Research led by The Hong Kong Polytechnic University finds that regional fat distribution exerts distinct effects on brain structure, connectivity and cognition, revealing patterns not explained by body mass index (BMI).

Obesity has been associated with structural and functional changes in the brain, including reductions in gray matter, disruptions in white matter and impaired connectivity, which have been associated with cognitive decline.

Previous studies frequently used BMI as the central measure of obesity, a highly generalized metric that cannot capture the biological differences in fat depots. Adipose tissue in different body regions is known to affect metabolic and inflammatory pathways differently, and earlier work has suggested that visceral (around organs in the abdominal cavity) and leg fat contribute unequally to disease risk.

Regular exercise is associated with pronounced health benefits. The molecular processes involved in physiological adaptations to exercise are best understood in skeletal muscle. Enhanced mitochondrial functions in muscle are central to exercise-induced adaptations. However, regular exercise also benefits the brain and is a major protective factor against neurodegenerative diseases, such as the most common age-related form of dementia, Alzheimer’s disease, or the most common neurodegenerative motor disorder, Parkinson’s disease. While there is evidence that exercise induces signalling from skeletal muscle to the brain, the mechanistic understanding of the crosstalk along the muscle–brain axis is incompletely understood. Mitochondria in both organs, however, seem to be central players.