MRI VOLUMETRY, OLFACTION ANDCOGNITION IN PATIENTS WITH MILDCOGNITIVE IMPAIRMENT AND HEALTHYCONTROLS

Abstract

Background: Alzheimer’s Disease (AD) is an increasing problem in today’s society andplaces a great cost and burden on the affected individuals and their families, and thesociety. Thus gaining knowledge of this disease is of vital importance. Patients with mildcognitive impairment (MCI) comprise a group at increased risk for developing dementia,as so offers the opportunity to understand the early stages of dementia. The aim of thisstudy was therefore to investigate the differences between MCI patients and elderlycontrols with respect to olfaction, cognition, and volumetric measures of brain structures.

Methods: Twelve MCI/early AD patients, one AD patient, and thirteen elderly controlsparticipated in this study. Subjects performed two odor identification tests, the BriefSmell Identification Test (BSIT) and Sniffin Sticks (SS) odor identification, and one SSodor discrimination test. The Rey-Osterrieth Complex Figure Test (RCFT) and the Mini-Mental State Examination (MMSE) were also done to investigate visuospatialconstruction/memory and global cognition, respectively. MRI and volumetry of brainstructures (forebrain parenchyma, cortical gray matter, lateral and inferior lateralventricles, and hippocampus) were performed in all subjects. Lastly, a correlationanalysis was done between hippocampal volumes and scores on the olfaction andneuropsychological tests in the two groups.

Results and discussion: The patient group performed generally worse on all tests. SSodor identification and discrimination scores were significantly lower than in the controlgroup, and there was a trend for lower BSIT scores. All subtests of the RCFT, and theMMSE also showed poorer performance in patients compared to controls. Brain structurevolumes were generally reduced in patients and the ventricles enlarged. Hippocampalvolumes for both groups were positively correlated with SS odor identification, RCFT,and MMSE. In conclusion, all tests and measures were generally poorer in the patientgroup compared to controls, though odor discrimination, the RCFT, and hippocampalvolumes showed the most marked difference, and are therefore perhaps most suited asearly diagnostic markers detecting differences between patients with cognitiveimpairment and healthy controls.