Evidence for Habitual and Goal-Directed Behavior Following Devaluation of Cocaine: A Multifaceted Interpretation of Relapse

BACKGROUND:Cocaine addiction is characterized as a chronically relapsing disorder. It is believed that cues present during self-administration become learned and increase the probability that relapse will occur when they are confronted during abstinence. However, the way in which relapse-inducing cues are interpreted by the user has remained elusive. Recent theories of addiction posit that relapse-inducing cues cause relapse habitually or automatically, bypassing processing information related to the consequences of relapse. Alternatively, other theories hypothesize that relapse-inducing cues produce an expectation of the drug's consequences, designated as goal-directed relapse. Discrete discriminative stimuli signaling the availability of cocaine produce robust cue-induced responding after thirty days of abstinence. However, it is not known whether cue-induced responding is a goal-directed action or habit. METHODOLOGY/PRINCIPAL FINDINGS:We tested whether cue-induced responding is a goal-directed action or habit by explicitly pairing or unpairing cocaine with LiCl-induced sickness (n = 7/group), thereby decreasing or not altering the value of cocaine, respectively. Following thirty days of abstinence, no difference in responding between groups was found when animals were reintroduced to the self-administration environment alone, indicating habitual behavior. However, upon discriminative stimulus presentations, cocaine-sickness paired animals exhibited decreased cue-induced responding relative to unpaired controls, indicating goal-directed behavior. In spite of the difference between groups revealed during abstinent testing, no differences were found between groups when animals were under the influence of cocaine. CONCLUSIONS/SIGNIFICANCE:Unexpectedly, both habitual and goal-directed responding occurred during abstinent testing. Furthermore, habitual or goal-directed responding may have been induced by cues that differed in their correlation with the cocaine infusion. Non-discriminative stimulus cues were weak correlates of the infusion, which failed to evoke a representation of the value of cocaine and led to habitual behavior. However, the discriminative stimulus-nearly perfectly correlated with the infusion-likely evoked a representation of the value of the infusion and led to goal-directed behavior. These data indicate that abstinent cue-induced responding is multifaceted, dynamically engendering habitual or goal-directed behavior. Moreover, since goal-directed behavior terminated habitual behavior during testing, therapeutic approaches aimed at reducing the perceived value of cocaine in addicted individuals may reduce the capacity of cues to induce relapse

Stress-Induced Reinstatement of Drug Seeking: 20 Years of Progress

In human addicts, drug relapse and craving are often provoked by stress. Since 1995, this clinical scenario has been studied using a rat model of stress-induced reinstatement of drug seeking. Here, we first discuss the generality of stress-induced reinstatement to different drugs of abuse, different stressors, and different behavioral procedures. We also discuss neuropharmacological mechanisms, and brain areas and circuits controlling stress-induced reinstatement of drug seeking. We conclude by discussing results from translational human laboratory studies and clinical trials that were inspired by results from rat studies on stress-induced reinstatement. Our main conclusions are (1) The phenomenon of stress-induced reinstatement, first shown with an intermittent footshock stressor in rats trained to self-administer heroin, generalizes to other abused drugs, including cocaine, methamphetamine, nicotine, and alcohol, and is also observed in the conditioned place preference model in rats and mice. This phenomenon, however, is stressor specific and not all stressors induce reinstatement of drug seeking. (2) Neuropharmacological studies indicate the involvement of corticotropin-releasing factor (CRF), noradrenaline, dopamine, glutamate, kappa/dynorphin, and several other peptide and neurotransmitter systems in stress-induced reinstatement. Neuropharmacology and circuitry studies indicate the involvement of CRF and noradrenaline transmission in bed nucleus of stria terminalis and central amygdala, and dopamine, CRF, kappa/dynorphin, and glutamate transmission in other components of the mesocorticolimbic dopamine system (ventral tegmental area, medial prefrontal cortex, orbitofrontal cortex, and nucleus accumbens). (3) Translational human laboratory studies and a recent clinical trial study show the efficacy of alpha-2 adrenoceptor agonists in decreasing stress-induced drug craving and stress-induced initial heroin lapse

Blunted endogenous opioid release following an oral amphetamine challenge in pathological gamblers

Pathological gambling is a psychiatric disorder and the first recognized behavioral addiction, with similarities to substance use disorders but without the confounding effects of drug-related brain changes. Pathophysiology within the opioid receptor system is increasingly recognized in substance dependence, with higher mu-opioid receptor (MOR) availability reported in alcohol, cocaine and opiate addiction. Impulsivity, a risk factor across the addictions, has also been found to be associated with higher MOR availability. The aim of this study was to characterize baseline MOR availability and endogenous opioid release in pathological gamblers (PG) using [(11)C]carfentanil PET with an oral amphetamine challenge. Fourteen PG and 15 healthy volunteers (HV) underwent two [(11)C]carfentanil PET scans, before and after an oral administration of 0.5 mg/kg of d-amphetamine. The change in [(11)C]carfentanil binding between baseline and post-amphetamine scans (ΔBPND) was assessed in 10 regions of interest (ROI). MOR availability did not differ between PG and HV groups. As seen previously, oral amphetamine challenge led to significant reductions in [(11)C]carfentanil BPND in 8/10 ROI in HV. PG demonstrated significant blunting of opioid release compared with HV. PG also showed blunted amphetamine-induced euphoria and alertness compared with HV. Exploratory analysis revealed that impulsivity positively correlated with caudate baseline BPND in PG only. This study provides the first evidence of blunted endogenous opioid release in PG. Our findings are consistent with growing evidence that dysregulation of endogenous opioids may have an important role in the pathophysiology of addictions

New technologies for examining neuronal ensembles in drug addiction and fear

Correlational data suggest that learned associations are encoded within neuronal ensembles. However, it has been difficult to prove that neuronal ensembles mediate learned behaviours because traditional pharmacological and lesion methods, and even newer cell type-specific methods, affect both activated and non-activated neurons. Additionally, previous studies on synaptic and molecular alterations induced by learning did not distinguish between behaviourally activated and non-activated neurons. Here, we describe three new approaches—Daun02 inactivation, FACS sorting of activated neurons and c-fos-GFP transgenic rats — that have been used to selectively target and study activated neuronal ensembles in models of conditioned drug effects and relapse. We also describe two new tools — c-fos-tTA mice and inactivation of CREB-overexpressing neurons — that have been used to study the role of neuronal ensembles in conditioned fear

Integrating substance abuse care with community diabetes care: implications for research and clinical practice

Udi E Ghitza,1 Li-Tzy Wu,2 Betty Tai11Center for the Clinical Trials Network, National Institute on Drug Abuse, National Institutes of Health, United States Department of Health and Human Services, Bethesda, MD, 2Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USAAbstract: Cigarette smoking and alcohol use are prevalent among individuals with diabetes in the US, but little is known about screening and treatment for substance use disorders in the diabetic population. This commentary discusses the scope and clinical implications of the public health problem of coexisting substance use and diabetes, including suggestions for future research. Diabetes is the seventh leading cause of death in the US, and is associated with many severe health complications like cardiovascular disease, stroke, kidney damage, and limb amputations. There are an estimated 24 million adults in the US with type 2 diabetes. Approximately 20% of adults aged 18 years or older with diabetes report current cigarette smoking. The prevalence of current alcohol use in the diabetic population is estimated to be around 50%–60% in epidemiological surveys and treatment-seeking populations. Cigarette smoking is associated with an increased risk of type 2 diabetes in a dose-dependent manner and is an independent modifiable risk factor for development of type 2 diabetes. Diabetic patients with an alcohol or other drug use disorder show a higher rate of adverse health outcomes. For example, these patients experience more frequent and severe health complications as well as an increased risk of hospitalization, and require longer hospital stays. They are also less likely to seek routine care for diabetes or adhere to diabetes treatment than those without an alcohol or other drug use disorder. The Affordable Care Act of 2010 and the Mental Health Parity Act and Addiction Equity Act of 2008 provide opportunities for facilitating integration of preventive services and evidence-based treatments for substance use disorders with diabetes care in community-based medical settings. These laws also offer emerging areas for research.Keywords: addiction, illicit drug use, substance use disorder, substance abuse treatment, alcohol use, diabetes care, primary care, screening, brief interventio

Preventing deaths from rising opioid overdose in the US – the promise of naloxone antidote in community-based naloxone take-home programs

Michele M Straus, Udi E Ghitza, Betty Tai Center for the Clinical Trials Network, National Institute on Drug Abuse, National Institutes of Health, United States Department of Health and Human Services, Bethesda, MD, USA Abstract: The opioid overdose epidemic is an alarming and serious public health problem in the United States (US) that has been escalating for 11 years. The 2011 National Survey on Drug Use and Health (NSDUH) demonstrated that 1 in 20 persons in the US aged 12 or older reported nonmedical use of prescription painkillers in the past year. Prescription drug overdose is now the leading cause of accidental death in the United States – surpassing motor vehicle accidents. Great efforts have been initiated to curb the overdose crisis. Notable examples of these efforts are (1) the Drug Enforcement Administration’s (DEA) National Take-Back Initiative instituted in 2010; (2) the Prescription Drug Monitoring Programs (PDMPs) implemented in most US states to provide practitioners with point-of-care information regarding a patient's controlled substance use; (3) the naloxone rescue programs initiated in the community to avert mortality resulting from overdose. The use of naloxone rescue strategies has gained traction as an effective measure to prevent fatal opioid overdose. Many US federal-government agencies are working to make these strategies more accessible to first responders and community participants. This new approach faces many challenges, such as accessibility to naloxone and the equipment and training needed to administer it, but none is more challenging than the fear of legal repercussions. US federal-government agencies, local governments, health care institutions, and community-based organizations have begun to tackle these barriers, and naloxone take-home programs have gained recognition as a feasible and sensible preventive strategy to avoid a fatal result from opioid overdose. Although many challenges still need to be overcome, it is important for federal government research agencies to initiate and support independent and rigorous evaluation of these programs to inform policymakers how effective these programs can be to save lives and curb the opioid overdose public health crisis. Keywords: prescription drug abuse, fatal opioid overdose, naloxone antidote, Good Samaritan laws, naloxone take-home progra

Expanding the National Drug Abuse Treatment Clinical Trials Network to address the management of substance use disorders in general medical settings

Betty Tai, Steven Sparenborg, Udi E Ghitza, David Liu Center for the Clinical Trials Network, National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland, USA Abstract: The Patient Protection and Affordable Care Act (2010) and the Mental Health Parity and Addiction Equity Act (2008) expand substance use disorder (SUD) care services in the USA into general medical settings. Care offered in these settings will engage substance-using patients in an integrated and patient-centered environment that addresses physical and mental health comorbidities and follows a chronic care model. This expansion of SUD services presents a great need for evidence-based practices useful in general medical settings, and reveals several research gaps to be addressed. The National Drug Abuse Treatment Clinical Trials Network of the National Institute on Drug Abuse can serve an important role in this endeavor. High-priority research gaps are highlighted in this commentary. A discussion follows on how the National Drug Abuse Treatment Clinical Trials Network can transform to address changing patterns in SUD care to efficiently generate evidence to guide SUD treatment practice within the context of recent US health care legislation. Keywords: Patient Protection and Affordable Care Act, National Drug Abuse Treatment Clinical Trials Network, substance use disorders, practice-based research network, electronic health record

The opioid overdose epidemic: opportunities for pharmacists

Li-Tzy Wu,1–4 Udi E Ghitza,5 Anne L Burns,6 Paolo Mannelli,1 1Department of Psychiatry and Behavioral Sciences, 2Department of Medicine, 3Duke Clinical Research Institute, Duke University School of Medicine, 4Center for Child and Family Policy, Sanford School of Public Policy, Duke University, Durham, NC, 5Center for Clinical Trials Network, National Institute on Drug Abuse, Bethesda, MD, 6American Pharmacists Association, Washington, DC, USA The USA is experiencing an opioid overdose epidemic. It has been driven largely by prescription opioids and intensified by a surge of illicit opioids (e.g., heroin and fentanyl).1,2 Drug-involved overdose, mainly opioids (e.g., prescription opioids and heroin), is a leading cause of accidental death in the USA. The opioid overdose epidemic has been escalating consistently for over a decade.2 Every day, an estimated 91 Americans die from opioid-related overdose.3 Opioid overdose appears to have disproportionally affected men, adults aged 25–64 years, and non-Hispanic whites.