Is obesity increasing my risk of dementia?
The risk of developing dementia may be much higher than previously thought, according to a study published Monday in the journal Nature Medicine.
Older studies estimated that about 14% of men and 23% of women would develop dementia in their lifetimes. This new study puts that estimate higher, at around 42% for both men and women.
It’s important to note that many factors may be affecting the data. Previous studies did not use diverse enough populations and people now are living longer with other conditions, including stroke, high blood pressure, Type 2 diabetes and obesity. Nevertheless, all of these comorbities increase a person’s risk for dementia. But how much of it can be attributed to obesity alone? Here is what the data tells us:
Evidence
Midlife obesity and dementia risk:
Obesity in middle age (BMI ≥30) increases the risk of dementia, Alzheimer's disease (AD), and vascular dementia significantly. Obese individuals were found to have a 74% higher risk compared to those with normal BMI (Whitmer et al., 2005).
A meta-analysis confirmed this risk, showing a 41% increased likelihood of dementia among obese individuals under 65 years (Pedditzi et al., 2016).
Late-life obesity:
Obesity's effects differ in later life. Studies indicate that while midlife obesity elevates dementia risk, late-life obesity might not have the same effect or may even reduce the risk of dementia, possibly due to weight loss being a marker of preclinical dementia (Qizilbash et al., 2015).
Central obesity (measured by waist circumference) also increases dementia risk, particularly in women (Ma et al., 2020).
How obesity affects brain structure:
Obesity influences brain health through inflammation, oxidative stress, vascular dysfunction, and hormonal changes, which may disrupt brain structure and function (Kiliaan et al., 2014).
Brain atrophy and white matter changes are more pronounced in individuals with higher BMI, which could explain the cognitive decline (Ho et al., 2009).
Adiposity and cognitive decline:
Metabolically unhealthy obesity is more strongly linked to dementia than metabolically healthy obesity, highlighting the role of metabolic disturbances (Su et al., 2024).
Takeaways
Obesity, particularly in midlife, is strongly associated with an increased risk of dementia, likely due to inflammation, metabolic dysregulation, and vascular damage. These findings underline the importance of managing weight and metabolic health across the lifespan to mitigate dementia risk.
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