The following is a summary of “Medial temporal lobe structure, mnemonic and perceptual discrimination in healthy older adults and those at risk for mild cognitive impairment,” published in the February 2023 issue of the Neurobiology of Aging by Gellersen et al.
Memory tests that distinguish between visually similar stimuli are especially attuned to damage to the medial temporal lobe (MTL). Such assessments may be useful predictors of future cognitive deterioration in older people. Yet, the role of MTL in this context is still relatively uncharted, even though it is known that MTL is necessary for the perceptual distinction of stimuli with overlapping features.
Here, researchers used neuropsychological screening results to assess the mnemonic and perceptual discrimination of objects and sceneries in 111 older persons living in the community with varying risk statuses for cognitive deterioration. The exams were given in both a Forced Choice and a Yes/No style, with the latter used to assess mnemonic discrimination. Researchers also investigated whether there was a correlation between the size and thickness of MTL sections and how well they performed. The at-risk group performed worse on perceptual and mnemonic discrimination tests, and their entorhinal layers were thinner. Differences in memory discrimination across groups were partially explained by a loss in perceptual discrimination, which correlated with entorhinal cortex thickness.
The fact that executive dysfunction was found to be responsible for yes/no impairments in at-risk individuals demonstrates the significance of test format in the examination of memory decline. Researchers’ results suggest that perceptual discrimination tests may be valuable tools for detecting the onset of cognitive impairment in nonclinical populations due to compromised MTL integrity. Its decline correlates with chronological age.
Source: sciencedirect.com/science/article/pii/S0197458022002330