The nature of lexico-semantic processing deficits in mild cognitive impairment

• Published in: Neuropsychologia 2006, Vol.44 (10), p.1928-1935
• Main Authors: Duong, Anh, Whitehead, Victor, Hanratty, Kate, Chertkow, Howard
• Format: Article
• Language: English
• Subjects: Adult and adolescent clinical studies; Aged; Aged, 80 and over; Alzheimer disease; Alzheimer Disease - physiopathology; Amnestic MCI; Analysis of Variance; Biological and medical sciences; Cognition Disorders - complications; Cognition Disorders - physiopathology; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Disorders of higher nervous function. Focal brain diseases. Central vestibular syndrome and deafness. Brain stem syndromes; Female; Frontal executive function; Humans; Language; Language Disorders - physiopathology; Male; Medical sciences; Memory - physiology; Mental Status Schedule; Nervous system (semeiology, syndromes); Neurology; Neuropsychological Tests; Organic mental disorders. Neuropsychology; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Reaction Time - physiology; Semantic memory; Semantics; Space Perception - physiology; Verbal Learning - physiology
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2006.01.034

Lexico-semantic impairments in Alzheimer disease (AD) have been attributed to abnormalities in both intentional and automatic access to semantic memory. However, the order in which these impairments appear during the course of the disease is unclear. We sought to answer this question by documenting lexico-semantic impairments in 61 subjects with mild cognitive impairment (MCI), a pre-AD stage, and by comparing them to those of 39 AD and 60 normal elderly (NE) subjects. All subjects were tested with intentional access tasks (picture naming and semantic probes), automatic access tasks (lexical decision and priming), and executive function tasks (Stroop and Stroop-Picture naming). Results indicated that the MCI group was only impaired on tasks of intentional access relative to the AD group who was impaired on both types of tasks. Because most MCI subjects eventually develop AD, these results suggest that intentional access to semantic memory is impaired before automatic access. Further, impairments on the Stroop-Picture naming task but not on the Stroop task, suggest that lexico-semantic impairments in the MCI group may be related to inhibition deficits during semantic search. Findings are discussed in light of executive dysfunctions within the framework of semantic memory theories.