Can education influence development of Alzheimer's disease?

NEW YORK, Sep 11 (Reuters Health) - Now people may have one more reason to continue their education--those with more than 8 years of schooling appear to develop Alzheimer's disease later than those with 8 years of education or less, according to a new report.

Individuals with higher educational levels may have a "greater cognitive reserve," which may delay the expression of cognitive symptoms of Alzheimer's disease, hypothesised Dr. Mirjam I. Geerlings and her colleagues from Erasmus University in Rotterdam, the Netherlands. Thus, differences in duration of illness and cognitive reserve capacity may cause the more highly educated group to have a lower Alzheimer's disease risk than do less-educated individuals, the authors speculate.

In a study of 3,147 Dutch elderly, those with 8 or fewer years of education "complained more often about their memory, reported more often feelings of guilt, and had more often subjective bradyphrenia than subjects with more than 8 years of education," the authors write in the September issue of the Journal of the American Geriatrics Society.

Bradyphrenia is a subjective feeling of being slowed down in thinking, the researchers explain.

Of the 1,911 individuals available for follow-up 3 years later, 53 were diagnosed with Alzheimer's disease. Twenty-two of these patients had more than 8 years of education and 31 had less than 8 years of education.

"Both depressed mood and subjective bradyphrenia remained strongly predictive of Alzheimer's disease in more highly educated subjects," the report indicates.

For example, roughly 1 in 10 of the study participants initially reported a depressed mood--8% of whom had 8 years of education or more and 10% of whom had 8 or less years of education.

Yet the investigators found during the follow-up surveys that Alzheimer's patients with more than 8 years of education were more than five times as likely than those with less schooling to report a depressed mood, suggesting that individuals with greater levels of education had a more rapid onset of the condition and depression with fewer predictive depressive symptoms, the study authors write.

"It could be argued that the observed association between depressed mood and subjective bradyphrenia and incident Alzheimer's disease is explained by the possibility that more highly educated people are more used to articulating their problems or are more critical about subtle changes they might notice," the authors theorise.

However, one question may remain: Do more highly educated individuals have a slower onset of the condition or are these individuals better able to hide such symptoms due to their education? The latter is possible, according to Dr. Richard Havlik, an epidemiologist with the National Institute on Ageing.

The discrepancy may be due to the sensitivity of the tests used in the study, Havlik speculated. "Especially if you're highly educated, you can score high on those tests and already be relatively diseased compared to what you were 10 years before," he explained.

But factors such as the inability to follow-up all of the participants may have caused the study results to be biased. Plus, "it's not always possible at the baseline in (long-term) studies to exclude people who are already on a track to get Alzheimer's disease," Havlik noted.

Clinicians should be aware that highly educated individuals may develop Alzheimer's disease in a relatively short period of time and that it may affect them differently depending on their educational level, the authors conclude.