5-Year trends in use of hallucinogens and other adjunct drugs among UK dance drug users

Acute toxicity and withdrawal syndromes related to γ-hydroxybutyrate (GHB) and its analogues γ-butyrolactone (GBL) and 1,4-butanediol (1,4-BD)

Gamma-hydroxybutyrate (GHB) has been used as a recreational drug since the 1990s and over the last few years there has been increasing use of its analogues gamma-butyrolactone (GBL) and to a lesser extent 1,4-butanediol (1,4BD). This review will summarize the literature on the pharmacology of these compounds; the patterns and management of acute toxicity associated with their use; and the clinical patterns of presentation and management of chronic dependency associated with GHB and its analogues.

Abuse liability profile of three substituted tryptamines

The abuse liability profile of three synthetic hallucinogens, N,N-diisopropyltryptamine (DIPT), 5-N,N-diethyl-5-methoxytryptamine (5-MeO-DET), and 5-methoxy-α-methyltryptamine (5-MeO-AMT), was tested in rats trained to discriminate hallucinogenic and psychostimulant compounds, including cocaine, methamphetamine, 3,4-methylenedioxymethylamphetamine (MDMA), lysergic acid diethylamide (LSD), (-)-2,5-dimethoxy-4-methylamphetamine (DOM), and dimethyltryptamine (DMT). Because abused hallucinogens act at 5-hydroxytryptamine 1A (5-HT(1A)) and 5-HT(2A) receptors, and abused psychostimulants act at monoamine transporters, binding and functional activities of DIPT, 5-MeO-DET, and 5-MeO-AMT at these sites were also tested. DIPT fully substituted in rats trained to discriminate DMT (ED(50) = 1.71 mg/kg) and DOM (ED(50) = 1.94 mg/kg), but produced only 68% LSD-appropriate responding. 5-MeO-DET fully substituted for DMT (ED(50) = 0.41 mg/kg) and produced 59% MDMA-appropriate responding. 5-MeO-AMT did not fully substitute for any of the training drugs, but produced 67% LSD-appropriate responding. None of the compounds produced substitution in rats trained to discriminate cocaine or methamphetamine. All three compounds showed activity at 5-HT(1A) and 5-HT(2A) receptors as well as blockade of reuptake by the serotonin transporter. In addition, 5-MeO-AMT produced low levels of serotonin release and low potency blockade of dopamine uptake. DIPT, 5-MeO-DET, and 5-MeO-AMT produced behavioral and receptor effects similar to those of abused hallucinogens, but were not similar to those of psychostimulants. DIPT and 5-MeO-DET may have abuse liability similar to known hallucinogens and may be hazardous because high doses produced activity and lethality.

Reduced dorsal prefrontal gray matter after chronic ketamine use

BACKGROUND

Use of ketamine as a recreational drug is spreading rapidly among young people all over the world. Epidemiological studies have linked chronic ketamine use with a number of problems, including cognitive impairments, bladder dysfunction, and ketamine-related death. However, little is known about the long-term effects of ketamine use on brain structure and function.

METHODS

We used voxel based morphometry in conjunction with statistical parametric mapping on the structural magnetic resonance images of ketamine-dependent (n = 41) and drug-naive control individuals (n = 44) to assess differences in gray matter volume between the two groups.

RESULTS

We observed significant decreases in gray matter volume in bilateral frontal cortex (left superior frontal gyrus and right middle frontal gyrus) of ketamine users in comparison with control subjects (p < .05 corrected for multiple comparisons at cluster-level). Duration of ketamine use was negatively correlated with gray matter volume in bilateral frontal cortex, whereas the estimated total lifetime ketamine consumption was negatively correlated with gray matter volume in left superior frontal gyrus.

CONCLUSIONS

We have demonstrated a reduction in frontal gray matter volume in patients after chronic ketamine use. The link between frontal gray matter attenuation and the duration of ketamine use and cumulative doses of ketamine perhaps suggests a dose-dependent effect of long-term use of the drug. Our results have important connotations for the clinical picture that is likely to emerge with the growing recreational use of ketamine and is also relevant to the status of the drug as a model for schizophrenia.

Mephedrone, new kid for the chop?

AIMS

Mephedrone (4-methylmethcathinone) is a novel synthetic stimulant drug that has recently become popular in the United Kingdom and elsewhere in Europe. It has a short history of human consumption and little is known about its prevalence and pattern of use. This study aimed to obtain preliminary data on its use and effects among dance drug users in the United Kingdom.

DESIGN

  Cross-sectional anonymous online survey of mephedrone recruited as part of larger study exploring patterns of drug use among those associated with the dance music scene. Setting  UK-based dance music and clubbing website.

PARTICIPANTS

A total of 947 ever users of mephedrone recruited as part of a wider study on dance drug use patterns.

MEASUREMENTS

Assessment of demographics, ever and current drug use and patterns and selected effects following use of mephedrone.

FINDINGS

A total of 947 (41.3%) of 2295 participants reported ever having used mephedrone. Mephedrone was the sixth most frequently used drug in the last month after tobacco, alcohol, cannabis, cocaine and 3,4-methylenedioxymethamphetamine (MDMA). Users were typically younger (P < 0.001) and male (P < 0.01); 15.1% reported using weekly or more frequently; 49.5% reported using between 0.5 and 1 g during a typical session; 69.5% reported that intranasal use was the most common route of use. Intranasal use was associated with increased abuse liability; 54.6% of those who have also used cocaine reported that the quality of the high obtained with mephedrone was better, with those using intranasally being significantly more likely than those who took the drug orally to report that mephedrone was more addictive (P < 0.02) and more risky (P < 0.02) than cocaine. Route of use was unrelated to any stimulant-related adverse effect apart from palpitations (P < 0.005).

CONCLUSIONS

Mephedrone appears to be used primarily intranasally and to have comparable abuse potential to cocaine, with more than half those who use both reporting that mephedrone gives a better quality high.

Glutamatergic model psychoses: prediction error, learning, and inference

Modulating glutamatergic neurotransmission induces alterations in conscious experience that mimic the symptoms of early psychotic illness. We review studies that use intravenous administration of ketamine, focusing on interindividual variability in the profundity of the ketamine experience. We will consider this individual variability within a hypothetical model of brain and cognitive function centered upon learning and inference. Within this model, the brains, neural systems, and even single neurons specify expectations about their inputs and responding to violations of those expectations with new learning that renders future inputs more predictable. We argue that ketamine temporarily deranges this ability by perturbing both the ways in which prior expectations are specified and the ways in which expectancy violations are signaled. We suggest that the former effect is predominantly mediated by NMDA blockade and the latter by augmented and inappropriate feedforward glutamatergic signaling. We suggest that the observed interindividual variability emerges from individual differences in neural circuits that normally underpin the learning and inference processes described. The exact source for that variability is uncertain, although it is likely to arise not only from genetic variation but also from subjects' previous experiences and prior learning. Furthermore, we argue that chronic, unlike acute, NMDA blockade alters the specification of expectancies more profoundly and permanently. Scrutinizing individual differences in the effects of acute and chronic ketamine administration in the context of the Bayesian brain model may generate new insights about the symptoms of psychosis; their underlying cognitive processes and neurocircuitry.

Near-death states reported in a sample of 50 misusers

Increase in recreational ketamine use may be a cause for concern. We aimed here at assessing, in a sample of ketamine misusers, concordance between the typical near-death experience (NDE) features and the on-drug psychoactive effects the subjects experienced. In 2003-2005, a sample of previous ketamine misusers recollecting a ketamine-related NDE were recruited through snowballing and screened with the means of the Greyson NDE Scale; 125 participants made an initial contact with the researcher and 50 reported a minimum score of seven at the "Greyson NDE Scale". Interviewees were in the range 21-66 years old; 27 participants (54%) were educated at BA level, 18 (36%) had an MSc, and 5 (10%) a PhD. Eight (16%) interviewees had a definite religious background. An average lifetime ketamine intake of 140 occasions was reported by the interviewees, who typically presented with a polydrug, including cannabis and MDMA/ecstasy, misuse history. In 45 (90%) cases, the NDE occurred during the first few occasions of intake. Most frequent features of reported NDE states included: altered perception of time (90%), strong sense of detaching from own physical body (88%), and a sense of peace/joy (76% of subjects). Although results here described were elicited from a self-selected, nonrandomized, limited size sample of misusers, we suggest that recreational ketamine intake may be associated with occurrence of near-death related states.

Ketamine cystitis as a mimic of carcinoma in situ

AIMS

To describe the histopathological features of a series of patients with ketamine-related cystitis.

METHODS AND RESULTS

Seventeen patients with ketamine-related cystitis, who had undergone biopsy, were identified and reviewed. Twelve showed ulceration with significant urothelial atypia. In 10 of these, immunohistochemistry was performed; 9/10 had high p53 immunoreactivity and 7/10 had moderate to high levels of Ki67 reactivity, but all were negative for cytokeratin 20.

CONCLUSIONS

Ketamine can lead to reactive urothelial changes that can mimic carcinoma in situ, but the long-term cancer risk remains unknown.

Consequences of chronic ketamine self-administration upon neurocognitive function and psychological wellbeing: a 1-year longitudinal study

BACKGROUND

'Recreational' use of ketamine is spreading rapidly among young people. In healthy individuals an acute dose of the N-methyl D-aspartate (NMDA) receptor antagonist ketamine induces marked psychosis-like effects and cognitive impairments, but little is known about the long-term effects of the drug.

AIMS

To evaluate the long-term neuropsychiatric or cognitive consequences.

METHODS

A total of 150 individuals were assessed, 30 in each of five groups: frequent ketamine users, infrequent ketamine users, abstinent users, polydrug controls and non-users of illicit drugs. Twelve months later, 80% of these individuals were re-tested.

RESULTS

Cognitive deficits were mainly observed only in frequent users. In this group, increasing ketamine use over the year was correlated with decreasing performance on spatial working memory and pattern recognition memory tasks. Assessments of psychological wellbeing showed greater dissociative symptoms in frequent users and a dose-response effect on delusional symptoms, with frequent users scoring higher than infrequent, abstinent users and non-users, respectively. Both frequent and abstinent using groups showed increased depression scores over the 12 months.

CONCLUSIONS

These findings imply that heavy use of ketamine is harmful to aspects of both cognitive function and psychological wellbeing. Health education campaigns need to raise awareness among young people and clinicians about these negative consequences of ketamine use.

Gamma-hydroxybutyrate withdrawal syndrome: dangerous but not well-known

Gamma-hydroxybutyrate (GHB) is an endogenous inhibitory neurotransmitter and anesthetic agent that is being abused as a 'club drug.' Withdrawal symptoms after cessation of GHB use are common and depend on the intensity of use. However, GHB withdrawal syndrome and delirium are unfamiliar to most psychiatrists, probably due to the fact that neither textbooks nor guidelines cover the subject. The GHB withdrawal syndrome may have a fulminant course that progresses to delirium. In those severe cases, admission to a general hospital and involvement of a psychiatrist become necessary. We present two cases of severe GHB withdrawal delirium, provide an overview of the literature and conclude with treatment recommendations.

Acute and chronic effects of ketamine on semantic priming: modeling schizophrenia?

Acute administration of the N-methyl-D-aspartate receptor antagonist ketamine induces schizophrenia-like symptoms in healthy volunteers; furthermore, a window on ketamine's chronic effects is provided by regular recreational users. The current study utilized both acute ketamine administration in healthy volunteers and chronic ketamine abusers to investigate semantic processing, one of the key cognitive deficits in schizophrenia. Semantic processing was examined using a semantic priming paradigm. In experiment 1, acute effects of low (75 ng/mL) and high (150 ng/mL) ketamine doses were compared in a placebo-controlled double-blind independent group design with 48 participants. In experiment 2, 19 regular recreational ketamine users were compared with 19 ketamine-naive polydrug controls and 26 non-drug-using controls. In both experiments, semantic priming parameters were manipulated to distinguish between ketamine's effects on (1) automatic and strategic processing and (2) the facilitation and inhibition components of semantic priming for strongly (directly) related primes and targets. Acute effects of ketamine on semantic priming for weakly (indirectly) related primes and targets were also assessed in experiment 1. Acutely, ketamine impaired the employment of strategic mechanisms but not automatic processing within both the direct and indirect semantic priming tasks. Acute ketamine administration also induced clear schizophrenia-like symptoms. Schizotypy traits in the cognitive and perceptual domains tended to correlate with increased semantic priming in long-term ketamine users. In summary, acute and chronic ketamine-induced changes partially mirrored the findings on semantic priming in schizophrenia.

Epidemiology of recreational drug toxicity in a nightclub environment

Data on 173 individuals with recreational drug toxicity requiring "medical" assistance in a large urban nightclub was collected from September 2007 to January 2008. Clubbers required assistance following use of a variety of recreational drugs, particularly gamma-hydroxybutyrate (GHB), gammabutyrolactone (GBL), and ketamine. The majority of individuals were not first-time recreational drug users, and a significant proportion have recurrent recreational drug toxicity requiring assistance. Limitations related to data collection are discussed. Further studies are needed to investigate the use brief interventions in those with problem recreational drug use within the nightclub environment.

Ketamine use, cognition and psychological wellbeing: a comparison of frequent, infrequent and ex-users with polydrug and non-using controls

INTRODUCTION

Preliminary research has indicated that recreational ketamine use may be associated with marked cognitive impairments and elevated psychopathological symptoms, although no study to date has determined how these are affected by differing frequencies of use or whether they are reversible on cessation of use. In this study we aimed to determine how variations in ketamine use and abstention from prior use affect neurocognitive function and psychological wellbeing.

METHOD

We assessed a total of 150 individuals: 30 frequent ketamine users, 30 infrequent ketamine users, 30 ex-ketamine users, 30 polydrug users and 30 controls who did not use illicit drugs. Cognitive tasks included spatial working memory, pattern recognition memory, the Stockings of Cambridge (a variant of the Tower of London task), simple vigilance and verbal and category fluency. Standardized questionnaires were used to assess psychological wellbeing. Hair analysis was used to verify group membership.

RESULTS

Frequent ketamine users were impaired on spatial working memory, pattern recognition memory, Stockings of Cambridge and category fluency but exhibited preserved verbal fluency and prose recall. There were no differences in the performance of the infrequent ketamine users or ex-users compared to the other groups. Frequent users showed increased delusional, dissociative and schizotypal symptoms which were also evident to a lesser extent in infrequent and ex-users. Delusional symptoms correlated positively with the amount of ketamine used currently by the frequent users.

CONCLUSIONS

Frequent ketamine use is associated with impairments in working memory, episodic memory and aspects of executive function as well as reduced psychological wellbeing. 'Recreational' ketamine use does not appear to be associated with distinct cognitive impairments although increased levels of delusional and dissociative symptoms were observed. As no performance decrements were observed in the ex-ketamine users, it is possible that the cognitive impairments observed in the frequent ketamine group are reversible upon cessation of ketamine use, although delusional symptoms persist.

Attentional bias to incentive stimuli in frequent ketamine users

BACKGROUND

The attention-grabbing properties of drugs to drug-using individuals have been well documented and recent research has begun to suggest that such attentional bias may be related to the severity of drug dependency. Dependence on ketamine has been reported anecdotally but no systematic study has investigated this phenomenon. We aimed to explore attentional biases to incentive stimuli in different populations of ketamine users.

METHOD

Using a dot-probe paradigm, attentional bias to both drug-related and money-related stimuli was investigated in 150 participants: 30 frequent ketamine users, 30 infrequent ketamine users, 30 ex-ketamine users, 30 poly-drug users and 30 non-drug-using controls. Two stimulus presentation times were used (200 and 2000 ms) to investigate whether attentional bias was as a result of an automatic or a more conscious attentional shift. Participants also rated the degree to which stimuli used in the dot-probe paradigm were pleasurable.

RESULTS

Frequent ketamine users demonstrated an attentional bias to both types of incentive stimuli only at the short stimulus presentation interval and this was significantly correlated with degree of ketamine use. No attentional biases were observed in any of the other groups. All groups rated money stimuli as more pleasurable than neutral stimuli.

CONCLUSIONS

These data support incentive models of drug use and demonstrate the ability of the attentional bias paradigm to discriminate recreational drug users from those with more dependent patterns of use. Ketamine is a potentially dependence-forming drug.

Improvement in the pre-hospital care of recreational drug users through the development of club specific ambulance referral guidelines

Background

Previously developed 'club guidelines' developed for club owners and promoters have tended to focus more on the legislative aspects of clubs, rather than the medical management of unwell clubbers within club environments. Despite this lack of guidance on the management of unwell clubbers, a significant proportion of clubs have 'club medic' rooms for managing these individuals. However, due to the lack of specific guidance on the training of staff working in these rooms and guidelines on when an ambulance should be called for an unwell clubber, there have been instances previously where clubbers have been inappropriately managed within the club environment, and often referred to hospital only after significant physiological derangement has occurred, thereby leading to an increased risk of morbidity and mortality.

Methods

We identified owners and promoters of local club venues within the catchment area of our Emergency Department and working jointly with them and other key stakeholders, in particular the London Ambulance Service and Metropolitan Police, identified strategies to improve pre-hospital care for clubbers who become unwell as a result of recreational drug use. These included developing guidelines detailing indications for ambulance transfer to hospital for clubbers with recreational drug toxicity and the training of club medic staff to use the guidelines

Results

Following the initial development of a pilot set of guidelines, an audit of their use identified training needed relating to the assessment of unwell clubbers with recreational drug toxicity and revisions required to the pilot version of the guidelines. After training related to the revised guidelines, all the club medic staff were confident in their ability to assess unwell clubbers with recreational drug toxicity, the use of the guidelines and also when to call an ambulance.

Conclusion

Working with key stakeholders in the local community, we have developed guidelines that can be used to improve the pre-hospital care of clubber unwell with recreational drug toxicity, and demonstrated that individuals with a variety of medical knowledge can be trained to use these guidelines. Wider dissemination of these guidelines, both regionally, nationally and potentially internationally, may help to reduce the pre-hospital morbidity and mortality associated with recreational drug toxicity encountered in club environments.

Sit Down to Float: The Cultural Meaning of Ketamine Use in Hong Kong

From the late 1990s onward, ketamine use among young persons in Hong Kong grew rapidly becoming the drug of choice. This article examines ketamine's attraction in Hong Kong, and in so doing uncover the cultural meaning of ketamine use. The analysis is organized around the emergence and shifts in meanings and experiences of those who initiate and continue to use ketamine. The data stems from a comparative study of the social setting of club drug use in Hong Kong, San Francisco, and Rotterdam. Here we draw from 100 in-depth interviews to examine the experiences of young persons who have used drugs in dance venues in Hong Kong. Our findings indicate that ketamine has become embedded in a distinctively working class youth dance scene, is accessible in terms of supply and cost, shared among a group of friends, and results in a stimulating yet liberating experience beyond that of ecstasy.

Journey through the K-hole: phenomenological aspects of ketamine use

Although recreational use of the dissociative anaesthetic drug ketamine is currently increasing, little is known about the phenomenological aspects of its use. We therefore designed a structured interview to examine initiation experiences, positive and negative effects of ketamine use, and concerns about the drug and its long-term effects. Ninety participants (30 frequent users, 30 infrequent 'recreational' users and 30 ex-users who had abstained from use for at least 3 months) were interviewed and reported drug use was verified by hair sample analysis. The most appealing aspects of ketamine for two-thirds of users were "melting into the surrounding", "visual hallucinations", "out-of-body experiences" and "giggliness". Unappealing effects for half of users were "memory loss" and "decreased sociability". Frequent ketamine users expressed more concerns than other groups about long-term effects on physical health problems, especially K-cramps and cystitis, whereas ex-users were more concerned about mental health problems. Addictive/dependent patterns of behaviour were also a concern: the majority of frequent users reported using the drug without stopping until supplies ran out and the mean increase in dosage in this group was six-fold from initiation to current use. We have identified specific health issues which seem uniquely related to ketamine use. Additionally, the dependence on ketamine frequently reported by users may be a cause for concern as its popularity grows and substance misuse services should be made aware of this when clients present in the future.