A Way to Diagnose Alzheimer’s More Easily

Doctors are often asked “Is it Alzheimer’s?” when a patient displays what’s called ‘mild cognitive impairment’, or MCI. This disorder affects about 20% of the US population over 70, which commonly causes memory problems. Many people with MCI go on to develop Alzheimer’s, but this is not inevitable. The dividing line between MCI and Alzheimer’s is not always easy to define, but a new study has shown a way to simplify this and provide a more definite answer, using common tests; it’s been published in Biological Psychiatry.

The study, done at Columbia University, New York, included 148 patients with broadly-defined MCI. They were followed at 6-month intervals over a 3-year period. At each exam a number of tests were done that represented commonly-accepted criteria for change from MCI to Alzheimer’s.

Five of the 8 ‘predictor’ tests were shown to have, combined, an excellent predictive record for eventual Alzheimer’s disease. They covered the areas: cognitive performance, an informant’s report of functional impairment, apolipoprotein E genotype, impaired sense of smell, and volumes of two brain parts (the hippocampus and entorhinal cortex) using magnetic resonance imaging (MRI).

Using these 5 predictors, there were 10% false positives (i.e. 90% specificity), and 85.2% sensitivity. This was markedly superior to combining age and Mini-Mental State Examination (MMSE) scores, which showed only 40% sensitivity.

If this approach can be confirmed independently, it should provide a much improved way of determining which subjects with MCI are likely to proceed to full-blown Alzheimer’s disease. Hopefully, it will allow earlier diagnosis than before, and permit effective treatment - when available - to be instituted earlier, too.