Washington: Researchers in the United States have taken a step further in finding out why memory deteriorates with age.

They revealed that memory loss might be linked to so-called brain tangles. These occur when twisted fragments of proteins within nerve cells clog up the cells. Large numbers of these tangles are already known to cause Alzheimer's disease, according to a report in BBC.

The research by Dr Angela Guillozet and colleagues at North Western University indicated that these tangles also occur in people who do not have Alzheimer's.

The team examined the brains of eight dead people. Three had suffered from mild cognitive impairment – a more severe form of memory loss than that associated with ageing, but less severe than Alzheimer's. The remaining five had healthy brains, the report said.

The researchers found tangles in all of the brains. However, the number of tangles was higher in those with mild cognitive impairment. They also found a direct link between the number of tangles and scores from memory tests carried out on the eight people before they died.

The findings come as a second study suggests that depression could be an early sign of the disease. Researchers at Boston University believe many people with Alzheimer's may also have a history of suffering from depression. The study showed that people with Alzheimer's were twice as likely to have suffered from depression when they were younger.

ANI