July 22, 2011 (Paris) -- Mild memory loss is relatively common, affecting between 10% and 20% of older adults in the U.S., new data suggest.
In addition to getting older, a new study shows that diabetes, stroke, and obesity increase the likelihood of mild memory loss. The ApoE4 gene, which has been linked to Alzheimer's, was also associated with mild cognitive impairment (MCI), the medical term for early memory loss.
Research has shown that people with MCI are at increased risk of developing Alzheimer's disease within a few years. But not everyone who gets a diagnosis of MCI goes on to develop Alzheimer's. Some factors that may cause MCI to progress to Alzheimer's are depression, anxiety, and other medical conditions.
MCI involves problems with memory or other brain functions that are noticeable to the affected person and those around him, but not serious enough to interfere with daily life.
In the U.S. study about 7% per year developed MCI, says Ronald Peterson, MD, PhD, professor of neurology at the Mayo Clinic College of Medicine in Rochester, Minn. He studied more than 1,600 people aged 70 to 89 who had no memory problems at the beginning of the study.
Also, 10% of people per year who developed MCI went on to develop Alzheimer's dementia, he says.
But the patients were only followed for about four years, Peterson says. "Based on the data we have, we would expect about 80% to convert from MCI to dementia if they were followed longer, for 10 years," he tells WebMD.
MCI: The Global View
In addition to the U.S. study, researchers at the MCI symposium presented data on more than 30,000 people aged 65 and older from Germany, Great Britain, Sweden, France, and Australia.
MCI was more common in Australia than in the other countries, affecting over 35% of people, but that's probably because the researchers used a less stringent definition of the condition, Peterson says.
If the same definition were used as in the other countries, the frequency was closer to 10%, he says.
These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.