BMI and waist-to-hip ratio link to brain health

Posted on 9th January 2019

Neurology: Association of body mass index and waist-to-hip ratio with brain structure

Researchers from Loughborough University and University College London have identified a link between body mass index (BMI), waist-to-hip ratio (WHR) and the structure of the brain. The study, published today (Wednesday 9 January) in the journal Neurology, found that participants with a higher BMI and WHR were more likely to have lower levels of grey matter in the brain.

BMI is used to measure a person’s weight relative to their height and is commonly used by doctors to help assess whether a person is a healthy weight. Waist-to-hip ratio is determined by dividing waist circumference by hip circumference and can provide an assessment of abdominal fat.

The study analysed data from 9,652 people between the ages of 40 and 69 who are part of the UK Biobank study. Participants took part in MRI brain scans and the researchers related BMI and waist-to-hip ratio scores to the size and structure of the brain.

They found a relationship between measures of obesity and the volume of grey matter – the part of the brain that contains most of the bodies of nerve cells. While a higher BMI and waist-to-hip ratio were each separately linked to a lower grey matter volume, the combination of a high score in both measures was most strongly linked to this indicator of brain health.

Dr Rosa Sancho, Head of Research at Alzheimer’s Research UK, said:

“While BMI can be a crude measure and not necessarily a good indication of our general health, this research suggests that taking a person’s waist-to-hip ratio into account may provide additional information that could be relevant to the health of the brain.

“The study adds to existing evidence highlighting a link between a healthy weight and a healthy brain, but the researchers didn’t look at whether participants went on to develop diseases like Alzheimer’s and this will need to be explored in future research.

“It is not clear what underlies the relationship between body weight and brain health and being overweight is associated with the risk of a number of different health conditions. It is important that researchers work to better understand the factors that affect the risk of dementia so that we can provide people with the best possible information about how to maintain a healthy brain.

“As well as maintaining a healthy weight, the best current evidence suggests that staying mentally and physically active, not smoking, only drinking in moderation, eating a healthy diet, and keeping blood pressure and cholesterol in check can help to support brain health as we age and keep our dementia risk as low as possible.”

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