Middle-aged obese people have ‘lower dementia risk’

Obese middle-aged people are nearly 30% less likely to develop dementia than those of a healthy weight, a study has revealed.

It also found that underweight people of the same age were a third more likely to develop the condition than those who had a healthy body mass index (BMI).

The research, published in the The Lancet Diabetes And Endocrinology journal, contradicts findings from previous studies, which suggested obesity leads to an increased risk of dementia.

Researchers at the London School of Hygiene and Tropical Medicine and Oxon Epidemiology analysed data from the Clinical Practice Research Datalink (CPRD).

The database — which represents around 9% of the UK population — contains patient information recorded during routine general practice over nearly two decades.

The records of 1,958,191 people with a median age of 55 at the start of the study period and a median BMI of 26.5kg/m2 — just within the range usually classed as overweight — were examined. They showed that within an average of nine years’ follow-up, 45,507 people were diagnosed with dementia.

People who were underweight in middle age were 34% more likely to be diagnosed with dementia than those of a healthy weight. As people’s BMI increased, the risk of dementia reduced.