How is semantic memory affected in Mild Cognitive Impairment?

Abstract

AbstractBackgroundMild cognitive impairment (MCI) is a condition considered by many as a transitional stage between healthy aging and Alzheimer’s disease. Although its diagnosis is typically based on the assessment of episodic memory, evidences show that impairment in semantic memory would be one of the first manifestations of cognitive impairment. This study aims to investigate how semantic memory is affected in MCI. Precisely, we will explore if core memory of common knowledge is impaired in MCI, and if the performance in semantic memory task vary with the modality of presentation of the stimuli (verbal vs visual).MethodA group of healthy people aged between 60 and 90 years old (mean: 77.4 N = 43), and a age‐matched group meeting the criteria for MCI (N = 32), who have lived in Quebec (Canada) for at least 30 years, completed two neuropsychological tests evaluating the semantic memory of famous people, which have been proven to be the most sensible way to detect even subtle variation in semantic memory.ResultResults indicate that performance in both tests is impaired in the MCI group, compared to the healthy elderly group. This means that the MCI group have more difficulty to name famous people (t (69) = 5,173, p < 0.01), as well as answer basic questions on them (ex: their profession, nationality, etc.), when presented from their picture (t (69) = 4.849, p < 0.01) or their name (t (65) = 3.488, p < 0.01), compared to healthy people of the same age. There was no difference between their performances when the stimuli was presented in the visual or verbal modality (t (30) = 0.928, p > 0.05).ConclusionThis study demonstrates that semantic memory of famous people is impaired in MCI, and that impairment affects the capacity to name famous people as well as remembering facts about them. In addition, there are no difference if the stimuli are presented visually or verbally. This suggests that the impairment in semantic memory in MCI is due to a degradation of the memory, and is not modulated by other cognitive functions or modality.