P3–043: Do impairments in lexical access predict deterioration in mild cognitive impairment?

Background: Previous studies have reported that individuals with mild cognitive impairment (MCI) who show multiple cognitive deficits are at increased risk of developing Alzheimer’s disease (AD). Language function, and specifically aspects of lexical access have not been studied in detail in MCI, despite word-finding difficulties being a common complaint in individuals attending memory clinics. Objective(s): This study aims to investigate a variety of measures of lexical access in MCI and their relationship to subsequent deterioration over the following 12 months. Methods: 76 subjects with MCI (MMSE 25-27, age 80.0 5.9, education 10.84 2.20), 32 patients with mild AD (MMSE 19-29, age 79.9 5.5, education 10.72 2.73) and 38 age and education matched controls (MMSE 28-30, age 80.4 5.1, 10.68 2.45) were assessed in a crosssectional and prospective longitudinal study design using the following measures: phonemic and semantic fluency, the Boston Naming Test and a novel measurement of the Tip-of-the-tongue-experience (TOT). General cognitive function was assessed using MMSE and CERAD, while NART and WAIS Vocabulary scale were used to determine premorbid verbal intelligence and vocabulary knowledge. Results: Cross-sectionally, significant group differences were found on all measures (One-way ANOVA, p 0.001), with the AD group performing worse than the other two groups in each instance, confirming the sensitivity of the measures to the clinical condition. Relative to the controls, the MCI group was impaired on the verbal fluency tasks and the number of correct responses on the TOT test (but not on the number of tip-of-the-tongue states reported). At follow-up, the MCI group showed significant additional decline relative to controls in word finding as indexed by the number of correct responses on the BNT and TOT test, and a greater number of ‘don’t know’ responses on the BNT. Conclusions: Some aspects of language function sensitive to AD are also impaired in MCI relative to age matched controls. Over a 12-month period, further deterioration is observed in word finding, suggesting that it may be an early marker of incipient dementia in some individuals.