Residual symptoms after partial remission: an important outcome in depression

This paper draws attention to an important adverse outcome in depression, the occurrence of residual symptoms after partial remission. Among patients with definite major depression followed every 3 months to remission and thereafter, residual symptoms reaching 8 or more on the Hamilton Depression Scale 17-item total were present in 32% (19) of the 60 who remitted below major depression by 15 months. The pattern was of mild but typical depressive symptoms. Residual symptoms were more common in subjects with more severe initial illness, but were not related to any other predictors, including longer prior illness, dysthymia, or lower dose of drug treatment during the illness episode. There were weak associations with personality that might have been consequences of symptom presence. Residual symptoms were very strong predictors of subsequent early relapse, which occurred in 76% (13/17) of those with residual symptoms and 25% (10/40) of those without.

The validity of the eating disorder examination and its subscales

The EDE is a semistructured interview which has been developed as a measure of the specific psychopathology of anorexia nervosa and bulimia nervosa. To establish its discriminant validity it was administered to 100 patients with anorexia nervosa or bulimia nervosa and to 42 controls. The two groups differed significantly on all items. Five subscales were derived on rational grounds and evaluated on the two populations. The alpha coefficients for each subscale indicated a satisfactory degree of internal consistency. The EDE provides clinicians and research workers with a detailed and comprehensive profile of the psychopathological features of patients with eating disorders.

Risk factors for anorexia nervosa: three integrated case-control comparisons

BACKGROUND

Many risk factors have been implicated in the development of anorexia nervosa. Little is known about their relative contributions, nor in most cases is it clear whether they are specific to anorexia nervosa or risk factors for all eating disorders or for psychiatric disorder in general.

METHODS

We used a case-control design involving the comparison of 67 female subjects with a history of anorexia nervosa with 204 healthy control subjects, 102 subjects with other psychiatric disorders, and 102 subjects with bulimia nervosa. A broad range of risk factors was assessed by interview.

RESULTS

The subjects with anorexia nervosa and the healthy controls differed in their exposure to most of the putative risk factors. There was no greater exposure to factors that increased the likelihood of dieting, once the influence of other classes of risk factors had been taken into account. Premorbid perfectionism and negative self-evaluation were especially common and more so than among the general psychiatric controls. Parental obesity and an early menarche, together with parental psychiatric disorder, distinguished those with bulimia nervosa from those with anorexia nervosa.

CONCLUSIONS

There appears to be a broad range of risk factors for anorexia nervosa and bulimia nervosa, some of which are shared with other psychiatric disorders. Factors that increase the likelihood of dieting seem to have more important influence as risk factors for bulimia nervosa than anorexia nervosa. Perfectionism and negative self-evaluation appear to be particularly common and characteristic antecedents of both eating disorders.

A cognitive behavioural theory of anorexia nervosa

A cognitive behavioural theory of the maintenance of anorexia nervosa is proposed. It is argued that an extreme need to control eating is the central feature of the disorder, and that in Western societies a tendency to judge self-worth in terms of shape and weight is superimposed on this need for self-control. The theory represents a synthesis and extension of existing accounts. It is 'new', not so much because of its content, but because of its exclusive focus on maintenance, its organisational structure and its level of specification. It is suggested that the theory has important implications for treatment.

The natural course of bulimia nervosa and binge eating disorder in young women

BACKGROUND

Little is known about the relative course and outcome of bulimia nervosa and binge eating disorder.

METHODS

Two community-based cohorts were studied prospectively over a 5-year year period. One comprised 102 participants with bulimia nervosa and the other 48 participants with binge eating disorder (21% [9/42] of whom had comorbid obesity). All participants were female and aged between 16 and 35 years at recruitment. The assessments were at 15-month intervals and addressed eating disorder features, general psychiatric symptoms, and social functioning.

RESULTS

Both cohorts showed marked initial improvement followed by gradual improvement thereafter. Between half and two thirds of the bulimia nervosa cohort had some form of eating disorder of clinical severity at each assessment point, although only a minority continued to meet diagnostic criteria for bulimia nervosa. Each year about a third remitted and a third relapsed. The outcome of the binge eating disorder cohort was better, with the proportion with any form of clinical eating disorder declining to 18% (7 of 40) by the 5-year follow-up. The relapse rate was low among this cohort. There was little movement of participants across the 2 diagnostic categories and few sought treatment. Both groups gained weight, with 39% of the binge eating disorder cohort (14 of 36) meeting criteria for obesity at 5-year follow-up.

CONCLUSIONS

These findings suggest that, among young women in the community, bulimia nervosa and binge eating disorder have a different course and outcome. Whereas the prognosis of those with bulimia nervosa was relatively poor, the great majority of those with binge eating disorder recovered.

Sex-Dependent Effects of Cannabis and Cannabinoids: A Translational Perspective

Recent policy changes have led to significant increases in the use of cannabis for both medical and recreational purposes. Although men are more likely to endorse past month cannabis use and are more frequently diagnosed with Cannabis Use Disorder relative to women, a growing proportion of medical cannabis users are reported to be women. The increased popularity of cannabis for medical purposes and the narrowing gap in prevalence of use between men and women raises questions regarding sex-dependent effects related to therapeutic efficacy and negative health effects of cannabis and cannabinoids. The objective of this review is to provide a translational perspective on the sex-dependent effects of cannabis and cannabinoids by synthesizing findings from preclinical and clinical studies focused on sex comparisons of their therapeutic potential and abuse liability, two specific areas that are of significant public health relevance. Hormonal and pharmacological mechanisms that may underlie sex differences in the effects of cannabis and cannabinoids are highlighted.

Weight maintenance and relapse in obesity: a qualitative study

OBJECTIVE

To investigate, among women with obesity who have lost weight, the psychological factors associated with successfully maintaining the new lower weight, as opposed to weight regain.

DESIGN

Qualitative research methods (in-depth individual interviews and group interviews) were used to assess the characteristics of successful weight maintainers, as compared with weight regainers and healthy-weight women.

SUBJECTS

In all, 76 females were recruited from the community, comprising 28 formerly obese women who had lost weight and maintained their new lower weight for at least 1 y; 28 obese women who had lost weight but regained the weight that they had lost; and 20 women with a stable weight in the healthy range.

RESULTS

Certain psychological factors were identified which characterised the regainers but not the maintainers. These factors were: failure to achieve weight goals and dissatisfaction with the weight achieved; the tendency to evaluate self-worth in terms of weight and shape; a lack of vigilance with regard to weight control; a dichotomous (black-and-white) thinking style; and the tendency to use eating to regulate mood.

CONCLUSION

The results suggest that psychological factors may provide some explanation as to why many people with obesity regain weight following successful weight loss. The factors identified in this study need to be examined further using prospective designs.

Comparison of subjective, pharmacokinetic, and physiological effects of marijuana smoked as joints and blunts

Recent increases in marijuana smoking among the young adult population have been accompanied by the popularization of smoking marijuana as blunts instead of as joints. Blunts consist of marijuana wrapped in tobacco leaves, whereas joints consist of marijuana wrapped in cigarette paper. To date, the effects of marijuana smoked as joints and blunts have not been systematically compared. The current within-subject, randomized, double-blind, placebo-controlled study sought to directly compare the subjective, physiological, and pharmacokinetic effects of marijuana smoked by these two methods. Marijuana blunt smokers (12 women and 12 men) were recruited and participated in a 6-session outpatient study. Participants were blindfolded and smoked three puffs from either a blunt or a joint containing marijuana with varying Delta(9)-tetrahydrocannabinol (THC) concentrations (0.0, 1.8, and 3.6%). Subjective, physiological (heart rate, blood pressure, and carbon monoxide levels) and pharmacokinetic effects (plasma THC concentration) were monitored before and at specified time points for 3h after smoking. Joints produced greater increases in plasma THC and subjective ratings of marijuana intoxication, strength, and quality compared to blunts, and these effects were more pronounced in women compared to men. However, blunts produced equivalent increases in heart rate and higher carbon monoxide levels than joints, despite producing lower levels of plasma THC. These findings demonstrate that smoking marijuana in a tobacco leaf may increase the risks of marijuana use by enhancing carbon monoxide exposure and increasing heart rate compared to joints.

A new cognitive behavioural approach to the treatment of obesity

While behavioural approaches to the management of obesity are often successful in achieving clinically significant weight loss, the weight lost is generally regained. The great majority of patients return to their pre-treatment weight within 3 years. There have been attempts to improve the long-term effectiveness of behavioural treatment but the results have been disappointing. In this paper we suggest that, among other factors, this is because of the neglect of the contribution of cognitive factors to weight regain, and because there is often ambiguity over the goals of treatment. We present a cognitive behavioural analysis of the processes involved in weight regain, and we describe a new cognitive behavioural treatment derived from it. This treatment is designed to minimise the problem of weight regain by addressing psychological obstacles to the acquisition of, and long-term adherence to, effective weight-control behaviour.

Remission and relapse in major depression: a two-year prospective follow-up study

This paper reports the course with respect to remission and relapse of a cohort of predominantly in-patient RDC major depressive subjects, who were followed at 3-monthly intervals to remission and for up to 15 months thereafter. Remission was comparatively rapid with 70% of subjects remitting within 6 months. Only 6% failed to do so by 15 months. However, 40% relapsed over the subsequent 15 months, with all the relapses occurring in the first 10 months. Greater severity of the depression and longer duration of the illness predicted a longer time to remission. Greater initial severity of depression also predicted relapse. Subjects with a worse outcome had not received less adequate treatment than the remainder. Our results confirm the comparatively poor outcome subsequent to remission that has been reported in recent literature, in spite of the availability of modern methods of treatment. The clustering of relapses in the first 10 months gives some support to the distinction between relapse and later recurrence.

Investigation of sex-dependent effects of cannabis in daily cannabis smokers

BACKGROUND

Women exhibit an accelerated progression from first cannabis use to cannabis use disorder (CUD) and show pronounced negative clinical issues related to CUD relative to men. Whether sex-dependent differences in cannabis' direct effects contribute to the heightened risk in women is unknown. This analysis directly compared cannabis' abuse-related subjective effects in men and women matched for current cannabis use.

METHODS

Data from four double-blind, within-subject studies measuring the effects of active cannabis (3.27-5.50% THC, depending on study) relative to inactive cannabis (0.00% THC) were combined for this analysis. Data from equal numbers of men and women from each study matched for current cannabis use were pooled (total n=35 men; 35 women); cannabis' effects were analyzed according to cannabis condition (active versus inactive) and sex.

RESULTS

Active cannabis produced more robust subjective effects associated with abuse liability ('Good,' 'Liking,' 'Take Again') and intoxication ('High,' 'Stimulated') relative to inactive cannabis (p≤0.0001). Women reported higher ratings of abuse-related effects ['Take Again' and 'Good' (p≤0.05)] relative to men under active cannabis conditions but did not differ in ratings of intoxication. Active cannabis increased heart rate (p≤0.0001) equally for both sexes.

CONCLUSIONS

The results from this study suggest that when matched for cannabis use, women are more sensitive to the subjective effects related to cannabis' abuse liability relative to men, which may contribute to the enhanced vulnerability to developing CUD. Thus, sex is an important variable to consider when assessing the development of CUD.

Adverse Effects of Synthetic Cannabinoids: Management of Acute Toxicity and Withdrawal

Although several chemical structural classes of synthetic cannabinoids (SCs) were recently classified as Schedule I substances, rates of use and cases of serious toxic effects remain high. While case reports and media bring attention to severe SC toxicity, daily SC use resulting in dependence and withdrawal is a significant concern that is often overlooked when discussing the risks of these drugs. There is a rich literature on evidence-based approaches to treating substance use disorders associated with most abused drugs, yet little has been published regarding how to best treat symptoms related to SC dependence given its recency as an emerging clinically significant issue. This review provides a background of the pharmacology of SCs, recent findings of adverse effects associated with both acute intoxication and withdrawal as a consequence of daily use, and treatment approaches that have been implemented to address these issues, with an emphasis on pharmacotherapies for managing detoxification. In order to determine prevalence of use in cannabis smokers, a population at high risk for SC use, we obtained data on demographics of SC users, frequency of use, and adverse effects over a 3.5-year period (2012-2015) in the New York City metropolitan area, a region with a recent history of high SC use. While controlled studies on the physiological and behavioral effects of SCs are lacking, it is clear that risks associated with using these drugs pertain not only to the unpredictable and severe nature of acute intoxication but also to the effects of long-term, chronic use. Recent reports in the literature parallel findings from our survey, indicating that there is a subset of people who use SCs daily. Although withdrawal has not been systematically characterized and effective treatments have yet to be elucidated, some symptom relief has been reported with benzodiazepines and the atypical antipsychotic, quetiapine. Given the continued use and abuse of SCs, empirical studies characterizing (1) SCs acute effects, (2) withdrawal upon cessation of use, and (3) effective treatment strategies for SC use disorder are urgently needed.

Impact of co-administration of oxycodone and smoked cannabis on analgesia and abuse liability

Cannabinoids combined with opioids produce synergistic antinociceptive effects, decreasing the lowest effective antinociceptive opioid dose (i.e., opioid-sparing effects) in laboratory animals. Although pain patients report greater analgesia when cannabis is used with opioids, no placebo-controlled studies have assessed the direct effects of opioids combined with cannabis in humans or the impact of the combination on abuse liability. This double-blind, placebo-controlled, within-subject study determined if cannabis enhances the analgesic effects of low dose oxycodone using a validated experimental model of pain and its effects on abuse liability. Healthy cannabis smokers (N = 18) were administered oxycodone (0, 2.5, and 5.0 mg, PO) with smoked cannabis (0.0, 5.6% Δ⁹ tetrahydrocannabinol [THC]) and analgesia was assessed using the Cold-Pressor Test (CPT). Participants immersed their hand in cold water (4 °C); times to report pain (pain threshold) and withdraw the hand from the water (pain tolerance) were recorded. Abuse-related effects were measured and effects of oxycodone on cannabis self-administration were determined. Alone, 5.0 mg oxycodone increased pain threshold and tolerance (p ≤ 0.05). Although active cannabis and 2.5 mg oxycodone alone failed to elicit analgesia, combined they increased pain threshold and tolerance (p ≤ 0.05). Oxycodone did not increase subjective ratings associated with cannabis abuse, nor did it increase cannabis self-administration. However, the combination of 2.5 mg oxycodone and active cannabis produced small, yet significant, increases in oxycodone abuse liability (p ≤ 0.05). Cannabis enhances the analgesic effects of sub-threshold oxycodone, suggesting synergy, without increases in cannabis's abuse liability. These findings support future research into the therapeutic use of opioid-cannabinoid combinations for pain.

Nabilone decreases marijuana withdrawal and a laboratory measure of marijuana relapse

Few individuals seeking treatment for marijuana use achieve sustained abstinence. The cannabinoid receptor agonist, Δ(9)-tetrahydrocannabinol (THC; dronabinol), decreases marijuana withdrawal symptoms, yet does not decrease marijuana use in the laboratory or clinic. Dronabinol has poor bioavailability, which may contribute to its poor efficacy. The FDA-approved synthetic analog of THC, nabilone, has higher bioavailability and clearer dose-linearity than dronabinol. This study tested whether nabilone administration would decrease marijuana withdrawal symptoms and a laboratory measure of marijuana relapse relative to placebo. Daily, nontreatment-seeking marijuana smokers (8 men and 3 women), who reported smoking 8.3±3.1 marijuana cigarettes/day completed this within-subject study comprising three, 8-day inpatient phases; each phase tested a different nabilone dose (0, 6, 8 mg/day, administered in counter-balanced order on days 2-8). On the first inpatient day, participants took placebo capsules and smoked active marijuana (5.6% THC) at six timepoints. For the next 3 days, they had the opportunity to self-administer placebo marijuana (0.0% THC; withdrawal), followed by 4 days in which active marijuana was available for self-administration (5.6% THC; relapse). Both nabilone dose conditions decreased marijuana relapse and reversed withdrawal-related irritability and disruptions in sleep and food intake (p<0.05). Nabilone (8 mg/day) modestly worsened psychomotor task performance. Neither dose condition increased ratings of capsule 'liking' or desire to take the capsules relative to placebo. Thus, nabilone maintenance produced a robust attenuation of marijuana withdrawal symptoms and a laboratory measure of relapse even with once per day dosing. These data support testing of nabilone for patients seeking marijuana treatment.

Abuse liability of intravenous buprenorphine/naloxone and buprenorphine alone in buprenorphine-maintained intravenous heroin abusers

BACKGROUND

Sublingual buprenorphine is an effective maintenance treatment for opioid dependence, yet intravenous buprenorphine misuse occurs. A buprenorphine/naloxone formulation was developed to mitigate this misuse risk. This randomized, double-blind, cross-over study was conducted to assess the intravenous abuse potential of buprenorphine/naloxone compared with buprenorphine in buprenorphine-maintained injection drug users (IDUs).

METHODS

Intravenous heroin users (n = 12) lived in the hospital for 8-9 weeks and were maintained on each of three different sublingual buprenorphine doses (2 mg, 8 mg, 24 mg). Under each maintenance dose, participants completed laboratory sessions during which the reinforcing and subjective effects of intravenous placebo, naloxone, heroin and low and high doses of buprenorphine and buprenorphine/naloxone were examined. Every participant received each test dose under the three buprenorphine maintenance dose conditions.

RESULTS

Intravenous buprenorphine/naloxone was self-administered less frequently than buprenorphine or heroin (P < 0.0005). Participants were most likely to self-administer drug intravenously when maintained on the lowest sublingual buprenorphine dose. Subjective ratings of 'drug liking' and 'desire to take the drug again' were lower for buprenorphine/naloxone than for buprenorphine or heroin (P = 0.0001). Participants reported that they would pay significantly less money for buprenorphine/naloxone than for buprenorphine or heroin (P < 0.05). Seven adverse events were reported; most were mild and transient.

CONCLUSIONS

These data suggest that although the buprenorphine/naloxone combination has intravenous abuse potential, that potential is lower than it is for buprenorphine alone, particularly when participants received higher maintenance doses and lower buprenorphine/naloxone challenge doses. Buprenorphine/naloxone may be a reasonable option for managing the risk for buprenorphine misuse during opioid dependence treatment.

The effects of ibudilast, a glial activation inhibitor, on opioid withdrawal symptoms in opioid-dependent volunteers

Glial activation is hypothesized to contribute directly to opioid withdrawal. This study investigated the dose-dependent effects of a glial cell modulator, ibudilast, on withdrawal symptoms in opioid-dependent volunteers after abrupt discontinuation of morphine administration. Non-treatment-seeking heroin-dependent volunteers (n = 31) completed the in-patient, double-blind, placebo-controlled, within-subject and between-group study. Volunteers were maintained on morphine (30 mg, QID) for 14 days and placebo (0 mg, QID) for the last 7 days of the 3-week study. Volunteers also received placebo (0 mg, PO, BID) capsules on days 1-7. On days 8-21, volunteers were randomized to receive ibudilast (20 or 40 mg, PO, BID) or placebo capsules. Subjective and clinical ratings of withdrawal symptoms were completed daily using daily using the Subjective Opioid Withdrawal Scale (SOWS) and Clinical Opioid Withdrawal Scale (COWS). Medication side effects were also monitored. Relative to the first 2 weeks, all groups exhibited withdrawal during the third week as assessed by the SOWS and COWS (P ≤ 0.0001). Although overall SOWS scores did not differ between groups, exploratory analyses pooling the two ibudilast groups demonstrated that they had lower ratings of withdrawal symptoms on SOWS items ('anxious,' 'perspiring,' 'restless,' 'stomach cramps') during detoxification relative to the placebo group. Ibudilast was well tolerated; no serious adverse events occurred during the study. Pharmacological modulation of glial activity with ibudilast decreased some subjective ratings of opioid withdrawal symptoms. These exploratory findings are the first to demonstrate the potential clinical utility of glial modulators for treating opioid withdrawal in humans.

Cannabis reinforcement and dependence: role of the cannabinoid CB1 receptor

Awareness of cannabis dependence as a clinically relevant issue has grown in recent years. Clinical and laboratory studies demonstrate that chronic marijuana smokers can experience withdrawal symptoms upon cessation of marijuana smoking and have difficulty abstaining from marijuana use. This paper will review data implicating the cannabinoid CB1 receptor in regulating the behavioral effects of Delta(9)-tetrahydrocannobinol (THC), the primary psychoactive component of cannabis, across a range of species. The behavioral effects that will be discussed include those that directly contribute to the maintenance of chronic marijuana smoking, such as reward, subjective effects, and the positive and negative reinforcing effects of marijuana, THC and synthetic cannabinoids. The role of the CB1 receptor in the development of marijuana dependence and expression of withdrawal will also be discussed. Lastly, treatment options that may alleviate withdrawal symptoms and promote marijuana abstinence will be considered.

Actions of delta-9-tetrahydrocannabinol in cannabis: relation to use, abuse, dependence

Cannabis use disorders have been recently identified as a relevant clinical issue: a subset of cannabis smokers seeks treatment for their cannabis use, yet few succeed in maintaining long-term abstinence. The rewarding and positive reinforcing effects of the primary psychoactive component of smoked cannabis, delta-9-tetrahydrocannabinol (THC) are mediated by the cannabinoid CB1 receptor. The CB1 receptor has also been shown to mediate cannabinoid dependence and expression of withdrawal upon cessation of drug administration, a phenomenon verified across species. This paper will review findings implicating the CB1 receptor in the behavioural effects of exogenous cannabinoids with a focus on cannabinoid dependence and reinforcement, factors that contribute to the maintenance of chronic cannabis smoking despite negative consequences. Opioidergic modulation of these effects is also discussed.

Life events, social support and marital relationships in the outcome of severe depression

The effects of life events, social support and marital relationships on outcome were examined in a predominantly recurrent in-patient sample of depressives studied longitudinally every 3 months to remission and up to 15 months thereafter. Outcomes examined were length of time to remission, presence of residual symptoms at remission, and subsequent relapse. There were few associations between these outcomes and the social variables. These findings add to other recent evidence that psychosocial factors are relatively unimportant in the subsequent course of severe and recurrent depressions, in contrast to their contribution to onset of such depressions and subsequent outcome of milder depressions.

Effects of baclofen and mirtazapine on a laboratory model of marijuana withdrawal and relapse

RATIONALE

Only a small percentage of individuals seeking treatment for their marijuana use achieves sustained abstinence, suggesting more treatment options are needed.

OBJECTIVES

We investigated the effects of baclofen (study 1) and mirtazapine (study 2) in a human laboratory model of marijuana intoxication, withdrawal, and relapse.

METHODS

In study 1, daily marijuana smokers (n = 10), averaging 9.4 (+/-3.9) marijuana cigarettes/day, were maintained on placebo and each baclofen dose (60, 90 mg/day) for 16 days. In study 2, daily marijuana smokers (n = 11), averaging 11.9 (+/-5.3) marijuana cigarettes/day, were maintained on placebo and mirtazapine (30 mg/day) for 14 days each. Medication administration began outpatient prior to each 8-day inpatient phase. On the first inpatient day of each medication condition, participants smoked active marijuana (study 1: 3.3% THC; study 2: 6.2% THC). For the next 3 days, they could self-administer placebo marijuana (abstinence phase), followed by 4 days in which they could self-administer active marijuana (relapse phase); participants paid for self-administered marijuana using study earnings.

RESULTS

In study 1, during active marijuana smoking, baclofen dose-dependently decreased craving for tobacco and marijuana, but had little effect on mood during abstinence and did not decrease relapse. Baclofen also worsened cognitive performance regardless of marijuana condition. In study 2, mirtazapine improved sleep during abstinence, and robustly increased food intake, but had no effect on withdrawal symptoms and did not decrease marijuana relapse.

CONCLUSIONS

Overall, this human laboratory study did not find evidence to suggest that either baclofen or mirtazapine showed promise for the potential treatment of marijuana dependence.

Subjective, cognitive and cardiovascular dose-effect profile of nabilone and dronabinol in marijuana smokers

Marijuana dependence is a substantial public health problem, with existing treatments showing limited efficacy. In laboratory and clinical studies, the cannabinoid receptor 1 agonist oral Δ9tetrahydrocannabinol (THC; dronabinol) has been shown to decrease marijuana withdrawal but not relapse. Dronabinol has poor bioavailability, potentially contributing to its failure to decrease relapse. The synthetic THC analogue, nabilone, has better bioavailability than dronabinol. We therefore aimed to characterize nabilone's behavioral and physiological effects across a range of acute doses in current marijuana smokers and compare these with dronabinol's effects. Participants (4 female; 10 male) smoking marijuana 6.6 (standard deviation = 0.7) days/week completed this outpatient, within-subjects, double-blind, randomized protocol. Over seven sessions, the time-dependent subjective, cognitive and cardiovascular effects of nabilone (2, 4, 6, 8 mg), dronabinol (10, 20 mg) and placebo were assessed. Nabilone (4, 6, 8 mg) and dronabinol (10, 20 mg) increased ratings of feeling a good effect, a strong effect and/or 'high' relative to placebo; nabilone had a slower onset of peak subjective effects than dronabinol. Nabilone (6, 8 mg) modestly lowered psychomotor speed relative to placebo and dronabinol. There were dose-dependent increases in heart rate after nabilone, and nabilone (2 mg) and dronabinol (10 mg) decreased systolic blood pressure. Thus, nabilone produced sustained, dose-related increases in positive mood, few cognitive decrements and lawful cardiovascular alterations. It had a longer time to peak effects than dronabinol, and effects were more dose-related, suggesting improved bioavailability. Nabilone was well tolerated by marijuana smokers, supporting further testing as a potential medication for marijuana dependence.

Frequency of cannabis and illicit opioid use among people who use drugs and report chronic pain: A longitudinal analysis

BACKGROUND

Ecological research suggests that increased access to cannabis may facilitate reductions in opioid use and harms, and medical cannabis patients describe the substitution of opioids with cannabis for pain management. However, there is a lack of research using individual-level data to explore this question. We aimed to investigate the longitudinal association between frequency of cannabis use and illicit opioid use among people who use drugs (PWUD) experiencing chronic pain.

METHODS AND FINDINGS

This study included data from people in 2 prospective cohorts of PWUD in Vancouver, Canada, who reported major or persistent pain from June 1, 2014, to December 1, 2017 (n = 1,152). We used descriptive statistics to examine reasons for cannabis use and a multivariable generalized linear mixed-effects model to estimate the relationship between daily (once or more per day) cannabis use and daily illicit opioid use. There were 424 (36.8%) women in the study, and the median age at baseline was 49.3 years (IQR 42.3-54.9). In total, 455 (40%) reported daily illicit opioid use, and 410 (36%) reported daily cannabis use during at least one 6-month follow-up period. The most commonly reported therapeutic reasons for cannabis use were pain (36%), sleep (35%), stress (31%), and nausea (30%). After adjusting for demographic characteristics, substance use, and health-related factors, daily cannabis use was associated with significantly lower odds of daily illicit opioid use (adjusted odds ratio 0.50, 95% CI 0.34-0.74, p < 0.001). Limitations of the study included self-reported measures of substance use and chronic pain, and a lack of data for cannabis preparations, dosages, and modes of administration.

CONCLUSIONS

We observed an independent negative association between frequent cannabis use and frequent illicit opioid use among PWUD with chronic pain. These findings provide longitudinal observational evidence that cannabis may serve as an adjunct to or substitute for illicit opioid use among PWUD with chronic pain.

Paradoxical effects of chronic morphine treatment on the temperature and pituitary-adrenal responses to acute restraint stress: a chronic stress paradigm

Body temperature and pituitary-adrenal responses to restraint (15 min or 4 h) stress were evaluated in nondependent and morphine-dependent rats. Male Sprague-Dawley rats were treated twice daily with increasing doses of morphine (10-100 mg/kg, s.c.) for 16 days. Transmitters were implanted in the peritoneal cavity to monitor body temperature and blood was collected for hormone assays. Acute withdrawal from chronic morphine treatment was associated with reduced body weight, increased adrenal weight and decreased thymus weight. Sixteen days after termination of chronic morphine treatment, rats had recovered normal adrenal size, but still displayed marked thymus involution and reduced body weight. Restraint-induced hyperthermia was attenuated in morphine-dependent rats that had undergone 12-h withdrawal. Sixteen days after withdrawal, rats still had not fully recovered the hyperthermic response to restraint. Chronic morphine treatment resulted in a marked elevation of basal corticosterone concentrations. Despite the negative-feedback effects of elevated basal corticosterone concentrations, morphine-dependent rats that had undergone 12-h withdrawal displayed a potentiated and prolonged corticosterone response to restraint stress. In contrast, rats that had undergone 8-day and 16-day morphine withdrawal had recovered normal basal pituitary-adrenal activity, but displayed significantly reduced and shorter adrenocorticotropic hormone and corticosterone responses to restraint. These results suggest that chronic morphine dependence is a chronic stressor, resulting in profound and long-lasting changes in the temperature and pituitary-adrenal responses to acute restraint stress in a time-dependent manner. This morphine-dependence model may be useful in understanding the role that hormonal stress responses play in the maintenance and relapse to opioid use in humans.

Rapid and robust protection against cocaine-induced lethality in rats by the bacterial cocaine esterase

There is no approved means to prevent the toxic actions of cocaine. Cocaine esterase (CocE) is found in a rhodococcal strain of bacteria that grows in the rhizosphere soil around the coca plant and has been found to hydrolyze cocaine in vitro. The esteratic activity of CocE (0.1-1.0 mg, i.v.) was characterized and confirmed in vivo by assessing its ability to prevent cocaine-induced convulsions and lethality in the rat. The therapeutic efficiency of the enzyme was demonstrated by the increasing dose of cocaine (100-1000 mg/kg, i.p.) required to produce toxic effects after a single intravenous injection of CocE. The enzyme demonstrated rapid kinetics for cocaine degradation in rat and human serum. Two catalytically inactive mutants of CocE (S117A or Y44F) failed to protect rats from the toxic effects of cocaine, confirming the protective effects are due to hydrolytic activity. However, butyrylcholinesterase, an endogenous cocaine-hydrolyzing enzyme, was inactive (1.3-13 mg, i.v.) in this rat toxicity procedure. Furthermore, CocE did not block the lethality of WIN-35065-2 (560 mg/kg, i.p.), a cocaine analog that lacks the benzoyl ester moiety targeted by CocE. This characterization of CocE provides preliminary evidence that the enzyme could serve as a suitable antidote to cocaine toxicity in humans.