A systematic review of the validity and reliability of apathy scales in neurodegenerative conditions

Background: There are several scales used to detect apathy in disease populations. Since apathy is a prevalent symptom in many neurodegenerative diseases, this is an especially important context in which to identify and compare scales. Aims: To provide an overview of apathy scales validated in generic and specific neurodegenerative disease populations, compare validation studies' methodological quality and the psychometric properties of the validated apathy scales. Methods: A systematic review of literature was conducted of articles published between 1980 and 2013. The final articles selected for review were rated on methodological quality and the psychometric properties of the scales used were interpreted. Results: Sixteen articles validating apathy scales were included in the review, five in a generic neurodegenerative sample and eleven in specific neurodegenerative samples. The methodological quality of specific studies varied from poor to excellent. The highest quality, which had psychometrically favorable scales, were the dementia apathy interview and rating (DAIR) and the apathy evaluation scale-clinical version (AES-C) in Alzheimer's disease and the Lille apathy rating scale (LARS) in Parkinson's disease. Generic neurodegenerative disease validation studies were of average methodological quality and yielded inconsistent psychometric properties. Conclusions: Several instruments can be recommended for use in some specific neurodegenerative diseases. Other instruments should either be validated or developed to assess apathy in more generic populations.