To test the hypothesis that magnetic resonance imaging (MRI)-based measurements of hippocampal volume were related to the risk of future conversion to Alzheimer's disease (AD) in elderly patients with a mild cognitive impairment (MCI)
Persons who develop AD pass through a transitional state which can be characterized as a MCI. However, in some patients MCI is a more benign condition which may not progress to AD or may do so slowly.
Eighty consecutive patients who met criteria for the diagnosis of MCI were recruited from the Mayo Clinic Alzheimer's Disease Center/Alzheimer's Disease Patient Registry.
At entry into the study each patient received a MRI examination of the head from which the volumes of both hippocampi were measured. Patients were then followed longitudinally with approximately annual clinical/cognitive assessments. The primary endpoint was the crossover of individual MCI patients to the clinical diagnosis of AD during longitudinal clinical followup.
Over the period of longitudinal observation, which averaged 32.6 months, 27 of the 80 MCI patients became demented. Hippocampal atrophy at baseline was associated with crossover from MCI to AD (relative risk, 0.69, p = 0.015). When hippocampal volume was entered into bivariate models with age, post menopausal estrogen replacement, standard neuropsychological tests, apolipoprotein E genotype, history of ischemic heart disease and hypertension the relative risks were not substantially different from that found univariately and the associations between hippocampal volume and crossover remained significant.
In elderly patients with MCI, hippocampal atrophy determined by premorbid MRI-based volume measurements is predictive of subsequent conversion to AD.