Associations between past alcohol, cannabis, and cocaine use and current schizotypy among first-degree relatives of patients with schizophrenia and non-psychiatric controls

Schizotypal traits in a large sample of high-school and university students from Tunisia: correlates and measurement invariance of the arabic schizotypal personality questionnaire across age and sex

BACKGROUND

The main goal of the present study was to examine the characteristics of schizotypal traits and their correlations with genetic (i.e., family history of mental illness), demographic (i.e., age, sex), environmental (e.g., income, urbanicity, tobacco/alcohol/cannabis use), and psychological (i.e., personal history of mental illness other than psychosis) factors in Tunisian high-school and university students. Our secondary goal was to contribute the literature by examining the factor structure and factorial invariance of the Arabic Schizotypal Personality Questionnaire (SPQ) across sex and age (adolescents [12-18 years] vs. young adults [18-35 years]) groups.

METHOD

This was a cross-sectional study involving 3166 students: 1160 (36.6%) high-school students (53.0% females, aged 14.9 ± 1.8); and 2006 (63.4%) university students (63.9% females, aged 21.8 ± 2.3). All students were asked to complete a paper-and-pencil self-administered questionnaire containing sociodemographic characteristics as well as the Arabic version of the SPQ.

RESULTS

The total sample yielded total SPQ scores of 24.1 ± 16.6 out of 74. The SPQ yielded good composite reliability as attested by McDonald's omega values ranging from .68 to .80 for all nine subscales. Confirmatory Factor Analysis indicated that fit of the 9-factor model of SPQ scores was acceptable. This model is invariant (at the configural, metric and structural levels) across sex and age. Except for "Odd or eccentric behavior", all schizotypy features were significantly higher among female students compared to males. Multivariable analyses showed that female sex, being a university student, lowest family incomes, tobacco use, and having a personal history of psychiatric illness were significantly associated with higher positive, negative and disorganized schizotypy subscales scores.

CONCLUSION

Future research still needs to confirm our findings and investigate the contribution of the identified factors in the development of clinical psychosis. We can also conclude that the Arabic SPQ is appropriate for measuring and comparing schizotypy across age and sex in clinical and research settings. These findings are highly relevant and essential for ensuring the clinical utility and applicability of the SPQ in cross-cultural research.

Alcohol use history increases the likelihood of suicide behavior among male chronic patients with schizophrenia in a Chinese population

AIMS

This study was designed to detect the association between the history of alcohol drinking and suicidality in schizophrenia (SCZ) inpatients in a Chinese population.

METHODS

We recruited 616 male SCZ inpatients and collected demographic and clinical data. Five-factor model of the Positive and Negative Syndrome Scale (PANSS) was used to assess their psychopathological symptoms.

RESULTS

Our results showed that 31.33% of SCZ patients had a history of alcohol drinking. They had higher rates of lifetime suicide attempt and suicidal ideation than those without a history of alcohol drinking. Moreover, patients with a history of drinking were more likely to attempt suicide (14.51% vs. 7.09%; χ²  = 7.70, df = 1, p = 0.006), with an odds ratio (OR) of 2.22 and have suicidal ideation (29.02% vs. 17.49%; χ²  = 9.89, df = 1, p = 0.002), with an OR of 1.93. In addition, patients who used to drink alcohol were more likely to be smokers and had more severe positive and depressive symptoms (all p < 0.05).

CONCLUSIONS

Our study indicates that history of alcohol drinking may increase the prevalence of lifetime suicide attempt and suicidal ideation in male patients with chronic SCZ. Moreover, the history of alcohol drinking may be associated with some demographic data and clinical symptoms.

Resting state alpha oscillatory activity is a valid and reliable marker of schizotypy

Schizophrenia is among the most debilitating neuropsychiatric disorders. However, clear neurophysiological markers that would identify at-risk individuals represent still an unknown. The aim of this study was to investigate possible alterations in the resting alpha oscillatory activity in normal population high on schizotypy trait, a physiological condition known to be severely altered in patients with schizophrenia. Direct comparison of resting-state EEG oscillatory activity between Low and High Schizotypy Group (LSG and HSG) has revealed a clear right hemisphere alteration in alpha activity of the HSG. Specifically, HSG shows a significant slowing down of right hemisphere posterior alpha frequency and an altered distribution of its amplitude, with a tendency towards a reduction in the right hemisphere in comparison to LSG. Furthermore, altered and reduced connectivity in the right fronto-parietal network within the alpha range was found in the HSG. Crucially, a trained pattern classifier based on these indices of alpha activity was able to successfully differentiate HSG from LSG on tested participants further confirming the specific importance of right hemispheric alpha activity and intrahemispheric functional connectivity. By combining alpha activity and connectivity measures with a machine learning predictive model optimized in a nested stratified cross-validation loop, current research offers a promising clinical tool able to identify individuals at-risk of developing psychosis (i.e., high schizotypy individuals).

Lifetime prevalence and potential determinants of psychotic experiences in the general population of Qatar

BACKGROUND

To estimate the lifetime prevalence and potential determinants of psychotic experience(s) (PEs) in the general population of Qatar - a small non-war afflicted, conservative, high-income, middle-eastern country with recent rapid urbanization including an influx of migrants.

METHODS

A probability-based sample (n = 1353) of non-migrants and migrants were interviewed face-to-face and administered a 7-item psychosis screener adapted from the Composite International Diagnostic Interview, the Kessler 6-item psychological distress scale, and the 5 items assessing odd (paranormal) beliefs and magical thinking (OBMT) from the Schizotypal Personality Questionnaire. Using bivariate and logistic regression analyses, lifetime prevalence rates of PEs were estimated then compared before and after adjustment for socio-demographics, Arab ethnicity, psychological distress, and OBMT.

RESULTS

Prevalence of PEs was 27.9%. Visual hallucinations were most common (12.8%), followed by persecutory delusions (6.7%) and auditory hallucinations (6.9%). Ideas of reference (3.6%) were least prevalent. PEs were significantly higher in Arabs (34.7%) compared with non-Arabs (16.4%, p < 0.001) with the exception of ideas of reference and paranoid delusions. Female gender was associated with a higher prevalence of PEs in the Arab group only (p < 0.001). Prevalence of PEs was significantly higher among Arabs (48.8% v. 15.8%, p < 0.001) and non-Arabs (35.2% v. 7.3%, p < 0.001) with OBMT. Arab ethnicity (OR = 2.10, p = 0.015), psychological distress (OR = 2.29 p = 0.003), and OBMT (OR = 6.25, p < 0.001) were independently associated with PEs after adjustment for all variables.

CONCLUSIONS

Ethnicity, but not migration was independently associated with PEs. Evidence linking Arab ethnicity, female gender, and psychological distress to PEs through associations with OBMT was identified for future prospective investigations.

Is there a common vulnerability in cannabis phenomenology and schizotypy? The role of the N170 ERP

Cannabis use is a known risk factor for the development of psychosis, although the precise nature of this relationship is unclear. The phenomenological experiences associated with cannabis use vary dramatically, and for some resemble certain features of psychosis. We hypothesized that individuals who report particularly unusual experiences associated with cannabis use would demonstrate similar electrophysiological patterns to those who score high on schizotypal personality traits. The Cannabis Experiences Questionnaire (CEQ) and the Schizotypal Personality Questionnaire (SPQ) were used to measure these experiences and traits. A sample of 97 individuals were placed into one of three experimental or two control groups based on their questionnaire scores. These were the "High CEQ", "High SPQ", "High on Both", "Average Users" and "Control" (non-using) groups. Participants completed a visual face perception task. Electroencephalography was used to measure the neural response to the stimuli. The N170 event-related potential (ERP) was used to measure perceptual encoding of the stimulus. The experimental groups elicited significantly reduced N170 ERPs compared to the Control group. The Average User group did not significantly differ from the Control group, and approached significance with the High SPQ group. None of the high scoring groups significantly differed in N170 ERP response from each other. Replicating past research, the CEQ and SPQ scales moderately correlated with each other. The attenuated N170 ERP demonstrated by the high scoring experimental groups may reflect a manifestation of an underlying shared vulnerability.

The role of schizotypy in the study of the etiology of schizophrenia spectrum disorders

Schizotypy provides a useful construct for understanding the development of schizophrenia spectrum disorders. As research on the epidemiology of psychotic symptoms and clinical risk for psychosis has expanded, conceptual challenges have emerged to comprehend the nature and borders of the space comprised between personality variation and psychosis. Schizotypy is considered in light of these more recent constructs. It is suggested that rather than being superseded by them due to their higher specificity and predictive power for transition to psychosis, schizotypy integrates them as it constitutes a dynamic continuum ranging from personality to psychosis. The advantages of schizotypy for studying schizophrenia etiology are discussed (eg, it facilitates a developmental approach and the identification of causal, resilience, and compensating factors and offers a multidimensional structure that captures etiological heterogeneity). An overview of putative genetic, biological, and psychosocial risk factors is presented, focusing on communalities and differences between schizotypy and schizophrenia spectrum disorders. The found notable overlap supports etiological continuity, and, simultaneously, differential findings appear that are critical to understanding resilience to schizophrenia. For example, discrepant findings in genetic studies might be interpreted as suggestive of sets of independent genetic factors playing a differential role in schizotypy and schizophrenia: some would influence variation specifically on schizotypy dimensions (ie, high vs low schizotypy, thereby increasing proneness to psychosis), some would confer unspecific liability to disease by impacting neural properties and susceptibility to environmental factors (ie, high vs low resilience to disorder) and some might contribute to disease-specific characteristics. Finally, schizotypy's promise for studying gene-environment interactions is considered.

Association between cannabis use and schizotypal dimensions--a meta-analysis of cross-sectional studies

Cannabis consumption can cause abuse and dependence and increase risk of developing psychiatric and somatic disorders. Several literature reviews explored the link between cannabis consumption and schizophrenia but none summarized the rich literature on cannabis and psychometric schizotypy. The aim of our review is to synthesize data from studies that explored the association between cannabis consumption and schizoptypal dimensions. A systematic review of the literature and, when needed, contact with the authors, allowed us to gather data from 29 cross-sectional studies. We compared schizotypy scores between subjects that never used cannabis and subjects that used it at least once ("never vs. ever") and between current users and subjects that do not use cannabis currently ("current vs. other"). We conducted separate analyses for total schizotypy score and each of the three classical schizotypal dimensions (positive, negative, disorganized). For all eight comparisons, the cannabis group ("ever" or "current") had higher schizotypy scores. Differences were in the small or medium range and, with the exception of the negative score in the current vs. other comparison, statistically significant. Cannabis consumption is associated with increased schizotypal traits. More research, using different approaches (e.g. longitudinal studies) is needed to explore the cause of this association.

Alcohol and Relatively Pure Cannabis Use, but Not Schizotypy, are Associated with Cognitive Attenuations

Elevated schizotypy relates to similar cognitive attenuations as seen in psychosis and cannabis/polydrug use. Also, in schizotypal populations cannabis and polydrug (including licit drug) use are enhanced. These cognitive attenuations may therefore either be a behavioral marker of psychotic (-like) symptoms or the consequence of enhanced drug use in schizotypal populations. To elucidate this, we investigated the link between cognitive attenuation and cannabis use in largely pure cannabis users (35) and non-using controls (48), accounting for the potential additional influence of both schizotypy and licit drug use (alcohol, nicotine). Cognitive attenuations commonly seen in psychosis were associated with cannabis and alcohol use, but not schizotypy. Future studies should therefore consider (i) non-excessive licit substance use (e.g., alcohol) in studies investigating the effect of cannabis use on cognition and (ii) both enhanced illicit and licit substance use in studies investigating cognition in schizotypal populations.

DSM-IV schizotypal personality disorder: a taxometric analysis among individuals with and without substance use disorders in the general population

This study examined the underlying structure of DSM-IV schizotypal personality disorder (SPD) among individuals with and without a substance use disorder. Using a nationally representative sample of U.S. adults, taxometric analyses were conducted on SPD in the total sample and among individuals with and without a substance use disorder. The structure of SPD in the total sample and among individuals without substance use disorders was dimensional (comparison curve fit indices (CCFI): 0.440, 0.365) whereas a taxonic structure was demonstrated among individuals with a substance use disorder (CCFI: 0.679). Taxonicity underlying schizotypy and SPD in prior taxometric research may have been the result of sampling high risk subsamples of the population. Taxometric research on SPD and other personality psychopathology among high risk subgroups of the population can help elucidate the complex etiology of SPD and the role played by comorbid substance use disorders in the expressivity of these disorders.

Comorbid substance use disorder in schizophrenia: a selective overview of neurobiological and cognitive underpinnings

Although individuals with schizophrenia show a lifetime prevalence of 50% for suffering from a comorbid substance use disorder, substance abuse usually represents an exclusion criterion for studies on schizophrenia. This implies that surprisingly little is known about a large group of patients who are particularly difficult to treat. The aim of the present work is to provide a brief and non-exhaustive overview of the current knowledgebase about neurobiological and cognitive underpinnings for dual diagnosis schizophrenia patients. Studies published within the last 20 years were considered using computerized search engines. The focus was on nicotine, caffeine, alcohol, cannabis and cocaine being among the most common substances of abuse. All drugs of abuse target dopaminergic, glutamatergic and GABAergic transmission which are also involved in the pathophysiology of schizophrenia. Current literature suggests that neurocognitive function might beless disrupted in substance-abusing compared to non-abusing schizophrenia patients, but in particular the neuroimaging database on this topic is sparse. Detrimental effects on brain structure and function were shown for patients for whom alcohol is the main substance of abuse. It is as yet unclear whether this finding might be an artifact of age differences of patient subgroups with different substance abuse patterns. More research is warranted on the specific neurocognitive underpinnings of schizophrenia patients abusing distinct psychoactive substances. Treatment programs might either benefit from preserved cognitive function as a resource or specifically target cognitive impairment in different subgroups of addicted schizophrenia patients.

Personality disorders and the 3-year course of alcohol, drug, and nicotine use disorders

CONTEXT

Little is known about the role of a broad range of personality disorders in the course of substance use disorder (SUD) and whether these differ by substance. The existing literature focuses mostly on antisocial personality disorder and does not come to clear conclusions.

OBJECTIVE

To determine the association between the 10 DSM-IV personality disorders and the persistence of common SUDs in a 3-year prospective study of a national sample.

DESIGN

Data were drawn from participants in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) who had alcohol dependence (n = 1172), cannabis use disorder (n = 454), or nicotine dependence (n = 4017) at baseline and who were reinterviewed 3 years later. Control variables included demographic characteristics, family history of substance disorders, baseline Axis I disorders and treatment status, and prior SUD duration. Main Outcome Measure  Persistent SUD, defined as meeting full criteria for the relevant SUD throughout the 3-year follow-up period.

RESULTS

Persistent SUD was found among 30.1% of participants with alcohol dependence, 30.8% with cannabis use disorder, and 56.6% with nicotine dependence at baseline. Axis I disorders did not have strong or consistent associations with persistent SUD. In contrast, antisocial personality disorder was significantly associated with persistent alcohol, cannabis, and nicotine use disorders (adjusted odds ratios, 2.46-3.51), as was borderline personality disorder (adjusted odds ratios, 2.04-2.78) and schizotypal personality disorder (adjusted odds ratios, 1.65-5.90). Narcissistic, schizoid, and obsessive-compulsive personality disorders were less consistently associated with SUD persistence.

CONCLUSIONS

The consistent findings on the association of antisocial, borderline, and schizotypal personality disorders with persistent SUD indicates the importance of these personality disorders in understanding the course of SUD. Future studies should examine dimensional representations of personality disorders and the role of specific components of these disorders, biological and environmental contributors to these relationships, and potential applications of these findings to treatment development.

A multivariate perspective on schizotypy and familial association with schizophrenia: a review

Although generally accepted that schizotypal personality disorder diagnosis is more prevalent among relatives of individuals with schizophrenia and may be associated with genetic liability to schizophrenia, it seems likely that this diagnosis is itself heterogeneous and thus perhaps not as useful in identifying genes that affect schizophrenia risk (i.e. endophenotypes) as it could be. In contrast, symptoms and dimensions of schizotypal personality disorder may be more etiologically homogeneous, and thus more useful in genetic studies. The current review evaluated and consolidated evidence to date regarding specific symptoms and dimensions of schizotypal personality disorder among non-psychotic relatives of schizophrenia patients. Comparisons were made with relatives of affective disorder patients and non-psychiatric controls. Findings indicate strong support for elevation of social-interpersonal schizotypal symptoms among relatives of schizophrenia patients versus other groups along with moderate specificity. Results suggest only a small elevation of cognitive-perceptual and disorganized symptoms in relatives of schizophrenia patients and results for disorganized symptoms were inconsistent across studies. Thus, evidence to date supports further investigation of genetic associations between symptoms of schizotypal personality disorder and schizophrenia, and suggests that social-interpersonal symptoms may be particularly promising in genetic analyses of schizophrenia.

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

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

Cannabis users differ from non-users on measures of personality and schizotypy

Accumulating evidence indicates that cannabis use may be a risk factor for schizophrenia (SZ), and chronic cannabis users score higher than non-users on measures of schizotypal personality traits. The purpose of the present study was to investigate the relations between normal personality, schizotypy, and cannabis use. Sixty-two chronic cannabis users and 45 cannabis-naïve controls completed a measure of normal personality, the NEO-Five Factor Inventory (NEO-FFI), and two measures of schizotypy, the schizotypal personality questionnaire (SPQ) and perceptual aberration scale (PAS). Substance use was assessed using the SCID I alcohol/drug module and a locally developed drug use questionnaire. On the NEO-FFI, users scored higher than controls on openness, but lower on agreeableness and conscientiousness, and endorsed greater schizotypy on the SPQ and PAS. Higher neuroticism predicted greater schizotypy in both groups, and, higher Extraversion predicted lower negative-syndrome schizotypy among users. Finally, duration of cannabis use was positively correlated with scores on the SPQ and PAS among users, suggesting a relation between overall cannabis use chronicity and schizotypy. These data show that cannabis users differ from non-users on dimensions of normal personality and schizotypy, and provide further evidence that cannabis use is associated with increased levels of psychosis-related personality traits.

A retrospective analysis of cannabis use in a cohort of mentally ill patients in Sri Lanka and its implications on policy development

BACKGROUND

Several epidemiological studies have shown that cannabis; the most widely used illegal drug in the world, is associated with schizophrenia spectrum disorders (SSD).

AIMS

To assess the characteristics of cannabis use and its association with SSD in a cohort of psychiatrically ill patients and discuss the implications for policy development

METHODS

This is a retrospective analytical study of a cohort of psychiatric patients who received treatment in the psychiatry unit of the Provincial General Hospital, Ratnapura, Sri Lanka over five years (2000 - 2004). The schizophrenia spectrum disorders defined in this article include schizophrenia and the schizoaffective disorders.

RESULTS

A total of 3644 patient records were analyzed. The percentage of self reported life time cannabis (LTC) use was 2.83% (103, all males). Sixteen percent (576) of the total cohort was diagnosed with SSD by 2009. Male sex and LTC use were significantly associated with SSD (p < 0.01 and 0.001 respectively). In the majority (91.5%), cannabis use preceded the diagnosis. There were 17(16.5%) patients diagnosed as cannabis induced psychosis and 7 (41.2%) of them were subsequently diagnosed as SSD. This group was significantly more likely to have had a past psychiatric consultation, but other demographic and clinical correlates did not differ from the rest of the LTC users.

CONCLUSIONS

Self reported LTC use was strongly associated with being diagnosed with SSD. However we could not identify a particular subgroup of users that are at increased risk to recommend targeted primary prophylaxis. The policy implications of this observation are discussed.

Cannabis and schizophrenia spectrum disorders: a review of clinical studies

Cannabis is the most widely used illegitimate substance in the world, and the number of users has increased by 10% over the last decade worldwide. Therefore, it is important to review the evidence on psychoactive properties of cannabis and its possible association with schizophrenia spectrum disorders (SSD). We searched MEDLINE with the key words cannabis and schizophrenia. The search was limited to articles published in English over the last 10 years (1999-2009). Bibliographies of cited literature were also searched. Data sources included reviews published in core clinical journals, cohort studies, interventional studies, case-control studies, cross-sectional analyses and epidemiological data. Results are discussed under 2 topics. Firstly, evidence related to biochemical functioning of cannabinoids and their relationship to endocannabinoid system is discussed briefly. Secondly, the evidence from clinical studies on cannabis, psychosis proneness and SSD are discussed in detail. The discussion is structured to fit in the evidence from results section to 3 plausible hypotheses on cannabis use and SSD. The evidence for and against each hypothesis is discussed. Despite new evidence, the exact relationship between cannabis and SSD is unclear. There is no firm evidence that cannabis causes SSD. The evidence for the argument that schizophrenic patients are attracted to cannabis is also not strong. The most plausible explanation is that cannabis use and psychosis proneness may have synergistic effects in a vulnerable minority.