Apathy in amyotrophic lateral sclerosis: insights from Dimensional Apathy Scale.

Apathy is associated with cognitive decline and worse survival in amyotrophic lateral sclerosis (ALS); an accurate evaluation of this aspect is relevant in clinical settings. The aims of this study are to evaluate the prevalence of apathy in a large ALS sample, using published diagnostic criteria, and to explore the psychometric properties, the sensitivity and the specificity of the Dimensional Apathy Scale (DAS) as a screening tool for apathy. One hundred and thirty-one patients underwent clinical interview based on diagnostic criteria for apathy, DAS, Apathy Evaluation Scale, and assessment of depression, global cognitive functioning, and non-verbal intelligence. According to diagnostic criteria, apathy occurred in 28.2% of the patients. The DAS showed high consistency, convergent, and discriminant validities. Apathetic and non-apathetic patients significantly differed on total DAS and executive and Behavioral/Cognitive Initiation subscales, indicating good criterion validity. Receiver operating characteristics analysis, considering diagnostic criteria for apathy as gold standard, revealed that a score of 26/27 was an optimal cut-off score for the identification of apathy. The DAS is a valid screening tool for apathy and its aspects in ALS through limiting the impact of physical disability. Executive and behavioral/cognitive aspects of apathy, rather than emotional aspects, are more frequent in ALS.