The impact of cannabis use on cognitive functioning and brain structure: implications for understanding the neural basis of psychosis


Wednesday, 8 August, 2012 - 16:00


Room 1016, Mathews Building


School of Psychology

Type of event: 


Presenter: Professor Murat Yucel

Institution: University of Melbourne


Cannabis is arguably the most hotly debated drug of abuse. Its profound effects on the mind have been known  for at least 5000 years and have polarised attitudes, with long-­‐standing controversies  surrounding the  ‘recreational’ use of cannabis, its legalisation, and its therapeutic potential, as well as harm. 

Prof Yücel will present data showing that long term and heavy cannabis use Is associated with  significantly  reduced brain volumes and white matter integrity in medial temporal and cerebellar regions, as well  as, having memory impairment and being more likely to develop sub-­‐threshold psychotic symptoms.  Importantly, the associations between cannabis exposure, loss of brain volume/integrity, and  severity of psychotic-­‐like experiences are dose-­‐dependent, suggesting that they are intricately  linked. 

 He will also present the results of two recent studies -­‐   a meta-­‐analysis and an empirical  study, which examined the effects of cannabis use on cognitive functioning in psychotic patients.  The findings showed that psychotic patients with an early onset and heavy use of cannabis are  associated with superior cognitive functioning compared to psychotic patients without a significant  cannabis use history. These findings are interpreted to suggest that heavy cannabis use during  early adolescence can be a component cause psychotic disorders in some individuals, despite the  fact that cognitive deficits associated with a neurodevelopmental vulnerability are not observed  in  this same group. 

 Our recent findings raise questions regarding the use of drugs during adolescence and have  important  implications for our understanding of the relationship between drug use, brain development and  mental  health, as well as prevention and early intervention approaches.