Rapid weight change linked to dementia risk

21 May 2019

BMJ Open: Effect of late-life weight change on dementia incidence: a 10-year cohort study using claim data in Korea

Researchers in Korea have identified a link between rapid weight changes in older people and the risk of dementia. The findings, published today in BMJ Open, are based on medical records from nearly 70,000 people.

Age is the biggest risk factor for dementia, but dementia is not an inevitable part of ageing. It is caused by diseases, most commonly Alzheimer’s disease. The number of people with dementia is predicted to increase dramatically, so it is vital to uncover the steps we can all take to reduce our risk.

Research suggests that leading a healthy lifestyle can help to keep our brains healthy as we age. World Health Organisation (WHO) guidelines published this month recommend not smoking, keeping physically active, controlling blood pressure and cholesterol, managing diabetes, avoiding excessive alcohol consumption, eating healthily, and maintaining a healthy weight as ways to maintain brain health into later in life.

While being overweight in midlife is an established risk factor for dementia, some previous research has found that, in later life, a lower body weight is linked with an increased risk of the condition.

In this study, researchers investigated the link between rapid weight changes and dementia risk by looking back at the medical records of almost 70,000 Koreans aged 60-79. All of the participants had their body mass index (BMI) measured as part of a health screening programme.

By using these BMI readings, the researchers calculated the individual changes in BMI over a two-year period. After a two-year gap, they monitored which individuals went on to develop dementia over a follow up period of around five years.

The researchers found that older people whose BMI increased or decreased by more than 10% were more likely to develop dementia than those with a stable BMI.

Dr Jana Voigt, Head of Research at Alzheimer’s Research UK, said:

“This study highlights a possible link between rapid weight changes in later life and the risk of developing dementia. While these findings are interesting, it is difficult to tease apart cause and effect from this kind of study and it is not clear what could be driving this link.

“Weight changes may be the result of early damage in the brain from diseases like Alzheimer’s and could indicate an underlying problem, but there are many reasons why a person’s weight can change.

“The study doesn’t tell us that losing or gaining weight causes dementia and it doesn’t provide a reason for people not to take action to achieve a healthy weight.

“Further research is important to reveal more about this relationship and whether this link could help to identify those at risk of dementia.

“A healthy weight at any point of life can have important health benefits, including helping to control dementia risk factors such as diabetes and high blood pressure. Current evidence suggests that, alongside maintaining a healthy weight, the best way to keep our brains healthy as we get older is to eat a balanced diet, keep blood pressure and cholesterol in check, not smoke, drink within recommended limits and stay mentally and physically active.”