Familial Predisposition for Psychiatric Disorder Comparison of Subjects Treated for Cannabis-Induced Psychosis and Schizophrenia

Centre for Psychiatric Research, Aarhus University Hospital, Skovagervej 2, Risskov, 8240 Risskov, Denmark.
Archives of general psychiatry (Impact Factor: 13.75). 12/2008; 65(11):1269-74. DOI: 10.1001/archpsyc.65.11.1269
Source: PubMed

ABSTRACT Cannabis-induced psychosis is considered a distinct clinical entity in the existing psychiatric diagnostic systems. However, the validity of the diagnosis is uncertain.
To establish rate ratios of developing cannabis-induced psychosis associated with predisposition to psychosis and other psychiatric disorders in a first-degree relative and to compare them with the corresponding rate ratios for developing schizophrenia spectrum disorders.
A population-based cohort was retrieved from the Danish Psychiatric Central Register and linked with the Danish Civil Registration System. History of treatment of psychiatric disorder in family members was used as an indicator of predisposition to psychiatric disorder. Rate ratios of cannabis-induced psychosis and schizophrenia associated with predisposition to psychiatric disorders were compared using competing risk analyses.
Nationwide population-based sample of all individuals born in Denmark between January 1,1955, and July 1, 1990 (N = 2,276,309). Patients During the 21.9 million person-years of follow-up between 1994 and 2005, 609 individuals received treatment of a cannabis-induced psychosis and 6476 received treatment of a schizophrenia spectrum disorder.
In general, the rate ratios of developing cannabis-induced psychosis and schizophrenia spectrum disorder associated with predisposition to schizophrenia spectrum disorder, other psychoses, and other psychiatric disorders in first-degree relatives were of similar magnitude. However, children with a mother with schizophrenia were at a 5-fold increased risk of developing schizophrenia and a 2.5-fold increased risk of developing cannabis-induced psychosis. The risk of a schizophrenia spectrum disorder following a cannabis-induced psychosis and the timing of onset were unrelated to familial predisposition.
Predisposition to both psychiatric disorders in general and psychotic disorders specifically contributes equally to the risk of later treatment because of schizophrenia and cannabis-induced psychoses. Cannabis-induced psychosis could be an early sign of schizophrenia rather than a distinct clinical entity.

Download full-text


Available from: Preben B Mortensen, Jun 09, 2014
  • Source
    • "Regarding the first knowledge gap, there is some support for the notion that greater cannabis use is associated with schizotypal traits. Numerous studies have found psychometrically-defined schizotypy (defined dimensionally in nearly every study) to be significantly associated with greater cannabis use (Bailey and Swallow, 2004; Dumas et al., 2002; Earleywine, 2006; Esterberg et al., 2009; Mass et al., 2001; Schiffman et al., 2005; Skosnik et al., 2001, 2006; see also Arendt et al., 2008; Caspi et al., 2005; Compton et al., 2009; Miller et al., 2001 for family/genetic studies). Notably, however, theory (Meehl, 1962) and research (e.g., note over a dozen taxometric studies to date; e.g., Lenzenweger and Korfine, 1992) suggest that schizotypy is categorical in nature with a population incidence of approximately 10%. "
    [Show abstract] [Hide abstract]
    ABSTRACT: 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.
    Journal of Psychiatric Research 04/2011; 45(4):548-54. DOI:10.1016/j.jpsychires.2010.08.013 · 4.09 Impact Factor
  • Source
    • "Arendt et al. (2008) reported that children of a mother treated with schizophrenia were at a 5-fold increased risk of developing schizophrenia and a 2.5-fold increased risk of developing cannabis-induced psychosis (Arendt et al., 2008). The risk of a schizophrenia spectrum disorder following a cannabis-induced psychosis and the timing of onset were not associated with familial predisposition (Arendt et al., 2008). Other authors revealed that progression to daily cannabis and tobacco use was associated with an increased risk of onset of psychotic symptoms (Compton et al., 2009). "
    [Show abstract] [Hide abstract]
    ABSTRACT: 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.
    Progress in Neuro-Psychopharmacology and Biological Psychiatry 11/2010; 35(1):212-7. DOI:10.1016/j.pnpbp.2010.11.007 · 4.03 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Numerical simulations were carried out for a piloted turbulent non-premixed methane/air flame. The solution method was based on a joint probability density function (PDF) for velocities, chemical composition, and turbulent frequency. A stand-alone Monte Carlo particle-mesh approach was applied to solve the modeled PDF transport equation. The pressure field could be obtained by the solution of a Poisson equation, and thus, the solution procedure did not need the aid of a CFD code. To take into account multistep finite-rate chemistry, the method of intrinsic low-dimensional manifolds (ILDM) was applied in a three-scalar formulation. All chemical information was stored in look-up tables, which could be efficiently implemented into the PDF scheme. The effects of chemical kinetics and mixing processes, which were modeled using the modified coalescence/dispersion model, are analyzed and discussed. The profile of axial mean velocity component and scatter plots of temperature and some intermediate species against mixture fraction are compared to experimental measurements. The overall agreement of the numerical results is good. The local flame characteristics are discussed in the critical state of burning, extinction, and reignition, where finite-rate chemistry becomes significant. These phenomena can also be predicted quite well by these simulations.
    Proceedings of the Combustion Institute 01/2000; 28(1-28):157-165. DOI:10.1016/S0082-0784(00)80207-6 · 3.83 Impact Factor
Show more