The impact of obesity on brain ageing and the risk of dementia has long been a concern in the medical community. In clinical practice, body mass index (BMI) is commonly used as an assessment indicator, but it does not accurately reflect differences in fat accumulation across various body regions. A recent study by The Hong Kong Polytechnic University (PolyU) has revealed that fat distribution in specific body regions is significantly and distinctly associated with brain structure and cognitive function. In particular, visceral fat was found to accelerate brain ageing and lead to cognitive decline, having more detrimental impact on brain health than any other type of fat.
Led by Prof. Anqi QIU, Chair Professor of Neuroinformatics of the PolyU Department of Health Technology and Informatics, Director of the Mental Health Research Centre and Global STEM Scholar, a PolyU research team conducted the world’s first large-scale multimodal study to systematically explore the correlation between regional adiposity and brain structure, functional connectivity, and cognitive performance. The study provides a new scientific basis for research into Alzheimer’s disease, vascular dementia and other age-related brain disorders. The findings have been published in the international journal Nature Mental Health.
The research has shown that BMI alone is insufficient when assessing brain decline and cognitive ageing, whereas regional adiposity is an indispensable indicator. This milestone in neuro-epidemiological research will assist the healthcare sector in developing more precise and personalised brain health prevention and intervention strategies.
The research team conducted a multidimensional correlation analysis of health data from over 18,000 participants in the UK Biobank, examining the relationship between regional adiposity data measured using dual-energy X-ray absorptiometry and results from multimodal brain imaging and cognitive testing. The findings revealed that fat accumulation in the arms, legs, trunk and visceral regions was differentially associated with, and affected, neural systems, including the morphology of the sensorimotor, limbic, default mode and subcortical–cerebellar–brainstem systems. The study specifically noted that visceral fat was the only type of fat directly linked to compromised white-matter integrity in the brain. White matter acts as the “cables” for transmitting neural signals in the brain, and damage to it is closely aligned with the pathogenic mechanisms of vascular cognitive impairment and cerebral small vessel disease.
Prof. Qiu said, “Fat in different parts of the body maps out entirely different trajectories of change in the brain, which cannot be detected by body weight or BMI alone. Our analytical model clearly demonstrates how fat in different regions causes differential damage to brain systems. Notably, regional adiposity is an intervenable and modifiable health risk factor. Reducing visceral fat through targeted lifestyle interventions can open up new pathways for the proactive prevention and treatment of neurodegenerative diseases.”
The research team suggested that visceral adiposity might be the most harmful type of regional adiposity for the brain due to its tendency to trigger chronic inflammation in the body, which may then lead to neuroinflammation. This study establishes a comprehensive analytical framework and highlights the importance of targeted reduction of visceral fat to help maintain mental acuity and prevent dementia.
