Apathy in multiple sclerosis: a validation study of the apathy evaluation scale.

Background: Apathy is defined as lack of motivation affecting cognitive, emotional, and behavioral domains and is usually assessed by standardized scales, such as the Apathy Evaluation Scale (AES). Recently, apathy has been recognized as a frequent behavioral symptom in multiple sclerosis (MS).

Objective: To evaluate applicability and clinical-metric properties of AES in MS and the agreement between patients' and caregivers' evaluation of apathy.

Materials And Methods: Seventy non-demented MS patients underwent a thorough clinical and neuropsychological assessment, including evaluation of apathy according to established clinical criteria. All patients also completed the self-report version of AES (AES-S).

Results: AES-S was easy to administer and acceptable, and showed fair internal consistency (Cronbach's alpha, α=0.87). The factorial analysis identified three factors, representing the cognitive dimension (α=0.87), a general aspect of apathy (α=0.84), and the behavioral-emotional aspects (α=0.74), respectively. The factors were significantly correlated with the total AES score (all rrho≥0.73, p<0.001). The total AES score showed fair convergent validity (rrho=0.38) and discriminant validity when compared to Expanded Disability Status Scale (rrho=0.38), Mini Mental State Examination (rrho=-0.17), and Hamilton Depression Rating Scale (rrho=0.37). Receiver-operating characteristic curve analysis demonstrated that a cutoff>35.5 can identify clinically significant apathy with good sensitivity (88%) and specificity (72%); such a cutoff identified apathy in 35.7% of our sample of non-demented MS patients. Total AES score was significantly correlated with reduced global cognitive efficiency and more severe frontal executive dysfunctions.

Conclusion: AES-S can be considered as an easy and reliable tool to assess apathy in non-demented MS. The use of AES-S in non-demented MS patients is clinically important since apathy is relatively frequent and is correlated to more severe cognitive dysfunction.