Not only memory: Investigating the sensitivity and specificity of the Mnemonic Similarity Task in older adults

Mnemonic discrimination, the process of distinguishing highly similar items in memory, relies on the dentate gyrus (DG) subregion of the hippocampus. The Mnemonic Similarity Task (MST) has been shown to be a sensitive behavioral measure of mnemonic discrimination that is in wide use (Liu et al., 2016). In this study, we evaluate the sensitivity and specificity of the MST in community-dwelling older adults who were administered the Montreal Cognitive Assessment (MoCA), a well-established screening measure for cognitive impairment. Using regression analyses, we tested a sample of 94 participants to determine whether MoCA overall score, MoCA score without the delayed recall subscale score, MoCA delayed recall subscale score, and MoCA status (MoCA score below or above the cut-off of 26/30) predicted MST lure discrimination performance. Regression models showed that all measures - except the MoCA delayed recall score - were significant predictors of MST lure discrimination performance. Our results support the sensitivity of the MST in detecting general cognitive decline but call into question the specificity of the MST with respect to memory and hippocampal function in a healthy older adult population.