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OBJECTIVES: Posttraumatic stress disorder (PTSD) and cannabis use disorder (CUD) commonly co-occur. Conditioned associations between psychological trauma cues, distress, cannabis use, and desired relief outcomes may contribute to the comorbidity. These conditioned associations can be studied experimentally by manipulating trauma cue exposure in a cue-reactivity paradigm (CRP) and examining effects on affective and cognitive outcomes in participants with and without PTSD. However, traditional CRPs take place in-lab limiting recruitment/power. We aimed to examine the effects of CRP condition (trauma and neutral) and PTSD group (likely PTSD+ and PTSD-) on affective and craving outcomes using a stand-alone online expressive writing CRP. METHODS: Participants (n = 202; 43.6% male; Mage = 42.94 years, SD = 14.71) with psychological trauma histories and past-month cannabis use completed a measure of PTSD symptoms (PTSD Checklist-5 for DSM-5 [PCL-5]) and were randomized to complete either a trauma or neutral expressive writing task. Then they completed validated measures of affect (Positive and Negative Affect Schedule-Short Form [PANAS-SF]) and cannabis craving (Marijuana Craving Questionnaire-Short Form [MCQ-SF]). RESULTS: Linear mixed models tested the hypothesized main and interactive effects of CRP condition (trauma and neutral) and PTSD group (likely PTSD+ and PTSD-) on negative and positive affect (PANAS-SF) and cannabis craving dimensions (MCQ-SF). The hypothesized main effects of trauma versus neutral expressive writing were found for negative affect and the expectancy dimension of cannabis craving and of PTSD group for negative affect and all cannabis craving dimensions; no interactions were observed. CONCLUSIONS: Expressive writing appears a useful online CRP. Interventions focused on reducing negative affect and expectancy craving to trauma cues may prevent/treat CUD among cannabis users with PTSD. PLAIN LANGUAGE SUMMARY TITLE: The Use of an Online Expressive Writing as a Trauma Cue Exposure: Effects on Craving and Emotions.
People who have gone through trauma sometimes experience both post-traumatic stress disorder (PTSD) and a tendency to use cannabis excessively (cannabis use disorder or CUD). Researchers believe that there's a connection between traumatic memories, emotional distress, cannabis use, and the relief people feel afterward. These associations can be studied experimentally by using a cue-reactivity paradigm (CRP) to examine effects on craving and affective outcomes in those with and without PTSD. This study included 202 participants who had a history of trauma and reported regular cannabis use. They were randomly assigned to write about a traumatic or neutral personal experience. After, they filled out questionnaires about their PTSD symptoms, emotions (both positive and negative), and cravings for cannabis during the task. We expected that the type of writing task (those assigned to the trauma vs. neutral condition) and PTSD status would be associated with increased cannabis craving, negative emotions, and reduced positive emotions. We found that writing about trauma increased negative feelings and positive expectations about using cannabis for relief, especially for those with PTSD. People with PTSD also seemed to have more ongoing negative feelings and cravings for cannabis. The authors suggest that traditional in-lab experiments might be necessary to fully understand how trauma reminders can influence cravings and emotions in individuals with PTSD-CUD.
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BACKGROUND: Distributed Medical Education (DME), a decentralized model focused on smaller cities and communities, has been implemented worldwide to bridge the gap in psychiatric education. Faculty engagement in teaching activities such as clinical teaching, supervision, and examinations is a crucial aspect of DME sites. Implementing or expanding DME sites requires careful consideration to identify enablers that contribute to success and barriers that need to be addressed. This study aims to examine enablers, barriers, and factors influencing psychiatrists' willingness to start or continue participating in teaching activities within Dalhousie University's Faculty of Medicine DME sites in two provinces in Atlantic Canada. METHODOLOGY: This cross-sectional study was conducted as part of an environmental scan of Dalhousie Faculty of Medicine's DME programs in Nova Scotia (NS) and New Brunswick (NB), Canada. In February 2023, psychiatrists from seven administrative health zones in these provinces anonymously participated in an online survey. The survey, created with OPINIO, collected data on sociodemographic factors, practice-related characteristics, medical education, and barriers to teaching activities. Five key outcomes were assessed, which included psychiatrists' willingness to engage in (i) clinical training and supervision, (ii) lectures or skills-based teaching, (iii) skills-based examinations, (iv) training and supervision of Canadian-trained psychiatrists, and (v) training and supervision of internationally trained psychiatrists. The study employed various statistical analyses, including descriptive analysis, chi-square tests, and logistic regression, to identify potential predictors associated with each outcome variable. RESULTS: The study involved 60 psychiatrists, primarily male (69%), practicing in NS (53.3%), with international medical education (69%), mainly working in outpatient services (41%). Notably, 60.3% lacked formal medical education training, yet they did not perceive the lack of training as a significant barrier, but lack of protected time as the main one. Despite this, there was a strong willingness to engage in teaching activities, with an average positive response rate of 81.98%. The lack of protected time for teaching/training was a major barrier reported by study participants. Availability to take the Royal College of Physicians and Surgeons of Canada Competency by Design training was the main factor associated with psychiatrists' willingness to participate in the five teaching activities investigated in this study: willingness to participate in clinical training and supervision of psychiatry residents (p = .01); provision of lectures or skills-based teaching for psychiatry residents (p < .01); skills-based examinations of psychiatry residents (p < .001); training/supervision of Canadian-trained psychiatrists (p < .01); and training and supervision of internationally trained psychiatrists (p < .01). CONCLUSION: The study reveals a nuanced picture regarding psychiatrists' engagement in teaching activities at DME sites. Despite a significant association between interest in formal medical education training and willingness to participate in teaching activities, clinicians do not consider the lack of formal training as a barrier. Addressing this complexity requires thoughtful strategies, potentially involving resource allocation, policy modifications, and adjustments to incentive structures by relevant institutions.
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Educación Médica , Psiquiatría , Humanos , Masculino , Psiquiatras , Estudios Transversales , Canadá , Psiquiatría/educación , Encuestas y Cuestionarios , Docentes MédicosRESUMEN
OBJECTIVE: Cannabis is commonly used by Canadian emerging adults (ages 18-25 years), many of whom attend post-secondary institutions. Frequent cannabis use is linked with psychotic-like experiences (PLEs); however, the exact nature of this association remains unclear. Anxiety symptoms may mediate this association, as they are prevalent in emerging adults and have been independently linked with both cannabis use and PLEs. Past work found that anxiety mediated the association between cannabis use frequency and attenuated positive psychotic symptoms (further along the psychosis continuum than PLEs), however this research had yet to be validated in the Canadian population, and trait rather than state anxiety (frequency of anxiety symptoms) was studied. Thus, our primary objective was to examine if anxiety symptoms mediated the association between cannabis use frequency and PLEs in Canadian emerging adult undergraduates. Despite known sex differences in cannabis use, expression of anxiety, and PLEs, past work did not evaluate the potential impact of biological sex on the anxiety-mediated model, and thus is the secondary objective of the present study. METHODS: 1,266 first-/second-year emerging adult undergraduates from five Canadian universities provided cross-sectional, self-report survey data in fall 2021 semester. Validated measures of cannabis use frequency, anxiety, and PLEs were administered. RESULTS: Path analyses supported mediation from cannabis use to PLEs through anxiety (b = 0.07, P < 0.001, 95% bootstrap CI [0.03, 0.10]). No direct effect was found (P = 0.457), suggesting that the cannabis-to-PLEs association was mediated by anxiety. Mediation did not depend on biological sex (i.e., bootstrapped 95% CIs crossed zero). CONCLUSIONS: Anxiety symptoms mediated the association between cannabis use and PLEs in emerging adults regardless of their biological sex. Assuming replication in prospective research, results highlight anxiety as an important intervention target in frequent cannabis-using emerging adults, to potentially prevent development/worsening of PLEs, and in turn psychotic illness.
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Cannabis , Trastornos Psicóticos , Humanos , Adulto , Masculino , Femenino , Adolescente , Adulto Joven , Estudios Transversales , Estudios Prospectivos , Canadá/epidemiología , Trastornos Psicóticos/epidemiología , Ansiedad/epidemiología , Encuestas y CuestionariosRESUMEN
Objective: Cannabis use is increasingly normalized; psychosis is a major adverse health outcome. We reviewed evidence on cannabis use-related risk factors for psychosis outcomes at different stages toward recommendations for risk reduction by individuals involved in cannabis use. Methods: We searched primary databases for pertinent literature/data 2016 onward, principally relying on reviews and high-quality studies which were narratively summarized and quality-graded; recommendations were developed by international expert consensus. Results: Genetic risks, and mental health/substance use problem histories elevate the risks for cannabis-related psychosis. Early age-of-use-onset, frequency-of-use, product composition (i.e., THC potency), use mode and other substance co-use all influence psychosis risks; the protective effects of CBD are uncertain. Continuous cannabis use may adversely affect psychosis-related treatment and medication effects. Risk factor combinations further amplify the odds of adverse psychosis outcomes. Conclusions: Reductions in the identified cannabis-related risks factors-short of abstinence-may decrease risks of related adverse psychosis outcomes, and thereby protect cannabis users' health.
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Cannabis , Trastornos Psicóticos , Trastornos Relacionados con Sustancias , Humanos , Cannabis/efectos adversos , Salud Mental , Trastornos Psicóticos/terapia , Factores de RiesgoRESUMEN
INTRODUCTION: The present study compared the mismatch negativity (MMN) and P3a waveforms among early-phase psychosis (EPP; n = 13) individuals and healthy controls (n = 30) to contribute to the research on these waveforms as potential biomarkers for schizophrenia. METHODS: MMN and P3a were elicited with a novelty paradigm using complex stimuli with electrophysiological technology. RESULTS: No significant group differences of amplitude were observed with either waveform. Increased asociality and blunted affect were associated with a reduction in both MMN and P3a waveforms indicating a relationship between these negative symptoms and cognitive deficits. Good social and occupational functioning correlated with improved MMN and P3a waveforms in the EPP group. CONCLUSIONS: This study suggests that MMN and P3a may be more appropriately used as an indicator of illness progression and symptomology rather than a biomarker in the early phase of the illness.
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Trastornos Psicóticos , Esquizofrenia , Humanos , Potenciales Relacionados con Evento P300/fisiología , Electroencefalografía , Trastornos Psicóticos/psicología , Esquizofrenia/diagnóstico , Trastornos del Humor , Potenciales Evocados Auditivos/fisiología , Estimulación AcústicaRESUMEN
BACKGROUND: The COVID-19 pandemic has had significant impacts on how mental health services are delivered to patients throughout Canada. The reduction of in-person healthcare services have created unique challenges for individuals with psychotic disorders that require regular clinic visits to administer and monitor long-acting injectable antipsychotic medications. METHODS: To better understand how LAI usage was impacted, national and provincial patient-level longitudinal prescribing data from Canadian retail pharmacies were used to examine LAI prescribing practices during the pandemic. Prescribing data on new starts of medication, discontinuations of medications, switches between medications, antipsychotic name, concomitant medications, payer plan, gender and age were collected from January 2019 to December 2020 for individuals ≥18-years of age, and examined by month, as well as by distinct pandemic related epochs characterized by varying degrees of public awareness, incidence of COVID-19 infections and public health restrictions. RESULTS: National, and provincial level data revealed that rates of LAI prescribing including new starts, discontinuations and switches between LAI products remained highly stable (i.e., no statistically significant differences) throughout the study period. CONCLUSIONS: Equal numbers of LAI new starts and discontinuations prior to and during the pandemic suggests prescribing of LAI antipsychotics, for those already in care, continued unchanged throughout the pandemic. The observed consistency of LAI prescribing contrasts with other areas of healthcare, such as cardiovascular and diabetes care, which experienced decreases in medication prescribing during the COVID-19 pandemic.
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Antipsicóticos , COVID-19 , Esquizofrenia , Adolescente , Antipsicóticos/uso terapéutico , Canadá , Preparaciones de Acción Retardada/uso terapéutico , Humanos , Pandemias , SARS-CoV-2 , Esquizofrenia/tratamiento farmacológicoRESUMEN
A position statement developed by the Canadian Psychiatric Association's (CPA) Research Committee and approved by the CPA's Board of Directors on May 13, 2020.
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Cannabinoides , Trastornos Mentales , Psiquiatría , Adulto , Canadá , Humanos , Trastornos Mentales/tratamiento farmacológico , Sociedades MédicasRESUMEN
OBJECTIVE: Alcohol and cannabis misuse are common in patients with early phase psychosis (EPP); however, research has tended to focus primarily on cannabis misuse and EPP outcomes, with a relative lack of data on alcohol misuse. This retrospective cross-sectional EPP study investigated the relationship between cannabis, alcohol, and cannabis combined with alcohol misuse, on age, gender, psychotic, depressive and anxiety symptom severity, and social/occupational functioning, at entry to service. METHODS: Two-hundred and sixty-four EPP patients were divided into 4 groups based on substance use measured by the Alcohol, Smoking and Substance Involvement Screening Test: (1) no to low-level cannabis and alcohol misuse (LU), (2) moderate to high alcohol misuse only (AU), (3) moderate to high cannabis misuse only (CU), and (4) moderate to high alcohol and cannabis misuse (AU + CU). RESULTS: We found significant between group differences in age (with the AU group being the oldest and AU + CU group the youngest) as well as gender (with the CU group having the highest percentage of men). There were also group differences in positive psychotic symptoms (lowest in AU group), trait anxiety (highest in AU + CU group), and social/occupational functioning (highest in AU group). Further regression analyses revealed a particularly strong relationship between AU + CU group and trait anxiety (3-fold increased odds of clinical trait anxiety for combined misuse of alcohol and cannabis compared to non/low users). CONCLUSIONS: This study demonstrates the unique demographic and clinical characteristics found in the EPP population at entry to care associated with alcohol and cannabis misuse both separately and in combination. This work highlights the importance of including the assessment of alcohol misuse in addition to cannabis misuse in future treatment guidelines and research.
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Cannabis , Trastornos Psicóticos , Trastornos de Ansiedad , Estudios Transversales , Humanos , Masculino , Trastornos Psicóticos/epidemiología , Estudios RetrospectivosRESUMEN
OBJECTIVE: Cannabis use in people with early phase psychosis (EPP) can have a significant impact on long-term outcomes. The purpose of this investigation was to describe current cannabis use treatment practices in English-speaking early intervention services (EISs) in Canada and determine if their services are informed by available evidence. METHOD: Thirty-five Canadian English-speaking EISs for psychosis were approached to complete a survey through email, facsimile, or online in order to collect information regarding their current cannabis use treatment practices. RESULTS: Data were acquired from 27 of the 35 (78%) programs approached. Only 12% of EISs offered formal services that targeted cannabis use, whereas the majority (63%) of EISs offered informal services for all substance use, not specifically cannabis. In programs with informal services, individual patient psychoeducation (86%) was slightly more common than individual motivational interviewing (MI) (76%) followed by group patient psychoeducation (52%) and information handouts (52%). Thirty-seven percent of EISs offered formal services for substance use, and compared to programs with informal services, more MI, cognitive-behavioural therapy, and family services were offered, with individual treatment modalities more common than groups. No EISs used contingency management, even though it has some preliminary evidence in chronic populations. Evidence-based service implementation barriers included appropriate training and administrative support. CONCLUSIONS: While most English-speaking Canadian EIS programs offer individual MI and psychoeducation, which is in line with the available literature, there is room for improvement in cannabis treatment services based on current evidence for both people with EPP and their families.
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Intervención Médica Temprana/estadística & datos numéricos , Uso de la Marihuana/terapia , Entrevista Motivacional/estadística & datos numéricos , Educación del Paciente como Asunto/estadística & datos numéricos , Psicoterapia/estadística & datos numéricos , Trastornos Psicóticos/terapia , Canadá , Estudios Transversales , Encuestas de Atención de la Salud , HumanosRESUMEN
Oculogyric crisis (OGC) is an often recurrent dystonic adverse effect of antipsychotic treatment characterized by a sustained fixed upward gaze lasting minutes to hours. The risk of OGC has not been established. We prospectively estimated the incidence rate of OGC in an early intervention service for psychosis and provided details regarding the antipsychotics implicated, clinical presentation, and long-term outcomes of OGC. The Nova Scotia Early Psychosis Program provides comprehensive, team-based care to youth and young adults with schizophrenia spectrum disorder. For 6 years (April 2008 to March 2014), 452 new patients were admitted to the program and participated in an individualized program of care. Eight patients (4 females; mean age, 19.8 years) developed recurrent episodes of OGC after 3 months to 2 years of treatment with 1 or more second-generation antipsychotics, yielding an incidence rate of 1.8% (95% confidence interval, 0.9%-3.4%). Risperidone or olanzapine (alone or in combination with a second antipsychotic) seemed causative in each case. Also implicated in the onset or recurrence of oculogyric episodes were ziprasidone, quetiapine, clozapine, aripiprazole, and the first-generation antipsychotic loxapine. Follow-up ranged between 2 and 7 years. Episodes stopped after switching antipsychotic treatment in 4 cases and after stopping antipsychotic treatment in 2 cases. In the other 2 cases, recurrences were ongoing at last follow-up 2 and 6 years after onset with antipsychotic treatment continuing. We observed a high rate of tardive-onset, recurrent, and potentially chronic ocular dystonias in patients with first-episode psychosis caused by the use of second-generation antipsychotics.
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Antipsicóticos/efectos adversos , Distonía/inducido químicamente , Trastornos de la Motilidad Ocular/inducido químicamente , Evaluación de Resultado en la Atención de Salud/estadística & datos numéricos , Trastornos Psicóticos/tratamiento farmacológico , Esquizofrenia/tratamiento farmacológico , Adolescente , Adulto , Distonía/epidemiología , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Masculino , Nueva Escocia/epidemiología , Trastornos de la Motilidad Ocular/epidemiología , Trastornos Psicóticos/epidemiología , Recurrencia , Esquizofrenia/epidemiología , Adulto JovenRESUMEN
BACKGROUND: This research is a one-site neuroimaging component of a two-site genetic study involving patients with schizophrenia at early and later stages of illness. Studies support a role for the neuronal Per-Arnt-Sim 3 (NPAS3) gene in processes that are essential for normal brain development. Specific NPAS3 variants have been observed at an increased frequency in schizophrenia. In humans, NPAS3 protein was detected in the hippocampus from the first trimester of gestation. In addition, NPAS3 protein levels were reduced in the dorsolateral prefrontal cortex of some patients with schizophrenia. Npas3 knockout mice display behavioural, neuroanatomical and structural changes with associated severe reductions in neural precursor cell proliferation in the hippocampal dentate gyrus. This study will evaluate the hypothesis that the severe reductions in neural precursor cell proliferation in the dentate gyrus will be present to some degree in patients carrying schizophrenia-associated NPAS3 variants and less so in other patients. METHODS/DESIGN: Patients enrolled in the larger genetic study (n = 150) will be invited to participate in this neuroimaging arm. The genetic data will be used to ensure a sample size of 45 participants in each genetic subgroup of patients (with and without NPAS3 variants). In addition, we will recruit 60 healthy controls for acquisition of normative data. The following neuroimaging measures will be acquired from the medial temporal region: a) an index of the microcellular environment; b) a macro-structural volumetric measure of the hippocampus; and c) concentration levels of N-acetylaspartate, a marker of neuronal health. DISCUSSION: This study will help to establish the contribution of the NPAS3 gene and its variants to brain tissue abnormalities in schizophrenia. Given the genetic and phenotypic heterogeneity of the disorder and the large variation in outcomes, the identification of biological subgroups may in future support tailoring of treatment approaches in order to optimize recovery.
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Proteínas del Tejido Nervioso/genética , Esquizofrenia/genética , Lóbulo Temporal/fisiopatología , Factores de Transcripción/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , Análisis Mutacional de ADN , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Humanos , Estudios Multicéntricos como Asunto , Neuroimagen , Esquizofrenia/fisiopatologíaRESUMEN
Over the past decade, there has been extensive research on the mismatch negativity (MMN) and its promise as a biomarker of illness in people with schizophrenia (SZ). Nevertheless, when attempting to assess the early stages of illness progression, the utility of MMN has been inconsistent. Recently, researchers have been investigating a more advanced MMN paradigm (the complex MMN [cMMN]) which is believed to index higher-order cognitive processing and has been suggested to be a more effective indicator of the early phases of SZ. The cMMN is defined as a paradigm that relies on alterations within a pre-established pattern of stimuli. In this meta-analysis, we investigated cMMN deficits in individuals with SZ, including an analysis involving those in the first 5 years of illness. Our search also included individuals with bipolar disorder who experience psychosis; however, no related papers were found and thus, no findings are reported. Our findings indicate a small/moderate effect (d = 0.47), suggesting that individuals with SZ exhibit reduced cMMN amplitudes compared to individuals without SZ. Interestingly, this effect seems to be more pronounced in individuals within the first 5 years of their illness (d = 0.58), suggesting that cMMN might be a more sensitive biomarker in the early phases of SZ compared to traditional paradigms.
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AIM: Most young adults experiencing psychosis enter early intervention services (EIS) via inpatient and emergency departments. These experiences are suggested to negatively impact their views of treatment and engagement in EIS. However, limited research has examined the impact of young adults' prior help-seeking experiences on these outcomes. The present study aimed to explore how young adults engaged in EIS have experienced initial help-seeking and make sense of these experiences in the context of their current treatment. METHODS: Using an interpretative phenomenological analysis approach, semi-structured interviews were conducted with 12 young adults (mean age = 24.83) within their first 3-12 months of treatment in EIS. Interviews aimed to examine their experiences of help-seeking and referral to EIS as well as the impact of these experiences on their subsequent perception of, and engagement with EIS. RESULTS: 3 superordinate themes emerged: (1) Navigating the Maze of Healthcare (2) Dignity and (3) Impact of Help-Seeking and Referral Experiences. Participants with referral pathways involving urgent care services described more adversity during their referral pathway and tended to describe help-seeking experiences as contributing to negative views towards EIS and diminished engagement in treatment. CONCLUSIONS: The impact of early negative experiences with healthcare on views towards EIS and engagement is evident in participants' accounts. Sense making was further contextualized by participants' illness insight, degree of recovery, and social support throughout experiences. Emergent themes highlight the need for psychiatric services to emphasize service users' dignity and for EIS to provide opportunities for patients to process past negative mental healthcare experiences to strengthen engagement.
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BACKGROUND: Cannabis use may be a modifiable risk factor for mental health problems; however, the role of cannabis use frequency in population seeking mental health and addiction services remains unclear. This study aimed to: 1) compare the prevalence and functional impact of psychiatric symptoms among frequent, infrequent, and non-users of cannabis; and 2) evaluate the associations between cannabis use frequency and functional impact of psychiatric symptoms in help-seeking individuals. METHODS: Data from the Mental Health and Addictions (MHA) Central Intake system in Nova Scotia, Canada was used. Participants aged 19-64 who received MHA Intake assessments from September 2019 to December 2021 with complete information about substance use were included (N = 20,611). Cannabis use frequency over past 30 days was categorized into frequent (>4 times a month), infrequent (≤4 times a month), and non-use. Psychiatric symptomatology consists of five domains: mood, anxiety, psychosis, cognition, and externalizing behaviors. Multivariate ordinal logistic regression was used to examine the associations between cannabis use frequency and functional impact of psychiatric symptoms. RESULTS: Frequent and infrequent cannabis users had a higher prevalence of psychiatric symptoms in each domain than non-users, while no significant differences were found between frequent and infrequent users. Frequent cannabis use was associated with greater functional impact of psychiatric symptoms in each domain compared to non-users, while infrequent use was only associated with greater functional impact of externalizing behaviors. CONCLUSION: Frequent cannabis use is associated with increased prevalence and functional impact of psychiatric symptoms among adults seeking mental health services.
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Cannabis , Abuso de Marihuana , Adulto , Humanos , Estudios Transversales , Nueva Escocia/epidemiología , Salud MentalRESUMEN
This study examined the relationship between terminal referral source and subsequent urgent health service use in a Canadian early intervention service (EIS) for psychosis. Administrative health record data of emergency and inpatient mental health service use over a 2-year follow up from entry to EIS were retrospectively analyzed (n = 515). Negative binomial regression models were used to assess for the relationship between referral source and care outcomes. Compared to those referred from primary care services, the rate of urgent health care use was significantly greater for individuals referred to early intervention services from urgent care services while accounting for social and occupational functioning and psychotic symptom severity. Findings suggest that those referred from urgent services may be at an increased risk for subsequent urgent health care use while attending EIS for psychosis. Further research examining this relationship while incorporating additional relevant predictors is needed.
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Pacientes Internos , Trastornos Psicóticos , Humanos , Estudios Retrospectivos , Canadá , Trastornos Psicóticos/epidemiología , Trastornos Psicóticos/terapia , Trastornos Psicóticos/diagnóstico , Derivación y ConsultaRESUMEN
Using electroencephalography (EEG) to examine the simple mismatch negativity (MMN), a marker of auditory cortex function, has been of great interest in the exploration of biomarkers for psychotic illness. Despite many studies reporting MMN deficits in chronic schizophrenia, there are inconsistent reports of MMN reductions in the early phases of psychotic illness, suggesting the MMN elicited by traditional paradigms may not be a sensitive enough measure of vulnerability to be used as a biomarker. Recently, a more computationally complex measure of auditory cortex function (the complex mismatch negativity; cMMN) has been hypothesized to provide a more sensitive marker of illness vulnerability. The current study employed a novel dual rule paradigm, in which two pattern rules are established and violated, to examine the cMMN in 14 individuals with early phase psychosis (EPP, < 5 years illness) and 15 healthy controls (HC). Relationships between cMMN waveforms, symptom severity, and measures of functioning were explored. We found reductions of cMMN amplitudes at the site of maximal amplitude in EPP (p = .017) with large effect sizes (Hedges' g = 0.96). This study is an early step in the exploration of the cMMN as a biomarker for psychosis. Our results provide evidence that the dual rule cMMN paradigm shows promise as a method for cMMN elicitation that captures more subtle neurofunctional changes in the early stages of illness.
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Many Canadian emerging adults (ages 18-25 years) use cannabis, with 60 % of past-three-month users experiencing one or more cannabis-related problems (i.e., adverse consequences of use). While psychotic-like experiences (PLEs) and cannabis problems overlap, little is known about the mechanisms explaining this link. One hypothesis is that PLEs are distressing and give rise to anxiety, with which emerging adults attempt to cope through increased cannabis use, in turn increasing their risk for cannabis-related problems. We tested a chained-mediational model to determine if anxiety and coping-with-anxiety motives for cannabis use sequentially mediated the link between PLEs and cannabis problems in emerging adult undergraduates; a conditional process model tested for moderation by sex. Emerging adult cannabis users (N = 413; mean [SD] age = 19.1 [1.5] years; 71.9 % female) from five Canadian universities provided cross-sectional, self-report survey data in fall 2021. Validated measures of PLEs, anxiety, cannabis coping-with-anxiety motives, and cannabis-related problems were administered. Path analyses supported the hypothesized chained mediational indirect effect (b = 0.027, 95 % bootstrap CI [0.012, 0.050]). No direct effect was found (p =.698), suggesting that the PLEs-to-cannabis problems association is fully explained by anxiety and cannabis coping-with-anxiety motives. Inconsistent with hypotheses, mediation did not depend on sex (95 % CIs crossed zero); therefore, anxiety and cannabis coping-with-anxiety motives explain the link between PLEs and cannabis problems in emerging adults regardless of their sex. Results highlight anxiety and cannabis coping-with-anxiety motives as potentially important intervention targets in cannabis-using emerging adults with PLEs, possibly preventing the development/worsening of cannabis-related problems.
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Cannabis , Alucinógenos , Adulto , Humanos , Femenino , Adolescente , Adulto Joven , Masculino , Estudios Transversales , Adaptación Psicológica , Canadá/epidemiología , Ansiedad/epidemiología , MotivaciónRESUMEN
Different lines of evidence suggest an abnormal cerebral energy metabolism as being critical to the pathophysiology of schizophrenia. However, it is unknown as to whether levels of creatine (Cr) would be involved in these anomalies. The study involved 33 unmedicated first episode psychosis patients and 41 healthy controls. Proton magnetic resonance spectroscopy ((1) H-MRS) was performed at 3 T using a long TE (TE/TM/TR of 240/27/3000 ms) such that within the total phosphocreatine (PCr) plus Cr signal (tCr(240)), mainly Cr was detectable. The target region was an 18 cm(3) prefrontal volume. A negative association was found between age of patients and tCr(240) levels referenced to internal water, with 20% of the variance in tCr(240) accounted for by Age. A secondary finding revealed 16% reduction of tCr(240) levels in patients, solely when comparing participants older than the median age of patients. No association existed between tCr(240) levels and clinical variables. These findings support previous data reporting abnormalities in brain creatine kinase isoenzymes involved with the maintenance of energy pools in schizophrenia. The implications of using a long TE are discussed in terms of the relative proportions of Cr and PCr within the tCr(240) signal, and of potential group differences in T(2) times.
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Encéfalo/metabolismo , Creatina/análisis , Espectroscopía de Resonancia Magnética/métodos , Trastornos Psicóticos/diagnóstico , Trastornos Psicóticos/metabolismo , Adolescente , Adulto , Antipsicóticos/uso terapéutico , Biomarcadores/análisis , Femenino , Humanos , Masculino , Protones , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Adulto JovenRESUMEN
BACKGROUND: A disturbance in connectivity between different brain regions, rather than abnormalities within the separate regions themselves, could be responsible for the clinical symptoms and cognitive dysfunctions observed in schizophrenia. White matter, which comprises axons and their myelin sheaths, provides the physical foundation for functional connectivity in the brain. Myelin sheaths are located around the axons and provide insulation through the lipid membranes of oligodendrocytes. Empirical data suggests oligodendroglial dysfunction in schizophrenia, based on findings of abnormal myelin maintenance and repair in regions of deep white matter. The aim of this in vivo neuroimaging project is to assess the impact of early adolescent onset of regular cannabis use on brain white matter tissue integrity, and to differentiate this impact from the white matter abnormalities associated with schizophrenia. The ultimate goal is to determine the liability of early adolescent use of cannabis on brain white matter, in a vulnerable brain. METHODS/DESIGN: Young adults with schizophrenia at the early stage of the illness (less than 5 years since diagnosis) will be the focus of this project. Four magnetic resonance imaging measurements will be used to assess different cellular aspects of white matter: a) diffusion tensor imaging, b) localized proton magnetic resonance spectroscopy with a focus on the neurochemical N-acetylaspartate, c) the transverse relaxation time constants of regional tissue water, d) and of N-acetylaspartate. These four neuroimaging indices will be assessed within the same brain region of interest, that is, a large white matter fibre bundle located in the frontal region, the left superior longitudinal fasciculus. DISCUSSION: We will expand our knowledge regarding current theoretical models of schizophrenia with a more comprehensive multimodal neuroimaging approach to studying the underlying cellular abnormalities of white matter, while taking into consideration the important confounding variable of early adolescent onset of regular cannabis use.