Aging frequently comes with a variety of comorbid conditions, among which dementia stands out as particularly daunting, given the difficulties in developing effective treatments. In light of these challenges, focusing on modifiable risk factors that could diminish the risk of this ailment presents a more practical strategy. Obesity has been pinpointed as one such factor.
It appears that obesity in midlife poses a risk for dementia, yet a higher BMI in older age is linked to a lower incidence of the disease. This paradox suggests that BMI might not be the most accurate measure of nutritional health in the elderly, who typically undergo shifts in body composition, including an increase in fat mass alongside a decrease in lean mass, without significant alterations in BMI.
In response, newer studies have shifted focus towards alternative health metrics like waist circumference and waist-to-hip ratio, pointing to the detrimental effects of abdominal fat on cognitive health. Nevertheless, the debate continues regarding the precise impact of different body measurements and fat types on cognitive decline.
This research monitored a cohort of 873 older adults from community settings in Japan. These individuals, all aged 60 years and above and free from cognitive impairments at the outset, were observed biennially over an average span of 9.67 years. The study measured each participant’s waist circumference, visceral fat area and subcutaneous fat area. Cognitive function was evaluated using the Mini-Mental State Examination (MMSE). For analysis, these measurements were categorized into three tiers: lowest, middle, and highest.
The analysis revealed that in men, the most significant reductions in MMSE scores were observed in those with the highest measurements of waist circumference, subcutaneous fat area, and visceral fat area, relative to their counterparts in the lowest measurement groups. For women, a similar pattern emerged for waist circumference and subcutaneous fat area, where those in the highest measurement groups experienced the greatest declines in MMSE scores compared to women in the lowest groups. This trend, however, did not hold for the groups categorized by visceral fat area in women.
The team sought to understand their findings by considering existing scientific insights. They suggested that the link between cognitive decline and both visceral and subcutaneous fat might be attributed to the function of adipose tissue as an endocrine entity that produces adipokines. The hypothesis is that abundant abdominal obesity could heighten the release of inflammatory cytokines, potentially leading to cognitive deterioration. This theory is supported by earlier studies, such as one indicating a correlation between elevated levels of the inflammatory cytokine IL-6, an adipokine, and a heightened risk of dementia.
Increased waist circumference (WC), subcutaneous fat area (SFA), and visceral fat area (VFA) in men, along with elevated WC and SFA in women, were linked to more significant cognitive deterioration over the following decade. Yet, no link was found between the accumulation of visceral fat and cognitive decline in women. These results indicate that abdominal fat buildup poses a risk for cognitive decline in the elderly. Additionally, the types of abdominal fat contributing to cognitive decline appear to vary between men and women, highlighting the need for further research to elucidate the sex-specific mechanisms underlying this difference.
To view the original scientific study click below:
Association between abdominal adiposity and cognitive decline in older adults: a 10-year community-based study
