Harms associated with psychoactive substances: findings of the UK National Drug Survey.

Nutt and colleagues' 'rational' scale to assess the harms of commonly used drugs was based on ratings by a panel of experts. This survey aimed to assess drug users' views of the harms of drugs using the same scale. As users' drug choices are not solely based on harms, we additionally assessed perceived benefits. The survey was hosted at http://www.nationaldrugsurvey.org. UK residents reported their experience of 20 commonly used substances; those with direct experience of a substance rated its physical, dependence-related and social harms as well as benefits. A total of 1501 users completed the survey. There was no correlation between the classification of the 20 drugs under the Misuse of Drugs Act and ranking of harms by users. Despite being unclassified substances, alcohol, solvents and tobacco were rated within the top ten most harmful drugs. There was a remarkably high correlation (r = 0.896) overall between rankings by users' and by experts. Ecstasy, cannabis and LSD were ranked highest by users on both acute and chronic benefits. These findings imply that users are relatively well informed about the harms associated with the drugs they use. They also suggest that the current UK legal classification system is not acting to inform users of the harms of psychoactive substances.

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.

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.

Perceptual organization in ketamine users: preliminary evidence of deficits on night of drug use but not 3 days later.

N-methyl-D-aspartate (NMDA)-receptor antagonists such as ketamine can induce transient schizophrenia-like symptoms and cognitive dysfunctions in healthy volunteers similar to those observed in patients with schizophrenia. Perceptual organization deficits have been documented in schizophrenia and are thought to be related to some symptoms associated with the illness. The current study was designed to determine whether people who repeatedly self-administer ketamine would also show deficits in perceptual organization. Using a psychophysically well-controlled measure of contour integration, we compared a group of recreational users (n = 16) to a group of poly-drug using controls (n = 16). Contour integration performance was measured on the night of drug use and 3 days later when drug free. The results showed that on the night of drug use, ketamine produced a dysfunction in contour integration however, this was not present 3 days later when drug free. Levels of dissociation were also higher in ketamine users only on the night of drug use. These preliminary data provide some support for the role of NMDA-receptor hypofunctioning in dysfunctional coordination of cognitive activity.