Parkinson's disease (PD) is associated with motor and cognitive impairment caused by dopamine dysregulation in the basal ganglia. Amongst a host of cognitive deficits, evidence suggests that decision-making is impaired in patients with PD, but the exact scope of this impairment is still unclear. The aim of this review was to establish which experimental manipulations commonly associated with studies involving decision-making tasks were most likely to generate impairments in performance in PD patients. This allowed us to address the question of the exact scope of the decision-making deficits in PD and to hypothesize about the role of the basal ganglia in decision-making processes. We conducted a meta-analysis of available literature, which revealed that the two key predictors of impairment in PD were the feedback structure of the decision-making task and the medication status of patients while performing the tasks. Rather than a global impairment in decision-making ability, these findings suggest that deficiencies in choice-behaviour in patients with PD stem from dysfunctions at the outcome evaluation stage of the decision-making process.
Background Deep brain stimulation in the ventral tegmental area (VTA-DBS) has provided remarkable therapeutic benefits in decreasing headache frequency and severity in patients with medically refractory chronic cluster headache (CH). However, to date the effects of VTA-DBS on cognition, mood and quality of life have not been examined in detail. Methods The aim of the present study was to do so in a case series of 18 consecutive patients with cluster headache who underwent implantation of deep brain stimulation electrodes in the ventral tegmental area. The patients were evaluated preoperatively and after a mean of 14 months of VTA-DBS on tests of global cognition (Mini Mental State Examination), intelligence (Wechsler Abbreviated Scale of Intelligence), verbal memory (California Verbal Learning Test-II), executive function (Delis–Kaplan Executive Function System), and attention (Paced Auditory Serial Addition Test). Depression (Beck Depression Inventory and Hospital Anxiety and Depression Rating Scale-D), anxiety (Hospital Anxiety and Depression Rating Scale-A), apathy (Starkstein Apathy Scale), and hopelessness (Beck Hopelessness Scale) were also assessed. Subjective pain experience (McGill Pain Questionnaire), behaviour (Pain Behaviour Checklist) and quality of life (Short Form-36) were also evaluated at the same time points. Results VTA-DBS resulted in significant improvement of headache frequency (from a mean of five to two attacks daily, p < .001) and severity (from mean Verbal Rating Scale [VRS] of 10 to 7, p < .001) which was associated with significant reduction of anxiety (from mean HADS-A of 11.94 to 8.00, p < .001) and help-seeking behaviours (from mean PBC of 4.00 to 2.61, p < .001). VTA-DBS did not produce any significant change to any tests of cognitive function and any other outcome measures (BDI, HADS-D, SAS, BHS, McGill Pain Questionnaire, Short Form-36). Conclusion We confirm the efficacy of VTA-DBS in the treatment of medically refractory chronic cluster headache. The reduction of headache frequency and severity was associated with a significant reduction of anxiety. Furthermore, the result suggests that VTA-DBS for chronic cluster headache improves pain-related help-seeking behaviours and does not produce any change in cognition.
Studies examining decision-making in people with Parkinson's disease (PD) show impaired performance on a variety of tasks. However, there are also demonstrations that patients with PD can make optimal decisions just like healthy age-matched controls. We propose that the reason for these mixed findings is that PD does not produce a generalized impairment of decision-making, but rather affects sub-components of this process. In this review we evaluate this hypothesis by considering the empirical evidence examining decision-making in PD. We suggest that of the various stages of the decision-making process, the most affected in PD are (1) the cost-benefit analysis stage and (2) the outcome evaluation stage. We consider the implications of this proposal for research in this area.
In the present study we address the following questions: (1) How is performance affected when patients with Parkinson's Disease (PD) perform a dynamic decision making task? (2) Does dopaminergic medication differentially affect dynamic decision making? To address these questions participants were trained with different goals during learning: either they made intervention-based decisions or prediction-based decisions during learning. The findings show that overall there is an advantage for those trained to intervene over those trained to predict. In addition, the results are the first demonstration that PD patients 'ON' (N=20) compared to 'OFF' L-Dopa (N=15) medication and also relative to healthy age matched controls (N=16) showed lower levels of relative improvement in the accuracy of their decisions in a dynamic decision making task, and tended to use sub-optimal strategies. These findings provide support for the 'Dopamine Overdose' hypothesis using a novel decision making task, and suggest that executive functions such as decision making can be adversely affected by dopaminergic medication in PD.
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