Cannabis and other variables affecting age at onset in a schizophrenia founder population
Johannes Lodewikus Roos, H.W. Pretorius, Maria Karayiorgou, H. Boraine
African Journal of Psychiatry July 17, 2006 DOI: 10.4314/ajpsy.v9i2.30212 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Sample size | 341 |
| Population | South African subjects with schizophrenia or schizoaffective disorder from a founder population, recruited since 1997 |
| Measures | Diagnostic Interview for Genetic Studies (DIGS) |
| Topics | Cannabis |
| Citations | 11 |
| Key findings | Cannabis use/abuse was common among male subjects with schizophrenia (44%) and was associated with an earlier mean age of illness onset (20.5 years) compared with non-using males and females. The authors argue that early deviant behaviour in the first ten years of life was the most important determinant of age at onset and may serve as a possible endophenotypic marker. |
Abstract
Objective: An ongoing collaborative study between the Human Neurogenetic Laboratory of Rockefeller University, New York and the Department of Psychiatry at the University of Pretoria, has been taking place since 1997, to map genes for schizophrenia. Aspects of cannabis use/abuse will be reported.Method: The Diagnostic Interview for Genetic Studies [DIGS] is used for all diagnosis. A narrative report is completed. From this database we determined: gender, diagnostic subtype, age of illness onset, early insults, early deviant behaviour, cannabis use/abuse and family history of schizophrenia.Results: From 341 subjects we found: 61% [n=209] males and 39% [n=132] females. In males, 75% [n=156] had schizophrenia and 25% [n=53] schizoaffective disorder[SADJ]. In females 74% [n=97] had schizophrenia and 26% [n=35] SAD. 35% of subjects, [n=118], 44% [n=91] males and 20% [n=27] female's used/abused cannabis. The mean age at onset of illness for the males was 20.5 years. This is significantly earlier than that of males with no cannabis use/abuse group as well as for both these groups in females. The long-term course of illness was similar in both cannabis use/abuse and non-use/abuse groups. An analysis of variance was used to determine the contribution of different factors in determining the age of criteria onset. According to the results obtained, early deviant behaviour was the most important determining age of criteria onset. The group with the lowest mean age of criteria were male users of cannabis with severe early deviant behaviour [18,4 years].
Conclusion: Cannabis use/abuse is common amongst male schizophrenia subjects, and affects age at onset of illness. Early deviant behaviour in the first ten years of life in these subjects is more important in this regard, and may be seen as a possible endophenotypical marker. Keywords: cannabis, psychosis, schizophrenia, founder population South African Psychiatry Review Vol. 9(2) 2006: 99-103
Comparable studies
Other observational and cohort studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| High-potency cannabis and the risk of psychosis People with first episode of psychosis and healthy controls from the local population | 2009 | Case-control study | n = 454 |
| Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada Rural aboriginal population | 2013 | Observational study | |
| Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) Otherwise healthy young people | 2000 | Observational | |
| Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study Individuals from the general population in Germany aged 14-24 at baseline | 2011 | Observational cohort | n = 1,923 |
| Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases Patients treated for cannabis-induced psychotic symptoms in Denmark between 1994 and... | 2005 | Observational cohort | n = 535 |