Body mass index (BMI), a commonly used measure of body fat based on a person’s weight and height, has long been associated with various health outcomes.
However, a recent study from Karolinska Institutet suggests that a significant drop in BMI may also serve as an early warning sign of cognitive decline, particularly the onset of mild cognitive impairment (MCI), which often precedes dementia.
The study focused on the relationship between BMI changes and cognitive health, tracking 1,390 adults over time. The participants had an average age of 78.4 years, and the majority were women (76.5%).
Researchers analyzed long-term trends in BMI leading up to the diagnosis of MCI and dementia, seeking to understand how weight changes might signal the early stages of cognitive decline.
What the researchers found was striking: BMI began to decline significantly about seven years before the diagnosis of MCI in those who would later be diagnosed with the condition.
This decline was more pronounced and started earlier compared to individuals who remained cognitively healthy throughout the study period.
Interestingly, the rate of BMI decline was similar among those who developed MCI, regardless of whether they eventually progressed to dementia. This suggests that the drop in BMI is an early indicator of cognitive issues rather than a sign of dementia itself.
The study also delved into the biological underpinnings of this phenomenon by examining a subset of 358 participants who had undergone autopsies.
The findings revealed that a faster decline in BMI was closely associated with a higher burden of Alzheimer’s disease-related brain changes or vascular issues, such as problems with blood vessels in the brain.
This suggests that the physical changes in the brain linked to Alzheimer’s disease or vascular conditions might contribute to the observed weight loss before cognitive symptoms become evident.
The results of this study highlight a potential early marker for MCI, suggesting that monitoring BMI trends in older adults could help in identifying individuals at risk of cognitive decline.
However, it’s important to note that the exact relationship between BMI changes and brain health remains complex and requires further investigation.
The researchers call for future studies, particularly those involving advanced brain imaging techniques like positron emission tomography (PET), to better understand the timing and mechanisms underlying the association between BMI decline and brain pathology.
Such studies could clarify whether the observed weight loss is a direct consequence of brain changes or if it results from other factors associated with cognitive decline.
Published in JAMA Psychiatry, the study led by Jie Guo and colleagues provides new insights into the early warning signs of cognitive impairment.
While BMI is typically used to assess physical health, this research suggests that it could also be a valuable tool in identifying those at risk for cognitive decline, enabling earlier interventions that might delay or prevent the progression to dementia.
If you care about dementia, please read studies about low choline intake linked to higher dementia risk, and how eating nuts can affect your cognitive ability.
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