Psychometric properties of apathy scales in Parkinson's disease: a systematic review.

Apathy is among the most prevalent neuropsychiatric symptom experienced in Parkinson's disease (PD) and can be assessed with a variety of scales. To identify which scale is most suitable for apathy assessment in PD, the psychometric properties of each scale and its sensitivity to change were analyzed. The methodological quality of the studies ranged from adequate to excellent. The Lille Apathy Rating Scale demonstrated consistently favorable psychometric properties and was used in two of four clinical trials found. The Starkstein Apathy Scale was the only other scale used in clinical trials. Further work is necessary to develop a gold standard for assessing apathy in PD.