Herzallah, M., Khdour, H., Taha, A., Elmashala, A., Mousa, H., Taha, M., Ghanim, Z., Sehwail, M., Misk, A., Balsdon, T., Moustafa, A., Myers, C. & Gluck, M. (2017). Depression Reduces Accuracy While Parkinsonism Slows Response Time for Processing Positive Feedback in Patients with Parkinson's Disease with Comorbid Major Depressive Disorder Tested on a Probabilistic Category-Learning Task. Frontiers in psychiatry, 8, 84. doi:10.3389/fpsyt.2017.00084