Effects of continuation, frequency, and type of cannabis use on relapse in the first 2 years after onset of psychosis: an observational study. Cannabis use and transition to psychosis in people at ultra-high risk. Continued cannabis use and outcome in first-episode psychosis: data from a randomized, open-label, controlled trial. Course of cannabis use and clinical outcome in patients with non-affective psychosis: a 3-year follow-up study. Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study The impact of cannabis use on clinical outcomes in recent onset psychosis. The temporal dynamics of relationships between cannabis, psychosis and depression among young adults with psychotic disorders: findings from a 10-month prospective study. Does change in cannabis use in established psychosis affect clinical outcome? Persistent cannabis users show neuropsychological decline from childhood to midlife Cannabis abuse and the course of recent onset schizophrenic disorders Cannabis use in adolescence and risk for adult psychosis: longitudinal prospective study Are deficits in cognition associated with psychotic-like experiences after cannabis? Motivational Intervention to Reduce Cannabis Use in Young People with Psychosis: A Randomized Controlled Trial A multi-center, randomized controlled trial of a group psychological intervention for psychosis with comorbid cannabis dependence over the early course of illness Does normal developmental expression of psychosis combine with environmental risk to cause persistence of psychosis? A psychosis proneness-persistence model. Cannabis use and expression of mania in the general population. Effect of cannabis use on the course of schizophrenia in male patients: A prospective cohort study
BACKGROUND Although cannabis use after a first episode of psychosis has been associated with relapse , little is known about the determinants of this most preventable risk factor for relapse of psychosis . Here we aim ed to study whether the effects on outcome vary depending on the type of cannabis consumed and usage pattern . METHODS In this observational study , we prospect ively recruited and followed up patients aged 18 - 65 years who presented with their first episode of psychosis to psychiatric services in south London , London , UK .  Relapse of psychosis within 2 years after onset of psychosis was defined as risk of subsequent admission to hospital . We classified patients into different patterns of cannabis use based on continuity of use after onset of psychosis , potency of cannabis consumed , and frequency of use after the onset of their illness . We used multiple regression analyses ( logistic or binominal ) to compare the different cannabis use groups and propensity score analysis to vali date the results . FINDINGS Between April 12 , 2002 , and July 26 , 2013 , 256 patients presented with a first episode of psychosis . We did follow-up assessment s for these patients until September , 2015 . Simple analyses showed that former regular users of cannabis who stopped after the onset of psychosis had the most favourable illness course with regards to relapse . In multiple analysis , continued high-frequency users ( ie , daily use in all 24 months ) of high-potency ( skunk-like ) cannabis had the worst outcome , indexed as an increased risk for a subsequent relapse ( odds ratio [ OR ] 3·28 ; 95 % CI 1·22 - 9·18 ) , more relapses ( incidence rate ratio 1·77 ; 95 % CI 0·96 - 3·25 ) , fewer months until a relapse occurred ( b -0·22 ; 95 % CI -0·40 to -0·04 ) , and more intense psychiatric care ( OR 3·16 ; 95 % CI 1·26 - 8·09 ) after the onset of psychosis . INTERPRETATION Adverse effects associated with continued use of cannabis after the onset of a first episode of psychosis depend on the specific patterns of use . Possible interventions could focus on persuading cannabis-using patients with psychosis to reduce use or shift to less potent forms of cannabis . FUNDING National Institute for Health Research ( NIHR ) BACKGROUND Cannabis use is associated with an increased risk of developing a psychotic disorder but the temporal relationship between cannabis use and onset of illness is unclear . The objective of this study was to assess prospect ively the influence of cannabis use on transition to psychosis in people at ultra-high risk ( UHR ) for the disorder . METHOD Lifetime and continued cannabis use was assessed in a consecutively ascertained sample of 182 people ( 104 male , 78 female ) at UHR for psychosis . Individuals were then followed clinical ly for 2 years to determine their clinical outcomes . RESULTS Lifetime cannabis use was reported by 134 individuals ( 73.6 % ) . However , most of these individuals had stopped using cannabis before clinical presentation ( n=98 , 73.1 % ) , usually because of adverse effects . Among lifetime users , frequent use , early-onset use and continued use after presentation were all associated with an increase in transition to psychosis . Transition to psychosis was highest among those who started using cannabis before the age of 15 years and went on to use frequently ( frequent early-onset use : 25 % ; infrequent or late-onset use : 5 % ; χ(2)1=10.971 , p=0.001 ) . However , within the whole sample , cannabis users were no more likely to develop psychosis than those who had never used cannabis ( cannabis use : 12.7 % ; no use : 18.8 % ; χ(2)1=1.061 , p=0.303 ) . CONCLUSIONS In people at UHR for psychosis , lifetime cannabis use was common but not related to outcome . Among cannabis users , frequent use , early-onset use and continued use after clinical presentation were associated with transition to psychosis OBJECTIVE Cannabis use has been found to increase the risk of psychosis .  It is unclear whether , after a first psychotic episode has occurred , continued cannabis use is associated with poor functional outcome of psychosis . METHOD As part of a r and omized , open-label , controlled trial , the association of cannabis use and measures for psychopathology and social role functioning after 2 years of follow-up and for the recently proposed outcome measures of symptomatic remission , functional remission , and clinical recovery was explored in a group of 124 patients suffering from nonaffective first-episode psychosis ( diagnosed according to DSM-IV and included from a catchment area in the Netherl and s of 3.1 million inhabitants from October 2001 through December 2002 ) . Other patient characteristics that were expected to be independently associated with outcome , among them alcohol and other drug use , were assessed at baseline . RESULTS Continued cannabis use was not associated with symptomatic or functional remission or clinical recovery . After 2 years , cannabis use was related to certain aspects of social role functioning ( economic and social activities ; explained variance 5.6 % and 8.4 % , respectively ) but not to psychopathology ( Positive and Negative Syndrome Scale Positive , Negative , or General symptoms ) . CONCLUSIONS Our findings support the notion that continued cannabis use after the onset of a first-episode psychosis is correlated with worse social outcome and should be discouraged whenever possible , but its role in outcome is modest in comparison to other factors . TRIAL REGISTRATION Nederl and s Trial Register : http://www.trialregister.nl ( ID : NTR 374 ) BACKGROUND Prospect i ve studies on the relationship between course of cannabis use and clinical outcome in patients with non-affective psychotic disorders are inconclusive . The current study examined whether ( 1 ) persistent , recently started , discontinued and non-cannabis-using patients with a psychotic disorder differed with regard to illness outcome at 3-year follow-up , and ( 2 ) whether timing of cannabis discontinuation was associated with course of clinical outcome . METHOD This 3-year follow-up study was part of a multi-center study in the Netherl and s and Belgium ( Genetic Risk and Outcome of Psychosis ; GROUP ) . We used mixed-model analyses to investigate the association between pattern of cannabis use and symptoms , global functioning and psychotic relapse . RESULTS In our sample of 678 patients , we found persistent users to have more positive and general symptoms , worse global functioning and more psychotic relapses compared with non-users and discontinued users [ Positive and Negative Syndrome Scale ( PANSS ) positive , p < 0.001 ; PANSS general , p < 0.001 ; Global Assessment of Functioning ( GAF ) symptoms , p = 0.017 ; GAF disability , p < 0.001 ; relapses , p = 0.038 ] . Patients who started using cannabis after study onset were characterized by worse functioning at baseline and showed an increase in general symptoms ( including depression and anxiety ) at the 3-year follow-up ( p = 0.005 ) . Timing of cannabis discontinuation was not associated with clinical outcome . CONCLUSIONS These findings suggest that cannabis use in patients with a psychotic disorder has a long-lasting negative effect on illness outcome , particularly when persistent . Treatment should focus on discouraging cannabis use Objective To determine whether use of cannabis in adolescence increases the risk for psychotic outcomes by affecting the incidence and persistence of sub clinical expression of psychosis in the general population ( that is , expression of psychosis below the level required for a clinical diagnosis ) . Design Analysis of data from a prospect i ve population based cohort study in Germany ( early developmental stages of psychopathology study ) . Setting Population based cohort study in Germany . Participants 1923 individuals from the general population , aged 14 - 24 at baseline . Main outcome measure Incidence and persistence of subthreshold psychotic symptoms after use of cannabis in adolescence .  Cannabis use and psychotic symptoms were assessed at three time points ( baseline , T2 ( 3.5 years ) , T3 ( 8.4 years ) ) over a 10 year follow-up period with the Munich version of the composite international diagnostic interview ( M-CIDI ) . Results In individuals who had no reported lifetime psychotic symptoms and no reported lifetime cannabis use at baseline , incident cannabis use over the period from baseline to T2 increased the risk of later incident psychotic symptoms over the period from T2 to T3 ( adjusted odds ratio 1.9 , 95 % confidence interval 1.1 to 3.1 ; P=0.021 ) . Furthermore , continued use of cannabis increased the risk of persistent psychotic symptoms over the period from T2 to T3 ( 2.2 , 1.2 to 4.2 ; P=0.016 ) . The incidence rate of psychotic symptoms over the period from baseline to T2 was 31 % ( 152 ) in exposed individuals versus 20 % ( 284 ) in non-exposed individuals ; over the period from T2 to T3 these rates were 14 % ( 108 ) and 8 % ( 49 ) , respectively . Conclusion Cannabis use is a risk factor for the development of incident psychotic symptoms . Continued cannabis use might increase the risk for psychotic disorder by impacting on the persistence of symptoms BACKGROUND There are inconsistencies in findings as to whether cannabis use has a negative impact on clinical outcomes for people with established psychosis . Effects may be more evident on patients with recent onset psychosis . AIM To investigate the relationship between cannabis use and clinical outcome , including whether change in cannabis use affects psychotic symptoms , affective symptoms , functioning and psychotic relapse in a sample of people in early psychosis with comorbid cannabis abuse or dependence . METHODS One hundred and ten participants were examined prospect ively with repeated measures of substance use antecedent to psychopathology at baseline , 4.5 , 9 , and 18 months . We used r and om intercept models to estimate the effects of cannabis dose on subsequent clinical outcomes and whether change in cannabis use was associated with change in outcomes . RESULTS There was no evidence of a specific association between cannabis use and positive symptoms , or negative symptoms , relapse or hospital admissions . However , a greater dose of cannabis was associated with subsequent higher depression and anxiety . Change in the amount of cannabis used was associated with statistically significant corresponding change in anxiety scores , but not depression . Additionally , reductions in cannabis exposure were related to improved patient functioning . CONCLUSIONS Reducing cannabis may be directly associated with improvements in anxiety and functioning , but not other specific symptoms BACKGROUND The aim was to examine the temporal relationships over 10 months between cannabis use and symptoms of psychosis and depression in people with schizophrenia and related disorders . The design was a prospect i ve study of 101 patients with schizophrenia and related disorders who were assessed monthly over 10 months on medication compliance , cannabis and other drug use , symptoms of depression and symptoms of psychosis . METHOD Linear regression methods to assess relationships between cannabis use and symptoms of psychosis and depression while adjusting for serial dependence , medication compliance and other demographic and clinical variables . RESULTS Cannabis use predicted a small but statistically significant increase in symptoms of psychosis , but not depression , after controlling for other differences between cannabis users and non-users . Symptoms of depression and psychosis did not predict cannabis use . CONCLUSION Continued cannabis use by persons with schizophrenia predicts a small increase in psychotic symptom severity but not vice versa BACKGROUND Cannabis use has been identified as a potent predictor of the earlier onset of psychosis , but meta- analysis has not indicated that it has a clear effect in established psychosis . AIM To assess the association between cannabis and outcomes , including whether change in cannabis use affects symptoms and functioning , in a large sample of people with established nonaffective psychosis and comorbid substance misuse . METHODS One hundred and sixty participants whose substance use included cannabis were compared with other substance users ( n = 167 ) on baseline demographic , clinical , and substance use variables . The cannabis using subgroup was examined prospect ively with repeated measures of substance use and psychopathology at baseline , 12 months , and 24 months . We used generalized estimating equation models to estimate the effects of cannabis dose on subsequent clinical outcomes and whether change in cannabis use was associated with change in outcomes . RESULTS Cannabis users showed cross-sectional differences from other substances users but not in terms of positive symptoms . Second , cannabis dose was not associated with subsequent severity of positive symptoms and change in cannabis dose did not predict change in positive symptom severity , even when patients became abstinent . However , greater cannabis exposure was associated with worse functioning , albeit with a small effect size . CONCLUSIONS We did not find evidence of an association between cannabis dose and psychotic symptoms , although greater cannabis dose was associated with worse psychosocial functioning , albeit with small effect size . It would seem that within this population , not everyone will demonstrate durable symptomatic improvements from reducing cannabis Recent reports show that fewer adolescents believe that regular cannabis use is harmful to health . Concomitantly , adolescents are initiating cannabis use at younger ages , and more adolescents are using cannabis on a daily basis . The purpose of the present study was to test the association between persistent cannabis use and neuropsychological decline and determine whether decline is concentrated among adolescent-onset cannabis users . Participants were members of the Dunedin Study , a prospect i ve study of a birth cohort of 1,037 individuals followed from birth ( 1972/1973 ) to age 38 y.  Cannabis use was ascertained in interviews at ages 18 , 21 , 26 , 32 , and 38 y.  Neuropsychological testing  was conducted at age 13 y , before initiation of cannabis use , and again at age 38 y , after a pattern of persistent cannabis use had developed . Persistent cannabis use was associated with neuropsychological decline broadly across domains of functioning , even after controlling for years of education . Informants also reported noticing more cognitive problems for persistent cannabis users . Impairment was concentrated among adolescent-onset cannabis users , with more persistent use associated with greater decline . Further , cessation of cannabis use did not fully restore neuropsychological functioning among adolescent-onset cannabis users . Findings are suggestive of a neurotoxic effect of cannabis on the adolescent brain and highlight the importance of prevention and policy efforts targeting adolescents OBJECTIVE We sought to examine the relation between cannabis abuse and the symptomatic course of recent-onset schizophrenia and related disorders . DESIGN A prospect i ve cohort study over a year using monthly Brief Psychiatric Rating Scale assessment s. PARTICIPANTS  Cannabis-abusing patients ( n = 24 ) were compared with nonabusers ( n = 69 ) . Eleven patients were mild and 13 were heavy cannabis-abusing patients . RESULTS Significantly more and earlier psychotic relapses occurred in the cannabis-abusing group ( P = .03 ) . This association became stronger when mild and heavy cannabis abuse were distinguished ( P = .002 ) . No confounding effect of other variables , eg , other street drugs , was found . In all but one patient , cannabis abuse preceded the onset of the first psychotic symptoms for at least 1 year . CONCLUSIONS Cannabis abuse and particularly heavy abuse can be considered a stressor eliciting relapse in patients with schizophrenia and related disorders and possibly a premorbid precipitant Papers pp 1195 , 1199 The strongest evidence that cannabis use may be a risk factor for later psychosis  comes from a Swedish cohort study which found that heavy cannabis use at age 18 increased the risk of later schizophrenia sixfold . 1 2 This study could not establish whether adolescent cannabis use was a consequence of pre-existing psychotic symptoms rather than a cause . We present the first prospect i ve longitudinal study of adolescent cannabis use as a risk factor for  adult schizophreniform disorder  , taking into account childhood psychotic symptoms3 antedating cannabis use . View this table : Association between  cannabis use in adolescence and schizophrenia and depressive symptoms and disorders at age 26 ( n=759 ) , controlling for childhood psychotic symptoms and use of other drugs in adolescence The Dunedin multidisciplinary health and development study ( a study of a general population birth cohort of 1037 individuals born in Dunedin , New Zeal and , in 1972 - 3)4 has a 96 % follow up rate at age 26 . It obtained information on psychotic symptoms at age 11 and drug use at ages 15 and 18 from self reports and assessed Not all individuals who smoke cannabis report psychotic-like experiences . Given that risk factors for psychotic disorders are multifaceted , precipitating factors to psychotic-like experiences after cannabis are likely to be equally complex . Reduced neurocognitive performance is associated with both psychosis risk and cannabis use . Therefore , it is possible cognitive performance may differentiate those who report psychotic-like experiences after cannabis from those who do not . We determined whether those reporting psychotic/dysphoric experiences after cannabis had reduced neurocognitive performance compared to those reporting primarily euphoric experiences . METHODS Participants were recruited on the basis of responses to the cannabis high captured by the Psychosis-Dysphoric and Euphoric experiences subscales from the Cannabis Experiences Question naire ( CEQ ) . RESULTS Compared to participants reporting primarily euphoric cannabis experiences ( n = 36 ; 44 % male ; mean age ( SD ) = 28 ( 9 ) years ) , those who reported psychotic/dysphoric experiences ( n = 40 ; 45 % male ; mean age ( SD ) = 26 ( 5 ) years ) demonstrated significantly faster responses to a trial and error learning task . In the presence of distracters , those with psychotic/dysphoric experiences after cannabis made more errors on a Continuous Performance Task . CONCLUSIONS Those who report psychotic/dysphoric experiences after cannabis have subtle inefficiencies in their cognitive processes . The multiple factors which predict vulnerability to psychotic-like experiences after cannabis require further investigation Background : Cannabis use has a negative impact on psychosis . Studies are needed to explore the efficacy of psychological interventions to reduce cannabis use in psychosis . Our aim is to study the efficacy of a specific motivational intervention on young cannabis users suffering from psychosis . Methods : Participants ( aged less than 35 years ) were r and omly assigned to treatment as usual ( TAU ) alone , or treatment as usual plus motivational intervention ( MI + TAU ) . TAU was comprehensive and included case management , early intervention and mobile team when needed . Assessment s were completed at baseline and at 3 , 6 and 12 months follow-up . Results : Sixty-two participants ( 32 TAU and 30 MI + TAU ) were included in the study .  Cannabis use decreased in both groups at follow-up . Participants who received MI in addition to TAU displayed both a greater reduction in number of joints smoked per week and greater confidence to change cannabis use at 3 and 6 months follow-up , but differences between groups were nonsignificant at 12 months . Conclusions : MI is well accepted by patients suffering from psychosis and has a short-term impact on cannabis use when added to st and ard care . However , the differential effect was not maintained at 1-year follow-up . MI appears to be a useful active component to reduce cannabis use which should be integrated in routine clinical practice BACKGROUND Patients who experience the onset of psychotic illness with a comorbid diagnosis of cannabis dependence experience poor clinical outcomes . Few studies have identified interventions that reduce cannabis use and improve clinical outcome in this population . AIMS We undertook a multi-center , r and omized controlled trial of a group psychological intervention for psychosis with comorbid cannabis dependence to determine whether there was any impact on cannabis use symptoms , global functioning , insight , attitudes to treatment and subjective quality of life . METHOD Across three centers , we compared a group psychological intervention , based on cognitive behavioral therapy and motivational interviewing , with treatment as usual among patients experiencing their first psychotic episode or early in the course of psychotic illness . Substance misuse and indices of clinical outcome were assessed at baseline , 3months and 1year . RESULTS At 3month and 1year follow-ups , there was no evidence for an intervention effect on cannabis use , symptoms , global functioning insight or attitude to treatment . However , the intervention improved subjective quality of life at 3months and this effect was sustained at 1year . CONCLUSIONS Over the early phase of psychotic illness , group psychological interventions for those with comorbid cannabis dependence improved subjective quality of life . However , this was not associated with reduction in use of cannabis or improvement in clinical outcomes BACKGROUND Research suggests that low- grade psychotic experiences in the general population are a common but transitory developmental phenomenon . Using two independent general population sample s , the hypothesis was examined that common , non- clinical developmental expression of psychosis may become abnormally persistent when synergistically combined with developmental exposures that may impact on behavioural and neurotransmitter sensitization such as cannabis , trauma and urbanicity . METHOD The amount of synergism was estimated from the additive statistical interaction between baseline cannabis use , childhood trauma and urbanicity on the one h and , and baseline psychotic experiences on the other , in predicting 3-year follow-up psychotic experiences , using data from two large , longitudinal , r and om population sample s from the Netherl and s [ The Netherl and s Mental Health Survey and Incidence Study ( NEMESIS ) ] and Germany [ The Early Developmental Stages of Psychopathology ( EDSP ) study ] . RESULTS The 3-year persistence rates of psychotic experiences were low at 26 % in NEMESIS and 31 % in EDSP . However , persistence rates were progressively higher with greater baseline number of environmental exposures in predicting follow-up psychotic experiences ( chi2=6.9 , df=1 , p=0.009 in NEMESIS and chi2=4.2 , df=1 , p=0.04 in EDSP ) . Between 21 % and 83 % ( NEMESIS ) and 29 % and 51 % ( EDSP ) of the subjects exposed to both environmental exposures and psychotic experiences at baseline had persistence of psychotic experiences at follow-up because of the synergistic action of the two factors . CONCLUSION The findings suggest that environmental risks for psychosis act additively , and that the level of environmental risk combines synergistically with non- clinical developmental expression of psychosis to cause abnormal persistence and , eventually , need for care BACKGROUND Cannabis use is common in patients with bipolar disorder , however little is known about cannabis as a risk factor for mania . In order to investigate the association between exposure to cannabis and subsequent development of manic symptoms whilst controlling for psychotic symptoms , a longitudinal population -based study was carried out . METHODS 4815 individuals aged 18 to 64 years were interviewed using the Composite International Diagnostic Interview at baseline , 1 year follow up and 3 year follow up , including assessment of substance use , manic symptoms and psychotic symptoms . RESULTS Use of cannabis at baseline increased the risk for manic symptoms during follow-up ( adjusted OR 2.70 , 95 % CI : 1.54 , 4.75 ) , adjusted for age , sex , educational level , ethnicity , single marital status , neuroticism , use of other drugs , use of alcohol , depressive symptoms and manic symptoms at baseline . The association between cannabis use and mania was independent of the prevalence and the incidence of psychotic symptoms . There was no evidence for reverse causality , as manic symptoms at baseline did not predict the onset of cannabis use during follow-up ( OR = 0.35 , 95 % CI : 0.03 , 3.49 ) . LIMITATIONS As 3 years is a relative short period of follow-up , long-term effects of cannabis use on mania outcomes could not be detected . CONCLUSION The results suggest that cannabis use may affect population expression of manic symptoms ( and subsequent risk to develop bipolar disorder [ Regeer , E.J. , Krabbendam , L. , R , DE Graaf , Ten Have , M. , Nolen , W.A. , Van Os , J. , 2006 . A prospect i ve study of the transition rates of subthreshold (hypo)mania and depression in the general population . Psychol Med , 1 - 9 . ] ) . These findings may not be due to the emergence of psychotic symptoms or the effects of self-medication BACKGROUND Findings on the impact of cannabis use on the course of schizophrenia are inconsistent and not conclusive . AIMS To study the effect of cannabis use on the course of schizophrenia taking into account the effects of the quantity of cannabis use and important confounders . METHODS Prospect i ve cohort study with assessment s of symptoms , confounders and hospitalizations at baseline , 6 month and 12 month follow up . RESULTS In a representative cohort of 145 male patients with schizophrenia , 68 ( 46.9 % ) used cannabis .  Mean age at onset of schizophrenia in cannabis using patients was significantly lower than in non-cannabis using patients . No other cross-sectional demographic or clinical differences were observed between users and non-users . In a series of longitudinal analyses , cannabis use was not associated with differences in psychopathology , but relapse in terms of the number of hospitalizations was significantly higher in cannabis using patients compared to non-cannabis using patients . CONCLUSIONS Patients with schizophrenia using cannabis are more frequently hospitalized than non-cannabis using patients but do not differ with respect to psychopathology . Possible explanations for these findings are discussed
INTERPRETATION Continued cannabis use after onset of psychosis predicts adverse outcome , including higher relapse rates , longer hospital admissions , and more severe positive symptoms than for individuals who discontinue cannabis use and those who are non-users .
BACKGROUND Although the link between cannabis use and development of psychosis is well established , less is known about the effect of continued versus discontinued cannabis use after the onset of psychosis .
We aim ed to summarise available evidence focusing on the relationship between continued and discontinued cannabis use after onset of psychosis and its relapse .