Regularly smoking cannabis can lead otherwise healthy people to develop psychosis, according to a study of 92 people by researchers at the University of Granada in Spain. The study's participants were all between 18 and 65 and had all suffered from their first episode of psychosis. 57% of the participants said they smoked cannabis daily, or nearly every day. Two-thirds of the cannabis smokers who went on to develop pychosis had no pre-existing signs of abnormal neurological development: they had no family history of psychosis, they were not socially isolated and they had good muscle coordination. While the regular cannabis smokers developed psychosis without having any risk factors the rest of the participants (43%) who already had risk factors such as a family history of psychosis and poor social and academic adjustment did not require an environmental trigger before they developed the condition.
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