THE ASSOCIATION BETWEEN APATHY AND COGNITIVE FUNCTION IN AMNESTIC MILD COGNITIVE IMPAIRMENT

Abstract

Apathy is a common neuropsychiatric symptom that can be observed in neurological disorders such as Alzheimer's Disease (AD), Parkinson's Disease (PD), and mild cognitive impairment (MCI). Several studies have shown that apathy appeared to be associated with cognitive impairment in AD. Amnestic MCI (aMCI) is a precursor of AD. Apathy in aMCI was associated with atrophy of the right caudate nucleus, medial and superior frontal lobes, inferior temporal lobe and occipital lobe. However, only few studies have investigated the association between apathy and cognitive function in aMCI. Thirty-one aMCI patients (mean age: 68.01 ± 4.91 years) were included. Apathy was assessed with the Apathy Evaluation Scale Clinical version (AES-C). A neuropsychological test battery was administered including the Mini Mental State Examination (MMSE), the 15 word Rey Auditory Verbal Learning Test (RAVLT), Digit Span (DS), Digit Symbol Substitution Test (DSST), Stroop test, Trail Making Test (TMT), Hayling Test and Boston Naming Test (BNT). Partial correlations between AES-C and RAVLT, DS, DSST, Stroop test, TMT and BNT were calculated with age and education as covariates. In addition, we calculated Spearman's correlation between AES-C & Hayling and Pearson's correlation between AES-C and the percentile scores of the delayed recall on the RAVLT relative to the encoding score, the percentile score of the TMT-B relative to the time on TMT-A and the percentile score of Stroop C relative to the time of parts A and B. Boot-strapping was applied to the analyses. There were significant relationships between AES-C and time to complete Stroop A (r= .551 [.126, .786] p= .002), DSST (r= - .400 [-.658, -.084] p= .039), and TMT-A (r= - .393 [-.669, -.074] p= .042). There were no associations between AES-C and the other cognitive measures. Higher levels of apathy were associated with slower processing speed. There were no associations between memory or executive functioning and apathy. This indicates that reduced processing speed may specifically affect the ability to select, initiate and execute goal-directed behavior.