Clinical trials of medicinal cannabis for appetite-related symptoms from advanced cancer: a survey of preferences, attitudes and beliefs among patients willing to consider participation.

BACKGROUND: Australian clinical trials are planned to evaluate medicinal cannabis in a range of clinical contexts. AIMS: To explore the preferences, attitudes and beliefs of patients eligible and willing to consider participation in a clinical trial of medicinal cannabis for poor appetite and appetite-related symptoms from advanced cancer. METHODS: A cross-sectional anonymous survey was administered from July to December 2015 online and in eight adult outpatient palliative care and/or cancer services. Respondents were eligible if they were ≥18 years, had advanced cancer and poor appetite/taste problems/weight loss and might consider participating in a medicinal cannabis trial. Survey items focused on medicinal rather than recreational cannabis use and did not specify botanical or pharmaceutical products. Items asked about previous medicinal cannabis use and preferences for delivery route and invited comments and concerns. RESULTS: There were 204 survey respondents, of whom 26 (13%) reported prior medicinal cannabis use. Tablets/capsules were the preferred delivery mode (n = 144, 71%), followed by mouth spray (n = 84, 42%) and vaporiser (n = 83, 41%). Explanations for preferences (n = 134) most commonly cited convenience (n = 66; 49%). A total of 82% (n = 168) of respondents indicated that they had no trial-related concerns, but a small number volunteered concerns about adverse effects (n = 14) or wanted more information/advice (n = 8). Six respondents volunteered a belief that cannabis might cure cancer, while two wanted assurance of efficacy before participating in a trial. CONCLUSION: Justification of modes other than tablets/capsules and variable understanding about cannabis and trials will need addressing in trial-related information to optimise recruitment and ensure that consent is properly informed.

Adverse effects of cannabis.

Cannabis is the most widely used illicit drug in many developed societies. Its health and psychological effects are not well understood and remain the subject of much debate, with opinions on its risks polarised along the lines of proponents' views on what its legal status should be. An unfortunate consequence of this polarisation of opinion has been the absence of any consensus on what health information the medical profession should give to patients who are users or potential users of cannabis. There is conflicting evidence about many of the effects of cannabis use, so we summarise the evidence on the most probable adverse health and psychological consequences of acute and chronic use. This uncertainty, however, should not prevent medical practitioners from advising patients about the most likely ill-effects of their cannabis use. Here we make some suggestions about the advice doctors can give to patients who use, or are contemplating the use, of this drug.

Differential impairments of selective attention due to frequency and duration of cannabis use.

The evidence for long-term cognitive impairments associated with chronic use of cannabis has been inconclusive. We report the results of a brain event-related potential (ERP) study of selective attention in long-term cannabis users in the unintoxicated state. Two ERP measures known to reflect distinct components of attention were found to be affected differentially by duration and frequency of cannabis use. The ability to focus attention and filter out irrelevant information, measured by frontal processing negativity to irrelevant stimuli, was impaired progressively with the number of years of use but was unrelated to frequency of use. The speed of information processing, measured by the latency of parietal P300, was delayed significantly with increasing frequency of use but was unaffected by duration of use. The results suggest that a chronic buildup of cannabinoids produces both short- and long-term cognitive impairments.

Do cognitive impairments recover following cessation of cannabis use?

Our previous research with long term cannabis users established an impaired ability to focus attention and filter out irrelevant information, which was progressive with the cumulative duration of exposure to cannabis. The current study examined these processes in a group of ex-cannabis users. The results suggested a partial recovery of function but the past duration of cannabis use continued to have an adverse effect on the ability to effectively reject complex irrelevant information. There was no indication of improvement with increasing length of abstinence. Whilst relatively subtle in nature, the consequences of such an enduring deficit associated with cannabis use are worthy of further investigation.

Biopsychosocial changes associated with cessation of cannabis use: a single case study of acute and chronic cognitive effects, withdrawal and treatment.

A 35 year old male was cognitively assessed prior to cessation of 18 years of daily cannabis use and monitored for several weeks post cessation. Brain event-related potential (ERP) measures of selective attention reflecting a difficulty in filtering out complex irrelevant information showed no indication of improvement over 6 weeks of abstinence. In contrast, when tested in the acutely intoxicated state prior to cessation of use, a dramatic normalisation of the ERP signature of this individual was observed. A treatment program based on supportive-expressive psychotherapy was administered and depression, anxiety and general psychological health were monitored over the course of withdrawal from cannabis.

Effects of long-term cannabis use on selective attention: an event-related potential study.

Brain event-related potentials (ERPs) were recorded from nine long-term cannabis users during a complex auditory selective attention task and compared with nine nonuser controls. Stimuli consisted of a random sequence of tones varying in location, pitch and duration. Subjects were instructed to respond to long-duration tones of a particular pitch and location. Cannabis users' task performance was significantly worse than controls. The most striking difference between the ERPs of the two groups was in the greatly enhanced early processing negativity in the user group to short-duration stimuli which matched the target on location only. This is indicative of users engaging in unnecessary pitch processing and thus having difficulty in setting up an accurate focus of attention and in filtering out irrelevant information. The data suggest a dysfunction in the allocation of attentional resources and stimulus evaluation strategies. These results imply that long-term cannabis use may impair the ability to efficiently process information.