Opioid-induced hypogonadism in opioid use disorder, its role in negative reinforcement, and implications for treatment and retention.

Hypogonadism is a highly prevalent complication of chronic opioid use associated with a constellation of affective, algesic, and cognitive symptoms as well as decreased quality of life. Given that the mainstays of pharmacologic opioid use disorder (OUD) treatment - methadone and buprenorphine - are themselves agonists or partial agonists at the mu opioid receptor, opioid-induced hypogonadism (OIH) remains an underappreciated clinical concern throughout the course of OUD treatment. Prominent theoretical frameworks for OUD emphasize the importance of negative reinforcement and hyperkatifeia, defined as the heightened salience of negative emotional and motivational states brought on by chronic opioid use. In this perspective article, we highlight the striking parallels between the symptom domains of hyperfakifeia and hypogonadism in males, who comprise the vast majority of existing clinical research on OIH. By extension we propose that future research and ultimately clinical care should focus on the identification and treatment of OIH in OUD patients to help address the longstanding paradox of poor treatment retention despite efficacious therapies, particularly in the setting of the current opioid overdose epidemic driven by high potency synthetic opioids such as fentanyl. We then review evidence from chronic pain patients that testosterone replacement provides clinically significant benefits to men with OIH. Finally, using this framework, we compare extant OUD therapeutics and discuss critical gaps in the clinical literature-including the relative dearth of data regarding hypothalamic-pituitary-gonadal function in females who use opioids-where future study should be focused.

Mixed amphetamine salts-extended release (MAS-ER) as a behavioral treatment augmentation strategy for cocaine use disorder: A randomized clinical trial.

Psychosocial interventions remain the primary strategy for addressing cocaine use disorder (CUD), although many individuals do not benefit from these approaches. Amphetamine-based interventions have shown significant promise and may improve outcomes among individuals continuing to use cocaine in the context of behavioral interventions. One hundred forty-five adults (122 males) who used cocaine a minimum of 4 days in the prior month and met the criteria for a CUD enrolled in a two-stage intervention. All participants received a computer-delivered skills intervention and contingency management for reinforcing abstinence for a 1-month period. Participants demonstrating less than 3 weeks of abstinence in the first month were randomized to receive mixed amphetamine salts-extended release (MAS-ER) or placebo (80 mg/day) for 10 weeks under double-blind conditions. All participants continued with the behavioral intervention. The primary outcome was the proportion of individuals who achieved 3 consecutive weeks of abstinence as measured by urine toxicology confirmed self-report at the study end. The proportion of participants demonstrating 3 consecutive weeks of abstinence at study end did not differ between the medication groups: MAS-ER = 15.6% (7/45) and placebo = 12.2% (5/41). Participants who received MAS-ER reported greater reductions in the magnitude of wanting cocaine, although no group differences were noted in either the perceived improvement or the frequency of wanting cocaine. Retention rates were greater for both medication groups compared to behavioral responders. Overall, augmenting a behavioral intervention with MAS-ER did not significantly increase the abstinence rate among individuals continuing to use cocaine following a month of behavioral therapy alone. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Open label trial of lofexidine-assisted non-opioid induction onto naltrexone extended-release injection for opioid use disorder.

Background: Opioid use disorder (OUD) continues to be major public health problem in the US and innovative medication strategies are needed. The extended-release injectable formulation of naltrexone (ER-NTX), an opioid receptor antagonist, is an effective treatment for OUD, but the need for an opioid-free period during the induction phase of treatment is a barrier to treatment success, particularly in the outpatient setting. Lofexidine, an alpha-2-adrenergic agonist, is an effective treatment for opioid withdrawal.Objectives: To evaluate the feasibility, safety, and tolerability of lofexidine for facilitating induction onto ER-NTX in the management of OUD.Methods: In an open-label, uncontrolled, 10-week outpatient clinical trial, 20 adults (four women) with OUD were treated with a fixed-flexible dosing strategy (maximum 0.54 mg 4×/daily) of lofexidine for up to 10 days to manage opioid withdrawal prior to receiving ER-NTX. The COVID-19 pandemic resulted in a modification of the study methods after enrolling 10 participants who attended all visits in person. The second group of 10 participants attended most induction period visits remotely.Results: Overall, 10 of the 20 participants (50%) achieved the primary outcome by receiving the first ER-NTX injection. Rates of induction success did not differ by the presence of fentanyl or remote visit attendance, although the small sample size provided limited statistical power. Six out of 20 participants (30%) initiated on lofexidine required dose adjustments. There were no study-related serious adverse events.Conclusions: This study provides preliminary evidence supporting the feasibility of inducting individuals with OUD onto ER-NTX using lofexidine.

Applications of technology in the assessment and treatment of cannabis use disorder.

Cannabis use and Cannabis Use Disorder (CUD) have been increasing. There are no FDA approved medications and evidence-based psychotherapy is limited by insufficient providers, serving very few patients effectively. The lack of resources for prevention and treatment of CUD has resulted in a significant gap between the need for services and access to treatment. The creation of a scalable system to prevent, screen, refer and provide treatment for a chronic, relapsing diagnosis like CUD could be achieved through the application of technology. Many studies have utilized ecological momentary assessments (EMA) in treatment seeking and non-treatment seeking cannabis users. EMA allows for repeated, intensive, longitudinal data collection in vivo. EMA has been studied in cannabis use and its association with affect, craving, withdrawal, other substances, impulsivity, and interpersonal behaviors. EMA has the potential to serve as a valuable monitoring tool in prevention, screening, and treatment for CUD. Research has also focused on the development of internet and application-based treatments for CUD, including a currently available prescription digital therapeutic. Treatment options have expanded to more broadly incorporate telehealth as an option for CUD treatment with broad acceptance and change in regulation following the COVID-19 pandemic. While technology has limitations, including cost, privacy concerns, and issues with engagement, it will be a necessary medium to meet societal health needs as a consequence of an ever-changing cannabis regulatory landscape. Future work should focus on improving existing platforms while ethically incorporating other functions (e.g., sensors) to optimize a public and clinical health approach to CUD.

The Rise of Prescription Digital Therapeutics in Behavioral Health.

Medicine is evolving to incorporate digital technologies of all kinds-technologies that may improve patient health, reduce clinician workload, lower costs, reduce health disparities, and expand access to needed treatments. Prescription digital therapeutics (PDTs) are an emerging technology with particular potential. These are software-based treatments delivered on mobile devices that address the behavioral dimensions of many diseases and conditions. Unlike health and wellness apps, PDTs are rigorously evaluated for safety and effectiveness and are authorized by the US Food and Drug Administration (FDA). Nine PDTs are currently authorized to treat conditions such as substance use disorders, attention-deficit disorder, and chronic insomnia. The findings reported in two recent research papers published by Advances in Therapy related to use of PDTs for substance use disorder and opioid use disorder provide real-world evidence of clinical and cost effectiveness, strengthening the evidence base for these technologies and suggesting a role for these technologies in the efforts to help patients recover from these often-chronic and deadly conditions.

Patient Engagement With a Game-Based Digital Therapeutic for the Treatment of Opioid Use Disorder: Protocol for a Randomized Controlled Open-Label, Decentralized Trial.

BACKGROUND: Prescription digital therapeutics are software-based disease treatments that are regulated by the US Food and Drug Administration; the reSET-O prescription digital therapeutic was authorized in 2018 and delivers behavioral treatment for individuals receiving buprenorphine for opioid use disorder. Although reSET-O improves outcomes for individuals with opioid use disorder, most of the therapeutic content is delivered as narrative text. PEAR-008 is an investigational device based on reSET-O that uses an interactive, game-based platform to deliver similar therapeutic content designed to enhance patient engagement, which may further improve treatment outcomes. OBJECTIVE: We aim to investigate how participants interact with the prescription digital therapeutic's new content delivery format. Secondary objectives include evaluating treatment success, symptoms of co-occurring mental health disorders, recovery capital, and skill development. METHODS: Due to the COVID-19 pandemic, this study was redesigned using a decentralized model because it was not possible to conduct medication initiation and study visits in person, as initially intended. A decentralized, randomized controlled trial design will be utilized to compare patient engagement with PEAR-008 and that with reSET-O using both subjective and objective assessments. The study population will consist of approximately 130 individuals with opioid use disorder (based on Diagnostic and Statistical Manual of Mental Disorders 5 criteria) who have recently started buprenorphine treatment for opioid use disorder. Participants will be virtually recruited and randomly assigned to receive either PEAR-008 or reSET-O. All study sessions will be virtual, and the duration of the study is 12 weeks. The primary outcome measure of engagement is operationalized as the number of active sessions per week with either PEAR-008 or reSET-O. (An active session is any session that contains some active participation in the app, such as navigating to a different screen, engaging with a learning module, or responding to a notification.) Subjective dimensions of engagement will be assessed with participant surveys. The hypothesis is that PEAR-008 will have significantly greater participant engagement than reSET-O. RESULTS: As of February 2021, participant enrollment is ongoing. CONCLUSIONS: This randomized controlled trial will investigate if changing the delivery format and enhancing the content of a prescription digital therapeutic for opioid use disorder will affect how participants use and interact with the prescription digital therapeutic. The study design may serve as a useful model for conducting decentralized studies in this patient population. TRIAL REGISTRATION: ClinicalTrials.gov NCT04542642; https://clinicaltrials.gov/ct2/show/NCT04542642. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/32759.

Open-label trial of a single-day induction onto buprenorphine extended-release injection for users of heroin and fentanyl.

BACKGROUND AND OBJECTIVES: Fentanyl and other highly potent synthetic opioids are the leading cause of opioid overdose deaths in the United States. METHODS: This study was an open-label, uncontrolled 12-week outpatient clinical trial to test the feasibility of a single-day induction onto extended-release buprenorphine (BXR) injection treatment for five adults (N = 5) with opioid use disorder using heroin-containing fentanyl. Participants were planned to receive three monthly BXR injections (300, 300, and 100 mg). RESULTS: After receiving 24 mg sublingual buprenorphine (SL-BUP), all five participants received the BXR 300 mg injection on the first day of induction. All five participants were retained for the full 3-month study period postinduction and received all three scheduled BXR injections. DISCUSSION AND CONCLUSION: This study provides preliminary evidence supporting the feasibility of inducting users of heroin-containing fentanyl onto BXR 300 mg in a single day. SCIENTIFIC SIGNIFICANCE: The ability to administer a long-acting injection of BXR that assures therapeutic serum levels for a month on the first day of treatment contact is a promising development for the treatment of OUD.

Non-abstinent treatment outcomes for cannabis use disorder.

BACKGROUND: Abstinence remains a standard outcome for potential treatment interventions for Cannabis Use Disorder (CUD). However, there needs to be validation of non-abstinent outcomes. This study explores reductions in self-reported days of use as another viable outcome measure using data from three completed randomized placebo-controlled clinical trials of pharmacological interventions for CUD. METHODS: The three trials tested the effect of quetiapine (QTP, n = 113); dronabinol (DRO, n = 156); and lofexidine + dronabinol (LFD, n = 122). Self-reported cannabis use was categorized into three use-groups/week: heavy (5-7 days/week), moderate (2-4 days/week) and light use (0-1 days/week). Multinomial logistic regressions analyzed the treatment by time effect on the likelihood of light and moderate use compared to heavy use in each study. RESULTS: Across the three trials, there was no significant overall time-by-treatment interaction (QTP: p = .06; DRO: p = .15; LFD: p = .21). However, the odds of moderate compared to heavy use were significantly higher in treatment than in placebo groups starting around the midpoint of each trial. No treatment differences were found between the odds of light compared to heavy use. CONCLUSIONS: While study-end abstinence rates have been a standard treatment outcome for CUD trials, reduction from heavy to moderate use has not been standardly assessed. During the last several weeks of each trial, those on active medication were more likely to move from heavy to moderate use, which suggests that certain medications may be more impactful than previously assessed. Future studies should determine if this pattern is associated with less CUD severity and/or improved quality of life.

An open-label pilot study of pregabalin pharmacotherapy for alcohol use disorder.

Background: There is a need for alcohol use disorder (AUD) pharmacotherapy that can be administered to actively drinking outpatients. Pregabalin, a gabapentoid anticonvulsant, has preliminary evidence supporting effects on alcohol withdrawal and AUD.Objectives: To evaluate the safety, tolerability, and optimal dosing of pregabalin for treating AUD.Methods: In an open-label, 8-week, outpatient trial of eighteen adults (nine women) with AUD, participants were titrated to 600 mg/day (or the maximum tolerated dose) over 3 weeks and then maintained for 5 weeks.Results: The majority (11/14, 78.6%) of participants with at least one-week of medication exposure achieved a maximum dose of 600 mg/day. Mean retention was 6.8 weeks (SD = 2.6). Eighty percent (12/15) of participants with post-enrollment data reported any adverse effects during the trial; and for those reporting adverse effects the most common were drowsiness (33.3%, 4/12), and fogginess (25%, 3/12), dizziness (25%, 3/12), and insomnia (25%, 3/12). Two participants discontinued study medication due to adverse effects and one had a dose reduction. Mean Heavy Drinking Days (HDD)/week decreased significantly by 3.43 days (SD = 2.47; median (IQR) = 4.00 (1.00 to 5.50)); Wilcoxon signed rank test statistic ((S) = 49.5, p = .0006). Mean proportion of HDD significantly decreased on average by 48.7% (SD = 35.1%; median (IQR) = 57.1% (14.3% to 78.6%)). The proportion of abstinent days increased significantly on average by 36.1% (SD = 35.0%; median (IQR) = 17.9% (14.3% to 75.0%); S = 49.5, p = .0005).Conclusions: Pregabalin treatment of AUD appears to be safe and well tolerated in doses up to 600 mg per day.Trial Registration: clinicaltrials.gov identifier: NCT03256253.

Digital Clinical Trials for Substance Use Disorders in the Age of Covid-19.

: As a result of the coronavirus 2019 (Covid-19) pandemic, clinical research for substance use disorders (SUDs) has been impeded due to widespread stay-at-home mandates limiting the operations of "non-essential" work. Although appropriate to proceed with an abundance of caution to prevent viral spread, there will be detrimental consequences for patients with SUDs if clinical trials research cannot adapt and continue uninterrupted. The field of digital health has strong evidence for its feasibility and effectiveness and offers tools that can facilitate the continuation of SUD clinical trials research remotely in accordance with Covid-19 precautions. Some digital tools have been used as components of SUD research in the past; however, no published clinical trial in SUDs to-date has been entirely virtual. This has important implications for disrupted clinical care, as providers seek guidelines for best digital practices. This paper provides a roadmap for integrating the fields of digital health and SUD clinical trials by proposing methods to complete recruitment, screening, informed consent, other study procedures, and internal lab operations digitally. The immediate future of SUD research depends on the ability to comply with social distancing. Investment in research of digital clinical trials for SUDs provides an opportunity to cultivate benefits for research and clinical care long-term as we can (1) define regulatory requirements for the implementation of digital systems, (2) develop consensus on system-wide standards and protocols in the appropriate use of technology, and (3) gain experience that can translate to the treatment of patients with SUDs through telehealth in the community.

Abstinence and reduced frequency of use are associated with improvements in quality of life among treatment-seekers with cannabis use disorder.

BACKGROUND AND OBJECTIVE: Many patients with cannabis use disorder (CUD) do not achieve or do not have abstinence as a goal of treatment, rather they reduce their use. Assessing outcome measures as they relate to functioning and reductions in cannabis use is an important area of study. Quality of life (QoL) shows promise as one such measure. Past studies have demonstrated gender differences in QoL and CUD. We aim to assess (1) the relationship between cannabis use and QoL and (2) gender effects in an outpatient medication treatment study for CUD. METHODS: Data from an 11-weeks, double-blind, placebo-controlled trial of lofexidine and dronabinol for CUD (n = 62) was analyzed. Pearson's correlations between baseline QoL as measured with the Quality of Life, Enjoyment, and Satisfaction Questionnaire-Short Form (QLES-Q-SF) and cannabis use assessed with modified timeline follow-back (TLFB) were examined. Multiple linear regression models of cannabis use on end of study QLES-Q-SF were analyzed, while adjusting for baseline QLES-Q-SF, study arm, and gender. Moderation effects with gender were also tested. RESULTS: No significant association between baseline cannabis use and QoL was found. End of study abstinence (F1,47 = 8.34, p = .006) and reduced proportion of using days (F1,47 = 9.48, p = .004) were each significantly associated with end of study QoL. Reduction in grams (F1,27 = 0.25, p = .62) was not associated with QoL at end of study. Gender was not a significant moderator. DISCUSSION AND CONCLUSIONS: Abstinence and lower frequency of use are associated with higher QoL, regardless of gender. SCIENTIFIC SIGNIFICANCE: This is the first time QoL has been demonstrated to change over the course of CUD medication treatment. QoL is an important outcome in CUD treatment. TRIAL REGISTRATION: NCT01020019. (Am J Addict 2018;27:101-107).

The Current State of Pharmacological Treatments for Cannabis Use Disorder and Withdrawal.

Cannabis use disorder (CUD) commonly occurs and carries a notable economic and functional burden at both individual and societal levels. While there are no clearly efficacious medication treatments for CUD, 20 years of committed and high-quality research in the human laboratory and clinical settings have resulted in medications with demonstrated effectiveness in the treatment of cannabis withdrawal, the ability to reduce cannabis use, and results that point to promising future work. The current state of pharmacology research for CUD highlights the need to consider particular characteristics of patients, such as gender, impulsivity, and severity of cannabis use, when selecting a medication in the off-label treatment of CUD or cannabis withdrawal. As a field, the body of work also exposes some areas in need of improvement in study design, selection of outcome measures, interpretation of results, and the overall process of evaluating candidate medications. Coming to a consensus as a field and addressing these gaps in future research will likely lend itself to further advances in improving the lives of patients with CUD.

Demographic and clinical characteristics of treatment seeking women with full and subthreshold PTSD and concurrent cannabis and cocaine use disorders.

While the detrimental effects of concurrent substance use disorders (SUDs) are now being well documented, very few studies have examined this comorbidity among women with posttraumatic stress disorder (PTSD). Data for these analyses were derived from the "Women and Trauma" study conducted within the National Drug Abuse Treatment Clinical Trials Network. Women with full or subthreshold PTSD and co-occurring cannabis use disorder (CUD) and cocaine use disorder (COD; N=99) were compared to their counterparts with co-occurring CUD only (N=26) and co-occurring COD only (N=161) on rates of trauma exposure, psychiatric disorders, psychosocial problems, and other substance use utilizing a set of multivariate logistic regressions. In models adjusted for age and race/ethnicity, women with PTSD and COD only were significantly older than their counterparts with CUD only and concurrent CUD+COD. Relative to those with CUD only, women with concurrent CUD+COD had higher odds of adult sexual assault. Relative to those with COD only, women with concurrent CUD+COD had higher odds of alcohol use disorder in the past 12months. Finally, relative to those with CUD only, women with COD only had higher odds of ever being arrested/convicted and adult sexual assault. The higher rates of adult sexual assault and alcohol use disorder among those with concurrent CUD+COD suggest the need for trauma-informed approaches that can respond to the needs of this dually-diagnosed population. Moreover, the causal link between repeated traumatic stress exposure and polysubstance use requires further examination.

The syndemic illness of HIV and trauma: implications for a trauma-informed model of care.

BACKGROUND: People living with HIV infection are disproportionately burdened by trauma and the resultant negative health consequences, making the combination of HIV infection and trauma a syndemic illness. Despite the high co-occurrence and negative influence on health, trauma and posttraumatic sequelae in people living with HIV infection often go unrecognized and untreated because of the current gaps in medical training and lack of practice guidelines. OBJECTIVE: We set out to review the current literature on HIV infection and trauma and propose a trauma-informed model of care to target this syndemic illness. METHODS: We searched PubMed, PsycINFO, and Cochrane review databases for articles that contained the following search terms: HIV AND either trauma (specifically violent trauma), PTSD, intimate partner violence (IPV), abuse, or trauma-informed care. Articles were limited to primary clinical research or metanalyses published in English. Articles were excluded if they referred to HIV-associated posttraumatic stress disorder or HIV-associated posttraumatic growth. RESULTS: We confirm high, but variable, rates of trauma in people living with HIV infection demonstrated in multiple studies, ranging from 10%-90%. Trauma is associated with (1) increased HIV-risk behavior, contributing to transmission and acquisition of the virus; (2) negative internal and external mediators also associated with poor health and high-risk HIV behavior; (3) poor adherence to treatment; (4) poor HIV-related and other health outcomes; and (5) particularly vulnerable special populations. CONCLUSIONS: Clinicians should consider using a model of trauma-informed care in the treatment of people living with HIV infection. Its adoption in different settings needs to be matched to available resources.

Aberrant supplementary motor complex and limbic activity during motor preparation in motor conversion disorder.

Conversion disorder (CD) is characterized by unexplained neurological symptoms presumed related to psychological issues. The main hypotheses to explain conversion paralysis, characterized by a lack of movement, include impairments in either motor intention or disruption of motor execution, and further, that hyperactive self-monitoring, limbic processing or top-down regulation from higher order frontal regions may interfere with motor execution. We have recently shown that CD with positive abnormal or excessive motor symptoms was associated with greater amygdala activity to arousing stimuli along with greater functional connectivity between the amygdala and supplementary motor area. Here we studied patients with such symptoms focusing on motor initiation. Subjects performed either an internally or externally generated 2-button action selection task in a functional MRI study. Eleven CD patients without major depression and 11 age- and gender-matched normal volunteers were assessed. During both internally and externally generated movement, conversion disorder patients relative to normal volunteers had lower left supplementary motor area (SMA) (implicated in motor initiation) and higher right amygdala, left anterior insula, and bilateral posterior cingulate activity (implicated in assigning emotional salience). These findings were confirmed in a subgroup analysis of patients with tremor symptoms. During internally versus externally generated action in CD patients, the left SMA had lower functional connectivity with bilateral dorsolateral prefrontal cortices. We propose a theory in which previously mapped conversion motor representations may in an arousing context hijack the voluntary action selection system, which is both hypoactive and functionally disconnected from prefrontal top-down regulation.

Dopamine agonists and risk: impulse control disorders in Parkinson's disease.

Impulse control disorders are common in Parkinson's disease, occurring in 13.6% of patients. Using a pharmacological manipulation and a novel risk taking task while performing functional magnetic resonance imaging, we investigated the relationship between dopamine agonists and risk taking in patients with Parkinson's disease with and without impulse control disorders. During functional magnetic resonance imaging, subjects chose between two choices of equal expected value: a 'Sure' choice and a 'Gamble' choice of moderate risk. To commence each trial, in the 'Gain' condition, individuals started at $0 and in the 'Loss' condition individuals started at -$50 below the 'Sure' amount. The difference between the maximum and minimum outcomes from each gamble (i.e. range) was used as an index of risk ('Gamble Risk'). Sixteen healthy volunteers were behaviourally tested. Fourteen impulse control disorder (problem gambling or compulsive shopping) and 14 matched Parkinson's disease controls were tested ON and OFF dopamine agonists. Patients with impulse control disorder made more risky choices in the 'Gain' relative to the 'Loss' condition along with decreased orbitofrontal cortex and anterior cingulate activity, with the opposite observed in Parkinson's disease controls. In patients with impulse control disorder, dopamine agonists were associated with enhanced sensitivity to risk along with decreased ventral striatal activity again with the opposite in Parkinson's disease controls. Patients with impulse control disorder appear to have a bias towards risky choices independent of the effect of loss aversion. Dopamine agonists enhance sensitivity to risk in patients with impulse control disorder possibly by impairing risk evaluation in the striatum. Our results provide a potential explanation of why dopamine agonists may lead to an unconscious bias towards risk in susceptible individuals.

Non-substance-addictive behaviors in youth: pathological gambling and problematic Internet use.

Adolescence is characterized by participation in multiple novel and potentially risky behaviors. Amongst these behaviors are gambling and use of the Internet, and excessive engagement in these activities (as seen in pathological gambling and problematic Internet use) may be accompanied by serious impairments in school, mental health, and social functioning. This article reviews the potential impact of pathological gambling and problematic Internet use in youth, the relevance of subsyndromal levels of participation, and how prevention and treatment strategies may be considered and tested within a developmental framework.

Emotional stimuli and motor conversion disorder.

Conversion disorder is characterized by neurological signs and symptoms related to an underlying psychological issue. Amygdala activity to affective stimuli is well characterized in healthy volunteers with greater amygdala activity to both negative and positive stimuli relative to neutral stimuli, and greater activity to negative relative to positive stimuli. We investigated the relationship between conversion disorder and affect by assessing amygdala activity to affective stimuli. We conducted a functional magnetic resonance imaging study using a block design incidental affective task with fearful, happy and neutral face stimuli and compared valence contrasts between 16 patients with conversion disorder and 16 age- and gender-matched healthy volunteers. The patients with conversion disorder had positive movements such as tremor, dystonia or gait abnormalities. We also assessed functional connectivity between the amygdala and regions associated with motor preparation. A group by affect valence interaction was observed. Post hoc analyses revealed that whereas healthy volunteers had greater right amygdala activity to fearful versus neutral compared with happy versus neutral as expected, there were no valence differences in patients with conversion disorder. There were no group differences observed. The time course analysis also revealed greater right amygdala activity in patients with conversion disorder for happy stimuli (t = 2.96, P = 0.006) (with a trend for fearful stimuli, t = 1.81, P = 0.08) compared with healthy volunteers, with a pattern suggestive of impaired amygdala habituation even when controlling for depressive and anxiety symptoms. Using psychophysiological interaction analysis, patients with conversion disorder had greater functional connectivity between the right amygdala and the right supplementary motor area during both fearful versus neutral, and happy versus neutral 'stimuli' compared with healthy volunteers. These results were confirmed with Granger Causality Modelling analysis indicating a directional influence from the right amygdala to the right supplementary motor area to happy stimuli (P < 0.05) with a similar trend observed to fearful stimuli (P = 0.07). Our data provide a potential neural mechanism that may explain why psychological or physiological stressors can trigger or exacerbate conversion disorder symptoms in some patients. Greater functional connectivity of limbic regions influencing motor preparatory regions during states of arousal may underlie the pathophysiology of motor conversion symptoms.

Mechanisms underlying dopamine-mediated reward bias in compulsive behaviors.

Pathological behaviors such as problem gambling or shopping are characterized by compulsive choice despite alternative options and negative costs. Reinforcement learning algorithms allow a computation of prediction error, a comparison of actual and expected outcomes, which updates our predictions and influences our subsequent choices. Using a reinforcement learning model, we show data consistent with the idea that dopamine agonists in susceptible individuals with Parkinson's disease increase the rate of learning from gain outcomes. Dopamine agonists also increase striatal prediction error activity, thus signifying a "better than expected" outcome. Thus, our findings are consistent with a model whereby a distorted estimation of the gain cue underpins a choice bias toward gains.