Apathy is not associated with performance in brief executive tests in patients with mild cognitive impairment and mild Alzheimer's disease.

Abstract

Neuropsychological correlates of apathy in Alzheimer's disease (AD) may shed some light on the neurobiology of this behavioral disorder. Whereas previous research has suggested an association between apathy and executive functions in AD, amnestic mild cognitive impairment (aMCI) cohorts point to an association with memory tests. We aimed to further investigate this issue in a sample of low educated, hitherto unexposed to cholinesterase inhibitors, aMCI (n=26) and mild AD (n=28) patients using brief executive tests, namely the Executive Interview (EXIT-25) and the Frontal Assessment Battery (FAB). Patients and controls (n=33) were included from a community-based survey of successful brain aging in Brazilian elderly (75+ years), The Pietà Study. The participants were submitted to a comprehensively neuropsychological assessment and apathy evaluation through the Apathy Scale (AS).We found a strong correlation in AD group between AS scores and functional performance measured by the Disability Assessment in Dementia (rho =-0.7 ; p<0,001). No association was found between any executive test performance and apathy symptoms. Apathy symptoms were also associated with the performance in memory tests and in the attention subscale of the Mattis Dementia Rating Scale. These findings reinforce the functional effect of apathy even in the mildest stages along the AD cognitive impairment spectrum, and challenges previous assumptions regarding the association between apathy and classical executive functions.