The relationship between substance use and psychotic disorders has pro
duced much controversy in clinical, public policy and research domains.
Given the role of regulators in determining the legality of substances of
abuse, the relationship between substance use and psychosis has been a
matter for contentious debate. Counter to these discussions, however, is the
indication that the most commonly used substances in patients with schizo
phrenia, and those who express schizotypal traits, are alcohol and nicotine.
There is evidence that substance use patterns are established before the
onset of illness. Therefore, consideration of substance use in relation to
schizotypy may help to elucidate the nature of the relationship between risk
and substance use. Ross and Peselow (2012) provide a classification system
for the potential relationships between psychotic and addictive disorders,
which is equally relevant to schizotypy. The diagnostic formulation has been
adapted to reflect schizotypy here.