Cannabis e Schizofrenia.
appunti del dott. Claudio Italiano
Gli studi appresso riportati vogliono rispondere al quesito che un nostro gentile
navigatore ci pone, se cioè sia possibile e provato scientificamente, che l'abuso
del fumo di canna possa slatentizzare la schizofrenia. Alcuni autori sembrano confermare
questa ipotesi, che cioè abusando droghe, in soggetti già predisposti geneticamente,
l'abuso della droga possa slatentizzare una psicosi latente. I passi salienti degli
abstracts sono stati riportati in rosso.
Cannabis abuse and risk for psychosis in a prodromal sample.
Kristensen K, Cadenhead KS.
Department of Psychiatry, 0810, University of California San Diego, 9500 Gilman
Drive, La Jolla, CA 92093-0810, USA.
The goal of the present study was to examine the rate of cannabis use among participants
in the Cognitive Assessment and Risk Evaluation (CARE) Program, a longitudinal program
for individuals who are "at risk" for developing a psychotic disorder. Cannabis
abuse was assessed in 48 individuals identified as at risk for psychosis based on
subsyndromal psychotic symptoms and/or family history. At 1 year follow-up, 6 of
the 48 (12.5%) at risk subjects had made the transition to psychosis. Of the 32
subjects who had no use or minimal cannabis use, one subject (3.1) converted to
psychosis. Of the 16 subjects who met criteria for cannabis abuse/dependence, five
(31.3%) converted to psychosis. The results show a significant association between
cannabis abuse and conversion to psychosis in this sample. Nicotine use was also
found to be significantly associated with later conversion. The significant associations
between cannabis and nicotine abuse and conversion to psychosis in individuals at
risk for schizophrenia suggest that early identification and intervention programs
should screen for and provide education about the deleterious effects of these substances.
Cannabis use and psychotic disorders: an update.
Hall W, Degenhardt L, Teesson M.
Office of Public Policy and Ethics, Institute for Molecular Bioscience University
of Queensland Australia.
This paper evaluates three hypotheses about the relationship between cannabis use
and psychosis in the light of recent evidence from prospective epidemiological studies.
These are that: (1) cannabis use causes a psychotic disorder that would not have
occurred in the absence of cannabis use; (2) that cannabis use may precipitate schizophrenia
or exacerbate its symptoms; and (3) that cannabis use may exacerbate the symptoms
of psychosis. There is limited support for the first hypothesis. As a consequence
of recent prospective studies, there is now stronger support for the second hypothesis.
Four recent prospective studies in three countries have found relationships between
the frequency with which cannabis had been used and the risk of receiving a diagnosis
of schizophrenia or of reporting psychotic symptoms. These relationships are stronger
in people with a history of psychotic symptoms and they have persisted after adjustment
for potentially confounding variables. The absence of any change in the incidence
of schizophrenia during the three decades in which cannabis use in Australia has
increased makes it unlikely that cannabis use can produce psychoses that would not
have occurred in its absence. It seems more likely that cannabis use can precipitate
schizophrenia in vulnerable individuals. There is also reasonable evidence for the
third hypothesis that cannabis use exacerbates psychosis.
Familial predisposition for psychiatric disorder: comparison of subjects treated
for cannabis-induced psychosis and schizophrenia.
Arendt M, Mortensen PB, Rosenberg R, Pedersen CB, Waltoft BL.
Centre for Psychiatric Research, Aarhus University Hospital, Skovagervej 2, Risskov,
8240 Risskov, Denmark. firstname.lastname@example.org
Cannabis-induced psychosis is considered a distinct clinical entity in the existing
psychiatric diagnostic systems. However, the validity of the diagnosis is uncertain.
OBJECTIVES: 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. DESIGN: 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. SETTING: 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. RESULTS: 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.
oppure cfr indice di psichiatria