Changes in visual memory in mild cognitive impairment: a longitudinal study with CANTAB

Abstract

Background: Mild cognitive impairment (MCI), as a stage in the cognitive continuum between normal aging and dementia, is mainly characterized by memory impairment. The aims of this study were to examine CANTAB measures of temporal changes of visual memory in MCI and to evaluate the usefulness of the baseline scores for predicting changes in cognitive status. Methods: The study included 201 participants aged over 50 years with subjective cognitive complaints. Visual memory was assessed with four CANTAB tests (PAL, DMS, PRM and SSP) administered at baseline and on two further occasions, with a follow-up interval of 18-24 months. Participants were divided into three groups according to the change in their cognitive status: participants with subjective cognitive complaints who remained stable (SCC-Stable), MCI participants who remained stable (MCI-Stable) and MCI participants whose cognitive deterioration continued (MCIWorsened). Linear Mixed Models were used to model longitudinal changes, with evaluation time as a fixed variable, and multinomial regression models were used to predict changes in cognitive status. Results: Isolated significant effects were obtained for Age and Group with all CANTAB tests used. Interactions between Evaluation Time and Group were identified in the PAL and DMS tests, indicating different temporal patterns depending on the changes in cognitive status. Regression models also indicated that CANTAB scores were good predictors of changes in cognitive status. Conclusions: Decline in visual memory measured by PAL and DMS tests can successfully distinguish different types of MCI, and considered together PAL, DMS, PRM and SSP can predict changes in cognitive status.