Tests may predict progression to Alzheimer's

Deficits in certain neurological and psychological areas strongly predict conversion to Alzheimer's disease (AD) in individuals with mild cognitive impairment, research shows.

"The use of specific neuropsychological tests are useful for making an early diagnosis of AD and will most likely play an important role in determining which patients in the pre-clinical/pre-symptomatic stages of the disease will receive the most benefit from drug therapies aimed at modifying the course of incipient AD," Dr. Matthias H. Tabert told Reuters Health.

Tabert and colleagues from Columbia University College of Physicians and Surgeons and the New York State Psychiatric Institute, New York, classified a group of patients according to the type of mild cognitive impairment present and examined whether baseline neuropsychological measures were predictive of conversion to AD.

The authors observed that patients who converted to AD scored lower than nonconverters on all measures of memory and so-called "executive function" abilities (i.e., overall reasoning and functioning).

The two groups differed on some tests of "visuospatial ability" - the type of skills that give you an accurate mental picture of where you are going when you drive a car, for example.

They also differed on some tests of language, but not on tests of attention.

Within 3 years, 50 percent of the patients with "multiple-domain" deficits and memory deficits converted to AD, the researchers note, compared with only 10 percent of patients with single-domain amnesic mild cognitive impairment.

The final predictive model was 86 percent accurate in predicting the conversion to AD, the investigators say.

"Our findings strongly support the use of physician referral for detailed cognitive testing of verbal memory and executive function in patients with mild cognitive impairment," Tabert said.

SOURCE: Archives of General Psychiatry August 2006.