Reasons for cannabis use: patients with schizophrenia versus matched healthy controls

Characterization of substance use in homeless patients with mental disorders

BACKGROUND

In Denmark, 42% of homeless people suffer from dual diagnosis, i.e. the co-occurrence of a substance use of alcohol and/or illegal substances and another psychiatric disorder. Dual diagnosis homeless patients often cause differential diagnostic difficulties and fail to receive effective treatment. A solid grasp of the role of substance use in these patients may inform the diagnostic decision and contribute to improve their treatment. Today, knowledge of these issues remains scarce. The purpose of this study was to explore substance use in homeless patients with mental disorders and their subjective perspectives on their substance use.

METHODS

44 homeless dual diagnosis patients were included in the study. They were examined in interviews focusing on their substance use and their subjective perspective on their substance use.

RESULTS

The most frequently used substances were cannabinoids (70.5%) and alcohol (45.5%), followed by cocaine, sedative/hypnotics, and amphetamine. The finding suggests that substance use in dual diagnosis homeless patients is a complex phenomenon with most patients (56.8%) using multiple substances. While substance use seems to contribute to keep the patients homeless, substance use was also reported to play an important role in coping with life on the streets by offering social contact and some relief from a desperate situation.

CONCLUSION

Substance use, mental disorder, and homelessness seem to be closely entangled, reinforcing each other and making it difficult to help these vulnerable patients. Diagnostic overshadowing may cause delays in adequate diagnosis and treatment of this group of patients.

Increased markers of inflammation after cannabis cessation and their association with psychotic symptoms

INTRODUCTION

A dysbalance of the immune system in psychotic disorders has been well investigated. However, despite a higher prevalence of cannabis (THC) consumption in patients with psychosis, few studies have investigated the impact of this use on inflammatory markers.

METHODS

One hundred and two inpatients were included in this retrospective study. Leukocytic formula, hsCRP, fibrinogen levels and urinary THC were measured, and comparisons were performed at baseline and after 4 weeks of cannabis cessation between cannabis users (THC+) and non-users (THC-).

RESULTS

After cannabis cessation, we found a greater increase in leucocyte level (p < 0.01), monocyte level (p = 0.05) and a statistical trend to a highest increase of lymphocyte level (p = 0.06) between baseline and 4 weeks in the THC+ group as compared to the THC- group. At 4 weeks, highest leucocyte (p = 0.03), lymphocyte (p = 0.04) and monocyte (p < 0.01) counts were found in the THC+ group, whereas at baseline no difference was found. A positive correlation was found between monocyte count at 4 weeks and baseline Positive and Negative Syndrome Scale (PANSS) negative subscore (p = 0.045) and between the variation of monocyte count between baseline and 4 weeks and the PANSS total score at 4 weeks (p = 0.05).

CONCLUSION

THC cessation is associated with an increase in inflammatory markers, including white blood cell, lymphocyte and monocyte levels, which correlates with symptomatology of patients with psychosis.

Scoping Review of Cannabis-Reduction Psychosocial Interventions and Reasons for Use among Young Adults with Psychosis

Objective: No evidence-based intervention effectively reduces cannabis use in young adults with psychosis (YAP). To generate hypotheses about why, a scoping review was conducted to synthesize evidence about motivations for cannabis use and reduction/cessation for YAP and the psychosocial interventions trialed to identify possible gaps between motivations and interventive strategies. Methods: A systematic literature search was conducted in December, 2022. Reviews of titles and abstracts (N = 3,216) and full-texts (n = 136) resulted in 46 articles. Results: YAP use cannabis for pleasure, to reduce dysphoria, and for social and recreational reasons; motivations for cessation include insight about cannabis-psychosis interactions, incompatibility with goals and social roles, and support from social networks. Interventions with at least minimal evidence of efficacy include motivational interviewing, cognitive-behavioral strategies, and family skills training. Conclusions: Authors recommend additional research on mechanisms of change and motivational enhancement therapy, behavioral activation, and family-based skills interventions matched to YAP motivations for use/cessation.

Cannabis use during the early COVID-19 pandemic: Use patterns, predictors, and subjective experiences

BACKGROUND

Even in the early stages, global crises such as the COVID-19 pandemic lead to serious dislocations of social life, secondary adjustment reactions to external restrictions and individual concerns. Coping mechanisms may also include dysfunctional strategies like an increase of drug use. Considering the wide-spread use of cannabis, the aim of this study was to elucidate the interplay of social restrictions, psychopathology, concerns related to the pandemic in addition to the users' experiences, motivations and consumption quantities during the early COVID-19 pandemic. It was presumed that cannabis intake would increase during the early phase of the crisis and that consumption quantities would be related to corona-related restrictions, concerns as well as subjective substance effects and psychopathology.

MATERIALS AND METHODS

As part of an international, cross-sectional, internet-based survey (N = 5,049) available in five languages, consumption quantities and patterns of cannabis use in the early phase of the pandemic from April to August 2020 were examined. Participants retrospectively rated restrictions and concerns related to the pandemic, motives of cannabis use prior to and during 1 month the pandemic, and subjective consumption effects.

RESULTS

Cannabis use behavior showed no significant differences when consumption quantities prior and during 1 month after the COVID-19 outbreak were compared. Higher quantities of cannabis intake prior and during 1 month of the pandemic as well as more corona-related concern were associated with an increased perception of positive effects of cannabis during the pandemic. Predictors of its use during 1 month of pandemic were higher pre-pandemic consumption quantity, older age, quarantinization, a lesser degree of being affected by negative effects of the pandemic and a stronger subjective experience of corona-related positive effects of cannabis. Comparisons of the motives for cannabis intake in the pre-pandemic versus the pandemic period showed that all rationales for consumption were reported less frequently, except boredom.

CONCLUSION

Frequencies of cannabis intake remained relatively stable in the early pandemic phase. Risk factors for increased use seem related to habitual consumption patterns that become more prominent under quarantinization. The use of cannabis as a dysfunctional coping strategy might not be amenable via self-report and should therefore receive special attention in clinical contexts.

Acceptance of pharmaceutical cannabis substitution by cannabis using patients with schizophrenia

Background

Cannabis-smoking patients with a psychotic disorder have poorer disease outcomes than non-cannabis-smoking patients with poorest outcomes in patients smoking high-potency cannabis (HPC) containing high Δ9-tetrahydrocannabinol (THC) and low cannabidiol (CBD). Quitting cannabis smoking or substitution of HPC by cannabis variants containing less THC and/or more CBD may benefit these patients. The present study explores whether daily HPC-smoking patients with schizophrenia accept smoking such variants.

Methods

Twelve male patients were asked to smoke on six different occasions one joint: on two occasions, the cannabis they routinely smoke (HPC; not blind), and blind in random order; on two occasions, cannabis containing low THC and no CBD; and on two occasions, cannabis containing low THC and high CBD.

Results

Both substitute variants were appreciated, but patients preferred the HPC they usually smoked. The effect of the low THC/high CBD variant was reported by 32% to be too short and by 36% to be not strong enough, whereas this was reported by 5% and 64%, respectively, for the low THC cannabis variant.

Conclusions

Based on these findings, a larger and longer study on the efficacy of cannabis substitution treatment in HPC-smoking patients with schizophrenia seems feasible and should be considered.

Trial registration

2014-005540-17NL. Registered 22 October 2014, 2014-005540-17NL 20141215 CTA.xml

Risperidone Provides Better Improvement of Sleep Disturbances Than Haloperidol Therapy in Schizophrenia Patients With Cannabis-Positive Urinalysis

A high percentage of persons with Schizophrenia also uses Cannabis and this may potentially alter the therapeutic benefits of the antipsychotic medications prescribed. The aim of this study was to assess the impact of Cannabis usage on antipsychotic therapy of sleep disturbances in schizophrenia subjects. Male subjects, ≥18 years, admitted to the University Hospital of the West Indies psychiatric ward between October 2015 and October 2016, and diagnosed with schizophrenia were recruited for the study. Following written informed consent to the study, subjects were prescribed either risperidone monotherapy or haloperidol monotherapy orally for 14 days and classified as Cannabis users (CU) or non-users (non-CU), with presence/absence of Cannabis metabolite in urine samples. After 1 week of admission, subjects wore the Actiwatch-2 device, to record sleep data for 7 consecutive nights. Inferential statistical analysis involved non-parametric tests, expressed as median and inter-quartile ranges (IQR), with p<0.05 considered statistically significant. Fifty subjects were assessed, with a median (IQR) age of 28 (14) years. Majority (30; 60%) were CU, displaying longer sleep latency (SL) than non-CU when receiving haloperidol; but equivalent SL when receiving risperidone. In comparison to non-CU, the CU also displayed longer time in bed, but shorter durations asleep, awoke more frequently during the nights and for longer durations, whether receiving haloperidol or risperidone. This resulted in lower sleep efficiency for the CU (<85%) compared to the non-CU (≥85%). Over the study period, sleep efficiency was significantly improved for non-CU receiving either risperidone (p = 0.032) or haloperidol (p = 0.010); but was only significantly improved with risperidone for the CU (p = 0.045). It is apparent that the presence of Cannabis may be impacting the therapeutic benefits of antipsychotic drugs on sleep. In schizophrenia subjects with concomitant Cannabis use, risperidone is more beneficial than haloperidol in improving sleep efficiency.

Effects of extended cannabis abstinence on clinical symptoms in cannabis dependent schizophrenia patients versus non-psychiatric controls

BACKGROUND

Rates of cannabis use among patients with schizophrenia are high, however little is understood about clinical effects of continued cannabis use and cessation after illness onset. Therefore, we investigated the effects of 28-days of cannabis abstinence on psychotic and depressive symptomatology in cannabis dependent patients with schizophrenia.

METHOD

Males with cannabis dependence and co-morbid schizophrenia (n=19) and non-psychiatric controls (n=20) underwent 28-days of monitored cannabis abstinence. Clinical symptoms were assessed at baseline and then weekly. Abstinence was encouraged using weekly therapy sessions and contingency reinforcement, confirmed by twice-weekly urine assays.

RESULTS

Forty-two percent (8/19) of patients and 55% (11/20) of controls achieved 28-days of sustained cannabis abstinence. In patients, PANSS subscores did not change over time irrespective of abstinence status. In contrast, patient abstainers demonstrated a more pronounced reduction in depression scores compared to non-abstainers, however, the Abstinence Status x Time interaction was non-significant.

DISCUSSION

Short-term (28-days) cannabis abstinence is not associated with improvement in psychotic symptoms, but may be associated with improvement in depressive symptomatology in patients with schizophrenia. Future studies employing larger samples as well as a continuous cannabis-using group may help to better characterize the causal effects of cannabis on symptom outcomes in this disorder.

Motivational changes of cannabis use prior to and during the course of schizophrenia

BACKGROUND AND OBJECTIVES

We investigated subjective reasons/motivation for cannabis use in patients with schizophrenia (n = 51) compared to otherwise healthy cannabis users (n = 109). Moreover, we explored possible changes in the motivational patterns of both groups over time.

METHODS

A questionnaire was developed with six dimensions of motivations to use cannabis: affect regulation, relaxation, habit, structuring everyday life, creativity, and sociability. Participants filled out the instrument regarding their present and initial use of cannabis.

RESULTS

At the time of onset of consumption, groups only differed significantly in habit with higher ratings for patients with schizophrenia and cannabis use (SCH+CAN group) and in sociability with higher ratings for otherwise healthy users (CAN group). In respect of present use, the motivation to consume cannabis was significantly higher for affect regulation and structuring everyday life in the SCH+CAN group and for relaxation and sociability in the CAN group. With reference to time-based variations, the SCH+CAN group reported increased relevance of structuring everyday life over time. Furthermore, the CAN group reported increased importance of habit over time, whereas the SCH+CAN patients showed decreased ratings of habit over time.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Our findings must be considered preliminary because of the retrospective nature of the assessment. Nevertheless, the present study provides an indication of the time-dependent variation of cannabis-use motivation in schizophrenia, which may provide a better understanding of the functions of cannabis use within the population. Results argue for specific motivational based interventions for the group of schizophrenia patients with regular cannabis use. (Am J Addict 2017;26:122-128).

Cannabis Use Is Associated With Increased Psychotic Symptoms and Poorer Psychosocial Functioning in First-Episode Psychosis: A Report From the UK National EDEN Study

OBJECTIVE

The use of cannabis during the early stage of psychosis has been linked with increased psychotic symptoms. This study aimed to examine the use of cannabis in the 12 months following a first-episode of psychosis (FEP) and the link with symptomatic course and outcome over 1 year post psychosis onset.

DESIGN AND SETTING

One thousand twenty-seven FEP patients were recruited upon inception to specialized early intervention services (EIS) for psychosis in the United Kingdom. Participants completed assessments at baseline, 6 and 12 months.

RESULTS

The results indicate that the use of cannabis was significantly associated with increased severity of psychotic symptoms, mania, depression and poorer psychosocial functioning. Continued use of cannabis following the FEP was associated with poorer outcome at 1 year for Positive and Negative Syndrome Scale total score, negative psychotic symptoms, depression and psychosocial functioning, an effect not explained by age, gender, duration of untreated psychosis, age of psychosis onset, ethnicity or other substance use.

CONCLUSION

This is the largest cohort study of FEP patients receiving care within EIS. Cannabis use, particularly "continued use," was associated with poorer symptomatic and functional outcome during the FEP. The results highlight the need for effective and early intervention for cannabis use in FEP.

Cannabis use in first episode psychosis: Meta-analysis of prevalence, and the time course of initiation and continued use

OBJECTIVES

Cannabis use is prevalent among people with first episode psychosis and the epidemiology of its use in early psychosis is unclear. We performed a meta-analysis of observational studies to determine; (1) the interval between age at initiation of cannabis use and age at onset of first episode psychosis, (2) the prevalence of cannabis use at time of first episode psychosis, and (3) the odds of continuing cannabis following treatment for first episode psychosis.

DATA SOURCES

Search of electronic databases MEDLINE, EMBASE, PsycINFO, Web of Science and CINAHL for English-language papers using search terms (psychosis OR schizophrenia) AND (cannabis OR marijuana) IN (title OR keyword OR abstract), current to October 2014.

STUDY SELECTION

Studies were included if they reported on prevalence of current cannabis use in first episode psychosis cohorts. A total of 37 samples were included for meta-analysis.

DATA EXTRACTION

Rates of cannabis use in each sample were extracted to determine prevalence estimates. The age at initiation of regular cannabis and age at onset of psychosis were used to determine the length of cannabis use preceding psychosis. Prevalence estimates at first episode psychosis and various time points of follow-up following first episode psychosis were analysed to determine odds ratio of continuing cannabis use. Data synthesis was performed using random-effects meta-analyses.

RESULTS

The pooled estimate for the interval between initiation of regular cannabis use and age at onset of psychosis was 6.3 years (10 samples, standardised mean difference = 1.56, 95% confidence interval = [1.40, 1.72]). The estimated prevalence of cannabis use at first episode psychosis was 33.7% (35 samples, 95% confidence interval = [31%, 39%]). Odds of continued cannabis use between 6 months and 10 years following first episode psychosis was 0.56 (19 samples, 95% confidence interval = [0.40, 0.79]).

Relationship between cannabis and psychosis: Reasons for use and associated clinical variables

The mechanism underneath the relationship between cannabis and psychosis remains controversial, for which several hypotheses have been proposed, including cannabis as self-medication and cannabis as a risk for the development of psychosis. The aim of this work was to study the relationship between cannabis and psychosis in first-episode psychosis cannabis users and non-users, and non-psychotic cannabis users. The age at the first psychotic episode, duration of untreated psychosis, psychopathology and reasons for cannabis use were assessed. First-episode psychosis cannabis users showed an earlier age at psychosis onset than non-user patients. No significant differences in symptomatology were found. The distinguishing reasons to use cannabis for patients with first-episode psychosis with respect to non-psychotic users were to arrange their thoughts and deal with hallucinations and suspiciousness. These findings are in agreement with both hypotheses: self-medication and secondary psychosis hypothesis. However, longitudinal prospective cohort studies assessing reasons for cannabis use are needed to investigate both hypotheses and their complementarity.

Reasons for cannabis use in first-episode psychosis: does strength of endorsement change over 12 months?

BACKGROUND

Why patients with psychosis use cannabis remains debated. The self-medication hypothesis has received some support but other evidence points towards an alleviation of dysphoria model. This study investigated the reasons for cannabis use in first-episode psychosis (FEP) and whether strength in their endorsement changed over time.

METHODS

FEP inpatients and outpatients at the South London and Maudsley, Oxleas and Sussex NHS Trusts UK, who used cannabis, rated their motives at baseline (n=69), 3 months (n=29) and 12 months (n=36). A random intercept model was used to test the change in strength of endorsement over the 12 months. Paired-sample t-tests assessed the differences in mean scores between the five subscales on the Reasons for Use Scale (enhancement, social motive, coping with unpleasant affect, conformity and acceptance and relief of positive symptoms and side effects), at each time-point.

RESULTS

Time had a significant effect on scores when controlling for reason; average scores on each subscale were higher at baseline than at 3 months and 12 months. At each time-point, patients endorsed 'enhancement' followed by 'coping with unpleasant affect' and 'social motive' more highly for their cannabis use than any other reason. 'Conformity and acceptance' followed closely. 'Relief of positive symptoms and side effects' was the least endorsed motive.

CONCLUSIONS

Patients endorsed their reasons for use at 3 months and 12 months less strongly than at baseline. Little support for the self-medication or alleviation of dysphoria models was found. Rather, patients rated 'enhancement' most highly for their cannabis use.

Reflections of young people who have had a first episode of psychosis: what attracted them to use alcohol and illicit drugs?

AIM

To identify factors that contribute to the initiation of alcohol and street drug use from the perspective of people who were enrolled in early intervention programmes for a first episode of psychosis.

METHOD

Eight focus groups were conducted involving an average of four to six participants per group, with each group consisting of young people who met provincial inclusion criteria for early intervention programmes. Thematic analysis was used to systematically code transcripts from the focus groups for concepts, patterns and themes related to early use of illicit substances.

RESULTS

Participants included 45 young people diagnosed with affective psychosis or non-affective spectrum disorders. Seventy-three percent were male, with a median age of 23 years. In general, substance use was an important topic that emerged across all focus groups. Participants talked about three main factors attracting them to initiate use of substances, most predominantly cannabis: (i) using within a social context; (ii) using as a self-medication strategy; and (iii) using to alter their perceptions.

CONCLUSIONS

The need for social relationships, coping strategies and pleasurable experiences appear to be important reasons for initiating substance use. Additional research is needed to identify whether prodromal youth report the same factors that attract them to initiate use in order to develop more effective prevention strategies.

Attitudes and perceptions towards substances among people with mental disorders: a systematic review

OBJECTIVE

To develop effective interventions for people with coexisting mental disorders (MD) and substance use, it may be beneficial to understand their attitudes and perceptions of substances.

METHOD

A systematic literature search regarding attitudes and perceptions towards tobacco, alcohol or cannabis among people with MD was conducted. Studies' methodological quality was assessed using the Newcastle-Ottawa Scale.

RESULTS

Twenty-one papers were included in the review and found to have generally low methodological quality. Papers investigated reasons for substance use, substance use expectancies, substances' perceived effects and reasons for quitting. People with psychotic disorders reported using substances primarily for relaxation and pleasure. Among people with mood disorders, alcohol was used primarily for social motives and tobacco for negative affect reduction.

CONCLUSION

For substance use interventions among people with MD to be more effective, it may be necessary to tailor interventions specifically for this population and customize by substance type. Gaps in the literature regarding attitudes and perceptions towards substance use among people with MD were identified, which future research should aim to address. These include designing and conducting methodologically rigorous research, investigating perceived harmfulness and knowledge of substances, and broadening recruitment of participants to include people with MD other than psychosis.

Reasons for substance use among people with mental disorders

BACKGROUND

Comorbidity of mental disorders and substance use continues to be a major problem. To inform the development of more effective interventions for these co-existing disorders, this paper aimed to determine if there are clear variations in the reasons for tobacco, alcohol or cannabis use across people with different mental disorders.

METHODS

Data from five randomized controlled trials on co-existing disorders that measured reasons for tobacco, alcohol or cannabis use using the Drug Use Motives Questionnaire, Reasons for Smoking Questionnaire or via free response are reported and combined. Two studies involved participants with depression, two involved participants with a psychotic disorder and one involved participants with a range of mental disorders. A series of logistic regressions were conducted to examine differences in reasons for tobacco, alcohol or cannabis use and to compare these reasons between people with psychotic disorders or depression.

RESULTS

Participants had a mean age of 38 (SD=12) and just over half (60%) were male. Forty-six percent of participants had a psychotic disorder and 54% experienced depression. Data from 976 participants across the five studies were included in the analyses. Tobacco and alcohol were primarily used to cope, while cannabis was primarily used for pleasure. People with psychotic disorders were more likely than people with depression to use tobacco for coping, pleasure and illness motives. People with depression, in contrast, were more likely to use alcohol for these reasons and social reasons.

CONCLUSIONS

It may be important to tailor interventions for co-existing mental disorders and substance use by substance type and type of mental disorder. For example, interventions might be improved by including alternative coping strategies to tobacco and/or alcohol use, by addressing the social role of alcohol and by helping people with mental disorders using cannabis to gain pleasure from their lives in other ways.

Differences in craving for cannabis between schizophrenia patients using risperidone, olanzapine or clozapine

Substance abuse and psychotic disorders have a high rate of comorbidity. Both disorders are associated with changes in the dopaminergic transmission in the mesocorticolimbic pathways of the brain. Since antipsychotic medications interact with the dopamine receptors in these pathways, these medications could affect craving for substances. In the current study, the effect of clozapine (n = 27, mean dosage 350 mg), risperidone (n = 54, mean dosage 3.46 mg) and olanzapine (n = 60, mean dosage 13.78 mg) on subjective craving for cannabis was compared in 123 patients with cannabis dependence and psychotic disorder. Patients treated with risperidone reported significantly more craving compared with patients treated with clozapine (Z = -3.19, p = .001) or olanzapine (Z = -2.24, p = .025). No significant differences in craving between clozapine and olanzapine were found. These results are in concordance with findings in the literature on this subject and could be explained by differences in three dopamine mediated mechanisms of these compounds: 1) occupancy rate of dopamine D(2) receptors, 2) dissociation rate of dopamine D(2) receptors, 3) D(1)/D(2) occupancy ratio. Risperidone and clozapine show a maximal difference in D(2) receptor occupancy rate, dissociation rate and D(1)/D(2) ratio. Olanzapine is intermediate between risperidone and clozapine in these characteristics.

Cannabis and psychometrically-defined schizotypy: use, problems and treatment considerations

Cannabis use is associated with onset of psychosis in individuals vulnerable for developing schizophrenia-spectrum disorders. The present study addressed three knowledge gaps pertaining to this issue: 1) clarifying the incidence of cannabis use in schizotypal individuals, 2) examining how cannabis use is related to psychosocial and physiological problems in schizotypy and interest in treatment, and 3) examining how cannabis use is associated with positive, negative and disorganization features of schizotypy. Scores from a measure of schizotypal traits were used to trichotomize 1665 young adults into schizotypy (top 5% of scorers), non-schizotypy (bottom 50% of scorers) and "unconventional" (scorers within the 50th to 85th percentile) groups. Nearly a quarter of the schizotypy group endorsed cannabis use at least weekly, a rate nearly two to four times that of the other groups. The schizotypy group also reported a much greater frequency of cannabis-related problems compared to the other groups. Despite this, interest in treatment for cannabis use in the schizotypy group was not elevated. Interestingly, 85% of individuals in the schizotypy group reported interest in psychological/psychiatric treatment more generally. Cannabis use was not associated with abnormal patterns of positive or disorganized schizotypy traits in the schizotypy group relative to the other groups. However, cannabis use was associated with lower severity of negative traits. Implications of these results are discussed.

Why do patients with psychosis use cannabis and are they ready to change their use?

Numerous studies have shown that patients with psychosis are more likely to use illicit drugs than the general population, with cannabis being the most popular. There exists overwhelming evidence that cannabis use can contribute to the onset of schizophrenia and poor outcome in patients with established psychosis. Therefore, understanding why patients use cannabis and whether they are motivated to change their habits is important. The evidence is that patients with psychosis use cannabis for the same reasons the general population does, to 'get high', relax and have fun. There is little support for the 'self-medication' hypothesis, while the literature points more towards an 'alleviation of dysphoria' model. There is a lack of research reporting on whether psychotic patients are ready to change their use of cannabis, which has obvious implications for identifying which treatment strategies are likely to be effective.

Reasons for illicit drug use in people with schizophrenia: Qualitative study

BACKGROUND

Drug misuse is an important clinical problem associated with a poorer outcome in patients who have a diagnosis of schizophrenia. Qualitative studies have rarely been used to elicit reasons for drug use in psychosis, but not in schizophrenia.

METHODS

Seventeen people with a diagnosis of schizophrenia and who had used street drugs were interviewed and asked to describe, in narrative form, their street drug use from their early experiences to the present day. Grounded theory was used to analyse the transcripts.

RESULTS

We identified five reasons for continuing street drug use. The reasons were: as an 'identity defining vocation', 'to belong to a peer group', due to 'hopelessness', because of 'beliefs about symptoms and how street drugs influence them' and viewing drugs as 'equivalent to taking psychotropic medication'. Street drugs were often used to reduce anxiety aroused by voice hearing. Some participants reported street drugs to focus their attention more on persecutory voices in the hope of outwitting their perceived persecutors.

CONCLUSIONS

It would be clinically useful to examine for the presence of the five factors in patients who have a diagnosis of schizophrenia and use street drugs, as this is likely to help the clinician to tailor management of substance misuse to the individual patient's beliefs.

Do patients think cannabis causes schizophrenia? - A qualitative study on the causal beliefs of cannabis using patients with schizophrenia

Background

There has been a considerable amount of debate among the research community whether cannabis use may cause schizophrenia and whether cannabis use of patients with schizophrenia is associated with earlier and more frequent relapses. Considering that studies exploring patients' view on controversial topics have contributed to our understanding of important clinical issues, it is surprising how little these views have been explored to add to our understanding of the link between cannabis and psychosis. The present study was designed to elucidate whether patients with schizophrenia who use cannabis believe that its use has caused their schizophrenia and to explore these patients other beliefs and perceptions about the effects of the drug.

Methods

We recruited ten consecutive patients fulfilling criteria for paranoid schizophrenia and for a harmful use of/dependence from cannabis (ICD-10 F20.0 + F12.1 or F12.2) from the in- and outpatient clinic of the Psychiatric University Hospital Zurich. They were interviewed using qualitative methodology. Furthermore, information on amount, frequency, and effects of use was obtained. A grounded theory approach to data analysis was taken to evaluate findings.

Results

None of the patients described a causal link between the use of cannabis and their schizophrenia. Disease models included upbringing under difficult circumstances (5) or use of substances other than cannabis (e. g. hallucinogens, 3). Two patients gave other reasons. Four patients considered cannabis a therapeutic aid and reported that positive effects (reduction of anxiety and tension) prevailed over its possible disadvantages (exacerbation of positive symptoms).

Conclusions

Patients with schizophrenia did not establish a causal link between schizophrenia and the use of cannabis. We suggest that clinicians consider our findings in their work with patients suffering from these co-occurring disorders. Withholding treatment or excluding patients from certain treatment settings like day-care facilities or in patient care because of their use of cannabis, may cause additional harm to this already heavily burdened patient group.

Modelle der Substanzabhängigkeit

Neurobiologische Modelle der Substanzabhängigkeit postulieren, dass Abhängigkeit aus einem Zusammenspiel zwischen positiver und negativer Verstärkung entsteht. Die positive Verstärkung wird über die dopaminerge Transmission im Striatum vermittelt, während die negative Verstärkung die neurobiologischen Stresssysteme involviert. Abhängigkeit geht mit lang anhaltenden Änderungen der zerebralen Motivationssysteme einher. Neuropsychologische Forschungsarbeiten weisen auf ein beeinträchtigtes Entscheidungsverhalten hin, welches mit einer Dysfunktion im ventromedialen präfrontalen Kortex zusammenhängen könnte. Sie betonen die Rolle der Insula, welche die neuronale Grundlage für die fehlende Einsicht ins problematische Suchtverhalten als auch für die Vermittlung des bewussten Drangs, die Substanz zu konsumieren, sein könnte. Neurobiologische und neuropsychologische Sichtweisen werden in einem Modell integriert, das impulsive subkortikale und dopamin-bezogene Prozesse mit einer Beeinträchtigung der kortikalen Hemmung und kognitiven Defiziten verbindet.

Cannabis and psychosis/schizophrenia: human studies

The association between cannabis use and psychosis has long been recognized. Recent advances in knowledge about cannabinoid receptor function have renewed interest in this association. Converging lines of evidence suggest that cannabinoids can produce a full range of transient schizophrenia-like positive, negative, and cognitive symptoms in some healthy individuals. Also clear is that in individuals with an established psychotic disorder, cannabinoids can exacerbate symptoms, trigger relapse, and have negative consequences on the course of the illness. The mechanisms by which cannabinoids produce transient psychotic symptoms, while unclear may involve dopamine, GABA, and glutamate neurotransmission. However, only a very small proportion of the general population exposed to cannabinoids develop a psychotic illness. It is likely that cannabis exposure is a "component cause" that interacts with other factors to "cause" schizophrenia or a psychotic disorder, but is neither necessary nor sufficient to do so alone. Nevertheless, in the absence of known causes of schizophrenia, the role of component causes remains important and warrants further study. Dose, duration of exposure, and the age of first exposure to cannabinoids may be important factors, and genetic factors that interact with cannabinoid exposure to moderate or amplify the risk of a psychotic disorder are beginning to be elucidated. The mechanisms by which exposure to cannabinoids increase the risk for developing a psychotic disorder are unknown. However, novel hypotheses including the role of cannabinoids on neurodevelopmental processes relevant to psychotic disorders are being studied.