The study provides the first biological proof of education's possible protective effect, although there have been earlier hints.
“The more education, the better the brain can tolerate the accumulation of the disease,'' said Dr David A. Bennett, lead investigator of the study and director of the Rush Alzheimer's Disease Centre in Chicago, in the United States.
“Even though education didn't alter the pathology of the disease process, it did prevent or slow cognitive decline.''
Bennett and his colleagues have been studying almost 1,000 nuns, priests and brothers since 1994 in an attempt to crack the mystery of Alzheimer's.
The Religious Orders Study provided the scientists with a population of older people who have spent virtually their entire adult lives in the order. They provided access to their earliest writings (essays used to enter the order) and donated their brains to the scientists upon their deaths. SCIENTISTS have analysed autopsy brain tissue from members of a religious order who had an average of 18 years of formal education and found that the more years of schooling,the less likely they were to exhibit Alzheimer's symptoms of dementia.
In this latest analysis, Bennett and his colleagues looked at 142 autopsy samples from the first volunteers to die. They were, on average, around 85 at the time of death.
They found that people who had 22 years of education had less clinical evidence of Alzheimer's when living, even though their brains showed the classic Alzheimer's pathology of a build-up of amyloid plaque in death.
The relationship between the number of plaques and cognitive performance changed with the level of education. As people moved up the educational ladder, the same number of amyloid plaques had less effect on cognitive test scores.
Bennett is now embarking on a study of 700 people in the Chicago area who represent a more average level of schooling, from 10 to 20 years. – LAT-WP