Study: Tougher Alzheimer Test Needed for Highly Intelligent People

Highly intelligent people should be held to a higher standard when it comes to testing them for early signs of Alzheimer's disease, according to a study reported in the January issue of Neuropsychology.

The early diagnosis of Alzheimer's has taken on growing importance, given new medical and psychological interventions that can slow the course of the disease. While highly intelligent people are more likely to exhibit signs of Alzheimer's later than the general population, their decline is much faster once they do.

"Highly intelligent elders are often told their memory changes are typical of normal aging when they are not," said study author Dorene Rentz, of Brigham and Women's Hospital Department of Neurology. "As a result, they would miss the advantages of disease-modifying medications when they become available."

Rentz and her colleagues studied the cognitive ability of 42 highly intelligent older people with IQ's of 120 or more, evaluating whether holding them to a higher standard based on their higher mental ability predicted Alzheimer's disease better than standard norm derived from a large cross-section of the population.

The raised cutoffs predicted that 11 of the 42 individuals were at risk for future decline, compared with the standard cutoffs, which indicated all were normal.

Three and a half years later, nine of those 11 people had declined. Six of those went on to develop mild cognitive impairment, a transitional illness from normal aging to a dementia of which one type is Alzheimer's. Five of these individuals have since received a diagnosis of Alzheimer's disease, two years after this study was submitted.

"With standard norms, people with higher levels of ability would be classified as normal for up to three years before they began demonstrating a decline on standardized tests," says Rentz. "In this case, they could be at risk for not receiving early treatment intervention."

Rentz and her co-authors believe that the adjusting the tests for early Alzheimer's disease to reflect mental ability can also help people at the other end of the scale. "People with below-average intelligence have the potential for being misdiagnosed as demented when they are not, because they score below the normative cutoffs," explained Rentz.

Other sources: American Psychological Association