Psychosis reactivity to cannabis use in daily life: an experience sampling study

The relationship between bipolar disorder and cannabis use in daily life: an experience sampling study

Objectives

Although cannabis use is common in bipolar disorder and may contribute to worse clinical outcomes, little is understood about the relationship between this drug and bipolar disorder over the course of daily life. The aim of study was to examine the effect of cannabis on affect and bipolar symptoms in a group of individuals with bipolar disorder.

Methods

Twenty-four participants with bipolar disorder type I or type II completed diaries for 6 days using Experience Sampling Methodology to investigate the temporal associations between cannabis, affect and bipolar disorder symptoms.

Results

The results indicated that higher levels of positive affect increase the odds of using cannabis (OR:1.25 ,CI:1.06–1.47, P=0.008). However, neither negative affect, manic nor depressive symptoms predicted the use of cannabis. Cannabis use was associated with subsequent increases in positive affect (β=0.35, CI:0.20-0.51, P=0.000), manic symptoms (β=0.20,CI:0.05-0.34, P=0.009) and depressive symptoms (β= 0.17,CI:0.04-0.29, P=0.008).

Conclusion

The findings indicate that cannabis use is associated with a number of subsequent psychological effects. However there was no evidence that individuals with BD were using cannabis to self-medicate minor fluctuations in negative affect or bipolar disorder symptoms over the course of daily life. The findings in relation to existing literature and clinical implications are discussed.

Psychedelic symptoms of cannabis and cocaine use as a function of trait impulsivity

Trait impulsivity has been linked to addiction in humans. It has been suggested that drug users with high trait impulsivity levels are more sensitive to subjective drug intoxication. This study assessed whether subjective response to drugs differs between drug users with normal or high levels of trait impulsivity. Regular drug users (N = 122) received doses of cocaine HCl, cannabis, and placebo in a three-way crossover study. Their mood, dissociative state, and psychedelic symptoms were measured with subjective rating scales (CADDS, Bowdle, POMS). Trait impulsivity was assessed with the Barratt Impulsiveness Scale. Cannabis increased dissociation and psychedelic state, as well as fatigue, confusion, depression and anxiety, and decreased arousal, positive mood, vigor, friendliness, and elation. Cocaine increased dissociation, psychedelic state, vigor, friendliness, elation, positive mood, anxiety and arousal, while decreasing fatigue. Only a few subjective items revealed a drug × trait impulsivity interaction, suggesting that psychedelic symptoms were most intense in high impulsivity subjects. Trait impulsiveness ratings were negatively correlated with ratings of vigor (r = -.197) and positively correlated with ratings of loss of thought control (r = .237) during cannabis intoxication. It is concluded that a broad association between trait impulsivity and psychedelic subjective drug experience appears to be absent.

To center or not to center? Investigating inertia with a multilevel autoregressive model

Whether level 1 predictors should be centered per cluster has received considerable attention in the multilevel literature. While most agree that there is no one preferred approach, it has also been argued that cluster mean centering is desirable when the within-cluster slope and the between-cluster slope are expected to deviate, and the main interest is in the within-cluster slope. However, we show in a series of simulations that if one has a multilevel autoregressive model in which the level 1 predictor is the lagged outcome variable (i.e., the outcome variable at the previous occasion), cluster mean centering will in general lead to a downward bias in the parameter estimate of the within-cluster slope (i.e., the autoregressive relationship). This is particularly relevant if the main question is whether there is on average an autoregressive effect. Nonetheless, we show that if the main interest is in estimating the effect of a level 2 predictor on the autoregressive parameter (i.e., a cross-level interaction), cluster mean centering should be preferred over other forms of centering. Hence, researchers should be clear on what is considered the main goal of their study, and base their choice of centering method on this when using a multilevel autoregressive model.

Three-Year Course of Cannabis Dependence and Prediction of Persistence

AIMS

To examine the course and the predictors of the persistence of cannabis dependence.

METHODS

Through cannabis outlets and chain referral, a prospective enriched community cohort of 207 young adults (aged 18-30) with DSM-IV cannabis dependence at baseline (T0) was formed and followed-up after 1.5 (T1) and 3 (T2) years. The presence of cannabis dependence, cannabis-related problems, functional impairment and treatment was assessed using the Composite International Diagnostic Interview (CIDI 3.0) and the Sheehan Disability Scale (SDS). Predictors of persistence were lifetime cannabis abuse and dependence symptoms, cannabis use characteristics, distant vulnerability factors (e.g. childhood adversity, family history of psychological/substance use problems, impulsivity, mental disorders), and proximal stress factors (recent life events, social support).

RESULTS

Four groups were distinguished: persistent dependent (DDD: 28.0%), stable non-persistent (DNN: 40.6%), late non-persistent (DDN: 17.9%) and recurrent dependent (DND: 13.5%). At T2, persisters (DDD) reported significantly more (heavy) cannabis use and cannabis problems than non-persisters (DNN/DDN/DND). Treatment seeking for cannabis-related problems was rare, even among persisters (15.5%). The number (OR = 1.23 (1.03-1.48)) and type ('role impairment' OR = 2.85 (1.11-7.31), 'use despite problems' OR = 2.34 (1.15-4.76)) of lifetime cannabis abuse/dependence symptoms were the only independent predictors of persistence with a total explained variance of 8.8%.

CONCLUSIONS

Persistence of cannabis dependence in the community is low, difficult to predict, and associated with a negative outcome. The substantial proportion of stable non-persisters suggests that screening and monitoring or low-threshold brief interventions may suffice for many non-treatment-seeking cannabis-dependent people. However, those with many lifetime abuse/dependence symptoms may benefit from more intensive interventions.

Testing an mHealth momentary assessment Routine Outcome Monitoring application: a focus on restoration of daily life positive mood states

BACKGROUND

Routine Outcome Monitoring (ROM) is used as a means to enrich the process of treatment with feedback on patient outcomes, facilitating patient involvement and shared decision making. While traditional ROM measures focus on retrospective accounts of symptoms, novel mHealth technology makes it possible to collect real life, in-the-moment ambulatory data that allow for an ecologically valid assessment of personalized and contextualized emotional and behavioural adjustment in the flow daily life (mROM).

METHOD

In a sample of 34 patients with major depressive disorder, treated with antidepressants, the combined effect of treatment and natural course was examined over a period of 18 weeks with Ecological Momentary Assessment (EMA). EMA consisted of repeated, within-subject, mini-measurements of experience (eg positive affect, negative affect, medication side effects) and context (eg stressors, situations, activities) at 10 unselected semi-random moments per day, for a period of six days, repeated three times over the 18-week period (baseline, week 6 and week 18).

RESULTS

EMA measures of emotional and behavioural adjustment were sensitive to the effects of treatment and natural course over the 18-week period, particularly EMA measures focussing on positive mood states and the ability to use natural rewards (impact of positive events on positive mood states), with standardized effect sizes of 0.4-0.5. EMA measures of activities, social interaction, stress-sensitivity and negative mood states were also sensitive to change over time.

CONCLUSION

This study supports the use of mROM as a means to involve the patient in the process of needs assessment and treatment. EMA data are meaningful to the patient, as they reflect daily life circumstances. Assessment of treatment response with mROM data allows for an interpretation of the effect of treatment at the level of daily life emotional and social adjustment--as an index of health, obviating the need for an exclusive focus on traditional measures of 'sickness'.

The Cannabis Pathway to Non-Affective Psychosis may Reflect Less Neurobiological Vulnerability

There is a high prevalence of cannabis use reported in non-affective psychosis. Early prospective longitudinal studies conclude that cannabis use is a risk factor for psychosis, and neurochemical studies on cannabis have suggested potential mechanisms for this effect. Recent advances in the field of neuroscience and genetics may have important implications for our understanding of this relationship. Importantly, we need to better understand the vulnerability × cannabis interaction to shed light on the mediators of cannabis as a risk factor for psychosis. Thus, the present study reviews recent literature on several variables relevant for understanding the relationship between cannabis and psychosis, including age of onset, cognition, brain functioning, family history, genetics, and neurological soft signs (NSS) in non-affective psychosis. Compared with non-using non-affective psychosis, the present review shows that there seem to be fewer stable cognitive deficits in patients with cannabis use and psychosis, in addition to fewer NSS and possibly more normalized brain functioning, indicating less neurobiological vulnerability for psychosis. There are, however, some familiar and genetic vulnerabilities present in the cannabis psychosis group, which may influence the cannabis pathway to psychosis by increasing sensitivity to cannabis. Furthermore, an earlier age of onset suggests a different pathway to psychosis in the cannabis-using patients. Two alternative vulnerability models are presented to integrate these seemingly paradoxical findings.

Impaired functional connectivity of brain reward circuitry in patients with schizophrenia and cannabis use disorder: Effects of cannabis and THC

Cannabis use disorder (CUD) occurs in up to 42% of patients with schizophrenia and substantially worsens disease progression. The basis of CUD in schizophrenia is unclear and available treatments are rarely successful at limiting cannabis use. We have proposed that a dysregulated brain reward circuit (BRC) may underpin cannabis use in these patients. In the present pilot study, we used whole-brain seed-to-voxel resting state functional connectivity (rs-fc) to examine the BRC of patients with schizophrenia and CUD, and to explore the effects of smoked cannabis and orally administered delta-9-tetrahydrocannabinol (THC) on the BRC. 12 patients with schizophrenia and CUD and 12 control subjects each completed two fMRI resting scans, with patients administered either a 3.6% THC cannabis cigarette (n=6) or a 15 mg THC capsule (n=6) prior to their second scan. Results revealed significantly reduced connectivity at baseline in patients relative to controls, with most pronounced hypoconnectivity found between the nucleus accumbens and prefrontal cortical BRC regions (i.e., anterior prefrontal cortex, orbitofrontal cortex, and anterior cingulate cortex). Both cannabis and THC administration increased connectivity between these regions, in direct correlation with increases in plasma THC levels. This study is the first to investigate interregional connectivity of the BRC and the effects of cannabis and THC on this circuit in patients with schizophrenia and CUD. The findings from this pilot study support the use of rs-fc as a means of measuring the integrity of the BRC and the effects of pharmacologic agents acting on this circuit in patients with schizophrenia and CUD.

Cognitive functioning associated with stimulant use in patients with non-affective psychosis, their unaffected siblings and healthy controls

BACKGROUND

Little is known about the effect of stimulant use (amphetamines, cocaine, ecstasy) on cognitive functioning in schizophrenia patients. The current study examined (1) whether recency and frequency of stimulant use is associated with cognitive functioning and (2) whether these associations differ between psychotic patients, their unaffected siblings and controls.

METHOD

Participants completed a comprehensive cognitive test battery. Stimulant use was assessed by urinalysis and by the Composite International Diagnostic Interview (CIDI). Using random effects regression models, the main effects of Stimulant Use and the interaction with Diagnostic Status on cognitive functioning were assessed.

RESULTS

The interaction term between Stimulant Use and Diagnostic Status was not significant for any of the cognitive outcome variables, indicating similar effects of stimulant use in all three groups. Recent stimulant users showed more errors deficit in verbal learning in comparison to never users (Cohen's d = -0.60, p < 0.005). Lifetime frequent stimulant use was significantly associated with worse immediate and delayed verbal recall, working memory and acquired knowledge (Cohen's d = -0.22 to -0.29, p < 0.005). Lifetime infrequent stimulant use was not associated with significant cognitive alterations in comparison to never use.

CONCLUSIONS

The presence of cognitive deficits associated with lifetime stimulant use is dependent on the frequency of use, with no observed deficits in infrequent users and modest negative effects in frequent users.

The effect of drug use on the age at onset of psychotic disorders in an Australian cohort

BACKGROUND

We aimed to examine the association between illicit substance use and age at onset in psychotic disorders in an Australian cohort.

METHODS

Retrospectively acquired information on substance use during the year prior to illness onset was collected from 1642 participants enrolled in the Australian National 2010 Survey of High Impact Psychosis study (SHIP), with an ICD-10 diagnosis of schizophrenia spectrum or affective psychosis. Latent class analysis was performed according to illicit substance use, using age as an active covariate; identified classes were subsequently validated. Cox regression was used to examine the independent contribution of the identified substance use classes and several confounding variables to the prediction of age at onset of psychosis.

RESULTS

Three classes according to substance use were identified: non-users (n=803), cannabis predominant users (n=582), and polysubstance users (n=257). For participants with schizophrenia spectrum disorders, cannabis predominant users had a higher hazard of earlier age at onset than for non-users (adjusted HR=1.38, 95% CI=1.2-1.6); polysubstance users had an even higher hazard (adjusted HR=1.95, 95% CI=1.5-2.4). In contrast, for participants with affective psychosis, cannabis predominant users (adjusted HR=1.10, 95% CI=0.8-1.4) and polysubstance users (adjusted HR=0.87, 95% CI=0.6-1.3) did not have a higher hazard of earlier age at onset compared with non-users.

CONCLUSIONS

Illicit substance use in the 12 months prior to psychosis onset has a differential effect on age at onset in schizophrenia spectrum and affective psychotic disorders. Our findings are compatible with the notion that illicit drugs bring forward age at onset in schizophrenia spectrum disorders but not affective psychotic disorders.

Profiling the subjective effects of Δ⁹-tetrahydrocannabinol using visual analogue scales

The subjective effects of cannabis and its main psychoactive component Δ(9) -tetrahydrocannabinol (THC) have played an important part in determining the therapeutic potential of cannabinoid agonists and antagonists. The effects mainly consist of feeling high, changes in perception, feelings of relaxation and occasionally dysphoric reactions. These effects are captured by two of the most frequently used visual analogue scales (VASs) in clinical (pharmacologic) research to measure subjective effects: VAS Bond and Lader (alertness, calmness and mood) and VAS Bowdle (psychedelic effects). In this analysis, the effects of THC on these VASs were compared within a total of 217 subjects who participated in 10 different studies. Not surprisingly, the item feeling high was found to be the best predictor for the effect of THC. Three separate clusters that describe the spectrum of subjective effects of THC were identified using different statistical methods, consisting of VAS "time", "thoughts" and "high" ("perception"), VAS "drowsy", "muzzy", "mentally slow" and "dreamy" ("relaxation") and VAS "voices", "meaning" and "suspicious" ("dysphoria"). These results provide experimental evidence that THC can evoke different classes of effects. These distinct subjective clusters could represent effects on various systems in the brain, which can be used to further differentiate the involvement of endocannabinoid systems in health and disease.

Evidence that a psychopathology interactome has diagnostic value, predicting clinical needs: an experience sampling study

BACKGROUND

For the purpose of diagnosis, psychopathology can be represented as categories of mental disorder, symptom dimensions or symptom networks. Also, psychopathology can be assessed at different levels of temporal resolution (monthly episodes, daily fluctuating symptoms, momentary fluctuating mental states). We tested the diagnostic value, in terms of prediction of treatment needs, of the combination of symptom networks and momentary assessment level.

METHOD

Fifty-seven patients with a psychotic disorder participated in an ESM study, capturing psychotic experiences, emotions and circumstances at 10 semi-random moments in the flow of daily life over a period of 6 days. Symptoms were assessed by interview with the Positive and Negative Syndrome Scale (PANSS); treatment needs were assessed using the Camberwell Assessment of Need (CAN).

RESULTS

Psychotic symptoms assessed with the PANSS (Clinical Psychotic Symptoms) were strongly associated with psychotic experiences assessed with ESM (Momentary Psychotic Experiences). However, the degree to which Momentary Psychotic Experiences manifested as Clinical Psychotic Symptoms was determined by level of momentary negative affect (higher levels increasing probability of Momentary Psychotic Experiences manifesting as Clinical Psychotic Symptoms), momentary positive affect (higher levels decreasing probability of Clinical Psychotic Symptoms), greater persistence of Momentary Psychotic Experiences (persistence predicting increased probability of Clinical Psychotic Symptoms) and momentary environmental stress associated with events and activities (higher levels increasing probability of Clinical Psychotic Symptoms). Similarly, the degree to which momentary visual or auditory hallucinations manifested as Clinical Psychotic Symptoms was strongly contingent on the level of accompanying momentary paranoid delusional ideation. Momentary Psychotic Experiences were associated with CAN unmet treatment needs, over and above PANSS measures of psychopathology, similarly moderated by momentary interactions with emotions and context.

CONCLUSION

The results suggest that psychopathology, represented as an interactome at the momentary level of temporal resolution, is informative in diagnosing clinical needs, over and above traditional symptom measures.

Gone to Pot - A Review of the Association between Cannabis and Psychosis

Cannabis is the most commonly used illicit drug worldwide, with ~5 million daily users worldwide. Emerging evidence supports a number of associations between cannabis and psychosis/psychotic disorders, including schizophrenia. These associations-based on case-studies, surveys, epidemiological studies, and experimental studies indicate that cannabinoids can produce acute, transient effects; acute, persistent effects; and delayed, persistent effects that recapitulate the psychopathology and psychophysiology seen in schizophrenia. Acute exposure to both cannabis and synthetic cannabinoids (Spice/K2) can produce a full range of transient psychotomimetic symptoms, cognitive deficits, and psychophysiological abnormalities that bear a striking resemblance to symptoms of schizophrenia. In individuals with an established psychotic disorder, cannabinoids can exacerbate symptoms, trigger relapse, and have negative consequences on the course of the illness. Several factors appear to moderate these associations, including family history, genetic factors, history of childhood abuse, and the age at onset of cannabis use. Exposure to cannabinoids in adolescence confers a higher risk for psychosis outcomes in later life and the risk is dose-related. Individuals with polymorphisms of COMT and AKT1 genes may be at increased risk for psychotic disorders in association with cannabinoids, as are individuals with a family history of psychotic disorders or a history of childhood trauma. The relationship between cannabis and schizophrenia fulfills many but not all of the standard criteria for causality, including temporality, biological gradient, biological plausibility, experimental evidence, consistency, and coherence. At the present time, the evidence indicates that cannabis may be a component cause in the emergence of psychosis, and this warrants serious consideration from the point of view of public health policy.

Is psychotic disorder associated with increased levels of craving for cannabis? An Experience Sampling study

OBJECTIVE

Although cannabis use among individuals with psychotic disorder is considerable, little is known about patterns of use and factors contributing to continuation of use. Therefore, we investigated craving in relation to cannabis use in patients with psychotic disorder and healthy controls.

METHOD

The study included 58 patients with non-affective psychotic disorder and 63 healthy controls; all were frequent cannabis users. Craving was assessed with the Obsessive Compulsive Drug Use Scale (OCDUS) for cannabis, as well as in daily life using the Experience Sampling Method (ESM).

RESULTS

Patients scored higher on the OCDUS (B = 1.18, P = 0.022), but did not differ from controls in ESM indices of craving (all P > 0.05). In daily life, ESM craving predicted cannabis use and this was stronger in controls (χ(2) = 4.5, P = 0.033; Bcontrols = 0.08, P < 0.001; Bpatients = 0.06, P < 0.001). In both groups ESM craving was predicted by negative affect, paranoia, and hallucinations (Bnegativeaffect = 0.12, P = 0.009; Bparanoia = 0.13, P = 0.013; Bhallucinations = 0.13, P = 0.028), and followed by an increase in negative affect at non-cannabis-using moments (B = 0.03, P = 0.002).

CONCLUSION

The temporal dynamics of craving as well as craving intensity in daily life appear to be similar in patients and controls. Further research is needed to elucidate the inconsistencies between cross-sectional and daily-life measures of craving in psychosis.

Duration of untreated psychosis in adolescents: ethnic differences and clinical profiles

BACKGROUND

Duration of Untreated Psychosis (DUP) is an important measure associated with outcome of psychosis. This first study in the UK compared DUP between adolescent and adult-onset individuals and explored whether the adolescent-onset group showed variations in DUP that could be accounted for by sociodemographic and selected risk factors.

METHODS

This naturalistic cohort study included 940 new first-episode psychosis cases aged 14-35years (136 adolescent-onset versus 804 adult-onset psychotic individuals) referred to nine Early Intervention Services for Psychosis in London (2003-2009). Sociodemographic characteristics, age of onset, family history of mental illness, duration of untreated psychosis, suicidality and substance use information were collected at entry to the services.

RESULTS

Adolescents presented with significantly greater median DUP (179days) than adults (81days, p=0.005). Large differences in DUP were found amongst adolescent ethnic groups (median DUP: White: 454days; Black: 103days; Asian and mixed: 28.5days). In addition, younger age of onset and higher lifetime cannabis use were associated with longer treatment delay amongst adolescents.

CONCLUSIONS

This study of DUP in adolescent-onset psychosis found it to be approximately twice the length of DUP amongst adults. For the adolescent White sub-group, DUP was far greater than the UK Department of Health target (<3months). Both the high rates of lifetime cannabis use and the lower age of onset might explain the long DUP in this ethnic group. Physicians need to be particularly vigilant about identifying and managing early psychosis in adolescents.

Dose-response effect between cannabis use and psychosis liability in a non-clinical population: evidence from a snowball sample

This study aimed to explore the associations between daily cannabis use and the specific profiles of subclinical symptoms in a non-clinical population obtained through snowball sampling, taking into account alcohol use, other drug use, social exclusion and age at onset of cannabis use. We included 85 daily cannabis users and 100 non-daily cannabis users. Both the case and the control populations were identified by snowball sampling. Daily cannabis use was associated with more alcohol intake and other drug use, as well as with early onset in the use of cannabis. Daily cannabis use appeared to exert a dose-response effect on first-rank symptoms, mania symptoms and auditory hallucinations, even after adjusting for sex, age, other drug use, social exclusion and age at onset of cannabis use. The paranoid dimension was only associated with the heaviest consumption of cannabis. Initial age of cannabis use modified the effects of daily cannabis use on the first-rank and voices experiences. Daily cannabis use was associated with significantly more first-rank and voices experiences among those subjects who started to use cannabis before 17 years of age. Our study supports the association of psychotic experiences with cannabis use even among non-psychotic subjects.

Delta-9-tetrahydrocannabinol-induced dopamine release as a function of psychosis risk: 18F-fallypride positron emission tomography study

Cannabis use is associated with psychosis, particularly in those with expression of, or vulnerability for, psychotic illness. The biological underpinnings of these differential associations, however, remain largely unknown. We used Positron Emission Tomography and (18)F-fallypride to test the hypothesis that genetic risk for psychosis is expressed by differential induction of dopamine release by Δ(9)-THC (delta-9-tetrahydrocannabinol, the main psychoactive ingredient of cannabis). In a single dynamic PET scanning session, striatal dopamine release after pulmonary administration of Δ(9)-THC was measured in 9 healthy cannabis users (average risk psychotic disorder), 8 patients with psychotic disorder (high risk psychotic disorder) and 7 un-related first-degree relatives (intermediate risk psychotic disorder). PET data were analyzed applying the linear extension of the simplified reference region model (LSRRM), which accounts for time-dependent changes in (18)F-fallypride displacement. Voxel-based statistical maps, representing specific D2/3 binding changes, were computed to localize areas with increased ligand displacement after Δ(9)-THC administration, reflecting dopamine release. While Δ(9)-THC was not associated with dopamine release in the control group, significant ligand displacement induced by Δ(9)-THC in striatal subregions, indicative of dopamine release, was detected in both patients and relatives. This was most pronounced in caudate nucleus. This is the first study to demonstrate differential sensitivity to Δ(9)-THC in terms of increased endogenous dopamine release in individuals at risk for psychosis.

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.

Genes and environments in schizophrenia: The different pieces of a manifold puzzle

Genetic research targeting schizophrenia has undergone tremendous development during recent years. Supported by recently developed high-throughput genotyping technologies, both rare and common genetic variants have been identified that show consistent association with schizophrenia. These results have been replicated by independent studies and refined in meta-analyses. The genetic variation uncovered consists of common alleles, i.e. single nucleotide polymorphisms (SNPs) conveying small effects (odds ratios below 1.1) on disease risk. The source of rare variants is copy number variations (CNVs), only detectable in a small proportion of patients (3-5% for all known CNVs) with schizophrenia, furthermore extremely rare de novo mutations captured by next generation sequencing, the most recent technological advancement in the field. Despite these findings, the search for the genetic architecture underlying schizophrenia continues since these variants explain only a small proportion of the overall phenotypic variance. Gene-environment interactions provide a compelling model for resolving this paradox and interpreting the risk factors of schizophrenia. Epidemiologically proven risk factors, such as prenatal infection, obstetric complications, urbanicity, cannabis, and trauma have been demonstrated to interact with genetic risk, giving rise to higher prevalence rates or more severe symptomatology in individuals with direct or indirect genetic predisposition for schizophrenia. Further research will have to explain how the different forms of genetic variation interact and how environmental factors modulate their effects. Moreover, the challenging question lying ahead of us is how genetic and environmental factors translate to molecular disease pathways. New approaches, including animal studies and in vitro disease modeling, as well as innovative real-world environment assessment methods, will help to understand the complex etiology of schizophrenia.

Cannabis and psychosis: what causes what?

Converging lines of evidence suggest that cannabinoids can produce a full range of transient schizophrenia-like positive, negative and cognitive symptoms. Cannabinoids also produce some psychophysiological deficits also known to be present in schizophrenia. It is also clear that, in individuals with an established psychotic disorder, cannabinoids can exacerbate symptoms, trigger relapse, and have negative consequences on the course of the illness. Increasing evidence suggests that early and heavy cannabis exposure may increase the risk of developing a psychotic disorder such as schizophrenia. The relationship between cannabis exposure and schizophrenia fulfills some, but not all, of the usual criteria for causality. However, most people who use cannabis do not develop schizophrenia, and many people diagnosed with schizophrenia have never used cannabis. Therefore, it is likely that cannabis exposure is a “component cause” that interacts with other factors to “cause” schizophrenia or other psychotic disorders, but is neither necessary nor sufficient to do so alone. Further work is necessary to identify the factors that underlie individual vulnerability to cannabinoid-related psychosis and to elucidate the biological mechanisms underlying this risk.

Prospective study of cannabis use in adolescents at clinical high risk for psychosis: impact on conversion to psychosis and functional outcome

BACKGROUND

Clinical and epidemiological studies suggest an association between cannabis use and psychosis but this relationship remains controversial.

METHOD

Clinical high-risk (CHR) subjects (age 12-22 years) with attenuated positive symptoms of psychosis (CHR+, n=101) were compared to healthy controls (HC, n=59) on rates of substance use, including cannabis. CHR+ subjects with and without lifetime cannabis use (and abuse) were compared on prodromal symptoms and social/role functioning at baseline. Participants were followed an average of 2.97 years to determine psychosis conversion status and functional outcome.

RESULTS

At baseline, CHR+ subjects had significantly higher rates of lifetime cannabis use than HC. CHR+ lifetime cannabis users (n=35) were older (p=0.015, trend), more likely to be Caucasian (p=0.002), less socially anhedonic (p<0.001) and had higher Global Functioning: Social (GF:Social) scores (p<0.001) than non-users (n=61). CHR+ cannabis users continued to have higher social functioning than non-users at follow-up (p<0.001) but showed no differences in role functioning. A small sample of CHR+ cannabis abusers (n=10) showed similar results in that abusers were older (p=0.008), less socially anhedonic (p=0.017, trend) and had higher baseline GF:Social scores (p=0.006) than non-abusers. Logistic regression analyses revealed that conversion to psychosis in CHR+ subjects (n=15) was not related to lifetime cannabis use or abuse.

CONCLUSIONS

The current data do not indicate that low to moderate lifetime cannabis use is a major contributor to psychosis or poor social and role functioning in clinical high-risk youth with attenuated positive symptoms of psychosis.

Medication adherence mediates the impact of sustained cannabis use on symptom levels in first-episode psychosis

Both medication non-adherence and co-morbid cannabis abuse are associated with poor clinical outcome in first episode psychosis (FEP). The nature of interaction between adherence to medication and continued cannabis use remains unexplored. The objectives of this study were to examine variation in medication adherence associated with cessation or continuation of cannabis use, and to determine the impact of interaction between cannabis use and adherence to medication on symptom outcome at 12 months. From a consecutive patient cohort (N=192) with a DSM-IV diagnosis of a FEP, 62 patients who met DSM-IV criteria for a currently active cannabis abuse disorder were followed up for one year. Complete data on repeated measures of medication adherence, symptoms, and cannabis use were available for 48 of the 62 patients. Twenty-eight patients (58.7%) continued while 20 (41.2%) stopped cannabis use after entering treatment. While both groups were relatively non-adherent at six months, 25/28 (92%) of the former group became adherent compared to 8/20 (40%) of those who stopped cannabis use (p<.01). While there was no overall effect of continued cannabis use on symptom levels at 12 months, after controlling for medication adherence patients with continuous cannabis use had significantly higher level of symptoms (F(1,30)=2.74, p=0.03). FEP patients with an active cannabis use disorder may make a choice of either stopping cannabis and not taking medications or continuing cannabis but becoming more adherent to medications, adherence to medication appears to help both groups but continuous users remain at higher risk of poor symptom outcome even while on medication.

A video ethnography approach to assessing the ecological validity of neurocognitive and functional measures in severe mental illness: results from a feasibility study

BACKGROUND

The ecological validity of neurocognitive and functional measures in severe mental illness is poorly understood because of a lack of validated research methods to study community life-as-lived. We describe the development of a video ethnography method that measures naturalistic behaviors with codes called community performance indicators (CPIs). The method could provide a strategy to test the ecological validity of neurocognitive and functional assessments.

METHODS

We gathered up to 18.5 hours of video ethnography data on each of 9 subjects with schizophrenia selected for high or low composite scores on the MATRICS Consensus Cognitive Battery (MCCB). We used video ethnography to capture subjects' everyday behaviors in their usual environments. We established 4 CPIs that showed excellent inter-rater and promising test-retest reliability: (1) behavioral activity level, (2) goal pursuit, (3) social interaction, and (4) problem solving.

RESULTS

(1) High and low MCCB subjects showed statistically significantly differences on all 4 CPIs. (2) MCCB composite scores were correlated with all 4 CPIs (r = .54 to -.77, P < .01 to .07). (3) The MCCB domain scores demonstrated some specificity in their correlations with the CPIs; eg, verbal learning, reasoning/problem solving, and social cognition were correlated with CPI domains of social interaction and problem solving.

CONCLUSIONS

We present a method for reliably measuring everyday functional performance in schizophrenia. Results from a small select sample suggest that CPIs capture skills associated with neurocognition, supporting their use in a larger study of ecological validity.

Mobile assessment guide for research in schizophrenia and severe mental disorders

Mobile assessment techniques have been used for nearly 3 decades in mental health research, including in investigations of individuals with schizophrenia and other severe disorders. This article reviews the benefits of these data collection strategies relative to traditional self-report or clinician-administered measures administered in hospital or laboratory settings. A detailed discussion of the technical decisions facing researchers in the field is then presented, covering study design issues, questionnaire content development, and choices in hardware and software selection. Following these points, sample recruitment and retention strategies are discussed, as well as the main statistical issues that are necessary to consider in the exploitation of repeated measures data generated by this methodology.

Mobile assessment in schizophrenia: a data-driven momentary approach

In this article, a data-driven approach was adopted to demonstrate how real-life diary techniques [ie, the experience sampling method (ESM)] could be deployed for assessment purposes in patients with psychotic disorder, delivering individualized and clinically relevant information. The dataset included patients in an acute phase of psychosis and the focus was on paranoia as one of the main psychotic symptoms (30 patients with high levels of paranoia and 34 with low levels of paranoia). Based on individual cases, it was demonstrated how (1) symptom and mood patterns, (2) patterns of social interactions or activities, (3) contextual risk profiles (eg, is being among strangers, as opposed to family, associated with higher paranoia severity?), and (4) temporal dynamics between mood states and paranoia (eg, does anxiety precipitate or follow the onset of increased paranoia severity?) substantially differ within individual patients and across the high vs low paranoid patient group. Most striking, it was shown that individual findings are different from what is found on overall group levels. Some people stay anxious after a paranoid thought came to mind. For others, paranoia is followed by a state of relaxation. It is discussed how ESM, surfacing the patient's implicit knowledge about symptom patterns, may provide an excellent starting point for person-tailored psychoeducation and for choosing the most applicable therapeutic intervention.

Cannabidiol enhances anandamide signaling and alleviates psychotic symptoms of schizophrenia

Cannabidiol is a component of marijuana that does not activate cannabinoid receptors, but moderately inhibits the degradation of the endocannabinoid anandamide. We previously reported that an elevation of anandamide levels in cerebrospinal fluid inversely correlated to psychotic symptoms. Furthermore, enhanced anandamide signaling let to a lower transition rate from initial prodromal states into frank psychosis as well as postponed transition. In our translational approach, we performed a double-blind, randomized clinical trial of cannabidiol vs amisulpride, a potent antipsychotic, in acute schizophrenia to evaluate the clinical relevance of our initial findings. Either treatment was safe and led to significant clinical improvement, but cannabidiol displayed a markedly superior side-effect profile. Moreover, cannabidiol treatment was accompanied by a significant increase in serum anandamide levels, which was significantly associated with clinical improvement. The results suggest that inhibition of anandamide deactivation may contribute to the antipsychotic effects of cannabidiol potentially representing a completely new mechanism in the treatment of schizophrenia.

A video ethnography approach for linking naturalistic behaviors to research constructs of neurocognition in schizophrenia

Few methods are available to explore the impact of neurocognition in schizophrenia on behaviors performed in usual contexts. The authors developed a video ethnography approach to examine the relationship between naturalistic behaviors and research constructs of neurocognition. Video ethnographers accompanied subjects through usual routines gathering continuous video data. Researchers developed codes to measure four behavioral domains observed on video. This paper describes the psychometric characteristics to be considered in the development of observational approaches. It also highlights differences between behaviors performed in usual environments and neuropsychological constructs. The authors demonstrate that everyday behaviors that have been shown to correspond to neurocognitive skills in a pilot feasibility study can be identified and rated. They further suggest that observational methods could provide novel strategies for linking research findings and clinical concerns.

Replication in two independent population-based samples that childhood maltreatment and cannabis use synergistically impact on psychosis risk

BACKGROUND

There may be biological plausibility to the notion that cannabis use and childhood trauma or maltreatment synergistically increase the risk for later development of psychotic symptoms. To replicate and further investigate this issue, prospective data from two independent population-based studies, the Greek National Perinatal Study (n=1636) and The Netherlands Mental Health Survey and Incidence Study (NEMESIS) (n=4842), were analyzed.

METHOD

Two different data sets on cannabis use and childhood maltreatment were used. In a large Greek population-based cohort study, data on cannabis use at age 19 years and childhood maltreatment at 7 years were assessed. In addition, psychotic symptoms were assessed using the Community Assessment of Psychic Experiences (CAPE). In NEMESIS, the Composite International Diagnostic Interview (CIDI) was used to assess psychotic symptoms at three different time points along with childhood maltreatment and lifetime cannabis use.

RESULTS

A significant adjusted interaction between childhood maltreatment and later cannabis use was evident in both samples, indicating that the psychosis-inducing effects of cannabis were stronger in individuals exposed to earlier sexual or physical mistreatment [Greek National Perinatal Study: test for interaction F(2, 1627)=4.18, p=0.02; NEMESIS: test for interaction χ2(3)=8.08, p=0.04].

CONCLUSIONS

Cross-sensitivity between childhood maltreatment and cannabis use may exist in pathways that shape the risk for expression of positive psychotic symptoms.

From environment to therapy in psychosis: a real-world momentary assessment approach

The current article discusses how momentary assessment may fundamentally contribute to identifying environmental risk factors and symptom patterns, as well as provide new opportunities for treatment. A new prototype device, the "PsyMate," was specifically developed to implement momentary assessment in clinical practice. It was shown that self-monitoring of both positive and negative psychotic symptoms (a) is feasible, (b) provides a much more detailed and fine-grained picture of symptoms, and (c) reveals patterns of behavior that may be relevant for treatment. Furthermore, the PsyMate could be instrumental for real-time and real-world delivery of psychological interventions. With PsyMate, patients can become active partners in the therapeutic process, resulting in greater patient ownership and empowerment as well as understanding of their symptoms and the environment.

Does cannabidiol protect against the negative effects of THC?

A recent study by Morgan and colleagues found that cannabidiol attenuates the acute cognitive effects of delta-9-tetrahydrocannabinol (THC). This is of interest as THC has been associated with the detrimental effects of cannabis on mental health in at-risk users, and the potency of cannabis is increasing across Europe.