Childhood obesity could increase risk of future dementia, study finds

Childhood obesity may be putting people at risk of developing dementia in future, a worrying study has suggested. As the 2025 Obesity Week continues in the UK, promoting awareness and education around weight issues, research on the connections between body and brain health has come to light.

A recent study from the University of Oxford ’s Department of Psychiatry looked at the links between the brain and physical activity, blood pressure, and Body Mass Index (BMI). Obesity, hypertension (high blood pressure), and physical inactivity are established cardiovascular risk factors for dementia in middle age.

Their impact on brain and heart health earlier in life, however, remains largely unknown. The research, conducted in collaboration with University College London and supported by the NIHR Oxford Health Biomedical Research Centre and Wellcome, analysed data from over 860 children and adolescents aged 7 to 17.

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The study included brain scans, as well as measurements of physical activity, blood pressure, and BMI. Published in the journal eBioMedicine, the findings revealed a clear link between increased BMI, higher blood pressure, and lower physical activity during adolescence and subsequent changes in brain structure during young adulthood, a critical period of development.

The study highlighted that these effects are particularly pronounced in brain regions commonly impacted by dementia in later life. This suggests that unhealthy habits established in childhood could lay the groundwork for brain health decline in the future.

The research highlighted the importance of adopting healthier lifestyles early on, emphasising that the choices made in childhood can have long-term implications for cognitive health.

Holly Haines, lead author on the paper, said: "Our research shows that cardiovascular health in the earliest stages of life may already be important for the structure of brain regions known to be affected in dementia in old age – much earlier than previously thought."

The researchers discovered that markers of poorer cardiovascular health, such as elevated childhood blood pressure and a faster increase in BMI during adolescence, were linked to structural differences in grey matter, a crucial type of brain tissue. These differences were particularly evident in areas of the brain responsible for memory and cognitive functions.

Interestingly, similar connections between heart health and brain health have already been observed in older adults experiencing memory issues or dementia, further emphasizing the lifelong relationship between the two.

The scientists believe these findings could pave the way for earlier identification and prevention of dementia risks.However, they stress that more research is needed, particularly involving a more diverse group of participants, to ensure the findings can be applied broadly across the population.

Co-author of the paper, Associate Professor Sana Suri from the Department of Psychiatry at the University of Oxford, added: "The findings suggest that we should be thinking about targeting modifiable lifestyle risk factors, such as obesity and exercise, decades before current lifespan models of dementia suggest. The early adolescent years merit greater consideration in the context of dementia prevention."

The study drew its data from the Avon Longitudinal Study of Parents and Children (ALSPAC), a globally renowned birth cohort study conducted by the University of Bristol.

David Thomas, Head of Policy and Public Affairs at Alzheimer’s Research UK, said: "This study suggests that not looking after our hearts even in adolescence could lead to changes in the brain later on in life, which may influence the risk of developing dementia.

"Up to 45 per cent of dementia cases can be prevented by avoiding risk factors that we can influence, such as physical inactivity and smoking. These are habits that some people pick up in early life, without knowing the potential long-term consequences for their brain health.

"Dementia is not just an inevitable part of aging. By supporting research like this study, we are gaining insights into how people might be able to prevent dementia happening in the first place, which is vital if we want to reach a cure for this devastating condition."

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