Atrophy in the medial temporal lobe is specifically associated with encoding and storage of verbal information in MCI and Alzheimer patients

Abstract

Background: Alzheimers dementia (AD) is characterized by a progressive decline in the encoding and storage of episodic memory. Word-list learning tests can characterize different aspects of episodic memory. Medial temporal lobe atrophy (MTA) seems to be an important anatomical feature of AD and its prodromal stage, mild cognitive impairment (MCI). The aim of this study is to define the relationships of the functional memory processes and MTA in patients with AD and MCI, while correcting for confounding factors. Methods: MTA was evaluated with a visual assessment scale using the MRIs of 53 patients diagnosed with AD or MCI and 19 controls. Reys Auditory Verbal Learning Test was used to assess the different aspects of memory processing, i.e., encoding, storage and retrieval. Multiple regression analysis was used to investigate the association of MTA with these different memory processes. In addition to general factors such as age, education and sex, white matter lesions, cortical and subcortical atrophy were evaluated for being confounders. Results: MTA was significantly associated with encoding (corrected beta = -0.45, sd = 0.11, P < 0.01), and storage (beta = -0.34, sd = 0.12, P < 0.01), but not with retrieval (beta = -0.18, sd = 0.12, P = 0.44). Conclusions: We can conclude that atrophy of the medial temporal lobe is associated with a decline in encoding and storage of verbal information in MCI and AD.