Daily consumption of cannabis predisposes to the appearance of psychosis and schizophrenia

The daily consumption of cannabis predisposes to the appearance of psychosis and schizophrenia, and those episodes of psychosis which are fruit of this substance present certain specific characteristics, both before their appearance and in the clinical presentation of the psychosis. This is one of the conclusions of the doctoral thesis "Neurodevelopment and environmental stress in initial psychosis: transversal analysis of the ESPIGAS study", carried out by researcher Miguel Ruiz Veguilla, of the Institute of Neurosciences of the University of Granada (Spain) and supervised by professors Manuel Gurpegui Fernández de Legaria and Jorge Cervilla Ballesteros. Ruiz Veguilla is also the person in charge fo the Unit of Development Neuropsychiatry of Jaén (Spain). This work has studied the risk factors associated with schizophrenia, identifying and characterizing in depth those psychosis associated with a continual consumption of cannabis. They carried out a study with 92 subjects, 50 of which had developed a psychosis without presenting signs of an "abnormal neurodevelopment", this is, they had been doing well academically, they had a group of friends (no social isolation) and they presented a good motor coordination. In addition, these subjects did not show a family history of episodes of psychosis in first or second degree.

Identifying a new type of psychosis

The research work carried out by Miguel Ruiz Veguilla has identified a connection between cannabis consumption and psychosis in subjects with a good premorbid performance, and without signs of minor neurological alterations, which in his opinion might point out "a psychopathological way associated with psychosis in subjects with less predisposition".

Thus, 66% of the patients with psychosis who participated in the study and had a normal neurodevelopment admitted to have consumed cannabis daily or almost every day, whereas 43% of the participants with markers of an abnormal neurodevelopment (those already indicated: bad previous social and academic behaviour, a family history and a "clumsier" attitude when they carry out tasks of motor coordination and complex motor acts) were drug users too.

In the light of the results of his doctoral thesis, the researcher of the University of Granada says that, after having identified a type of psychosis where the environmental factor plays a more relevant role, we should now answer the question of which is the prognosis, in the long term, of those subjects with a good previous behaviour, whose psychosis is associated with a high consumption of cannabis.

The results of this research work have been published in the journals Schizophrenia Research and European Psychiatry, two of the most renowned worldwide publications in this research field.

Source: University of Granada