23 de janeiro de 2022

Age at Initiation of Cannabis Use Predicts Age at Onset of Psychosis: The 7- to 8-Year Trend

15 de janeiro de 20136min26

We investigated the existence of a temporal association between age at initiation of cannabis use and age at onset of psychotic illness in 997 participants from the 2010 Survey of High Impact Psychosis (SHIP) in Australia. We tested for group differences in age at onset of psychotic illness and in the duration of premorbid exposure to cannabis (DPEC). Analyses were repeated in subgroups of participants with a schizophrenia-spectrum disorder (SSD), a diagnosis of lifetime cannabis dependence (LCD), and a comorbid SSD/LCD diagnosis.

Vera Anne Morgan1

The association between age at initiation of cannabis use and age at onset of psychotic illness was linear and significant, F(11, 984) = 13.77, P< .001, even after adjusting for confounders. The effect of age at initiation of cannabis use on DPEC was not significant (mean duration of 7.8 years), and this effect was similar in participants with a SSD, LCD, and comorbid SSD/ LCD diagnosis although a shift toward shorter premorbid exposure to cannabis was noted in the SSD/LCD subgroup (mean duration of 7.19 years for SSD/LCD). A temporal direct relationship between age at initiation of cannabis use and age at onset of psychotic illness was detected with a premorbid exposure to cannabis trend of 7–8 years, modifiable by higher severity of premorbid cannabis use and a diagnosis of SSD. Cannabis may exert a cumulative toxic effect on individuals on the pathway to developing psychosis, the manifestation of which is delayed for approximately 7–8 years, regardless of age at which cannabis use was initiated.


Author Affiliations

  1. 1School of Psychiatry and Clinical Neurosciences, and Centre for Clinical Research in Neuropsychiatry, the University of Western Australia;
  2. 2Clinical Research Centre, North Metropolitan Health Service—Mental Health, WA, Australia;
  3. 3Peel and Rockingham Kwinana Older Adult Mental Health Service, South Metropolitan Area Health Service, Perth, Australia;
  4. 4St Vincent’s Hospital, University of Melbourne

*To whom correspondence should be addressed; Private Bag No 1, Claremont WA 6910, Australia; tel: (+61) 08 9347 6429, fax: (+61) 08 9384 5128, e-mail: nikos.stefanis@uwa.edu.au

Sobre a UNIAD

A Unidade de Pesquisa em álcool e Drogas (UNIAD) foi fundada em 1994 pelo Prof. Dr. Ronaldo Laranjeira e John Dunn, recém-chegados da Inglaterra. A criação contou, na época, com o apoio do Departamento de Psiquiatria da UNIFESP. Inicialmente (1994-1996) funcionou dentro do Complexo Hospital São Paulo, com o objetivo de atender funcionários dependentes.