How Are Obesity and Alzheimer’s Disease Alike?

While the relationship between obesity and cognitive decline remains complex, there's increasing evidence that they are, indeed, connected.


Traditionally, obesity has been linked to conditions such as hypertension and type 2 diabetes, but recent research suggests that obesity may also impact the nervous system.

For instance, a study found that increased body mass index (BMI) and body fat percentage are related to worse cognitive performance. Obesity has also been identified as a risk factor for Alzheimer’s disease, a neurodegenerative condition characterized by cognitive decline. Moreover, animal models have demonstrated that similar brain regions affected in neurodegenerative diseases are affected in the brains of obese animals.

Nonetheless, it remains unclear whether Alzheimer’s-related brain pathologies are similar to obesity-related brain pathologies in humans. Thus, Dr. Filip Morys, a postdoctoral researcher from the Montreal Neurological Institute at McGill University, led a project that explored brain structure between otherwise healthy obese older adults compared to those living with Alzheimer’s disease.

The study, which also included contributions from the CERVO Brain Research Centre at Laval University, was published in the Journal of Alzheimer’s Disease.

For their study, the researchers focused in particular on cortical thickness, which is the brain’s outer layer — commonly known as grey matter. Cortical thickness plays a crucial role in receiving and regulating information within the brain.

They utilized data from two large cohorts, namely the UK Biobank and the Alzheimer’s Disease Neuroimaging Initiative. The cortical thickness of more than 1,300 participants around the age of 75 was analyzed, and participants were grouped as individuals living with Alzheimer’s disease patients or cognitively healthy obese individuals, based on BMI, who did not have a diagnosis of any neurological illness including Alzheimer’s disease.

The study’s findings revealed patterns of cortical thinning, also known as brain shrinkage, in obese participants. Remarkably, these patterns closely resembled cortical thinning seen in the participants living with Alzheimer’s disease. In simpler terms, the brain structure in otherwise healthy obese older adults mimicked that of individuals with Alzheimer’s. These findings align with previous research suggesting that midlife obesity is a risk factor for Alzheimer’s.

Overall, this study underscores the importance of addressing obesity as a potential risk factor for neurodegenerative diseases like Alzheimer’s disease. By understanding the complex relationship between obesity and brain health, targeted interventions and prevention strategies can be developed to promote cognitive well-being and reduce the burden of neurodegeneration in our society.

Therefore adopting a healthy lifestyle, specifically in terms of excess weight management, not only benefits individuals in their present life but may also have a positive impact on their future cognitive health.

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Alexandria (Alex) Samson is a PhD student in the Department of Psychology at the University of Toronto. She completed her BSc in Neuroscience from Dalhousie University. Alex is a strong believer in open science and is passionate about making scientific research accessible to all audiences.