Losing weight in middle age could increase risk of Alzheimer’s, study finds

Losing weight in middle age has been linked to an increased risk of Alzheimer’s.

Being obese or overweight has long been known to increase the risk of dementia, and older people are advised to stay lean to ward off the disease.

But researchers from Boston and China found that adults who lost body mass in their middle years had an increased risk of developing dementia later in life.

They are calling for the “unexpected” finding to be investigated further to ensure other lifestyle factors are not to blame for the increased risk.

Researchers identified a subgroup with a pattern of initially increasing BMI followed by decreasing BMI. Both occurred in middle age — which appeared to be central to the declining BMI-dementia association

The study’s lead author, Professor Rhoda Au of the University of Boston, said: “If there is an unexpected shift towards weight loss after midlife, after a steady weight gain that is common with aging, it could be good to look into it to advise healthcare providers and pinpoint why.’

The results show that the seeds of dementia are sown over many years – probably even over the entire lifespan.

According to Columbia University researchers, nearly 10 percent of US adults ages 65 and older have dementia, while another 22 percent have mild cognitive impairment.

Dementia is a global problem affecting 50 million people and is expected to increase dramatically to more than 150 million cases worldwide by 2050.

Obesity, meanwhile, is responsible for some of the leading causes of preventable premature death, including heart disease, stroke, type 2 diabetes and certain types of cancer. About 42 percent of adults ages 20 and older were obese from 2017 to March 2020.

The US-Chinese team analyzed data from the Framingham Heart Study, which followed a group of participants from the city of Massachusetts for four decades.

Their weight was measured about every two to four years. Prof. Au and colleagues compared rates of dementia in those whose weight increased, decreased, or remained stable.

Prof Au said: “These results are important because previous studies looking at weight trajectories failed to consider how patterns of weight gain/stability/loss might help signal that dementia may be imminent.”

The researchers found that the overall trend of decreasing BMI was associated with a higher risk of dementia.

However, upon further investigation, they identified a subgroup with a pattern of initially increasing BMI followed by decreasing BMI.

A declining body mass index (BMI) was associated with a greater risk of developing cognitive problems that affect memory, thinking, and social skills

Both occurred in middle age — which appeared to be central to the declining BMI-dementia association. Findings appear online in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

The results should not be interpreted as a recommendation to gain extra pounds.

Obesity is linked to a range of health problems, including high blood pressure and cholesterol, inflammation and cardiovascular death.

It increases the risk of heart disease, which kills 647,000 people each year in the US – making it the number one killer. Obesity has also been linked to 12 different types of cancer.