in the outpatient sector. Also, the average life expectancy of the general population in the USA is 76 years and we analyzed only people until 55 years. But in schizophrenia the average life expectancy is 51–61 years (Newman & Bland 1991; Harris & Barraclough 1998; Colton & Manderscheid, 2006). Finally, there is accumulating evidence that cannabis use, particularly in those genetically at risk (Caspi et al., 2005), may be associated with an increased risk of schizophreniform disorder. We did not examine genetic effects and risk, nor did we examine the age of onset of illness and relate this to the onset of cannabis use. Thus, we cannot comment on the relationship of cannabis to schizophrenia per se in this study.
