People who are overweight or obese have a greater risk of developing Alzheimer's, the degenerative brain disease, a new study by US and Australian researchers has claimed.
The research team - from Thomas Jefferson University in Philadelphia and the Edith Cowan University in Western Australia - say that being obese 'almost certainly' increases risk from Alzheimer's.
They have found a link between body mass index (BMI) and high levels of beta-amyloid, the sticky protein that builds up on the brain of Alzheimer's sufferers. The protein is thought to play a major part in the destruction of nerve cells in the brain and is linked to the behavioral and memory problems associated with the disease.
Alzheimer's is a form of dementia which affects the brain's memory function. It causes impaired memory followed by diminished thought and speech. The exact cause of the disease is not yet known.
Dr Sam E Gandy, co-author of the study, which appears in the Journal of Alzheimer's Disease, says they have found a relationship between obesity and circulating amyloid, and that is why the risk of Alzheimer's is higher for obese people. In fact, heightened levels of amyloid in the blood vessels and the brain indicate the start of the Alzheimer's process.
Dr Gandy and his colleagues measured the body mass index and beta-amyloid levels in the blood. They also looked at several other factors associated with heart disease and diabetes, such as the inflammatory marker C-reactive protein, insulin, and high-density lipoprotein in 18 healthy adults who were either extremely overweight or obese. They found a statistically significant correlation between body mass index and beta-amyloid.
They also looked at several other factors associated with obesity including heart disease and diabetes in 18 healthy -but obese - adults. They found a 'statistically significant correlation' between BMI and beta-amyloid levels.
There have been previous studies showing that many conditions associated with obesity increase risk from Alzheimer's. But this is the first time that researchers have been able to pinpoint how obesity and its related illnesses are linked to Alzheimer's.
One implication of these findings could be that by losing excess weight and maintaining normal body weight, an individual might reduce the risk of developing Alzheimer's. However, this has not been proven, notes Dr. Gandy.
Dr Gandy says the next step is to follow people with obesity and see if, over time, they develop Alzheimer's. He said it was also important to develop medication to fight the harmful beta-amyloid brain plaques which seem to be responsible for many of the characteristics of Alzheimer's disease.