The Hidden Brain Cost of Obesity: Groundbreaking Study Reveals Long-Term Impacts

Long-term obesity is linked to progressive brain decline, while reducing obesity helps preserve brain health, according to a large-scale study.

As obesity rates continue to rise globally, understanding its effects on brain structure and cognitive function has become increasingly important. The relationship between obesity and brain health is complex and multifaceted, requiring in-depth investigation into its underlying neural mechanisms.

Professor Anqi Qiu, from the Department of Health Technology and Informatics at The Hong Kong Polytechnic University (PolyU) and a Global STEM Scholar, has conducted groundbreaking research to clarify how obesity influences brain and cognitive health in adults.

While obesity is known to affect the brain, its long-term impact, particularly how patterns of obesity over time influence brain aging and cognitive decline, remains poorly understood. Most current studies rely on cross-sectional data, limiting the ability to distinguish between persistent and temporary obesity. Moreover, it is unclear whether different trajectories of obesity have distinct effects on brain structure and function.

Professor Qiu’s research addresses these critical gaps by conducting a comprehensive longitudinal analysis of obesity trajectories. Her work provides new insights into how long-term patterns of obesity relate to changes in brain anatomy and cognitive performance, offering a more accurate understanding of obesity’s lasting impact on brain health.

Distinct Patterns of Obesity and Their Cognitive Effects

Drawing on multifaceted obesity measurements from the UK Biobank, the study identifies five distinct obesity trajectories: low-stable, moderate-stable, high-stable, increasing, and decreasing. Significantly, the study examines how these obesity patterns influence brain morphology, function, and cognition in middle-aged and older adults, offering deeper insights into their long-term neurological effects.

Notably, individuals in the decreasing trajectory showed minimal adverse effects on brain structure and cognitive performance compared to those in the low-stable group. In contrast, the increasing, moderate-stable, and high-stable trajectories were associated with progressively greater impairment in brain structure, functional connectivity, and cognitive abilities. Specifically, these adverse effects began in the fronto-mesolimbic regions for the increasing trajectory, extended to parietal and temporal regions in the moderate-stable group, and ultimately led to widespread brain abnormalities in the high-stable group.

Implications for Clinical Practice and Brain Aging

The research highlights the dynamic relationship between obesity progression and brain-cognitive health, underscoring the clinical importance of long-term monitoring and management of obesity through a multifaceted approach. It reveals a distinct, progressive pattern of brain deterioration linked to obesity, suggesting that sustained obesity may accelerate brain aging. These findings indicate that persistent obesity could serve as a potential biomarker for assessing brain aging. Therefore, reducing both the severity and duration of obesity exposure may be crucial for preserving brain health.

Prof. Qiu said, “As the aging population grows, there has been a notable rise in neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, and others, that currently lack a cure. This research proposes that maintaining long-term weight control can contribute to improved brain health.” Looking ahead, the research team plans to integrate multi-omics approaches to explore the biological pathways that influence both brain and body health.

The study extracted obesity measures, brain images, and cognition from the UK Biobank database, which comprised over 500,000 participants aged 40 years and above with diverse ethnic backgrounds.

Reference: “Long-term obesity impacts brain morphology, functional connectivity and cognition in adults” by Die Zhang, Chenye Shen, Nanguang Chen, Chaoqiang Liu, Jun Hu, Kui Kai Lau, Zhibo Wen and Anqi Qiu, 3 March 2025, Nature Mental Health.
DOI: 10.1038/s44220-025-00396-5