Author Response: Cross-Sectional and Longitudinal Association of Clinical and Neurocognitive Factors With Apathy in Patients With Parkinson Disease.

Campbell Le Heron,

Kyla-Louise Horne,

Michael R Macaskill,

Leslie Livingston,

Tracy R Melzer,

Daniel Myall,

Toni L Pitcher,

John Dalrymple-Alford,

Tim Anderson,

Samuel J Harrison