Conceptual implicit memory impaired in amnestic mild cognitive impairment patient.

Explicit memory has been well proven to be impaired in amnestic mild cognitive impairment (aMCI), and conceptual implicit memory is impaired in Alzheimer's disease. However, it is unclear whether implicit memory is affected in aMCI. In the present study, 35 patients with aMCI and 35 healthy elderly subjects were administered a neuropsychological battery of tests including conceptual and perceptual implicit memory tasks (category exemplar generation, image identification) as well as explicit memory tasks. Patients with aMCI exhibited impairment in explicit memory tasks and selective impairment in conceptual priming tasks, while the effect of perceptual priming was preserved. More importantly, category exemplar generation task priming, but not perceptual priming, was positively correlated with verbal fluency test performance in the aMCI group. The dissociation between the 2 components of implicit priming suggests that conceptual priming impairment in aMCI patients may be related to frontal lobe dysfunction.