Temporal changes in semantic and lexical access related to mild cognitive impairment.

Abstract

It has been hypothesized that the deterioration in the ability to name famous people in normal aging and cognitive impairment is a continuum in which meaning-based representations and form-based representations are differentially impaired, with early impairments in lexical access but not in semantic access. This hypothesis is tested in a follow-up study comparing the performance of fifty-six participants with amnestic mild cognitive impairment and forty-one control participants were assessed. A lexical task was conducted involving recognition and naming of famous people from photographs. Proportional semantic and phonological access measures were calculated. Comparisons revealed significant differences between baseline and follow-up, with improvements in semantic access in the control group and decrements in phonological access in the group with amnestic mild cognitive impairment. Phonological access and reaction time measures were significantly and positively correlated, and semantic access and reaction time were significantly and negatively correlated. These results add evidence to the hypothesis that the decrease of processing resources is related to the increase of difficulties in lexical access throughout aging. Patterns of change must be replicated over longer periods of time.