Fifty five million people worldwide are believed to be living with Alzheimer’s disease, and the number is expected to almost double in the next 20 years.

A new study suggests that ‘middle-aged’ spread or having a beer belly could make people increasingly more likely to develop Alzheimer’s within 20 years.

American researchers discovered that those with more visceral fat, the fat that forms around the vital organs like the heart, stomach and liver, had more abnormal proteins in the brain that act as hallmarks of the disease.

Alzheimer’s affects almost seven million people in the US where it is also the leading cause of dementia.

The disease primarily affects the brain and causes gradual and complete loss of memory as well as thinking and reasoning skills.

The researchers are positive about their findings and believe it could be a source of hope for many.

They explained that linking Alzheimer’s risk to visceral fat levels in people in their 40s and 50s meant efforts to slim it down through diet and exercise could have a huge impact on dementia risk.

Visceral fat differs from other types of fat as it is often hidden, and wraps around the organs instead of making the person look bigger.

It can even make little difference to the person’s body mass index (BMI), meaning even people who have a healthy BMI can be at risk. In most cases, however, particularly in men, the fat presents as belly fat settled around the middle.

The study was presented at the annual meeting of the Radiological Society of North America, where researchers looked at health data from 80 people in their 40s and 50s with normal cognitive abilities, with no current signs of dementia.

Just over half the participants were obese while all of them underwent scans of their body to track visceral fat and scans of their brain to detect the amyloid proteins linked to Alzheimer’s.

The results showed that higher levels of visceral fat were linked to increased amyloid proteins.

Obesity has previously been linked to increasing the risk of dementia, but in this study, the researchers calculated that visceral fat in particular contributed to 77 percent of obesity-related amyloid accumulation in the brain.

Dr Mahsa Dolatshahi is a research associate at Washington University School of Medicine in St. Louis, Missouri and author of the paper. She confirmed that the study is the first to establish this link.

She said, “To our knowledge, our study is the only one to demonstrate these findings at midlife where our participants are decades out from developing the earliest symptoms of the dementia that results from Alzheimer’s disease.

“This crucial result was discovered because we investigated Alzheimer’s disease pathology as early as midlife—in the 40s and 50s—when the disease pathology is at its earliest stages, and potential modifications like weight loss and reducing visceral fat are more effective as a means of preventing or delaying the onset of the disease.”