CARLTON, AUSTRALIA. Alzheimer's disease is preceded by the development of a mild cognitive impairment that can appear as much as 10 years prior to Alzheimer's becoming apparent. The impairment can be detected by testing patients over a period of years. Australian researchers have just discovered that it is possible to determine the presence of mild cognitive impairment (MCI) in a single day. Their study involved 20 older people who had been tested every 6 months for 2 years and were known to have MCI. They were matched by age, gender, and education level with 40 people without MCI. The study participants completed a series of cognitive tests (CogState) on 4 occasions within a 3-hour period. The computerized tests were designed to evaluate working memory, episodic learning, attention and psychomotor speed. The researchers found that normal subjects improved their performance with each test while MCI patients did not improve or plateaued early. The test accurately predicted the presence of MCI in 80 per cent of the subjects actually diagnosed with MCI (80 per cent sensitivity) and correctly assigned participants to the normal category in 95 per cent of cases (95 per cent specificity). The researchers emphasize that the high degree of specificity is particularly important as studies have shown that 50 per cent of all people classified as having MCI during a single assessment were found not to have MCI on subsequent assessments. In other words, they just happened to have a "bad" day on the day they were tested.
Darby, D., et al. Mild cognitive impairment can be detected by multiple assessments in a single day. Neurology, Vol. 59, October 2002, pp. 1042-46