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Depression Impairs Learning Whereas Anticholinergics Impair Transfer Generalization in Parkinson Patients Tested on Dopaminergic Medications

Herzallah, Mohammad M. MD* †; Moustafa, Ahmed A. PhD; Misk, Adel J. MD*; Al-Dweib, Lara H. MD*; Abdelrazeq, Samer A. MD*; Myers, Catherine E. PhD‡ §; Gluck, Mark A. PhD

Cognitive and Behavioral Neurology: June 2010 - Volume 23 - Issue 2 - p 98-105
doi: 10.1097/WNN.0b013e3181df3048
Original Studies

In a study of acquired equivalence in Parkinson disease (PD), in which patients were tested on normal dopaminergic medication, we found that comorbid clinical depression impairs initial acquisition, whereas the use of anticholinergic therapy impairs subsequent transfer generalization. In addition, this study provides a replication of the basic finding of Myers et al (2003) that patients with PD on dopaminergic therapy are impaired at initial acquisition, but normal at subsequent transfer generalization, generalizing these results to an Arabic-speaking population including many participants with no formal education. These results are consistent with our past computational modeling, which argues that acquisition of incrementally acquired, feedback-based learning tasks is dependent on cortico-striatal circuits, whereas transfer generalization is dependent on medial temporal (MT) structures. They are also consistent with prior computational modeling, and with empiric work in humans and animals, suggesting that anticholinergic drugs may particularly impair cognitive abilities that depend on the MT lobe.

*Faculty of Medicine, Al Quds University-Abu Dis, Palestinian Territories/West Bank

Center for Molecular and Behavioral Neuroscience

Department of Psychology, Rutgers University-Newark

§NeuroBehavioral Research Laboratory, Department of Veterans Affairs-New Jersey Health Care System, East Orange, NJ

Reprints: Ahmed A. Moustafa, PhD, Center for Molecular and Behavioral Neuroscience, Rutgers University-Newark, NJ (e-mail:

Received for publication December 2, 2009; accepted March 14, 2010

© 2010 Lippincott Williams & Wilkins, Inc.