As outlined on the slide, many substances interact with the dopamine system of the brain, as well as with other neurotransmitter systems, dysregulation of which may lead to psychotic symptoms or schizophrenia.[1] It has been proposed that, if schizophrenia and substance-use disorders share genetic risk factors, then the use of substances of abuse during adolescence (i.e., potentially before the emergence of either psychotic symptoms or addiction) may increase any subsequent risk of developing both schizophrenia and substance-use disorder.[2]
References:
[1] Fiorentini A, Cantù F, Crisanti C, et al. Substance-induced psychoses: an updated literature review. Front Psychiatry 2021; 12: 694863.