Irritability following abstinence from cocaine predicts euphoric effects of cocaine administration

Cocaine Use Disorder (CUD): Current Clinical Perspectives

Cocaine use disorder (CUD) is a devastating disorder, impacting both individuals and society. Individuals with CUD face many barriers in accessing treatment for CUD, and most individuals with CUD never receive treatment. In this review, we provide an overview of CUD, including risk factors for CUD, common co-occurring disorders, acute and chronic effects of cocaine use, and currently available pharmacological and behavioral treatments. There are no FDA-approved pharmacological treatments for CUD. Future studies with larger sample sizes and testing treatment combinations are warranted. However, individuals with CUD and co-occurring disorders (eg, a mood or anxiety disorder) may benefit from medication treatments. There are behavioral interventions that have demonstrated efficacy in treating CUD – contingency management (CM) and cognitive-behavioral therapy for substance use disorders (CBT-SUD) in particular – however many barriers remain in delivering these treatments to patients. Following the discussion of current treatments, we highlight some promising emerging treatments, as well as offer a framework that can be used in building a treatment plan for individuals with CUD.

Deep brain stimulation of the nucleus accumbens shell attenuates cocaine withdrawal but increases cocaine self-administration, cocaine-induced locomotor activity, and GluR1/GluA1 in the central nucleus of the amygdala in male cocaine-dependent rats

BACKGROUND

Cocaine addiction is a major public health problem. Despite decades of intense research, no effective treatments are available. Both preclinical and clinical studies strongly suggest that deep brain stimulation of the nucleus accumbens (NAcc) is a viable target for the treatment of cocaine use disorder (CUD).

OBJECTIVE

Although previous studies have shown that DBS of the NAcc decreases cocaine seeking and reinstatement, the effects of DBS on cocaine intake in cocaine-dependent animals have not yet been investigated.

METHODS

Rats were made cocaine dependent by allowing them to self-administer cocaine in extended access conditions (6 h/day, 0.5 mg/kg/infusion). The effects of monophasic bilateral high-frequency DBS (60 μs pulse width and 130 Hz frequency) stimulation with a constant current of 150 μA of the NAcc shell on cocaine intake was then evaluated. Furthermore, cocaine-induced locomotor activity, irritability-like behavior during cocaine abstinence, and the levels of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits 1 and 2 (GluR1/GluA1 and GluR2/GluA2) after DBS were investigated.

RESULTS

Contrary to our expectations, DBS of the NAcc shell induced a slight increase in cocaine self-administration, and increased cocaine-induced locomotion after extended access of cocaine self-administration. In addition, DBS decreased irritability-like behavior 18 h into cocaine withdrawal. Finally, DBS increased both cytosolic and synaptosomal levels of GluR1, but not GluR2, in the central nucleus of the amygdala but not in other brain regions.

CONCLUSIONS

These preclinical results with cocaine-dependent animals support the use of high-frequency DBS of the NAcc shell as a therapeutic approach for the treatment of the negative emotional state that emerges during cocaine abstinence, but also demonstrate that DBS does not decrease cocaine intake in active, long-term cocaine users. These data, together with the existing evidence that DBS of the NAcc shell reduces the reinstatement of cocaine seeking in abstinent animals, suggest that NAcc shell DBS may be beneficial for the treatment of the negative emotional states and craving during abstinence, although it may worsen cocaine use if individuals continue drug use.

Drug-induced dysphoria is enhanced following prolonged cocaine abstinence and dynamically tracked by nucleus accumbens neurons

Negative reinforcement models postulate that addicts use drugs to alleviate negative affective states (e.g. dysphoria) associated with withdrawal. In a pre-clinical model, rats exhibit negative affect to a normally rewarding tastant when it predicts impending, but delayed cocaine, and nucleus accumbens (NAc) neurons dynamically track this state. Here, we examined the effects of short versus prolonged experimenter-imposed cocaine abstinence on negative affect, cocaine seeking and self-administration. Rats were given 14 saccharin-cocaine sessions; NAc activity and affective responses to the taste (i.e. taste reactivity) were measured during sessions 1 and 14. Next, following 1 or 30 days of abstinence, taste reactivity and cell firing were recorded in a three-phase test session: (1) intraoral saccharin infusions, (2) extinction and (3) cocaine self-administration. Results showed that 30 days of abstinence led to a significant enhancement of aversive responses to the cocaine-paired tastant, accompanied by a dramatic decline in NAc phasic activity during tastant infusion. While extinction behavior did not differ across groups, NAc phasic firing reemerged during drug seeking. Further, when drug was again readily available, greater aversion to the drug-paired tastant before and after abstinence was associated with increased self-administration following prolonged (30-day) abstinence in rats classified as high (not low) aversive. Collectively, these findings show that drug-induced dysphoria is enhanced following prolonged cocaine abstinence and that NAc neural signaling is dynamic, dampening when negative affect is at its highest (phase 1), but transitioning back 'online' during subsequent drug seeking and taking (phases 2 and 3).

Conditioned aversive responses produced by delayed, but not immediate, exposure to cocaine and morphine in male Sprague-Dawley rats

RATIONALE

To determine the conditions under which tastes paired with delayed access to experimenter-delivered cocaine and morphine elicit a conditionally aversive affective state.

OBJECTIVES AND METHODS

The potential of saccharin paired with immediate access to cocaine (5, 10, 20 mg/kg, sc and ip) and delayed (30 and 10 min) access to cocaine (20 mg/kg, sc and ip) and morphine (10 mg/kg, sc) to elicit a pattern of aversive responding in the taste reactivity test (Grill and Norgren 1978a) was evaluated. Cocaine-induced aversions were compared with those produced by a moderate dose of LiCl (50 mg/kg). Finally, as an independent measure of cocaine withdrawal, the potential of exposure to saccharin paired with delayed access to cocaine to produce anxiogenic-like responding in the Light-Dark Emersion test was evaluated.

RESULTS

Immediate access to cocaine did not produce conditioned aversion at any dose. Delayed (30 or 10 min) access to sc cocaine (20 mg/kg) produced robust conditioned aversion and delayed access to ip cocaine (20 mg/kg; 30 min) and to sc morphine (10 mg/kg; 10 min) produced weaker conditioned aversion. Yawning emerged as a potential withdrawal response in rats conditioned with delayed (30 min) access to 20 mg/kg, sc, cocaine. Contextual cues did not produce conditioned aversion when paired with delayed access to sc cocaine (20 mg/kg). Finally, exposure to saccharin paired with delayed access to cocaine produced anxiogenic-like responding in the Light-Dark Emersion test.

CONCLUSION

Our results support the contention that a conditioned aversive state develops when a taste cue comes to predict the delayed availability of drugs of abuse.

Addiction in Extreme Sports: An Exploration of Withdrawal States in Rock Climbers

Background and aims Extreme sports athletes are often labeled "adrenaline junkies" by the media, implying they are addicted to their sport. Research suggests during abstinence these athletes may experience withdrawal states characteristic of individuals with an addiction (Celsi, Rose, & Leigh, 1993; Franken, Zijlstra, & Muris, 2006; Willig, 2008). Despite this notion, no research has directly explored withdrawal experiences of extreme sports athletes. Methods Using semi-structured interviews, we explored withdrawal experiences of high (n = 4) and average-ability (n = 4) male rock climbers during periods of abstinence. We investigated the psychological and behavioral aspects of withdrawal, including craving, anhedonia, and negative affect; and differences in the frequency and intensity of these states between groups. Results Deductive content analysis indicated support for each of the three categories of anhedonia, craving, and negative affect. Consistent with existing substance addiction literature, high-ability climbers recalled more frequent and intense craving states and negative affect during abstinence compared with average-ability climbers. No differences in anhedonic symptoms between high and average-ability participants were found. Conclusions Rock climbing athletes appear to experience withdrawal symptoms when abstinent from their sport comparable to individuals with substance and behavioral addictions. The implications of these findings and suggestions for future research are discussed.

The neural encoding of cocaine-induced devaluation in the ventral pallidum

Cocaine experience affects motivation structures such as the nucleus accumbens (NAc) and its major output target, the ventral pallidum (VP). Previous studies demonstrated that both NAc activity and hedonic responses change reliably as a taste cue comes to predict cocaine availability. Here we extended this investigation to examine drug-experience induced changes in hedonic encoding in the VP. VP activity was first characterized in adult male Sprague-Dawley rats in response to intraoral infusions of palatable saccharin and unpalatable quinine solutions. Next, rats received 7 daily pairings of saccharin that predicted either a cocaine (20mg/kg, ip) or saline injection. Finally, the responses to saccharin and quinine were again assessed. Of 109 units recorded in 11 rats that received saccharin-cocaine pairings, 71% of responsive units significantly reduced firing rate during saccharin infusions and 64% increased firing rate during quinine exposure. However, as saccharin came to predict cocaine, and elicited aversive taste reactivity, VP responses changed to resemble quinine. After conditioning, 70% of saccharin-responsive units increased firing rate. Most units that encoded the palatable taste (predominantly reduced firing rate) were located in the anterior VP, while most units that were responsive to aversive tastes were located in the posterior VP. This study reveals an anatomical complexity to the nature of hedonic encoding in the VP.

Continuous infusion versus intermittent bolus dosing of morphine: a comparison of analgesia, tolerance, and subsequent voluntary morphine intake

Improved utilization of continuous or intermittent opioid administration in pain treatment necessitates a comparison of the antinociceptive effect and tolerance of these two treatment methods. More importantly, the effect of treatment method on subsequent opioid consumption has not been directly compared, although it is widely assumed that continuous opioid treatment may produce lower addictive liability relative to intermittent opioid treatment. In this study, we compared the antinociceptive effect and tolerance of morphine in rats that received repeated injection (10 mg/kg twice daily for 7 days) or continuous infusion (20 mg/kg daily for 7 days) subcutaneously and the self-administration of intravenous morphine in these rats after 7 days of withdrawal. Both intermittent and continuous morphine treatment produced antinociceptive tolerance, but the exhibition of tolerance differed. Moreover, intermittent morphine pretreatment facilitated subsequent morphine self-administration, whereas continuous morphine pretreatment produced minimal effects, as shown by comparable levels of active responses and morphine consumption between continuous morphine and saline-treated rats. These results suggest that the administration method of opioid should be selected according to the specific pain situation and that continuous opioid administration or long-acting therapy may be advantageous, producing less influence on drug-taking behavior than intermittent administration of short-acting drugs.

Correlates of polysomnographic sleep changes in cocaine dependence: self-administration and clinical outcomes

BACKGROUND

Abstinence from chronic cocaine use is associated with abnormal sleep architecture. As sleep abnormalities are associated with clinical outcome in alcohol dependence, we hypothesized a similar relationship in cocaine dependence.

METHODS

We report data from a cocaine self-administration study (N=12) and the placebo arm of a randomized clinical trial (N=20). Self-administration participants underwent three cocaine self-administration sessions during a three-week inpatient stay. Treatment participants underwent two weeks of inpatient followed by six weeks of outpatient treatment including once-weekly cognitive behavioral therapy. Measurements included polysomnography from early and late in abstinence during the inpatient stays. Clinical outcomes included amount of cocaine self-administered, urine tests, and self-reported use and withdrawal symptoms.

RESULTS

Change in slow-wave sleep from early to late abstinence (ΔSWS; p=0.05), late abstinence rapid eye movement sleep (REM; p=0.002), and late abstinence total sleep time (p=0.02) were negatively correlated with the amount of cocaine self-administered. Early abstinence REM was positively correlated with withdrawal symptoms (p=0.02). Late abstinence REM was positively correlated with percent negative urines and maximum consecutive number of days abstinent (both p<0.001). ΔSWS was positively correlated with percent negative urines (p=0.03) and participants with increased SWS had greater percent negative urines (p=0.008) and maximum consecutive number of days abstinent (p=0.009).

CONCLUSIONS

Correlations between sleep deficits and amount of cocaine self-administered, clinical outcomes, and severity of withdrawal symptoms underscore the relevance of sleep in clinical outcomes in the treatment of cocaine dependence.

Psychometric properties of the Spanish version of the Cocaine Selective Severity Assessment to evaluate cocaine withdrawal in treatment-seeking individuals

Reliable and valid assessment of cocaine withdrawal is relevant for treating cocaine-dependent patients. This study examined the psychometric properties of the Spanish version of the Cocaine Selective Severity Assessment (CSSA), an instrument that measures cocaine withdrawal. Participants were 170 cocaine-dependent inpatients receiving detoxification treatment. Principal component analysis revealed a 4-factor structure for CSSA that included the following components: 'Cocaine Craving and Psychological Distress', 'Lethargy', 'Carbohydrate Craving and Irritability', and 'Somatic Depressive Symptoms'. These 4 components accounted for 56.0% of total variance. Internal reliability for these components ranged from unacceptable to good (Chronbach's alpha: 0.87, 0.65, 0.55, and 0.22, respectively). All components except Somatic Depressive Symptoms presented concurrent validity with cocaine use. In summary, while some properties of the Spanish version of the CSSA are satisfactory, such as interpretability of factor structure and test-retest reliability, other properties, such as internal reliability and concurrent validity of some factors, are inadequate.

A double-blind, placebo-controlled trial of topiramate for the treatment of comorbid cocaine and alcohol dependence

BACKGROUND

Topiramate increases GABAergic activity and antagonizes the AMPA/kainate subtype of glutamate receptors. Through these mechanisms of action, topiramate may reduce alcohol and cocaine reward and may reduce alcohol and cocaine craving. Topiramate has been shown to reduce drinking in persons with alcohol dependence, and reduce relapse in stimulant-dependent patients. The current trial was intended to test the ability of topiramate to promote cocaine and alcohol abstinence among patients addicted to both drugs.

METHODS

The study was a double-blind, placebo-controlled, 13-week trial involving 170 cocaine and alcohol dependent subjects. After achieving a period of cocaine and alcohol abstinence, subjects were randomized to topiramate, 300 mg daily, or identical placebo capsules. In addition, subjects received weekly individual psychotherapy. Primary outcome measures included self-reported alcohol and cocaine use, and thrice weekly urine drug screens. Secondary outcome measures included cocaine and alcohol craving, Addiction Severity Index results, cocaine withdrawal symptoms, and clinical global improvement ratings.

RESULTS

Topiramate was not better than placebo in reducing cocaine use on the a priori primary outcome measure, or in reducing alcohol use. Topiramate was not better than placebo in reducing cocaine craving. Topiramate-treated subjects, compared to placebo-treated subjects, were more likely to be retained in treatment and more likely to be abstinent from cocaine during the last three weeks of the trial. Subjects who entered treatment with more severe cocaine withdrawal symptoms responded better to topiramate.

DISCUSSION

Topiramate plus cognitive behavioral therapy may reduce cocaine use for some patients with comorbid cocaine and alcohol dependence.

Topiramate's effects on cocaine-induced subjective mood, craving and preference for money over drug taking

Topiramate, presumably through antagonism of excitatory glutaminergic pathways and facilitation of inhibitory gamma-aminobutyric acid neurons in the cortico-mesolimbic system, might reduce cocaine's abuse liability. We tested whether topiramate (100 mg twice daily) would reduce the euphoria, subjective mood, craving and preference for cocaine over money induced by low and high doses (0.325 and 0.65 mg/kg i.v., respectively) of experimentally administered cocaine in 24 male and female, cocaine-dependent, non-treatment-seeking research volunteers in a university in-patient laboratory. We utilized a randomized, double-blind, placebo-controlled, within-subject, Latin-square cross-over design in which three experimental challenge doses of low-dose cocaine, high-dose cocaine and placebo were administered in counterbalanced order after 5 days of topiramate or matching placebo pre-treatments separated by a 1-week washout period (2006-2009). After placebo pre-treatments, cocaine produced dose-related increases in euphoria, stimulant effects, craving for more cocaine and monetary value of cocaine in a behavioral preference test of cocaine versus money choice. Topiramate pre-treatment reduced the cocaine-related craving and monetary value of high-dose cocaine while increasing the monetary value, euphoria and stimulant effects of low-dose cocaine. Validated and standardized human experimental methods evaluating the potential for topiramate to alter cocaine's abuse liability suggest that topiramate may reduce the reinforcing effects and craving induced by higher cocaine doses. Low-dose cocaine might appear to have some enhancement of its stimulant properties in the presence of topiramate's prominent sedative effects.

When a good taste turns bad: Neural mechanisms underlying the emergence of negative affect and associated natural reward devaluation by cocaine

An important feature of cocaine addiction in humans is the emergence of negative affect (e.g., dysphoria, irritability, anhedonia), postulated to play a key role in craving and relapse. Indeed, the DSM-IV recognizes that social, occupational and/or recreational activities become reduced as a consequence of repeated drug use where previously rewarding experiences (e.g., food, job, family) become devalued as the addict continues to seek and use drug despite serious negative consequences. Here, research in the Carelli laboratory is reviewed that examined neurobiological mechanisms that may underlie these processes using a novel animal model. Oromotor responses (taste reactivity) were examined as rats learned that intraoral infusion of a sweet (e.g., saccharin) predicts impending but delayed access to cocaine self-administration. We showed that rats exhibit aversive taste reactivity (i.e., gapes/rejection responses) during infusion of the sweet paired with impending cocaine, similar to aversive responses observed during infusion of quinine, a bitter tastant. Critically, the expression of this pronounced aversion to the sweet predicted the subsequent motivation to self-administer cocaine. Electrophysiology studies show that this shift in palatability corresponds to an alteration in nucleus accumbens (NAc) cell firing; neurons that previously responded with inhibition during infusion of the palatable sweet shifted to excitatory activity during infusion of the cocaine-devalued tastant. This excitatory response profile is typically observed during infusion of quinine, indicating that the once palatable sweet becomes aversive following its association with impending but delayed cocaine, and NAc neurons encode this aversive state. We also review electrochemical studies showing a shift (from increase to decrease) in rapid NAc dopamine release during infusion of the cocaine-paired tastant as the aversive state developed, again, resulting in responses similar to quinine infusion. Collectively, our findings suggest that cocaine-conditioned cues elicit a cocaine-need state that is aversive, is encoded by a distinct subset of NAc neurons and rapid dopamine signaling, and promotes cocaine-seeking behavior. Finally, we present data showing that experimentally induced abstinence (30 days) exacerbates this natural reward devaluation by cocaine, and this effect is correlated with a greater motivation to lever press during extinction. Dissecting the neural mechanisms underlying these detrimental consequences of addiction is critical since it may lead to novel treatments that ameliorate negative affective states associated with drug use and decrease the drive (craving) for the drug. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Cocaine produces conditioned place aversion in mice with a cocaine-insensitive dopamine transporter

Cocaine is an inhibitor of the dopamine, norepinephrine and serotonin reuptake transporters. Because its administration would elevate signaling of all these three neurotransmitters, many studies have been aimed at attributing individual effects of cocaine to specific transmitter systems. Using mice with a cocaine-insensitive dopamine transporter (DAT-CI mice), we previously showed that cocaine-induced dopamine elevations were necessary for its rewarding and stimulating effects. In this study, we observe that DAT-CI mice exhibit cocaine-conditioned place aversion (CPA), and that its expression depends on their genetic background. Specifically, DAT-CI mice backcrossed to the C57Bl/6J strain background did not display a preference or an aversion to cocaine, whereas DAT-CI mice that were on a mixed 129S1/SvImJ × C57Bl/6J (129B6) background had a robust CPA to cocaine. These results indicate that while inhibition of the DAT is necessary for cocaine reward, other cocaine targets and neurotransmitter systems may mediate the aversive properties of cocaine. Furthermore, the aversive effect of cocaine can be observed in the absence of a DAT-mediated rewarding effect, and it is affected by genomic differences between these two mouse strains.

Pharmacologically-mediated reactivation and reconsolidation blockade of the psychostimulant-abuse circuit: a novel treatment strategy

Psychostimulant abuse continues to present legal, socioeconomic and medical challenges as a primary psychiatric disorder, and represents a significant comorbid factor in major psychiatric and medical illnesses. To date, monotherapeutic drug treatments have not proven effective in promoting long-term abstinence in psychostimulant abusers. In contrast to clinical trials utilizing monotherapies, combinations of dopamine (DA) agonists and selective 5-HT(3), 5HT(2A/2C), or NK(1) antagonists have shown robust efficacy in reversing behavioral and neurobiological alterations in animal models of psychostimulant abuse. One important temporal requirement for these treatments is that the 5-HT or NK(1) receptor antagonist be given at a critical time window after DA agonist administration. This requirement may reflect a necessary dosing regimen towards normalizing underlying dysfunctional neural circuits and "addiction memory" states. Indeed, chronic psychostimulant abuse can be conceptualized as a consolidated form of dysfunctional memory maintained by repeated drug- or cue-induced reactivation of neural circuit and subsequent reconsolidation. According to this concept, the DA agonist given first may reactivate this memory circuit, thereby rendering it transiently labile. The subsequent antagonist is hypothesized to disrupt reconsolidation necessary for restabilization, thus leading progressively to a therapeutically-mediated abolishment of dysfunctional synaptic plasticity. We propose that long-term abstinence in psychostimulant abusers may be achieved not only by targeting putative mechanistic pathways, but also by optimizing drug treatment regimens designed to disrupt the neural processes underlying the addicted state.

Measuring the incentive value of escalating doses of heroin in heroin-dependent Fischer rats during acute spontaneous withdrawal

RATIONALE/OBJECTIVES

Although continued heroin use and relapse are thought to be motivated, in part, by the positive incentive-motivational value attributed to heroin, little is understood about heroin's incentive value during the relapse-prone state of withdrawal. This study uses place preference to measure the incentive value attributed to escalating-dose heroin in the context of heroin dependence.

METHODS

Male Fischer rats were exposed chronically to escalating doses of heroin in the homecage and during place preference conditioning sessions. Conditioned preference for the context paired with escalating-dose heroin was tested after homecage exposure was discontinued and rats entered acute spontaneous withdrawal. Individuals' behavioral and locomotor responses to heroin and somatic withdrawal signs were recorded.

RESULTS

Conditioned preference for the heroin-paired context was strong in rats that received chronic homecage exposure to escalating-dose heroin and were tested in acute withdrawal. Behavioral responses to heroin (e.g., stereotypy) varied widely across individuals, with rats that expressed stronger heroin preference also expressing stronger behavioral activation in response to heroin. Individual differences in preference were also related to locomotor responses to heroin but not to overt somatic withdrawal signs.

CONCLUSIONS

Escalating doses of heroin evoked place preference in rats, suggesting that positive incentive-motivational value is attributed to this clinically relevant pattern of drug exposure. This study offers an improved preclinical model for studying dependence and withdrawal and provides insight into individual vulnerabilities to addiction-like behavior.

Effects of major depression on crack use and arrests among women in drug court

AIMS

We examined whether a current major depressive episode (MDE) at baseline predicted crack use and arrests at follow-up among women enrolled in drug court.

DESIGN

Primary analyses used zero-inflated Poisson (ZIP) and zero-inflated negative binomial (ZINB) regression analyses to predict both yes/no and number of (i) days of crack use and (ii) arrests at 4-month follow-up from current (30-day) MDE at baseline. Secondary analyses addressed risk conferred by current versus past MDE at baseline.

SETTING/PARTICIPANTS

Participants were 261 women in drug court.

MEASUREMENTS

MDE was assessed using the Diagnostic Interview Schedule. Days using crack and number of arrests were assessed using the Washington University Risk Behavior Assessment for Women.

FINDINGS

Having a current MDE at baseline predicted likelihood of crack use at follow-up, but not days of crack use among those who used. Current MDE at baseline did not predict presence or number of arrests at the 4-month follow-up. Women with current MDE at baseline were more likely to be using crack at follow-up than were those with recent (31+ days to 12 months) but not current MDE (odds ratio = 5.71); past MDE at baseline did not increase risk of crack use.

CONCLUSIONS

Predictors of any versus no crack use or arrests appear to differ from predictors of frequency of these behaviors. Current major depression, but not past major depression, appears to be associated with increased risk of crack use among women attending drug court.

Reversal of long-term methamphetamine sensitization by combination of pergolide with ondansetron or ketanserin, but not mirtazapine

Psychostimulant abuse represents a psychiatric disorder and societal concern that has been largely unamenable to therapeutic interventions. We have previously demonstrated that the 5-HT₃ antagonist ondansetron or non-selective 5-HT(₂A/₂C) antagonist ketanserin administered 3.5 h following daily pergolide, a non-selective DA agonist, reverses previously established cocaine sensitization. The present study was conducted to evaluate whether the same treatments or delayed pairing of pergolide with the antidepressant mirtazapine can also reverse consolidated methamphetamine (METH) behavioral sensitization. Sprague-Dawley rats received METH infusion via osmotic minipumps (25 mg/kg/day, s.c.) for 7 days, with accompanying daily injections of escalating METH doses (0-6 mg/kg, s.c.). This regimen takes into account the faster elimination of METH in rats, and is designed to replicate plasma METH concentrations with superimposed peak drug levels as observed during METH binging episodes in humans. Following a 7-day METH withdrawal, ondansetron (0.2 mg/kg, s.c.), ketanserin (1.0 mg/kg, s.c.), or mirtazapine (10mg/kg, i.p.) was administered 3.5 h after pergolide injections (0.1 mg/kg, s.c., qd) for 7 days. Behavioral sensitization as a model of METH abuse was assessed 14 days after the combination treatment cessation (i.e., day 28 of METH withdrawal) through an acute challenge with METH (0.5 mg/kg, i.p.). Pergolide combined with ondansetron or ketanserin reversed METH behavioral sensitization, but pergolide-mirtazapine combination was ineffective. The role of reactivation of addiction "circuit" by a non-selective DA agonist, and subsequent reconsolidation blockade through 5-HT₃ or 5-HT₂ antagonism in reversal of METH sensitization and treatment of METH addiction is discussed.

Psychosocial treatments for cocaine dependence: the role of depressive symptoms

BACKGROUND

The association between cocaine use and depression has been frequently observed. However, less is known about the significance of depression in the treatment of cocaine use disorders. This study examined possible interrelations between drug use and depression severity among cocaine-dependent patients in psychosocial treatments for cocaine dependence.

METHODS

Monthly assessed drug use and depression severity scores of N = 487 patients during 6-month psychosocial treatments for cocaine dependence were analyzed using hybrid latent growth models.

RESULTS

Results indicated a moderate but statistically significant (z = 3.13, p < .01) influence of depression severity on increased drug use in the upcoming month, whereas drug use did not affect future depression severity.

CONCLUSIONS

Findings suggest that depression symptoms are an important predictor of drug use outcomes during psychosocial treatments for cocaine dependence and, hence, underline the importance of adequately addressing depression symptoms to improve treatment outcomes.

Episodic withdrawal promotes psychomotor sensitization to morphine

The relative intermittency or continuity of drug delivery is a major determinant of addictive liability, and also influences the impact of drug exposure on brain function and behavior. Events that occur during the offset of drug action (ie, acute withdrawal) may have an important role in the consequences of intermittent drug exposure. We assessed whether recurrent episodes of acute withdrawal contribute to the development of psychomotor sensitization in rodents during daily morphine exposure. The acoustic startle reflex--a measure of anxiety induced by opiate withdrawal-was used to resolve and quantify discrete withdrawal episodes, and pharmacological interventions were used to manipulate withdrawal severity. Startle potentiation was observed during spontaneous withdrawal from a single morphine exposure, and individual differences in initial withdrawal severity positively predicted the subsequent development of sensitization. Manipulations that reduce or exacerbate withdrawal severity also produced parallel changes in the degree of sensitization. These results demonstrate that the episodic experience of withdrawal during daily drug exposure has a novel role in promoting the development of psychomotor sensitization--a prominent model of drug-induced neurobehavioral plasticity. Episodic withdrawal may have a pervasive role in many effects of intermittent drug exposure and contribute to the development of addiction.

Behavioral and electrophysiological indices of negative affect predict cocaine self-administration

The motivation to seek cocaine comes in part from a dysregulation of reward processing manifested in dysphoria, or affective withdrawal. Learning is a critical aspect of drug abuse; however, it remains unclear whether drug-associated cues can elicit the emotional withdrawal symptoms that promote cocaine use. Here we report that a cocaine-associated taste cue elicited a conditioned aversive state that was behaviorally and neurophysiologically quantifiable and predicted subsequent cocaine self-administration behavior. Specifically, brief intraoral infusions of a cocaine-predictive flavored saccharin solution elicited aversive orofacial responses that predicted early-session cocaine taking in rats. The expression of aversive taste reactivity also was associated with a shift in the predominant pattern of electrophysiological activity of nucleus accumbens (NAc) neurons from inhibitory to excitatory. The dynamic nature of this conditioned switch in affect and the neural code reveals a mechanism by which cues may exert control over drug self-administration.

A double-blind, placebo-controlled trial of modafinil for cocaine dependence

Despite years of active research, there are still no approved medications for the treatment of cocaine dependence. Modafinil is a glutamate-enhancing agent that blunts cocaine euphoria under controlled conditions, and the current study assessed whether modafinil would improve clinical outcome in cocaine-dependent patients receiving standardized psychosocial treatment. This was a randomized, double-blind, placebo-controlled trial conducted at a university outpatient center (from 2002 to 2003) on a consecutive sample of 62 (predominantly African American) cocaine-dependent patients (aged 25-63) free of significant medical and psychiatric conditions. After screening, eligible patients were randomized to a single morning dose of modafinil (400 mg), or matching placebo tablets, for 8 weeks while receiving manual-guided, twice-weekly cognitive behavioral therapy. The primary efficacy measure was cocaine abstinence based on urine benzoylecgonine levels. Secondary measures were craving, cocaine withdrawal, retention, and adverse events. Modafinil-treated patients provided significantly more BE-negative urine samples (p=0.03) over the 8-week trial when compared to placebos, and were more likely to achieve a protracted period (> or =3 weeks) of cocaine abstinence (p=0.05). There were no serious adverse events, and none of the patients failed to complete the study as a result of adverse events. This study provides preliminary evidence, which should be confirmed by a larger study, that modafinil improves clinical outcome when combined with psychosocial treatment for cocaine dependence.

Treatment of cocaine dependence and depression

In common with all other classes of substance use disorders, cocaine dependence has been shown to be strongly associated with depression by community and clinical surveys. Diagnosing depression in cocaine abusers can be challenging because it is difficult to distinguish transient symptoms caused by cocaine from enduring depression syndromes. Nonetheless, both "substance-induced" and "independent" depression syndromes require clinical attention, especially when symptoms have been persistent and severe before entering treatment. Use of antidepressant medications for combined cocaine dependence and depression is supported by a preponderance of evidence from 4 randomized clinical trials (RCTs) that prospectively targeted both depression and cocaine dependence and 7 RCTs in which a post hoc analyses demonstrated efficacy in the subgroup of cocaine abusers with comorbid depression. Notably, most negative studies have evaluated SSRIs while positive studies have used agents such as desipramine or buproprion. A substantial clinical trials literature supports the efficacy of behavioral treatments for general populations of cocaine abusers and of patients with depression but few studies have addressed patients with both disorders. Treatment development and research are needed on models of care that truly integrate strategies for addressing both cocaine use and depression. Recent advances have paved the way for a new generation of research. These include validation of efficacious cocaine treatments, improved diagnostic methods, organization of the Clinical Trials Network and development of guidelines for managing methodological challenges posed by high rates of current medication use and polysubstance abuse in treatment entering cocaine abusers.

Recent advances in the pharmacotherapy of cocaine dependence

The pharmacotherapy of cocaine dependence is a rapidly developing field of research that may soon produce efficacious medications. Expanding research on reward-related brain circuitry, which is acutely activated and chronically dysregulated by cocaine, has helped reveal the neurobiological features of cocaine dependence and is guiding pharmacologic strategies that have significant potential to improve clinical outcome. Cocaine dependence is a multifaceted disorder with distinct clinical components that may respond to different pharmacologic approaches. Pharmacologic strategies for this disorder include blocking euphoria, reducing withdrawal and negative mood symptoms, ameliorating craving, and enhancing the prefrontal cortical function that seems to be impaired in cocaine-dependent patients. One medication may not be sufficient to treat these diverse elements of cocaine dependence because preliminary studies report efficacy with medications that have opposite actions on reward-related circuits. This review highlights pertinent advances in cocaine neurobiology, recent clinical trials, and controversies in the pharmacologic treatment of cocaine dependence.

Die neuropsychologischen Effekte von Kokain

Zusammenfassung: Kokainkonsumenten sind in der Regel entweder Gelegenheitskonsumenten mit geringem und relativ gut kontrollierbarem Kokainkonsum oder Kokainabhängige, die exzessiv große Mengen Kokain einnehmen (Binge-Taking). Neuropsychologische Untersuchungen bei Gelegenheitskonsumenten mit kleinen bis mittleren Kokaindosen, die geeignet sind, “Euphorie” und “Hochgefühle” auszulösen, ergaben bisher keine Hinweise auf neuropsychologische Funktionsbeeinträchtigungen in der akuten Phase. Vielmehr wurden in der akuten Kokainphase verbesserte Aufmerksamkeitsleistungen und schnellere Reaktionszeiten gemessen, die bis zum Beginn der postakuten Phase anhielten. Explizite Untersuchungen zur postakuten Phase oder Studien über die Effekte von Kokain in einem hohen Dosisbereich liegen derzeit nicht vor. Kokainabhängige weisen in einem Abstinenzzeitraum von bis zu mindestens 3 Monaten neuropsychologische, neurologische und unter Umständen auch psychiatrische Defizite auf. Deutliche Defizite abstinenter Kokainabhängiger wurden bei der Aufmerksamkeitsleistung, der Konzentration, der inhibitorischen Kontrolle und im Gedächtnis gefunden, wobei die verschiedenen Gedächtnistypen unterschiedlich betroffen sind. Kommt es bei Kokainabhängigen zu einer erneuten Kokaineinnahme, d.h. zu einer Binge-Phase, so ist unmittelbar danach in der so genannten Crash-Phase noch zusätzlich mit zum Teil schweren emotional-motivationalen Beeinträchtigungen zu rechnen.