Evens Ricarda, Hoefler Michael, Biber Karolina, Lueken Ulrike
Institute of Clinical Psychology and Psychotherapy, Technische Universität Dresden, Chemnitzer Str. 46, 01187 Dresden, Germany.
Institute of Clinical Psychology and Psychotherapy, Technische Universität Dresden, Chemnitzer Str. 46, 01187 Dresden, Germany.
Neuropsychologia. 2016 Oct;91:163-172. doi: 10.1016/j.neuropsychologia.2016.07.032. Epub 2016 Jul 27.
Decision-making under uncertainty as measured by the Iowa Gambling Task has frequently been studied in Parkinson's disease. The dopamine overdose hypothesis assumes that dopaminergic effects follow an inverted U-shaped function, restoring some cognitive functions while overdosing others. The present work quantitatively summarizes disease and medication effects on task performance and evaluates evidence for the dopamine overdose hypothesis of impaired decision-making in Parkinson's disease.
A systematic literature search was performed to identify studies examining the Iowa Gambling Task in patients with Parkinson's disease. Outcomes were quantitatively combined, with separate estimates for the clinical (patients ON medication vs. healthy controls), disease (patients OFF medication vs. healthy controls), and medication effects (patients ON vs. OFF medication). Furthermore, using meta-regression analysis it was explored whether the study characteristics drug level, disease duration, and motor symptoms explained heterogeneous performance between studies.
Patients with Parkinson's disease ON dopaminergic medication showed significantly impaired Iowa Gambling Task performance compared to healthy controls. This impairment was not normalized by short-term withdrawal of medication. Heterogeneity across studies was not explained by dopaminergic drug levels, disease durations or motor symptoms.
While this meta-analysis showed significantly impaired decision-making performance in Parkinson's disease, there was no evidence that this impairment was related to dopamine overdosing. However, only very few studies assessed patients OFF medication and future studies are needed to concentrate on the modulation of dopaminergic drug levels and pay particular attention to problems related to repeated testing. Furthermore, short- vs. long-term medication effects demand further in-depth investigation.
通过爱荷华赌博任务所衡量的不确定性下的决策制定在帕金森病中已得到频繁研究。多巴胺过量假说认为多巴胺能效应遵循倒U形函数，在使某些认知功能恢复的同时使其他功能过量。本研究定量总结了疾病和药物治疗对任务表现的影响，并评估帕金森病中决策受损的多巴胺过量假说的证据。
进行系统的文献检索以识别研究帕金森病患者爱荷华赌博任务的研究。对结果进行定量合并，分别估计临床（服用药物的患者与健康对照）、疾病（未服用药物的患者与健康对照）和药物治疗效果（服用药物的患者与未服用药物的患者）。此外，使用元回归分析探讨研究特征药物水平、疾病持续时间和运动症状是否能解释研究之间表现的异质性。
与健康对照相比，服用多巴胺能药物的帕金森病患者在爱荷华赌博任务中的表现明显受损。这种损害并未因短期停药而恢复正常。多巴胺能药物水平、疾病持续时间或运动症状均无法解释研究之间的异质性。
虽然这项荟萃分析显示帕金森病患者的决策表现明显受损，但没有证据表明这种损害与多巴胺过量有关。然而，只有极少数研究评估了未服用药物的患者，未来的研究需要集中于多巴胺能药物水平的调节，并特别关注与重复测试相关的问题。此外，短期与长期药物治疗效果需要进一步深入研究。
