Neuropsychological correlates of apathy in mild cognitive impairment and Alzheimer's disease: the role of executive functioning

Abstract

Apathy is a common and important behavioral syndrome in various neuropsychiatric diseases, such as mild cognitive impairment (MCI) and Alzheimer's disease (AD). So far, only few studies have compared the neuropsychological correlates of apathy in patients with MCI and dementia. The aim of the current study was to examine the association between apathy and neuropsychological functioning in patients with MCI and AD. Two-hundred-and-sixty AD patients and 178 MCI patients visiting the Memory Clinic of the Maastricht University Medical Centre participated in the study. Linear regression analysis, corrected for age, gender, level of education and depression, was performed to reveal cross-sectional associations between apathy and scores on neuropsychological tests of memory, attention, psychomotor speed and executive functioning. In patients with MCI, apathy was characterized by decreased verbal fluency and psychomotor tracking. In AD, patients with apathy differed from non-apathetic patients only on a verbal fluency task. Apathy is related to executive dysfunction in the early phases of cognitive decline. In particular, in the prodromal phase of AD, apathy seems to be characterized by poor initiating. In the more advanced stages of cognitive deterioration, associations between apathy and specific neuropsychological correlates may be obscured by the more severe neuropathology. Awareness of apathy in the early phase of cognitive impairment may help in early diagnosis of AD.