Effects of country of origin and wave of immigration on prevalence of schizophrenia among first and second-generation immigrants: A 30-year retrospective study.

OBJECTIVES: To compare the rates of schizophrenia among 1st and 2nd generation immigrants from two distinct backgrounds and across sequential periods of immigration. METHODS: A 30-years retrospective cohort study (187,184 individuals) of 1st and 2nd generation East-African immigrants (EAIs) and former Soviet-Union immigrants (FSUIs) who migrated to Israel between 1980 and 2012. EAIs were further divided according to waves of immigration. Period prevalence was calculated between the years 2002-2012. Multivariate logistic regression models were used to examine the association between immigration-related factors and prevalence of schizophrenia (Native-Born Israelis serving as reference group). RESULTS: The prevalence of schizophrenia in 1st generation EAIs and FSUIs was 1.8% and 1.2%, respectively, compared to 1.0% among NBIs (p<0.001). The prevalence of schizophrenia among 2nd generation EAIs and FSUIs was 1.3% and 0.8%, respectively, compared to 0.6% among NBIs (p<0.001). Adjusted odds ratios for developing schizophrenia compared to NBIs were 1.6 (95%CI:1.4-1.8) and 2.1 (95%CI:1.6-2.7), among 1st and 2nd generation EAIs and 1.1 (95%CI:0.9-1.2) and 1.3 (95%CI:1.0-1.8) among 1st and 2nd generation FSUIs respectively. Among EAIs, we observed the highest rate of schizophrenia in the pioneer wave of immigrants with gradual decline across subsequent waves: 2.4%, 1.9% and 1.0% for the 1st, 2nd and 3rd waves of immigration, respectively (p<0.001). CONCLUSIONS: The increased risk for developing schizophrenia among 2nd generation immigrants and among pioneer groups of immigrants emphasizes the importance of persistent investment in acculturation. Further studies elucidating the impact of country of origin and ethnic density on the risk for developing schizophrenia are warranted.

The association between cannabis use and depression: a systematic review and meta-analysis of longitudinal studies.

BACKGROUND: Longitudinal studies reporting the association between cannabis use and developing depression provide mixed results. The objective of this study was to establish the extent to which different patterns of use of cannabis are associated with the development of depression using meta-analysis of longitudinal studies. METHOD: Peer-reviewed publications reporting the risk of developing depression in cannabis users were located using searches of EMBASE, Medline, PsychINFO and ISI Web of Science. Only longitudinal studies that controlled for depression at baseline were included. Data on several study characteristics, including measures of cannabis use, measures of depression and control variables, were extracted. Odds ratios (ORs) were extracted by age and length of follow-up. RESULTS: After screening for 4764 articles, 57 articles were selected for full-text review, of which 14 were included in the quantitative analysis (total number of subjects = 76058). The OR for cannabis users developing depression compared with controls was 1.17 [95% confidence interval (CI) 1.05-1.30]. The OR for heavy cannabis users developing depression was 1.62 (95% CI 1.21-2.16), compared with non-users or light users. Meta-regression revealed no significant differences in effect based on age of subjects and marginal difference in effect based on length of follow-up in the individual studies. There was large heterogeneity in the number and type of control variables in the different studies. CONCLUSIONS: Cannabis use, and particularly heavy cannabis use, may be associated with an increased risk for developing depressive disorders. There is need for further longitudinal exploration of the association between cannabis use and developing depression, particularly taking into account cumulative exposure to cannabis and potentially significant confounding factors.

Remission of positive symptoms according to the "remission in Schizophrenia Working Group" criteria: a longitudinal study of cognitive functioning.

Schizophrenia patients in positive symptomatic remission (PSR; n=39) were assessed using a longitudinal research design. The patients were found to exhibit widespread cognitive impairments that were stable over the three-year follow-up period. The findings support a generalized and stable cognitive impairment profile among schizophrenia patients in partial symptomatic remission.

Clinical correlates of cannabis use among adolescent psychiatric inpatients.

OBJECTIVES: This study sought to determine the clinical correlates of adolescents with cannabis use and no additional drug use (CU) compared to adolescents with no drug use (NDU) among a group of adolescent psychiatric inpatients in Israel. METHODS: Two hundred and thirty-six patients consecutively admitted to an adolescent inpatient unit at a university-affiliated mental health center in Israel during a 3-year period were screened. Individuals with polydrug use were excluded from the study. RESULTS: Prevalence of cannabis use was 13%. In the CU group, 39% were diagnosed with attention deficit and disruptive behavior disorders compared with 16% in the NDU group. Antipsychotics were the most common medications prescribed in both groups. Mood stabilizers were more frequently prescribed to CU than to NDU patients (39% vs 16%, respectively). A higher prevalence of alcohol abuse and criminal behaviors was found among CU compared to NDU patients (61% and 39% vs 6% and 4%, respectively). CONCLUSIONS: The high prevalence of disruptive behaviors and frequent treatment with antipsychotics and mood stabilizers in the CU group may be related to the strong association between externalizing behavior and cannabis use and the non-specific pharmacological treatment of disruptive behaviors. Formal screening for cannabis use should be considered in psychiatric facilities. Specifically, adolescents with disruptive behaviors could benefit from early interventions, before and after cannabis initiation.

Transcranial magnetic stimulation of the ventromedial prefrontal cortex impairs theory of mind learning.

Imaging and lesion studies indicate that the prefrontal cortex plays a prominent role in mediating theory of mind (ToM) functioning. Particularly, the ventromedial prefrontal cortex (VMPFC) appears to be involved in mediating ToM functioning. This study utilized slow repetitive transcranial magnetic stimulation (rTMS) over the VMPFC in 13 healthy subjects in order to test whether normal functioning of the VMPFC is necessary for ToM functioning. We found that rTMS to the VMPFC, but not sham-rTMS, significantly disrupted ToM learning. Performance on a control task, not involving affective ToM functioning, was not significantly altered after applying rTMS to the VMPFC or sham-rTMS. In an additional experiment, rTMS to the vertex did not significantly affect ToM learning, confirming specificity of the VMPFC region. These findings indicate that the VMPFC is critical for intact ToM learning and shed further light on the concept and localization of ToM in particular and empathic functioning in general.

Neurocognitive functions of heavy cannabis using schizophrenia patients.

This current study assessed neurocognitive functioning in a carefully selected sample of schizophrenia patients with and without heavy cannabis use and healthy controls. All subjects were negative for any other substance use. Schizophrenia subjects had impaired neurocognitive functions across a wide range of tasks compared to healthy controls. Cannabis using schizophrenia patients had focused impairments on tasks of attention, and the findings suggest an impulsive pattern of response among these patients.