2011 The trajectory of apathy following deep brain stimulation: from pre-surgical treatment to six months submit-operation in Parkinson's disease. 2011 Apathy and despair: individual things in Parkinson's sickness. 2013 A latent class investigation of psychological disturbance in Parkinson's sickness. 2015 Latent development-curve investigation reveals that worsening Parkinson’s illness quality of existence is driven by despair.