Schizophrenia is a genetic condition that begins its presentation in utero. It isn’t a single gene disorder, but instead hundreds of risk genes have been identified through genome-wide association studies (GWAS). Increased cannabis consumption during an individual’s adolescent years causes the symptoms to have an earlier onset. Increased dopamine signalling leads to stronger positive symptoms.
Genetic: the risk alleles identified through GWAS, that have an association with the development of schizophrenia
Environmental: cannabis consumption during an individuals adolescent years makes the onset of the symptoms earlier and stronger.