Study ties obesity and “inflammaging” to cognitive decline, raising stakes for retirement health
Obesity may be the most powerful lifestyle factor driving the “inflammaging” that seems to underlie cognitive decline and dementia in older adults, new Canadian research suggests.
A Baycrest study of older adults found that participants with elevated inflammation made up about two thirds of those with cognitive impairment, compared with roughly one third of cognitively healthy adults.
That pattern points to systemic inflammation as a key factor in the cognitive changes that often accompany aging, and it underscores the potential importance of weight and cardiometabolic health in preserving brain function.
Researchers describe this chronic, low-grade inflammation as “inflammaging.”
It gradually increases with age and contributes to vulnerability to age-related diseases, including dementia.
While inflammation tends to rise naturally over time, its severity is strongly influenced by body weight, cardiovascular health and other aspects of physical health.
Over time, this persistent inflammation, even when it occurs outside the brain, may contribute to changes in brain function.
Bruna Seixas-Lima, Scientific Associate at Baycrest's Rotman Research Institute and lead author of the study, says the findings provide new evidence that “systemic inflammation, shaped by lifestyle and overall health, may be a key mechanism connecting physical health to long-term brain function.”
Researchers drew on extensive data from 514 participants in the Comprehensive Assessment of Neurodegeneration and Dementia Study (COMPASS-ND), part of the Canadian Consortium on Neurodegeneration in Aging (CCNA).
They collected measures of systemic inflammation, age and sex, cardiovascular and medical history, lifestyle factors such as diet, sleep, smoking and body weight, cognitive assessments and changes in brain white matter observed through magnetic resonance imaging (MRI).
This large and diverse cohort included older adults living with different forms of dementia, mild cognitive impairment and no cognitive impairment.
That range allowed the team to examine how lifestyle and health factors contribute to inflammaging across real-world cognitive and medical conditions.
While diet quality and sleep also influenced inflammation, obesity emerged as the strongest lifestyle-related contributor, exceeding the influence of diet and sleep quality.
Among individuals living with dementia, those with vascular conditions showed higher levels of inflammation.
Many contributors to inflammation in aging adults are modifiable through changes in habits and lifestyle.
COMPASS-ND is one of the world's most detailed collections of health and brain data, comprising nearly 1,200 Canadians between the ages of 50 and 90 who are living with or at risk of developing dementia.
The study includes individuals with mixed dementia, multiple health conditions, complex diagnoses and frailty, reflecting real-world aging and cognitive decline.
It is the signature observational cohort study of the CCNA, described as Canada's largest dementia research initiative, headquartered at Baycrest.
Researchers note that it remains unclear whether directly treating inflammation can prevent dementia.
However, they say these findings may help inform strategies for earlier identification of risk and prevention, especially those targeting obesity and cardiovascular health.
The team is conducting follow-up studies to further explore the relationship between inflammation and cognitive decline.
The study, titled “Peripheral inflammation in a Canadian cohort of neurodegenerative conditions: Occurrence, determinants, and impact,” was recently published in the Journal of Alzheimer’s Disease.
