Just like a crowded room can make it difficult for a person to concentrate and remember things, a heavy body can have a similar effect on the brain’s ability to function properly. A recent study examined the relationship between body mass index (BMI) and the hippocampus, a key region involved in memory processing. The researchers found that individuals with higher BMI had worse blood flow and reduced cerebrovascular reactivity (CVR) in the hippocampus when exposed to carbon dioxide. This suggests that obesity could be a risk factor for cognitive decline, as diminished blood flow to the brain can impair memory function. The findings highlight the importance of maintaining a healthy weight for optimal brain health. Future studies should explore whether weight loss interventions can improve blood flow and reduce inflammation in the brain, potentially mitigating the risk of cognitive decline. To learn more about this fascinating research, check out the full article!

Background and objectivesObesity is a risk factor for cognitive decline. Probable mechanisms involve inflammation and cerebrovascular dysfunction, leading to diminished cerebral blood flow (CBF) and cerebrovascular reactivity (CVR). The hippocampus, crucially involved in memory processing and thus relevant to many types of dementia, poses a challenge in studies of perfusion and CVR, due to its location, small size, and complex shape. We examined the relationships between body mass index (BMI) and hippocampal resting CBF and CVR to carbon dioxide (CVRCO2) in a group of cognitively normal middle-aged and older adults.MethodsOur study was a retrospective analysis of prospectively collected data. Subjects were enrolled for studies assessing the role of hippocampal hemodynamics as a biomarker for AD among cognitively healthy elderly individuals (age > 50). Participants without cognitive impairment, stroke, and active substance abuse were recruited between January 2008 and November 2017 at the NYU Grossman School of Medicine, former Center for Brain Health. All subjects underwent medical, psychiatric, and neurological assessments, blood tests, and MRI examinations. To estimate CVR, we increased their carbon dioxide levels using a rebreathing protocol. Relationships between BMI and brain measures were tested using linear regression.ResultsOur group (n = 331) consisted of 60.4% women (age 68.8 ± 7.5 years; education 16.8 ± 2.2 years) and 39.6% men (age 70.4 ± 6.4 years; education 16.9 ± 2.4 years). Approximately 22% of them (n = 73) were obese. BMI was inversely associated with CVRCO2 (β = −0.12, unstandardized B = −0.06, 95% CI −0.11, −0.004). A similar relationship was observed after excluding subjects with diabetes and insulin resistance (β = −0.15, unstandardized B = −0.08, 95% CI −0.16, −0.000). In the entire group, BMI was more strongly related to hippocampal CVRCO2 in women (β = −0.20, unstandardized B = −0.08, 95% CI −0.13, −0.02).DiscussionThese findings lend support to the notion that obesity is a risk factor for hippocampal hemodynamic impairment and suggest targeting obesity as an important prevention strategy. Prospective studies assessing the effects of weight loss on brain hemodynamic measures and inflammation are warranted.

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