Researchers find obesity linked to reduced blood flow to the brain

A new study from scientists at The Irish Longitudinal Study on Ageing (TILDA) at Trinity College Dublin reveals important findings, indicating that being overweight or obese significantly reduces blood flow in the brain. The study also shows that increased physical activity can positively modify, or even negate, this reduction in brain blood flow.

The study contains relevant information which is of great interest to the general public; since reduced blood flow in the brain, or ‘cerebral hypoperfusion’, is an early mechanism in vascular dementia and Alzheimer’s disease.

Weighing scales. Image credit: Pikrepo (free licence)

Obesity and health challenges

According to the World Health Organization (WHO), obesity is a worsening health crisis that has reached epidemic proportions globally, with over 1 billion adults overweight – and at least 300 million clinically obese. It continues to be a major contributor to global rates of chronic disease and disability, affecting overall quality of life, while placing increased strain on the immune system which is of the upmost importance given the current COVID-19 situation. Obesity is also a significant public health concern given its negative impact on physiological function, especially as we age. Finding easily implemented and cost-effective ways to tackle the impact of obesity is particularly important to help protect against negative health outcomes in later life.

What are the findings of the TILDA study?

The study investigates three different measures of obesity – body mass index (BMI), waist-to-hip ratio and waist circumference, as well as physical activity, in adults over 50 years.

Brain blood flow was measured using cutting-edge MRI scanning and analysis techniques. The findings reveal that being overweight or obese is associated with reduced blood supply to the brain. Whereas brain blood flow is known to decline with age, in this study the negative influence of obesity on brain blood flow was shown to be greater than that of age. However, being physically active helps to cancel out the negative effects of obesity on brain blood flow.

Key Findings

  • Increased BMI, waist-to-hip ratio, and waist size are associated with less blood supply to the brain.
  • A waist size increase of +1cm is associated with the same reduction in brain blood flow as +1 year of age.
  • Higher levels of physical activity modify the associations between reduced brain blood flow and obesity.

Source: Trinity College Dublin