More evidence ties education to lower dementia risk

NEW YORK (Reuters Health) - Older adults with more education seem to have a lower likelihood of developing Alzheimer’s disease, regardless of other risk factors for dementia, researchers reported Monday.

In a study of more than 1,400 Finnish adults followed for two decades, researchers found that the more years of education participants had, the lower their risk of developing dementia, including Alzheimer’s disease.

The findings, reported in the journal Neurology, bolster previous evidence linking greater education to a lower dementia risk.

The researchers were able to account for numerous factors that are related to both a person’s education and to the risk of dementia. These included income and occupation in middle-age, lifestyle factors like smoking and exercise, and mid-life health problems such as high blood pressure and high cholesterol.

“We saw that even when taking into account the effects of other risk factors, low education was still related to increased risk of becoming demented,” lead study author Dr. Tiia Ngandu, of the Karolinska Institute in Stockholm, Sweden, told Reuters Health.

She and her colleagues found that compared to study participants with fewer than five years of education, those with six to eight years were 43 percent less likely to develop dementia. Men and women with nine or more years of schooling had an 84-percent lower risk of dementia.

The figures were nearly identical when the researchers looked specifically at Alzheimer’s disease, the most common form of dementia.

The findings, Ngandu said, can be seen as support for the “brain reserve” hypothesis on dementia risk.

According to this theory, older adults with more education or higher IQs are able to withstand more Alzheimer-linked brain damage before showing symptoms.

It’s possible, for instance, that in people with more education, the brain’s circuitry operates more efficiently, making it better equipped to compensate for the pathological changes seen in the brains of people with Alzheimer’s.

Ngandu and her colleagues based their findings on 1,449 adults who were followed from as early as 1972 until 1998, when they were between 65 and 79 years old. When they entered the study, participants completed surveys on their education, income, occupation, lifestyle habits and medical history.

In 1998, they were given a standard test of memory and other cognitive abilities. In general, the researchers found, the risk of dementia and Alzheimer’s declined as participants’ years of education climbed, regardless of other factors the study measured.

A key question, according to Ngandu, is whether education can actually generate a greater brain reserve -- or whether people with an innately greater reserve go further in their education.

Other studies have suggested that staying mentally active later in life -- reading or doing crossword puzzles, for instance -- may forestall dementia. But again, Ngandu noted, experts are not certain whether people with greater brain reserve maintain these activities into old age, or whether the activities themselves protect the brain.

SOURCE: Neurology, October 2, 2007.