A comparison of symptoms and family history in schizophrenia with and without prior cannabis use: implications for the concept of cannabis psychosis

Serum brain-derived neurotrophic factor level and its relation with cannabis use disorder and schizophrenia: A cross-sectional exploratory study in patients at a tertiary care hospital

BACKGROUND

Brain-derived neurotrophic factor (BDNF) has considerable relevance in neural growth and differentiation. It has been evaluated as a biomarker for individuals with various psychiatric disorders such as substance-related disorders and psychotic disorders.

OBJECTIVE

The present study explored differences in the levels of BDNF (in serum) among subjects using cannabis (with and without schizophrenia).

METHODS

This cross-sectional observational study compared the serum BDNF level in male subjects aged 18-45 years. Four groups of 20 subjects each were included: individuals with tobacco use disorder only, patients having schizophrenia, patients with cannabis use disorder, and finally patients with comorbid cannabis use disorder and schizophrenia.

RESULTS

The BDNF levels were found to be significantly different across the four groups. The BDNF levels in subjects with concurrent schizophrenia and cannabis use disorder were higher than each of the other three groups (cannabis use disorder, schizophrenia, and tobacco use disorder only).

CONCLUSION

We find that BDNF may be higher when cannabis use disorder and schizophrenia co-occur, as compared to either of the conditions alone. The findings should be interpreted with caution due to the low sample size and potential confounders.

Does a history of cannabis use influence onset and course of schizophrenia?

INTRODUCTION

While evidence strongly supports a causal effect of cannabis on psychosis, it is less clear whether the symptom pattern, clinical course, and outcomes differ in cases of schizophrenia with and without a background of cannabis use.

METHODS

Analysis of medical records from a longitudinal follow-up of Swedish conscripts with data on cannabis use in adolescence and subsequent incidence of schizophrenia. One hundred sixty patients with schizophrenia were assessed using the OPCRIT protocol. Cases were validated for diagnosis schizophrenia according to OPCRIT.

RESULTS

Patients with a cannabis history (n = 32), compared to those without (n = 128), had an earlier age at onset, a higher number of hospital admissions and a higher total number of hospital days. There was no significant difference in type of onset and clinical symptom profiles between the groups.

CONCLUSION

Our findings indicate that the disease burden of schizophrenia is greater in individuals who use cannabis during adolescence. Strengthening evidence on causality and teasing out long-term effects of pre-illness cannabis use from continued post-illness has clinical implications for improving schizophrenia outcomes.

Association between formal thought disorder and cannabis use: a systematic review and meta-analysis

Formal thought disorder (FTD) is a multidimensional syndrome mainly occurring along the psychosis continuum. Cannabis use is known to increase symptoms of psychosis, particularly positive symptoms. However, the impact of cannabis use on FTD in individuals presenting symptoms along the psychosis continuum remains unclear. To address this knowledge gap, we conducted a meta-analysis examining the association between cannabis use and FTD in those individuals. We hypothesized that cannabis would worsen FTD. We conducted a systematic search of the PubMed, ScienceDirect, PsycINFO, Web of Science, Embase and Google Scholar databases up to July 2022. The results were collated through a random-effects model using the statistical software R. Reference lists of included studies were searched for additional relevant publications. Nineteen studies were included, totalling 1840 cannabis users and 3351 non-cannabis users. The severity of FTD was found to be higher in cannabis users (SMD = 0.21, 95%CI [0.12–0.29], p = 0.00009). Subgroup analyses revealed that FTD severity was increased among cannabis users, regardless of the disorder severity: healthy individuals (SMD = 0.19, 95%CI [0.05–0.33], p = 0.02); patients with first-episode psychosis (SMD = 0.21, 95%CI [0.01–0.41], p = 0.04); patients with schizophrenia (SMD = 0.25, 95%CI [0.11–0.38], p = 0.005). Between-group differences were not significant. In line with its already known effect on positive symptoms in psychosis, cannabis use appears to be associated with increased FTD severity all along the psychosis continuum. Future research should consider potential confounding variables such as other substance use disorders and explore how FTD dimensions are impacted by cannabis use.

The Epigenetics of Psychosis: A Structured Review with Representative Loci

The evidence for an environmental component in chronic psychotic disorders is strong and research on the epigenetic manifestations of these environmental impacts has commenced in earnest. In reviewing this research, the focus is on three genes as models for differential methylation, MCHR1, AKT1 and TDO2, each of which have been investigated for genetic association with psychotic disorders. Environmental factors associated with psychotic disorders, and which interact with these model genes, are explored in depth. The location of transcription factor motifs relative to key methylation sites is evaluated for predicted gene expression results, and for other sites, evidence is presented for methylation directing alternative splicing. Experimental results from key studies show differential methylation: for MCHR1, in psychosis cases versus controls; for AKT1, as a pre-existing methylation pattern influencing brain activation following acute administration of a psychosis-eliciting environmental stimulus; and for TDO2, in a pattern associated with a developmental factor of risk for psychosis, in all cases the predicted expression impact being highly dependent on location. Methylation induced by smoking, a confounding variable, exhibits an intriguing pattern for all three genes. Finally, how differential methylation meshes with Darwinian principles is examined, in particular as it relates to the “flexible stem” theory of evolution.

Daily use of high-potency cannabis is associated with more positive symptoms in first-episode psychosis patients: the EU-GEI case-control study

BACKGROUND

Daily use of high-potency cannabis has been reported to carry a high risk for developing a psychotic disorder. However, the evidence is mixed on whether any pattern of cannabis use is associated with a particular symptomatology in first-episode psychosis (FEP) patients.

METHOD

We analysed data from 901 FEP patients and 1235 controls recruited across six countries, as part of the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions (EU-GEI) study. We used item response modelling to estimate two bifactor models, which included general and specific dimensions of psychotic symptoms in patients and psychotic experiences in controls. The associations between these dimensions and cannabis use were evaluated using linear mixed-effects models analyses.

RESULTS

In patients, there was a linear relationship between the positive symptom dimension and the extent of lifetime exposure to cannabis, with daily users of high-potency cannabis having the highest score (B = 0.35; 95% CI 0.14-0.56). Moreover, negative symptoms were more common among patients who never used cannabis compared with those with any pattern of use (B = -0.22; 95% CI -0.37 to -0.07). In controls, psychotic experiences were associated with current use of cannabis but not with the extent of lifetime use. Neither patients nor controls presented differences in depressive dimension related to cannabis use.

CONCLUSIONS

Our findings provide the first large-scale evidence that FEP patients with a history of daily use of high-potency cannabis present with more positive and less negative symptoms, compared with those who never used cannabis or used low-potency types.

[Differential diagnostic distinction between substance-induced and primary psychoses: : Recommendations for general psychiatric and forensic practice]

Substanzinduzierte psychotische Störungen (SIPS) sind häufig und für ca. 25 % der ersten Einweisungen in eine psychiatrische Klinik verantwortlich. Aus klinischer Sicht ist aufgrund ähnlicher psychopathologischer Phänomene die diagnostische Unterscheidung zwischen SIPS und primären (genuinen oder kryptogenen) psychotischen Störungen oft eine Herausforderung. Dieser Umstand wird dadurch erschwert, dass SIPS im Zusammenhang mit Cannabis, Halluzinogenen und Amphetaminen ein erhebliches Risiko des Übergangs in eine primäre psychotische Störung (z. B. Schizophrenie) haben. Im ersten Abschnitt dieser Arbeit werden zunächst zwei exemplarische Fallvignetten aus der allgemeinpsychiatrischen und forensischen Praxis vorgestellt. Danach wird im Sinne einer selektiven Literaturübersicht die Relevanz der differenzialdiagnostischen Unterscheidung beider Störungsbilder aus der Sicht der allgemeinen und forensischen Psychiatrie in Bezug auf Therapie, Prognose und richterliche Entscheidung bezüglich der Unterbringung im Maßregelvollzug (§ 63 vs. § 64 StGB) beleuchtet. Der letzte Abschnitt hat das Ziel, ein strukturiertes Vorgehen zur differenzialdiagnostischen Unterscheidung zwischen SIPS und primären psychotischen Störungen zu erarbeiten. Die in dieser Arbeit dargestellten und diskutierten Konzepte und Befunde sollen klinisch tätigen Psychiatern und Psychologen die Diagnosestellung im allgemeinen und forensischen Kontext erleichtern.

Do the Transmissible Liability Index (TLI) and Adolescent Cannabis Use Predict Paranoid and Schizotypal Symptoms at Young Adulthood?

Background: Adolescent cannabis use is an established risk factor for the development of psychosis, but the premorbid vulnerability factors and specificity versus generality of the psychotic symptom domains affected in cannabis-psychosis relationships remain incompletely understood. To improve our understanding of these relationships, we used longitudinal data to examine the individual and interactive effects of preadolescent transmissible liability to substance use disorders (SUD), measured via the transmissible liability index (TLI), and adolescent cannabis use on the development of two distinct psychotic symptom domains, paranoid and schizotypal personality traits in young adulthood. Methods: We performed secondary analysis of data from the Center for Education and Drug Abuse (CEDAR) study, which longitudinally assessed offspring of men with (N = 211) and without (N = 237) lifetime history of SUD at ages 10-12, and across adolescence as they transitioned to young adulthood. TLI scores were calculated at age 10-12, self-reported cannabis use was assessed at age 16, and paranoid and schizotypal symptoms were assessed at age 19. Results: Cannabis use at age 16 and family history of SUD were significantly associated with paranoid and schizotypal symptoms at age 19, but TLI scores were not. The interactive effect of TLI x cannabis use was also not significant. Paranoid and schizotypal symptoms showed different dose-dependent sensitivities to cannabis exposure at age 16. Conclusions: These findings indicate that adolescent cannabis use and family history of SUD differentially contribute to the development of paranoid and schizotypal personality traits through mechanisms that do not include behavioral disinhibition.

Clinical characteristics of primary psychotic disorders with concurrent substance abuse and substance-induced psychotic disorders: A systematic review

BACKGROUND

Distinguishing between a primary psychotic disorder with concurrent substance abuse (PPD+SA) and a substance-induced psychotic disorder (SIPD) can be diagnostically challenging. We aimed to determine if these two diagnoses are clinically distinct, particularly in relation to psychopathology. In addition, we aimed to examine the specific clinical features of cannabis-induced psychotic disorder (CIPD) as compared to primary psychotic disorder with concurrent cannabis abuse (PPD+CA) and also to SIPD associated with any substance.

METHODS

A systematic review of SIPD literature using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Using strict inclusion criteria, a total of six studies examining SIPD were included in the review (two of which only considered psychosis induced by cannabis alone). The findings did not reveal many consistent differences in psychopathology. However, we did find that that compared to PPD+SA, individuals with SIPD have a weaker family history of psychotic disorder; a greater degree of insight; fewer positive symptoms and fewer negative symptoms; more depression (only in CIPD) and more anxiety.

CONCLUSION

There remains a striking paucity of information on the psychopathology, clinical characteristics and outcome of SIPD. Our review highlights the need for further research in this area.

The clinical impact of a positive family history of psychosis or mental illness in psychotic and non-psychotic mentally ill adolescents

BACKGROUND

A family history of psychosis is associated with negative clinical characteristics of psychosis.

AIM

We aimed to determine the relationship between a family history (in first-degree relatives) of psychosis (FHP) or of any mental illness (FHM), and the clinical features (including cannabis use) of first episode early onset psychosis (EOP).

METHOD

Forty-five adolescents with first episode EOP presenting to psychiatric services were assessed by clinical interview with the following tools: socio-demographic questionnaire, Positive and Negative Syndrome Scale (PANSS), Symptom Onset in Schizophrenia (SOS) inventory, and the World Health Organisation's (WHO) Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST) for cannabis misuse. Forty-five gender and age matched controls with incident non-psychotic mental illness were recruited from the same clinical sites.

RESULTS

While there was evidence of trend associations, EOP adolescents and controls did not differ in terms of either FHP or FHM. However, adolescents with a non-psychotic mental illness (controls) were significantly more likely to have a family history of non-psychotic mental illness (EOP = 13%; controls = 47%, p = 0.001). In EOP adolescents, a positive FHP was associated with a significantly lower mean PANSS positive score (p = 0.009), but not with other clinical features.

CONCLUSION

FHP may be a diagnostic clue in adolescents and is not necessarily associated with negative clinical characteristics at disease onset in EOP. However, this requires further research.

Cannabis use related to early psychotic onset: Role of premorbid function

The present cross-sectional study investigates the relation between Cannabis and the development of a psychotic disorder. The main objective is to explore the relations between Cannabis use and psychosis onset, premorbid adjustment cognitive impairment and familiarity. Forty-three patients with a diagnosis of Psychotic Disorder were recruited and divided in two groups based on Cannabis use before onset: Cannabis-using patients (PCU, N=21) and Cannabis-free patients (PCF, N=22). Cognitive functioning was evaluated by Trail Making Test A and B (TMT), Rey-Osterrieth Complex Figure Test (ROCF), and the Rey Auditory-Verbal Learning Test (RAVLT). Premorbid functioning was assessed retrospectively through the Premorbid Adjustment Scale (PAS). PCU group showed earlier onset of the psychotic disorder compared to PCF (p=0.008). This finding was not influenced by age or positive family history for psychiatric illness. PCU subjects showed a worse premorbid functioning respect to PCF and this difference was found to impact on the early onset in the PCU group. In conclusion the present study suggests the hypothesis of an interactive role of Cannabis and poor premorbid school adjustment in the development of psychotic disorders.

Cannabis use is associated with 3years earlier onset of schizophrenia spectrum disorder in a naturalistic, multi-site sample (N=1119)

BACKGROUND

Patients with schizophrenia spectrum disorders and substance use may have an earlier onset of illness compared to those without substance use. Most previous studies have, however, too small samples to control for confounding variables and the effect of specific types of substances. The present study aimed to examine the relationship between substance use and age at onset, in addition to the influence of possible confounders and specific substances, in a large and heterogeneous multisite sample of patients with schizophrenia spectrum disorders.

METHODS

The patients (N=1119) were recruited from catchment areas in Oslo, Stavanger and Bergen, Norway, diagnosed according to DSM-IV and screened for substance use history. Linear regression analysis was used to examine the relationship between substance use and age at onset of illness.

RESULTS

Patients with substance use (n=627) had about 3years earlier age at onset (23.0years; SD 7.1) than the abstinent group (n=492; 25.9years; SD 9.7). Only cannabis use was statistically significantly related to earlier age at onset. Gender or family history of psychosis did not influence the results.

CONCLUSION

Cannabis use is associated with 3years earlier onset of psychosis.

The Epidemiology and Associated Phenomenology of Formal Thought Disorder: A Systematic Review

BACKGROUND

Authors of the Diagnostic and Statistical Manual, Fifth Edition (DSM-V) have recommended to "integrate dimensions into clinical practice." The epidemiology and associated phenomenology of formal thought disorder (FTD) have been described but not reviewed. We aimed to carry out a systematic review of FTD to this end.

METHODS

A systematic review of FTD literature, from 1978 to 2013, using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

A total of 881 abstracts were reviewed and 120 articles met inclusion criteria; articles describing FTD factor structure (n = 15), prevalence and longitudinal course (n = 41), role in diagnosis (n = 22), associated clinical variables (n = 56), and influence on outcome (n = 35) were included. Prevalence estimates for FTD in psychosis range from 5% to 91%. Dividing FTD into domains, by factor analysis, can accurately identify 91% of psychotic diagnoses. FTD is associated with increased clinical severity. Poorer outcomes are predicted by negative thought disorder, more so than the typical construct of "disorganized speech."

CONCLUSION

FTD is a common symptom of psychosis and may be considered a marker of illness severity. Detailed dimensional assessment of FTD can clarify diagnosis and may help predict prognosis.

Cannabis use and family history in adolescent first episode psychosis in Durban, South Africa

OBJECTIVES

To investigate the clinical correlates of cannabis use in adolescents with first episode psychosis (FEP).

METHODS

Inpatient psychiatric records provided demographic, lifetime cannabis use, family history of mental illness, and clinical data on 45 FEP adolescents, aged 12-18 years, admitted to a psychiatric unit in Durban, KwaZulu-Natal, South Africa, over a 2-year period.

RESULTS

Thirty-one (68.8%) of the 45 FEP adolescents reported a history of lifetime cannabis use. The age of FEP presentation and pre-diagnosis symptom duration was not significantly different in cannabis users versus non cannabis users. Of the 15/43 (34.8%) FEP patients with family history of mental illness, 10 had a history of cannabis use. The 26 (57.8%) schizophrenia spectrum disorder patients did not differ significantly from the 19 (42.2%) with other psychoses in terms of cannabis use and family history of mental illness. They were, however, significantly younger at age of presentation and had a significantly longer duration of pre-diagnosis symptoms.

CONCLUSIONS

These preliminary findings suggest a high prevalence of cannabis use in adolescents with FEP and highlight the public health concern of addressing substance abuse in the adolescent population.

A clinical comparison of schizophrenia with and without pre-onset cannabis use disorder: a retrospective cohort study using categorical and dimensional approaches

BACKGROUND

A high prevalence of cannabis use disorder has been reported in subjects suffering from schizophrenia, fuelling intense debate about whether schizophrenia with pre-onset cannabis use disorder may be a distinct entity with specific features or whether cannabis use disorder can precipitate schizophrenia in genetically vulnerable subjects.

METHODS

We retrospectively assessed schizophrenia subjects with and without pre-onset cannabis use disorder on the basis of their clinical features, assessed categorically and dimensionally with the operational criteria checklist for psychotic illnesses (OCCPI). We also investigated whether the two groups could be differentiated on the basis of a history of psychiatric disorders in first-degree relatives. A principal component factor analysis of the OCCPI items was used to identify specific symptom dimensions. The relationships between symptom dimensions and cannabis status were analysed by point-biserial correlation analysis to control for sex and age at time of the assessment and illness duration.

RESULTS

One hundred and seventy-one subjects with a diagnosis of schizophrenia were included. Among them, forty-one patients (18.2 % of the sample) had a cannabis use disorder before or at the time of the onset of schizophrenia. We found similar results in symptoms patterns or family history between patients with and without pre-onset cannabis use disorder.

CONCLUSIONS

Our results clearly argue against cannabis-associated schizophrenia being a relevant distinct clinical entity of schizophrenia with specific features.

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.

A controlled family study of cannabis users with and without psychosis

BACKGROUND

Cannabis is one of the most highly abused illicit drugs in the world. Several studies suggest a link between adolescent cannabis use and schizophrenia. An understanding of this link would have significant implications for legalization of cannabis and its medicinal value. The present study aims to determine whether familial morbid risk for schizophrenia is the crucial factor that underlies the association of adolescent cannabis use with the development of schizophrenia.

METHODS

Consecutively obtained probands were recruited into four samples: sample 1: 87 non-psychotic controls with no drug use; sample 2: 84 non-psychotic controls with cannabis use; sample 3: 32 patients with a schizophrenia spectrum psychosis with no drug use; sample 4: 76 patients with schizophrenia spectrum psychosis with cannabis use. All cannabis using subjects used this drug during adolescence, and no other substance, with the exception of alcohol. Structured interviews of probands and family informants were used to obtain diagnostic information about probands and all their known relatives.

RESULTS

There was an increased morbid risk for schizophrenia in relatives of the cannabis using and non-using patient samples compared with their respective non-psychotic control samples (p=.002, p<.001 respectively). There was no significant difference in morbid risk for schizophrenia between relatives of the patients who use or do not use cannabis (p=.43).

CONCLUSIONS

The results of the current study suggest that having an increased familial morbid risk for schizophrenia may be the underlying basis for schizophrenia in cannabis users and not cannabis use by itself.

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.

Unemployment, ethnicity and psychosis

OBJECTIVE

This study describes the incidence of psychosis in unemployed people and determines whether unemployment has a greater impact on the development of psychosis amongst Black minority groups than White groups.

METHOD

Patients with a first diagnosis of Research Diagnostic Criteria psychosis, in a defined area of London from 1998 to 2004, were identified. Crude and standardised incidence rates of psychosis amongst unemployed people for each ethnic group were calculated. Poisson regression modelling tested for interactions between unemployment and ethnicity.

RESULTS

Hundred cases occurred amongst employed people and 78 cases occurred amongst the unemployed people. When standardised to the employed White population of the area, White unemployed people had a standardised incidence ratio (SIR) of 11.7 (95% CI 6.4-19.7), Black Caribbean people had a SIR of 60.1(95% CI 39.3-88) and Black African people had a SIR of 40.7 (95% CI 25.8-61.1). There was no interaction however between ethnicity and unemployment (Likelihood ratio test P = 0.54).

CONCLUSION

Rates of psychosis are high amongst unemployed people in south London and extremely high amongst Black Caribbean and Black African unemployed people. There was no evidence however that the minority groups were particularly sensitive to the stresses, limitations or meaning of unemployment.

Executive functioning in individuals with schizophrenia and/or cocaine dependence

OBJECTIVE

Although little is known about neurocognition in Dual Diagnosis, it has been suggested that Schizophrenia (SZ) patients with comorbid substance use belong to a subgroup with lower genetic vulnerability to develop SZ and, consequently, they show better executive and social premorbid functioning. The first aim of this study was to assess the executive functioning, and the second one was to explore the effect of age of onset of substance use in neurocognition in SZ patients with cocaine dependence.

METHODS

The total sample consisted of 95 male patients, aged 20 to 60 years, divided in three groups: one group with SZ and cocaine dependence (SZ+; n = 30), another group with SZ without cocaine dependence (SZ-; n = 30), and a control group with cocaine dependence without psychiatric comorbidity (COC; n = 35).

RESULTS

We found a better executive functioning in both SZ+ and COC than SZ-. We observed a worse performance of SZ+ patients compared with COC in cognitive set-shifting regardless the age of onset of consumption.

CONCLUSIONS

The results agree with the hypothesis of a lower genetic vulnerability in SZ+ patients to develop psychosis compared with SZ-, who develop it without any additional trigger. However, future research is needed to clarify the current knowledge gaps.

Differential effects of chronic cannabis use on preattentional cognitive functioning in abstinent schizophrenic patients and healthy subjects

INTRODUCTION

A number of studies indicate a higher risk for psychosis as well as for neurocognitive deficits in healthy cannabis users. However, little is known about the impact of cannabis use on outcome in schizophrenia. In fact, there is growing evidence that cannabis-using schizophrenic patients may show preserved or even better neurocognitive performance compared to schizophrenic non-users.

METHODS

We measured mismatch negativity (MMN) to investigate preattentional neurocognitive functioning in long-term abstinent chronic cannabis users with (SZCA n=27) and without schizophrenia (COCA n=32) compared to schizophrenic patients (SZ n=26) and healthy controls (CO n=34) without any chronic drug use.

RESULTS

Healthy cannabis users showed reduced frontal MMN compared to controls (p=0.036). In contrast, cannabis-using schizophrenic patients showed increased frontal MMN compared to schizophrenic patients without cannabis use (p=0.038). Comparing non-cannabis users, schizophrenic patients showed reduced frontal MMN (p=0.001). No significant differences were found between CO and SZCA (p=0.27), and COCA and SZCA (p=0.50).

CONCLUSION

Results suggest that chronic cannabis use may have different effects on preattentional neurocognitive functioning in schizophrenic patients when compared to healthy subjects. This may be related to preexisting differences in the endocannabinoid system between schizophrenic patients and healthy subjects. However, due to the naturalistic design of the study, the results must be interpreted with caution.

Early risk factors for suicide in an epidemiological first episode psychosis cohort

BACKGROUND

Much remains unknown about whether there are early risk factors for suicide in psychosis.

AIM

The aim of the study was to determine whether there are any identifiable early symptom clusters, aetiological factors or illness course markers for suicide in first episode psychosis.

METHOD

A total of 2132 patients with first episode psychosis presenting to secondary care services in London (1965-2004; n=1474), Nottingham (1997-1999; n=195) and Dumfries and Galloway (1979-1998; n=463) were traced after up to 40 years (mean 13 years) following first presentation. Risk factors were identified from the Operational Checklist for Psychotic Disorders rated for the first year following presentation.

RESULTS

Overall, there were 51 suicides and 373 deaths from other causes. Male gender (RR 2.84, 95% CI 1.20-6.69, p=0.02) and a cumulative threshold effect of symptoms early in the illness (RR 6.81, 95% CI 2.33-19.85, p<0.001) were associated with a higher propensity for later completed suicide. There was also a suggestion that early manic symptoms might increase the risk of later suicide irrespective of initial diagnosis.

CONCLUSION

Suicide risk was associated with a cumulative threshold effect of symptoms and manic symptoms. As suicide is a relatively rare event in psychotic disorders, general population-based prevention strategies may have more impact in this vulnerable group as well as the wider population.

Psychopharmacological comparison of schizophrenia spectrum disorder with and without cannabis dependency

BACKGROUND

Although incidence of schizophrenia is higher among cannabis users and marijuana is the most common abused drug by adolescents, etiological linkage between schizophrenia and cannabis use is still not clarified. Clinical experiences suggest that regular cannabis user can show similar psychotic episode to schizophrenic disorders but it is still unclear if chronic cannabis use with schizophreniform disorder is a distinct entity requiring special therapy or it can be treated as classical schizophrenia. There are no data available on the comparison of pharmacotherapy between schizophreniform patients with and without cannabis use.

METHODS

Clinical data of 85 patients with schizophrenia spectrum disorder were analyzed retrospectively. Cannabis use was not reported by 43 persons (Cnbs0 subgroup) and 42 patients used regularly cannabis during at least 1 year (Cnbs1 subgroup). Comparison of anamnesis, family history, social-demographic condition, positive and negative symptoms, acute and long-term therapies recorded by clinical interviews was performed with chi square tests, logistic binary regression and t-tests using SPSS 13.0 for Windows software.

RESULTS

Men were over-represented in cannabis dependent group while mean age was lower among them compared to Cnbs0 subgroup. Prevalence of suicidal attempt was increased in men without cannabis use (OR = 5.25, p = 0.016). Patients without cannabis use spent more time in hospital (p = 0.026) and smoking was more frequent among them (OR = 1.36, p = 0.047). The chance to get olanzapine for acute therapy and aripiprazol for long term therapy was more than two fold in Cnbs1 subgroup (OR = 2.66, OR = 3.67, respectively). However, aripiprazol was used for acute therapy with significantly lower risk in Cnbs1 subgroup (OR = 0.47, p = 0.023). Olanzapine was administered for long term therapy in a higher dose to Cnbs0 patients (p = 0.040). Also higher dose of risperidon LAI was used in women without cannabis dependency compared to women of Cnbs1 subgroup (p=0.020). Positive and negative symptoms and family history did not differ significantly between the two subgroups.

CONCLUSION

Although symptom profile was similar, hospitalization time, suicidal anamnesis, smoking habit and also dosage, intensity and lasting of therapy were different between the two subgroups. Further prospective studies are required for the investigation of the clinical and molecular background of this discrepancy in order to determine a relevant protocol of prevention and treatment of the chronic cannabis use related psychotic disorder.

Early signs, diagnosis and therapeutics of the prodromal phase of schizophrenia and related psychotic disorders

During recent decades, interest in the prevention of mental illnesses has increased. Improved diagnostic tools, the advent of atypical antipsychotic medications and the development of phase-specific psychosocial treatments have made intervention research in people at ultra-high risk for developing schizophrenia or a related psychotic disorder possible. Preliminary data suggest that low doses of atypical antipsychotic medications augmented by psychosocial treatments may delay the onset of psychosis in some individuals. Findings support further research for the establishment of best-practice standards.

Deletion 17q12 is a recurrent copy number variant that confers high risk of autism and schizophrenia

Autism spectrum disorders (ASD) and schizophrenia are neurodevelopmental disorders for which recent evidence indicates an important etiologic role for rare copy number variants (CNVs) and suggests common genetic mechanisms. We performed cytogenomic array analysis in a discovery sample of patients with neurodevelopmental disorders referred for clinical testing. We detected a recurrent 1.4 Mb deletion at 17q12, which harbors HNF1B, the gene responsible for renal cysts and diabetes syndrome (RCAD), in 18/15,749 patients, including several with ASD, but 0/4,519 controls. We identified additional shared phenotypic features among nine patients available for clinical assessment, including macrocephaly, characteristic facial features, renal anomalies, and neurocognitive impairments. In a large follow-up sample, the same deletion was identified in 2/1,182 ASD/neurocognitive impairment and in 4/6,340 schizophrenia patients, but in 0/47,929 controls (corrected p = 7.37 × 10⁻⁵). These data demonstrate that deletion 17q12 is a recurrent, pathogenic CNV that confers a very high risk for ASD and schizophrenia and show that one or more of the 15 genes in the deleted interval is dosage sensitive and essential for normal brain development and function. In addition, the phenotypic features of patients with this CNV are consistent with a contiguous gene syndrome that extends beyond RCAD, which is caused by HNF1B mutations only.

Cannabis use and cognition in schizophrenia

People with schizophrenia frequently report cannabis use, and cannabis may be a risk factor for schizophrenia, mediated through effects on brain function and biochemistry. Thus, it is conceivable that cannabis may also influence cognitive functioning in this patient group. We report data from our own laboratory on the use of cannabis by schizophrenia patients, and review the existing literature on the effects of cannabis on cognition in schizophrenia and related psychosis. Of the 23 studies that were found, 14 reported that the cannabis users had better cognitive performance than the schizophrenia non-users. Eight studies reported no or minimal differences in cognitive performance in the two groups, but only one study reported better cognitive performance in the schizophrenia non-user group. Our own results confirm the overall impression from the literature review of better cognitive performance in the cannabis user group. These paradoxical findings may have several explanations, which are discussed. We suggest that cannabis causes a transient cognitive breakdown enabling the development of psychosis, imitating the typical cognitive vulnerability seen in schizophrenia. This is further supported by an earlier age of onset and fewer neurological soft signs in the cannabis-related schizophrenia group, suggesting an alternative pathway to psychosis.

Substance misuse and early psychosis

OBJECTIVE

This paper sought to review current knowledge about the relationship between substance misuse and early psychosis.

METHODS

A literature search was conducted using Medline and restricting the search to articles after 1996. Additional articles were sourced from reference lists of relevant articles.

RESULTS

There is a high prevalence of substance misuse among persons with early psychosis, with cannabis and alcohol featuring prominently. Substance misuse is associated with earlier onset and possibly more positive symptoms, although apparently not with greater cognitive impairment. Cannabis appears to confer an increased likelihood of developing schizophrenia in biologically vulnerable individuals. Amphetamines also cause psychosis which may become chronic, although specific vulnerability to this effect is less well established. Many cases of so-called 'drug-induced psychosis' become diagnosed as schizophrenia in later years. Specific intervention programs report positive outcomes with regard to substance misuse and the course of psychosis.

CONCLUSIONS

Substance misuse should always be assessed in this patient group, bearing in mind the potential interactive causes of psychopathology. Intervention is of value in improving outcomes.

Delusions of reference: a new theoretical model

INTRODUCTION

Although delusions of reference are one of the most common psychotic symptoms, they have been the focus of little research, possibly because they have been considered to be integral to persecutory delusions. Evidence has now emerged that there are two kinds of delusion of reference. One of these, referential delusions of communication, which involves beliefs that others are communicating in subtle, nonverbal ways, is the focus of this paper.

METHODS

We present a new model designed to account for the four crucial aspects of the phenomenology of these delusions: (1) that neutral stimuli are experienced as having personal significance; (2) that the neutral stimuli are experienced as communicating a message nonverbally; (3) that the content of the message concerns the self; (4) that the experience of a self-referent communication is believed rather than being dismissed as implausible. We used PsycINFO and Scopus, using the term "delusion* of reference", to search for publications with a bearing on our model.

RESULTS

The amount of research we found that was designed to test aspects of this model is small but other published research appears to provide some support for its various steps. Much of this research was not explicitly intended to provide an account of delusions of reference but its relevance nevertheless seems clear.

CONCLUSIONS

There is preliminary support for the plausibility of our model but much additional research is needed. We conclude by summarising what we consider to be the main desiderata.

Psychiatric comorbidities and schizophrenia

Psychiatric comorbidities are common among patients with schizophrenia. Substance abuse comorbidity predominates. Anxiety and depressive symptoms are also very common throughout the course of illness, with an estimated prevalence of 15% for panic disorder, 29% for posttraumatic stress disorder, and 23% for obsessive-compulsive disorder. It is estimated that comorbid depression occurs in 50% of patients, and perhaps (conservatively) 47% of patients also have a lifetime diagnosis of comorbid substance abuse. This article chronicles these associations, examining whether these comorbidities are "more than chance" and might represent (distinct) phenotypes of schizophrenia. Among the anxiety disorders, the evidence at present is most abundant for an association with obsessive-compulsive disorder. Additional studies in newly diagnosed antipsychotic-naive patients and their first-degree relatives and searches for genetic and environmental risk factors are needed to replicate preliminary findings and further investigate these associations.

Prevalence of psychotic symptoms in substance users: a comparison across substances

BACKGROUND

Psychotic symptoms (delusions and hallucinations) are reported to be increased among persons using illicit substances, but little is known about the comparative frequency with which the symptoms occur with abuse of different substances. To establish this, we interviewed individuals who had wide experience of commonly used drugs.

METHODS

Four hundred seventy-six intravenous drug users, crack-cocaine users, and heroin snorters recruited via street outreach were interviewed using the Composite International Diagnostic Interview-Substance Abuse Model to assess dependence on a number of substances including amphetamines, cannabis, cocaine, and opioids. As a part of this assessment, we assessed a history of delusions and hallucinations in the context of use of, or withdrawal from, these specific substances.

RESULTS

From 27.8% to 79.6% users of amphetamine, cannabis, cocaine, and opiates met Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised, dependence for that specific substance. The prevalence of psychotic symptoms associated with each specific substance ranged from users with no diagnosis to users with severe dependence as follows: amphetamines (5.2%-100%), cannabis (12.4%-80.0%), cocaine (6.7%-80.7%), and opiates (6.7%-58.2%). The risk of psychotic symptoms increased for respondents who abused (odds ratio [OR], 12.2) or had mild (OR, 17.1), moderate (OR, 47.0), or severe dependence (OR, 114.0) on cocaine when compared to those who were users with no diagnosis. A similar pattern was evident in cannabis, opiate, and amphetamine users.

CONCLUSIONS

Most users dependent on illicit substances experience psychotic symptoms in the context of use of, or withdrawal from, these substances. Psychotic symptoms increased with the severity of the substance use disorders for all 4 substances. These findings emphasize the importance of developing services to target this population as they are at a heightened risk for developing psychotic symptoms.

Gene-environment interplay between cannabis and psychosis

Cannabis use is considered a contributory cause of schizophrenia and psychotic illness. However, only a small proportion of cannabis users develop psychosis. This can partly be explained by the amount and duration of the consumption of cannabis and by its strength but also by the age at which individuals are first exposed to cannabis. Genetic factors, in particular, are likely to play a role in the short- and the long-term effects cannabis may have on psychosis outcome. This review will therefore consider the interplay between genes and exposure to cannabis in the development of psychotic symptoms and schizophrenia. Studies using genetic, epidemiological, experimental, and observational techniques will be discussed to investigate gene-environment correlation gene-environment interaction, and higher order interactions within the cannabis-psychosis association. Evidence suggests that mechanisms of gene-environment interaction are likely to underlie the association between cannabis and psychosis. In this respect, multiple variations within multiple genes--rather than single genetic polymorphisms--together with other environmental factors (eg, stress) may interact with cannabis to increase the risk of psychosis. Further research on these higher order interactions is needed to better understand the biological pathway by which cannabis use, in some individuals, may cause psychosis in the short- and long term.

Familial psychopathology in the First Episode Psychosis Outcome Study

OBJECTIVE

The aim of the present study was to characterize the utility of family history data for predicting psychiatric and functional status in first-episode psychosis (FEP) during the pre-treatment phase of illness, at first presentation, and at 18 months follow up.

METHOD

An epidemiological study based upon a consecutive file audit of 661 patients admitted to the Early Psychosis Prevention and Intervention Centre between January 1998 and December 2000 using a standardized questionnaire.

RESULTS

In the total sample of FEP patients family history was not significantly associated with psychiatric or functional status pre-treatment, at first presentation, or at 18 months. Male patients with a family history of psychotic illness had a longer duration of prodrome compared to those with no family history of psychiatric illness (mean=481.4 days, SD=678.0 vs mean=383.5 days, SD=524.7; p=0.03). Family history of non-psychotic illness was associated with comorbidity at first presentation in female patients, both for substance-use related comorbidity (p=0.02) and non-substance-use related comorbidity (p=0.03). There was substantial agreement between clinician reports of family history of psychosis and those obtained using a structured interview instrument (kappa=0.69, 95% confidence interval (CI)=0.41-0.86), but agreement for non-psychotic family history was comparatively low (kappa=0.28, 95%CI:=-0.03 to 0.52).

CONCLUSIONS

There are gender differences in the association between substance use disorder, duration of prodrome and family history. This supports the hypothesis that psychotic illness manifests differently in men and women. In the present sample, reports of family history of non-psychotic illness had lower convergent validity than reports of psychotic illness. The present reported associations with non-psychotic family history should therefore be interpreted with caution. Information on gender and family history of psychiatric illness may assist clinical diagnosis and determination of treatment in FEP patients, especially if specific familial risk factors can be identified.

Case registers in psychiatry: do they still have a role for research and service monitoring?

PURPOSE OF REVIEW

To follow up on reviews of case register research. Literature searches over a 2-year period were conducted to determine whether psychiatric case registers still have a role for research and service monitoring.

RECENT FINDINGS

Case register research covers a wide range of topics, and is most often found in Denmark where national databases support all kinds of record linkage studies. Typically, case registers are used in studies of treated prevalence and incidence of psychiatric disorders, in research on patterns of care, as sampling frames in epidemiological studies, and in studies on risk factors and treatment outcome.

SUMMARY

Despite a wide range of research based on administrative data, stakeholders in most countries are probably not well served by current priorities. Few studies investigate longitudinal patterns of service use to evaluate healthcare policies. There is a lack of comparative record linkage studies to inform local authorities on the cooperation between mental healthcare and public services. Implementing standard tools and procedures for routine outcome assessment seems still to be in an early phase in most register areas. When case register staff can capitalize on new opportunities, old and new case registers will continue to be important for research and service monitoring.

Cannabinoids in health and disease

Cannabis sativa L. preparations have been used in medicine for millenia. However, concern over the dangers of abuse led to the banning of the medicinal use of marijuana in most countries in the 1930s. Only recently, marijuana and individual natural and synthetic cannabinoid receptor agonists and antagonists, as well as chemically related compounds, whose mechanism of action is still obscure, have come back to being considered of therapeutic value. However, their use is highly restricted. Despite the mild addiction to cannabis and the possible enhancement of addiction to other substances of abuse, when combined with cannabis, the therapeutic value of cannabinoids is too high to be put aside. Numerous diseases, such as anorexia, emesis, pain, inflammation, multiple sclerosis, neurodegenerative disorders (Parkinson's disease, Huntington's disease, Tourette's syndrome, Alzheimer's disease), epilepsy, glaucoma, osteoporosis, schizophrenia, cardiovascular disorders, cancer, obesity, and metabolic syndrome-related disorders, to name just a few, are being treated or have the potential to be treated by cannabinoid agonists/antagonists/cannabinoid-related compounds. In view of the very low toxicity and the generally benign side effects of this group of compounds, neglecting or denying their clinical potential is unacceptable--instead, we need to work on the development of more selective cannabinoid receptor agonists/antagonists and related compounds, as well as on novel drugs of this family with better selectivity, distribution patterns, and pharmacokinetics, and--in cases where it is impossible to separate the desired clinical action and the psychoactivity--just to monitor these side effects carefully.

New directions in the conceptualization of psychotic disorders

PURPOSE OF REVIEW

Recent studies raise controversies about the nature of psychotic illnesses, and the role of life experiences and drug abuse as causative agents in the onset of psychoses.

RECENT FINDINGS

Evidence from studies across many geographic locales and cultures finds increased risk of psychoses in first- and second-generation immigrant populations. Trauma incurred in war and civil unrest, trauma of child abuse, and the experience of being bullied in childhood are correlated with increased rates of psychoses in the populations at risk. The risk of onset of psychoses is increased by maternal and infant starvation, and by substance misuse (marijuana, khat) in late childhood and adolescence. These studies question the validity of a categorical distinction between the schizophrenic and affective illnesses.

SUMMARY

A variety of extrinsic factors, such as in-utero and infant malnutrition, substance abuse, and traumatic experiences, appear to be significant risk factors for the development of schizophrenia-like and psychotic affective disorders. These findings raise the issue of whether the present classification of the psychoses is in urgent need of reconceptualization.