Symptoms of Medication Withdrawal in Parkinson’s Disease: Considerations for Informed Consent in Patient-Oriented Research

Fetal cellular transplantation therapy research in Parkinson’s Disease has raised important ethical questions from its beginning. One of the most hotly debated aspects of the recent clinical research has been the use of sham surgery as a placebo for the control group. Ethicists and researchers have focused on the unique risk surgical placebos pose to research subjects as compared to conventional, medical placebos. This review will deal with informed consent and the use of use of sham surgery in the placebo arm of recent fetal tissue transplantation randomized, placebo controlled, double blind, clinical trials. Do current procedures for obtaining informed consent meet the challenge of adequately informing patients enrolling in experiments with significant risks not only in the experimental group but also in the placebo group?

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Cognitive and motor effects of dopaminergic medication withdrawal in Parkinson’s disease

Neuropsychologia ◽

10.1016/j.neuropsychologia.2004.05.004 ◽

2004 ◽

Vol 42 (14) ◽

pp. 1917-1926 ◽

Cited By ~ 23

Author(s):

Liory Fern-Pollak ◽

Alan L. Whone ◽

David J. Brooks ◽

Mitul A. Mehta

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Dopaminergic Medication ◽

Medication Withdrawal ◽

Motor Effects

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Reward learning deficits in Parkinson's disease depend on depression

Psychological Medicine ◽

10.1017/s0033291717000769 ◽

2017 ◽

Vol 47 (13) ◽

pp. 2302-2311 ◽

Cited By ~ 7

Author(s):

M. H. M. Timmer ◽

G. Sescousse ◽

M. E. van der Schaaf ◽

R. A. J. Esselink ◽

R. Cools

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Reversal Learning ◽

Learning Deficits ◽

Medication Withdrawal ◽

History Of ◽

Depression History ◽

Non Motor Symptoms ◽

History Of Depression

BackgroundDepression is one of the most common and debilitating non-motor symptoms of Parkinson's disease (PD). The neurocognitive mechanisms underlying depression in PD are unclear and treatment is often suboptimal.MethodsWe investigated the role of striatal dopamine in reversal learning from reward and punishment by combining a controlled medication withdrawal procedure with functional magnetic resonance imaging in 22 non-depressed PD patients and 19 PD patients with past or present depression.ResultsPD patients with a depression (history) exhibited impaired reward v. punishment reversal learning as well as reduced reward v. punishment-related BOLD signal in the striatum (putamen) compared with non-depressed PD patients. No effects of dopaminergic medication were observed.ConclusionsThe present findings demonstrate that impairments in reversal learning from reward v. punishment and associated striatal signalling depend on the presence of (a history of) depression in PD.

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Source memory and frontal functioning in Parkinson’s disease

Journal of the International Neuropsychological Society ◽

10.1017/s1355617709090572 ◽

2009 ◽

Vol 15 (3) ◽

pp. 399-406 ◽

Cited By ~ 26

Author(s):

LAUREN L. DRAG ◽

LINAS A. BIELIAUSKAS ◽

ALFRED W. KASZNIAK ◽

NICOLAAS I. BOHNEN ◽

ELIZABETH L. GLISKY

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Prefrontal Cortex ◽

Executive Functioning ◽

Source Memory ◽

Dopaminergic Neurons ◽

Medication Administration ◽

Substantia Nigra Pars Compacta ◽

Medication Withdrawal ◽

Healthy Control

AbstractThe most extensively described pathological abnormality in Parkinson’s disease (PD) is loss of dopaminergic neurons in the substantia nigra pars compacta and the ventral tegmental area, with degeneration of their striatal terminals. Because of the intimate connections between the striatum and the frontal lobes, individuals with PD often demonstrate impairments on those tasks relying on the prefrontal cortex (e.g., tests of executive functioning). Source memory, or memory for context, is believed to rely on the prefrontal cortex and has been previously associated with executive functioning performance, although it has received little attention in the PD literature. Executive functioning and source memory were measured in a group of nondemented PD patients and healthy control participants. Within the PD group, an anti-Parkinson’s medication withdrawal manipulation was used to examine whether source memory was affected by phasic changes in dopamine levels. Compared to healthy control participants, PD patients were impaired in source memory (both on- and off-medication) and on a composite measure of executive functioning. Within the PD group, medication administration improved motor performance but did not have a significant effect on source memory. (JINS, 2009, 15, 399–406.)

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Reward learning deficits in Parkinson’s disease depend on depression

10.1101/069062 ◽

2016 ◽

Author(s):

Monique H.M. Timmer ◽

Guillaume Sescousse ◽

Marieke E. van der Schaaf ◽

Rianne A.J. Esselink ◽

Roshan Cools

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Reversal Learning ◽

Learning Deficits ◽

Medication Withdrawal ◽

History Of ◽

Depression History ◽

Non Motor Symptoms ◽

History Of Depression

AbstractBackgroundDepression is one of the most common and debilitating non-motor symptoms of Parkinson’s disease (PD). The neurocognitive mechanisms underlying depression in PD are unclear and treatment is often suboptimal.MethodsWe investigated the role of striatal dopamine in reversal learning from reward and punishment by combining a controlled medication withdrawal procedure with functional magnetic resonance imaging (fMRI) in 22 non-depressed PD patients and 19 PD patients with past or present PD-related depression.ResultsPD patients with a PD-related depression (history) exhibited impaired reward versus punishment reversal learning as well as reduced reward versus punishment-related BOLD signal in the striatum (putamen) compared with non-depressed PD patients. No effects of dopaminergic medication were observed.ConclusionsThe present findings demonstrate that impairments in reversal learning from reward versus punishment and associated reward-related striatal signalling depend on the presence of (a history of) depression in PD.

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