People with more years of education tend to develop Alzheimer's disease later in life than those with less formal schooling, but once the symptoms begin, better-educated people lose their memory faster than those with less education, a new study reveals Tuesday.
The study, published in today's issue of Neurology, involved 488 seniors who were followed for an average of six years using annual cognitive tests, including 117 who eventually developed Alzheimer's or another dementia.
The participants from New York City's Bronx borough ranged in formal education levels of less than three years of elementary school to people with postgraduate education.
The study found that for each additional year of formal education, the rapid accelerated memory decline associated with oncoming dementia was delayed by about two-and-a-half months. However, once that accelerated decline stopped, the people with more education saw their rate of cognitive decline accelerate four percent faster for each additional year of education.
"People with more education experience a delay in the actual decline in memory that is characteristic of people who are developing dementia, in particular Alzheimer's disease," said Charles Hall, a biostatistician at the Albert Einstein College of Medicine.
"However, once that decline begins, it proceeds more rapidly and by the time people are actually diagnosed, they're about at the same place" as less-educated people diagnosed earlier, Hall added.
"What we think this represents is that there's some amount of neuronal reserve or compensational ability . . . such that the pathology of Alzheimer's disease will develop at whatever rate it develops and people with more education have more neuronal capacity... and therefore aren't affected until much later in the natural history of the disease process."
"However, once that disease process gets to a certain level, the brain cannot handle it anymore and the decline begins and proceeds more rapidly because there's more pathology there," he said, referring to the death of cells and other abnormalities in the brain caused by the progressive disease.
However, Hall said because the subjects were born at a time when educational opportunities differed markedly from more modern schooling, it's hard to know how the findings would apply to subsequent generations.
"Whether that (would) apply to people who were born in the 1920s or the 1950s who had different life experiences is not known," he said. "Although I don't know any reason why it would not hold, I haven't proven it."
(Agencies via Xinhua News Agency October 23, 2007)