Estimating the degree of cognitive impairment

A team of scientists across Europe has devised an index to measure the severity of mild cognitive impairment in patients, with the potential to estimate clinical progression towards Alzheimer's disease. At present, this disease can only be diagnosed definitely by post-mortem examination, but the novel technique, based on MRI data from the brain, shows promise in predicting its onset.

The study involved data from 1064 patients in the EU AddNeuroMed program and the Alzheimer’s Disease Neuroimaging Initiative (ADNI), as described in Journal of Internal Medicine. MRI data from different parts of the brain were used to make a severity index which was then applied to patients with mild cognitive impairment.

The model discriminated between stable and progressive forms of the disease with an accuracy far better than chance. Of 173 patients who later developed Alzheimer's disease, 64.7% were classified as disease-like. The future incorporation of other factors such as age, apolipoprotein E4 status and the level of education will help to set cut-off values for the index and longer follow-ups will improve the specificity.

Although the results are promising, several obstacles remain to be overcome, such as the consistency of MRI data from different sites and variations in imaging protocols.