Department of Psychology, University of Georgia, 125 Baldwin Street, Athens, GA, 30602, USA.
Peter Boris Centre for Addiction Research, St. Joseph's Healthcare Hamilton/McMaster University, 100 West 5th Street, Hamilton, ON, L8P 3R2, Canada.
Syst Rev. 2017 Jul 11;6(1):138. doi: 10.1186/s13643-017-0537-0.
Delayed reward discounting (DRD), the degree to which future rewards are discounted relative to immediate rewards, is used as an index of impulsive decision-making and has been associated with a number of problematic health behaviors. Given the robust behavioral association between DRD and addictive behavior, there is an expanding literature investigating the differences in the functional and structural correlates of DRD in the brain between addicted and healthy individuals. However, there has yet to be a systematic review which characterizes differences in regional brain activation, functional connectivity, and structure and places them in the larger context of the DRD literature. The objective of this systematic review is to summarize and critically appraise the existing literature examining differences between addicted and healthy individuals in the neural correlates of DRD using magnetic resonance imaging (MRI) or functional magnetic resonance imaging (fMRI).
A systematic search strategy will be implemented that uses Boolean search terms in PubMed/MEDLINE and PsycINFO, as well as manual search methods, to identify the studies comprehensively. This review will include studies using MRI or fMRI in humans to directly compare brain activation, functional connectivity, or structure in relation to DRD between addicted and healthy individuals or continuously assess addiction severity in the context of DRD. Two independent reviewers will determine studies that meet the inclusion criteria for this review, extract data from included studies, and assess the quality of included studies using the Grading of Recommendations Assessment, Development and Evaluation framework. Then, narrative review will be used to explicate the differences in structural and functional correlates of DRD implicated by the literature and assess the strength of evidence for this conclusion.
This review will provide a needed critical exegesis of the MRI studies that have been conducted investigating brain differences in addictive behavior in relation to healthy samples in the context of DRD. This will provide clarity on the elements of neural activation, connectivity, and structure that are most implicated in the differences in DRD seen in addicted individuals.
PROSPERO CRD42017056857.
延迟奖励折扣（DRD）是指未来奖励相对于即时奖励的折扣程度，它被用作冲动决策的指标，与许多不良健康行为有关。鉴于 DRD 与成瘾行为之间存在强有力的行为关联，越来越多的文献研究了成瘾个体和健康个体之间大脑中 DRD 的功能和结构相关性的差异。然而，目前还没有系统的综述来描述 DRD 相关的大脑区域激活、功能连接和结构的差异，并将其置于 DRD 文献的更大背景下。本系统综述的目的是总结和批判性评价使用磁共振成像（MRI）或功能磁共振成像（fMRI）研究成瘾个体和健康个体之间 DRD 神经相关性差异的现有文献。
我们将采用系统的搜索策略，在 PubMed/MEDLINE 和 PsycINFO 中使用布尔搜索词，并结合手动搜索方法，全面检索研究。本综述将包括使用 MRI 或 fMRI 的人类研究，这些研究直接比较成瘾个体和健康个体之间与 DRD 相关的大脑激活、功能连接或结构差异，或在 DRD 背景下连续评估成瘾严重程度。两名独立的评审员将确定符合本综述纳入标准的研究，从纳入研究中提取数据，并使用推荐评估、制定与评估分级（Grading of Recommendations Assessment, Development and Evaluation）框架评估纳入研究的质量。然后，我们将使用叙述性综述来阐明文献中暗示的 DRD 结构和功能相关性差异，并评估得出这一结论的证据强度。
本综述将对已经进行的关于 DRD 背景下成瘾行为与健康样本大脑差异的 MRI 研究进行批判性评价，这将为理解成瘾个体中 DRD 差异最相关的神经激活、连接和结构因素提供清晰的认识。
PROSPERO CRD42017056857。
