We review behavioral-and neuroeconomic research that identifies temporal discounting as an important component in the development and maintenance of drug addiction. First we review behavioral economic research that explains and documents the contribution of temporal discounting to addiction. This is followed with recent insights from neuroeconomics that may provide an explanation of why drug dependent individuals discount the future. Specifically, neuroeconomics has identified two competing neural systems that are related to temporal discounting using brainimaging techniques that examine the relative activation of different brain regions for temporal discounting. According to the competing neural systems account, choices for delayed outcomes are related to the prefrontal cortex (i.e., the "executive system") and choices for immediate outcomes are related to the limbic brain regions (i.e., the "impulsive system"). Temporal discounting provides a useful framework for future imaging research, and suggests a novel approach to designing effective drug dependence prevention and treatment programs.
Intertemporal choice is predicated on the valuation of commodities with respect to delay until their receipt. Subjective value of a future outcome decreases, or is discounted, as a function of that delay . Although behavioral studies suggest no difference between the devaluation of real and fictive outcomes, no neuroimaging studies have investigated potential differences in the underlying deliberative process. Here, we compare behavioral and neural correlates of intertemporal valuation of real and hypothetical monetary gains as well as hypothetical losses, which have been posited to involve different mechanisms. Behavioral and neuroimaging sessions were conducted in which participants made intertemporal choice decisions in a gains condition using both real and hypothetical $100 money and in a loss condition using a fictive $100 money. Within-subject comparison of behavioral data revealed no significant difference between levels of discounting across the three conditions. Random-effects analysis of functional magnetic resonance imaging (fMRI) data of each of the three discounting conditions independently revealed significant signal change in limbic (anterior cingulate, striatum, posterior cingulate) and executive functioning areas (lateral prefrontal cortex), whereas a repeated-measures ANOVA failed to detect differences in signal change across the three discounting conditions after correcting for multiple comparisons. These data support a concordance between real and hypothetical conditions from delay-discounting studies and further suggest a congruence of the fMRI blood oxygen level-dependent signal across brain regions associated with the deliberative process of different forms of intertemporal choice.
Key Points
Question
Collaborative chronic care models for mental health conditions are supported by extensive randomized clinical trial data, but what is the evidence that these models can be implemented and can have beneficial effects in general clinical settings?
Findings
In this randomized clinical implementation trial of 5596 veterans, a collaborative chronic care model was shown to be effectively implemented with practical, scalable facilitation support for clinicians. Effects on self-reported health outcomes were limited, but mental health hospitalization rate improved.
Meaning
These findings suggest that collaborative chronic care models can be exported to general clinical practice settings using implementation facilitation and, at least for individuals with complex mental health conditions, can improve health outcomes.
Background
Integrating mental health services into primary care settings is complex and challenging. Although facilitation strategies have successfully supported implementation of primary care mental health integration and other complex innovations, we know little about the time required or its cost.
Objective
To examine the time and organizational cost of facilitating implementation of primary care mental health integration.
Design
Descriptive analysis.
Participants
One expert external facilitator and two internal regional facilitators who helped healthcare system stakeholders, e.g., leaders, managers, clinicians, and non-clinical staff, implement primary care mental health integration at eight clinics.
Intervention
Implementation facilitation tailored to the needs and resources of the setting and its stakeholders.
Main Measures
We documented facilitators’ and stakeholders’ time and types of activities using a structured spreadsheet collected from facilitators on a weekly basis. We obtained travel costs and salary information. We conducted descriptive analysis of time data and estimated organizational cost.
Key Results
The external facilitator devoted 263 h (0.09 FTE), including travel, across all 8 clinics over 28 months. Internal facilitator time varied across networks (1792 h versus 1169 h), as well as clinics. Stakeholder participation time was similar across networks (1280.6 versus 1363.4 person hours) but the number of stakeholders varied (133 versus 199 stakeholders). The organizational cost of providing implementation facilitation also varied across networks ($263,490 versus $258,127). Stakeholder participation accounted for 35% of the cost of facilitation activities in one network and 47% of the cost in the other.
Conclusions
Although facilitation can improve implementation of primary care mental health integration, it requires substantial organizational investments that may vary by site and implementation effort. Furthermore, the cost of using an external expert to transfer facilitation skills and build capacity for implementation efforts appears to be minimal.
Previous studies by our group have demonstrated fMRI signal changes and synchronized gamma rhythm EEG oscillations between thalamus and cortical regions as subjects recall objects from visually presented features. Here, we extend this work by estimating the time course of fMRI signal changes in the cortical and subcortical regions found to exhibit evidence for task-related activation. Our results indicate that there are separate loci of signal changes in the thalamus (dorsomedial and pulvinar) that exhibit notable differences in times of onset, peak and return to baseline of signal changes. The signal changes in the pulvinar demonstrate the slowest transients of all the cortical and subcortical regions we examined. Evaluation of cortical regions demonstrated salient differences as well, with the signal changes in Brodmann area 6 (BA6) rising, peaking, and returning to baseline earlier than those detected in other regions. We conclude that BA6 mediates early designation or refinement of search criteria, and that the pulvinar may be involved in the binding of feature stimuli for an integrated object memory.
The SORT is a specific test of semantic memory, and is a sensitive measure of semantic memory deficits in patients who otherwise meet criteria for amnestic MCI. Using this specific assessment tool, a significant number of MCI patients were found to have semantic memory deficits. As these patients may be early in the course of possible progression toward dementia, the SORT or other tests of semantic memory may provide important diagnostic or prognostic information in patients with MCI.
The SORT task provides a direct, specific assessment of semantic memory, and has now been administered to 121 healthy, aging controls for normative ranges of performance, and to AD patients. The task detected semantic memory deficits in approximately half of patients with mild-moderate AD, which is comparable to other studies assessing semantic deficits in AD with less specific measures.
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