Alzheimer's disease, a leading cause of dementia in the elderly, appears later in highly educated people — but once it does, it advances more quickly, scientists said on Thursday.
"We find that after the onset of manifestations of Alzheimer's disease patients with higher education decline faster," Dr. Nikolaos Scarmeas, of Columbia University Medical Center in New York, said in an interview.
He and his team followed the progression of the illness in 312 people who ranged from being illiterate to highly educated. The patients were given brain function tests and monitored for five years.
Cognitive decline occurred in all the patients. But the researchers noted that each additional year of education was related to an additional 0.3 percent deterioration, particularly in memory and speed of thought processes.
The researchers looked at other factors, such as changes in the brain, high blood pressure, depression and age, that could have an impact on the disease.
"We couldn't find any other explanation for it," said Scarmeas, who reported the finding in the Journal of Neurology, Neurosurgery and Psychiatry.
An estimated 12 million people worldwide suffer from Alzheimer's disease. The number is expected to increase as the population ages.
There is no cure for the progressive illness, which robs people of their memory and mental ability, but drug treatments may slow the early progression of the disorder.
Researchers said a theory called cognitive reserve could be a possible explanation for the findings. It suggests that people with higher brain skills and function seem more able to delay the onset of illness and its symptoms.
"When more and more of the disease accumulates in the brain they are able to compensate for a long time, but at some point they cannot cope with it anymore and they manifest the disease," Scarmeas explained.
"Because a lot of disease has accumulated they decline faster," he added.
