declines in volume inside multiple brain regions, including the medial temporal lobe of the hippocampus and entorhinal cortex during aging. Specifically, age-related reduction of hippocampal volume, resulting from neuronal cell loss and a decrease in neurogenesis, is related to decreased cognitive performance on memory, spatial learning, and emotional regulation tasks. 

Effect of weight loss program and exercise on aging 

It’s crucial to grasp the connection between nutrient consumption and neuronal function, neurometabolic processes, and cognitive decline. 

There’s growing evidence that nutrients from various foods across multiple food groups have synergistic effects beyond the results of individual nutrients. For instance, the absorption of vitamins from green salad improves when served with olive oil and vinegar slightly than a fat-free ranch dressing. 

Thus far, the Mediterranean weight loss program (MeDi), Dietary Approaches to Stop Hypertension (DASH), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diets are most regularly referenced within the literature. Each of those diets appears to enhance neurological signs of aging, including cell membrane and vascular integrity, inflammation, resolution, and oxidation, in addition to lipid and glucose metabolism.

Considerable evidence suggests that the MeDi and MIND diets are related to each general and domain-specific facets of cognitive ability. For instance, several studies have associated the MeDi weight loss program with attention and long-term memory. Likewise, adherence to the MIND weight loss program is positively related to visuospatial ability, perceptual speed, and executive function.

The impact of the ketogenic weight loss program (KD) and intermittent fasting (IF) on cognition and brain function have also been widely studied, as weight management diets appear to enhance cognitive functioning. Likewise, weight reduction achieved through bariatric surgery enhances attention, memory, and executive function.

Along with weight loss program, exercise positively affects cognition, as demonstrated by a previous study by which obese and obese adults were enrolled in a one-year behavioral weight reduction intervention. These patients were on an energy-restricted weight loss program, an energy-restricted weight loss program with 150 minutes of moderate-intensity exercise every week, or an energy-restricted weight loss program with 250 minutes of exercise every week. 

Post-intervention, weight markedly decreased across each groups. More specifically, the high-exercise group improved their performance on Iowa Gambling Task (IGT) reward relative to the opposite two study groups. Overall, more exercise with behavioral weight reduction regimens had a further profit on executive functioning, even with no weight reduction advantages.

Endurance exercise typically encompasses walking, jogging, running, swimming, and cycling, with walking being probably the most practiced form amongst older adults. Higher endurance fitness levels are related to less age-related brain volume decline. 

Randomized controlled trials examining the role of endurance exercise on cognition have led to mixed results. Nevertheless, all evidence suggests that endurance exercise in older adults improved cognitive performance, visual attention, and memory, promoted brain plasticity, and weakened hippocampal atrophy.

Similarly, a recent systematic review found that resistance training positively affected older adults’ executive and global cognitive functions. This kind of exercise also positively impacted memory, albeit weakly, and didn’t significantly improve attention. Moreover, tri-weekly, as in comparison with biweekly resistance training, positively affected general cognitive abilities.

No evidence of an interference effect of aerobic and resistance training has been reported. Nevertheless, literature comparing resistance or combined exercise to a non-exercise control is restricted. Thus, it stays unclear which exercises needs to be prescribed to keep up and enhance cognition and brain health amongst older adults.

Behavioral interventions like yoga appear to mitigate age-related and neurodegenerative decline. In a single review examining the results of practicing yoga on brain structures, function, and cerebral blood flow, yoga positively affected the structure and performance of the hippocampus, prefrontal and cingulate cortex, amygdala, and neuronal networks. 

A recent literature review evaluating the effect of tai chi, a conventional Chinese martial art, on brain structure and neurobehavior changes found that this way of exercise also increased cortical grey matter volume, improved neural activity and homogeneity, and increased neural connectivity within the frontal, temporal, and occipital lobes, cerebellum, and thalamus.

Conclusions

All diets evaluated on this review addressed aspects related to aging and neurodegenerative diseases like Alzheimer’s disease and related dementias (ADRD). Depending on the kind and intensity, exercises were found to positively affect brain vascularization, neurotransmitter regulation, growth aspects, and neurogenesis.