Obesity-Linked Inflammation Tied to Cognitive Decline and Dementia, Study Finds - Video

Obesity and advancing age are strongly linked to chronic low-grade inflammation in the body, a condition increasingly associated with cognitive decline and dementia, according to a new study from Baycrest’s Rotman Research Institute. The findings, published in the Journal of Alzheimer’s Disease, suggest that systemic inflammation—shaped by lifestyle and physical health—may play a significant role in age-related changes in brain function.

The study found that nearly two-thirds of individuals with cognitive impairment had elevated levels of inflammation, compared with only about one-third of cognitively healthy adults. This pattern supports the idea that persistent inflammation outside the brain may contribute to declining cognition over time, a process often referred to as “inflammaging.”

“Systemic inflammation, influenced by lifestyle and overall health, may be a key mechanism linking physical health to long-term brain function,” said Dr. Bruna Seixas-Lima, lead author of the study.

Researchers analyzed data from 514 participants enrolled in the Comprehensive Assessment of Neurodegeneration and Dementia Study (COMPASS-ND), part of the Canadian Consortium on Neurodegeneration in Aging. Participants included cognitively healthy adults, individuals with mild cognitive impairment, and those living with various forms of dementia, allowing for real-world comparisons across diverse aging populations.

The study examined inflammatory markers alongside age, sex, cardiovascular history, body weight, diet, sleep, smoking habits, cognitive testing results, and brain imaging findings. Among all lifestyle factors evaluated, obesity emerged as the strongest contributor to elevated inflammation—exceeding the influence of diet quality and sleep. Participants with dementia and coexisting vascular conditions showed particularly high inflammation levels.

Importantly, many contributors to inflammation were found to be modifiable. “These findings highlight opportunities for early risk reduction through lifestyle changes that support physical and metabolic health,” the researchers noted.

While it remains unclear whether directly targeting inflammation can prevent dementia, the study provides valuable insight into how physical health and brain health are interconnected. Ongoing follow-up studies aim to further clarify whether reducing inflammation earlier in life could help slow or prevent cognitive decline in aging adults.

REFERENCE: Seixas-Lima B, Rosa-Neto P, Phillips NA, et al. Peripheral inflammation in a Canadian cohort of neurodegenerative conditions: Occurrence, determinants, and impact. Journal of Alzheimer’s Disease. 2025;109(2):1020-1035. doi:10.1177/13872877251401611