Volume loss of the medial temporal lobe structures in subjective memory impairment.

BACKGROUND/AIMS Subjective memory impairment (SMI) has been suggested as a manifestation of Alzheimer's Disease (AD) preceding mild cognitive impairment (MCI). In this study, we determined the volumes of the hippocampus, the entorhinal cortex (EC) and the amygdala to provide biological evidence for AD in SMI. METHODS Regional volumetric measures were manually traced on 3-Tesla MRI scans. RESULTS Total brain volume did not differ between the groups. Individuals with SMI had reduced volumes of the hippocampus bilaterally (right p = 0.001; left p < 0.001), the bilateral EC (right p = 0.031, left p = 0.006) and the right amygdala (p = 0.01) compared to the control group. CONCLUSION Volume reduction of bilateral hippocampus, bilateral EC and right amygdala supports the concept of SMI as a very early manifestation of AD prior to MCI. SMI may indicate awareness of a degenerative process that can still be functionally compensated.