Silvia Lopez-Guzman, M.D., Ph.D.

@article{pmid34916590,

title = {A neuroeconomic signature of opioid craving: How fluctuations in craving bias drug-related and nondrug-related value},

author = {Kathryn Biernacki and Silvia Lopez-Guzman and John C Messinger and Nidhi V Banavar and John Rotrosen and Paul W Glimcher and Anna B Konova},

url = {https://pubmed.ncbi.nlm.nih.gov/34916590/},

doi = {10.1038/s41386-021-01248-3},

issn = {1740-634X},

year  = {2021},

date = {2021-12-01},

urldate = {2021-12-01},

journal = {Neuropsychopharmacology},

abstract = {How does craving bias decisions to pursue drugs over other valuable, and healthier, alternatives in addiction? To address this question, we measured the in-the-moment economic decisions of people with opioid use disorder as they experienced craving, shortly after receiving their scheduled opioid maintenance medication and ~24 h later. We found that higher cravers had higher drug-related valuation, and that moments of higher craving within-person also led to higher drug-related valuation. When experiencing increased opioid craving, participants were willing to pay more for personalized consumer items and foods more closely related to their drug use, but not for alternative "nondrug-related" but equally desirable options. This selective increase in value with craving was greater when the drug-related options were offered in higher quantities and was separable from the effects of other fluctuating psychological states like negative mood. These findings suggest that craving narrows and focuses economic motivation toward the object of craving by selectively and multiplicatively amplifying perceived value along a "drug relatedness" dimension.},

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@article{pmid34328052,

title = {Impulsivity and Medical Care Utilization in Veterans Treated for Substance Use Disorder},

author = {James M Bjork and Jarrod Reisweber and Jason R Burchett and Paul E Plonski and Anna B Konova and Silvia Lopez-Guzman and Clara E Dismuke-Greer},

url = {https://pubmed.ncbi.nlm.nih.gov/34328052/},

doi = {10.1080/10826084.2021.1949603},

issn = {1532-2491},

year  = {2021},

date = {2021-01-01},

urldate = {2021-01-01},

journal = {Subst Use Misuse},

volume = {56},

number = {12},

pages = {1741--1751},

abstract = {BACKGROUND: Impulsivity has been defined by acting rashly during positive mood states (positive urgency; PU) or negative mood states (negative urgency; NU) and by excessive de-valuation of deferred rewards. These behaviors reflect a "live in the now" mentality that is not only characteristic of many individuals with severe substance use disorder (SUD) but also impedes medical treatment compliance and could result in repeated hospitalizations or other poor health outcomes.  We sought preliminary evidence that impulsivity may relate to adverse health outcomes in the veteran population. Impulsivity measured in 90 veterans receiving inpatient or outpatient SUD care at a Veterans Affairs Medical Center was related to histories of inpatient/residential care costs, based on VA Health Economics Resource Center data.  We found that positive urgency, lack of persistence and lack of premeditation, but not sensation-seeking or preference for immediate or risky rewards, were significantly higher in veterans with a history of one or more admissions for VA-based inpatient or residential health care that either included ( = 30) or did not include ( = 29) an admission for SUD care. Among veterans with a history of inpatient/residential care for SUD, NU and PU, but not decision-making behavior, correlated with SUD care-related costs.  In veterans receiving SUD care, questionnaire-assessed trait impulsivity (but not decision-making) related to greater care utilization within the VA system. This suggests that veterans with high impulsivity are at greater risk for adverse health outcomes, such that expansion of cognitive interventions to reduce impulsivity may improve their health.},

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}

@article{pmid31812982,

title = {Computational Markers of Risky Decision-making for Identification of Temporal Windows of Vulnerability to Opioid Use in a Real-world Clinical Setting},

author = {Anna B Konova and Silvia Lopez-Guzman and Adelya Urmanche and Stephen Ross and Kenway Louie and John Rotrosen and Paul W Glimcher},

url = {https://pubmed.ncbi.nlm.nih.gov/31812982/},

doi = {10.1001/jamapsychiatry.2019.4013},

issn = {2168-6238},

year  = {2020},

date = {2020-01-01},

urldate = {2020-01-01},

journal = {JAMA Psychiatry},

volume = {77},

number = {4},

pages = {368--377},

abstract = {Importance: Opioid addiction is a major public health problem. Despite availability of evidence-based treatments, relapse and dropout are common outcomes. Efforts aimed at identifying reuse risk and gaining more precise understanding of the mechanisms conferring reuse vulnerability are needed.



Objective: To use tools from computational psychiatry and decision neuroscience to identify changes in decision-making processes preceding opioid reuse.



Design, Setting, and Participants: A cohort of individuals with opioid use disorder were studied longitudinally at a community-based treatment setting for up to 7 months (1-15 sessions per person). At each session, patients completed a risky decision-making task amenable to computational modeling and standard clinical assessments. Time-lagged mixed-effects logistic regression analyses were used to assess the likelihood of opioid use between sessions (t to t + 1; within the subsequent 1-4 weeks) from data acquired at the current session (t). A cohort of control participants completed similar procedures (1-5 sessions per person), serving both as a baseline comparison group and an independent sample in which to assess measurement test-retest reliability. Data were analyzed between January 1, 2018, and September 5, 2019.



Main Outcomes and Measures: Two individual model-based behavioral markers were derived from the task completed at each session, capturing a participant's current tolerance of known risks and ambiguity (partially unknown risks). Current anxiety, craving, withdrawal, and nonadherence were assessed via interview and clinic records. Opioid use was ascertained from random urine toxicology tests and self-reports.



Results: Seventy patients (mean [SE] age, 44.7 [1.3] years; 12 women and 58 men [82.9% male]) and 55 control participants (mean [SE] age, 42.4 [1.5] years; 13 women and 42 men [76.4% male]) were included. Of the 552 sessions completed with patients (mean [SE], 7.89 [0.59] sessions per person), 252 (45.7%) directly preceded opioid use events (mean [SE], 3.60 [0.44] sessions per person). From the task parameters, only ambiguity tolerance was significantly associated with increased odds of prospective opioid use (adjusted odds ratio, 1.37 [95% CI, 1.07-1.76]), indicating patients were more tolerant specifically of ambiguous risks prior to these use events. The association of ambiguity tolerance with prospective use was independent of established clinical factors (adjusted odds ratio, 1.29 [95% CI, 1.01-1.65]; P = .04), such that a model combining these factors explained more variance in reuse risk. No significant differences in ambiguity tolerance were observed between patients and control participants, who completed 197 sessions (mean [SE], 3.58 [0.21] sessions per person); however, patients were more tolerant of known risks (B = 0.56 [95% CI, 0.05-1.07]).



Conclusions and Relevance: Computational approaches can provide mechanistic insights about the cognitive factors underlying opioid reuse vulnerability and may hold promise for clinical use.},

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tppubtype = {article}

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@article{pmid30966919,

title = {Computational psychiatry of impulsivity and risk: how risk and time preferences interact in health and disease},

author = {Silvia Lopez-Guzman and Anna B Konova and Paul W Glimcher},

url = {https://pubmed.ncbi.nlm.nih.gov/30966919/},

doi = {10.1098/rstb.2018.0135},

issn = {1471-2970},

year  = {2019},

date = {2019-01-01},

urldate = {2019-01-01},

journal = {Philos Trans R Soc Lond B Biol Sci},

volume = {374},

number = {1766},

pages = {20180135},

abstract = {Choice impulsivity is an important subcomponent of the broader construct of impulsivity and is a key feature of many psychiatric disorders. Choice impulsivity is typically quantified as temporal discounting, a well-documented phenomenon in which a reward's subjective value diminishes as the delay to its delivery is increased. However, an individual's proclivity to-or more commonly aversion to- risk can influence nearly all of the standard experimental tools available for measuring temporal discounting. Despite this interaction, risk preference is a behaviourally and neurobiologically distinct construct that relates to the economic notion of utility or subjective value. In this opinion piece, we discuss the mathematical relationship between risk preferences and time preferences, their neural implementation, and propose ways that research in psychiatry could, and perhaps should, aim to account for this relationship experimentally to better understand choice impulsivity and its clinical implications. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.},

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tppubtype = {article}

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@article{pmid30622500,

title = {Interaction Between Stress and Addiction: Contributions From Latin-American Neuroscience},

author = {Angélica Torres-Berrio and Santiago Cuesta and Silvia Lopez-Guzman and Mauricio O Nava-Mesa},

url = {https://pubmed.ncbi.nlm.nih.gov/30622500/},

doi = {10.3389/fpsyg.2018.02639},

issn = {1664-1078},

year  = {2018},

date = {2018-01-01},

urldate = {2018-01-01},

journal = {Front Psychol},

volume = {9},

pages = {2639},

abstract = {Drug addiction is a chronic neuropsychiatric disorder that escalates from an initial exposure to drugs of abuse, such as cocaine, cannabis, or heroin, to compulsive drug-seeking and intake, reduced ability to inhibit craving-induced behaviors, and repeated cycles of abstinence and relapse. It is well-known that chronic changes in the brain's reward system play an important role in the neurobiology of addiction. Notably, environmental factors such as acute or chronic stress affect this system, and increase the risk for drug consumption and relapse. Indeed, the HPA axis, the autonomic nervous system, and the extended amygdala, among other brain stress systems, interact with the brain's reward circuit involved in addictive behaviors. There has been a growing interest in studying the molecular, cellular, and behavioral mechanisms of stress and addiction in Latin-America over the last decade. Nonetheless, these contributions may not be as strongly acknowledged by the broad scientific audience as studies coming from developed countries. In this review, we compile for the first time a series of studies conducted by Latin American-based neuroscientists, who have devoted their careers to studying the interaction between stress and addiction, from a neurobiological and clinical perspective. Specific contributions about this interaction include the study of CRF receptors in the lateral septum, investigations on the neural mechanisms of cross-sensitization for psychostimulants and ethanol, the identification of the Wnt/β-catenin pathway as a critical neural substrate for stress and addiction, and the emergence of the cannabinoid system as a promising therapeutic target. We highlight animal and human studies, including for instance, reports coming from Latin American laboratories on single nucleotide polymorphisms in stress-related genes and potential biomarkers of vulnerability to addiction, that aim to bridge the knowledge from basic science to clinical research.},

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@article{pmid29373590,

title = {Risk preferences impose a hidden distortion on measures of choice impulsivity},

author = {Silvia Lopez-Guzman and Anna B Konova and Kenway Louie and Paul W Glimcher},

url = {https://pubmed.ncbi.nlm.nih.gov/29373590/},

doi = {10.1371/journal.pone.0191357},

issn = {1932-6203},

year  = {2018},

date = {2018-01-01},

urldate = {2018-01-01},

journal = {PLoS One},

volume = {13},

number = {1},

pages = {e0191357},

abstract = {Measuring temporal discounting through the use of intertemporal choice tasks is now the gold standard method for quantifying human choice impulsivity (impatience) in neuroscience, psychology, behavioral economics, public health and computational psychiatry. A recent area of growing interest is individual differences in discounting levels, as these may predispose to (or protect from) mental health disorders, addictive behaviors, and other diseases. At the same time, more and more studies have been dedicated to the quantification of individual attitudes towards risk, which have been measured in many clinical and non-clinical populations using closely related techniques. Economists have pointed to interactions between measurements of time preferences and risk preferences that may distort estimations of the discount rate. However, although becoming standard practice in economics, discount rates and risk preferences are rarely measured simultaneously in the same subjects in other fields, and the magnitude of the imposed distortion is unknown in the assessment of individual differences. Here, we show that standard models of temporal discounting -such as a hyperbolic discounting model widely present in the literature which fails to account for risk attitudes in the estimation of discount rates- result in a large and systematic pattern of bias in estimated discounting parameters. This can lead to the spurious attribution of differences in impulsivity between individuals when in fact differences in risk attitudes account for observed behavioral differences. We advance a model which, when applied to standard choice tasks typically used in psychology and neuroscience, provides both a better fit to the data and successfully de-correlates risk and impulsivity parameters. This results in measures that are more accurate and thus of greater utility to the many fields interested in individual differences in impulsivity.},

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