The relationships between apathy and executive dysfunction in multiple sclerosis

Background: Neuropsychiatric symptoms are common in multiple sclerosis (MS). Among these, apathy is relatively frequent but its relationships with cognitive dysfunctions have been poorly investigated. Objective: To explore cognitive correlates of apathy with or without depression ("pure apathy") in MS patients. Material and Method: Nondemented MS patients (n = 125), consecutively referred to the Multiple Sclerosis Center of Moscati Hospital, in Avellino, Italy, underwent the Apathy Evaluation Scale Self-Rated (AES-S), the Hamilton Depression Rating Scale (HDRS), and a comprehensive neuropsychological battery. Results: According to cut-off scores of AES-S (≥ 36), of HDRS (≥ 15) and criteria for diagnosis of apathy and major depression, the sample was divided into 4 subgroups: 49 patients without apathy or depression (A-D-), 20 patients with "pure" apathy (A+D+), 29 patients with depression only (A-D+), and 27 patients with apathy and depression (A+D+). Cognitive performance significantly differed in the 4 groups: in particular MS patients with apathy (A+D- and A+D+) performed significantly worse on executive tasks than patients without apathy, whereas patients with "pure" apathy (A+D-) performed significantly worse than patients without apathy only on executive tasks tapping cognitive control abilities. Conclusions: We found a significant relationship between apathy and dysexecutive defects in MS, consistent with the hypothesis that dysfunctions of prefrontal cortico-subcortical circuits contribute to specific neuropsychiatric syndromes in MS patients.