Implicit Memory In Patients With Amnestic Mild Cognitive Impairment

Objective Implicit memory is a type of memory in which previous experiences aid in the performance of a task without conscious awareness of these previous experiences. Evidence for implicit memory arises in priming, a process whereby subjects show improved performance on tasks for which they have been subconsciously prepared. However, the implicit memory deficits in amnestic mild cognitive impairment patients are not well understood. This study aimed is to investigate the characteristics of memory impairment in patients with amnestic mild cognitive impairment (aMCI).Methods We set up a neuropsychological battery to measure the performance of implicit memory. 35 patients with aMCI and 35 healthy adults matched with age and education level were administered with a neuropsychological battery of tests including conceptual and perceptual implicit memory tasks (category exemplar, picture identification), as well as explicit memory tasks (immediate recall, delay recall, delay recognition).Results Compared with healthy elders, patients with aMCI were impaired in the conceptual implicit memory task[(33.71±8.20)vs.(43.28±6.74),t=-4.33, P<0.01], as well as in explicit memory(immediate recall, t=6.40, P<0.01;delay recall, t=9.29,P<0.01; delay recognition, t=7.65,P<0.05),but not in perceptual implicit memory task (t=-0.78, P>0.05).The conceptual implicit memory scores is positively correlate with verbal fluency test (r=0.74,P<0.01). Conclusions The present results indicated that patients with aMCI were impaired in explicit memory as well as conceptual implicit memory. The conceptual implicit memory impairment in aMCI may be related to their frontal lobe dysfunction.