The United Nations Office on Drugs and Crime reported that, in 2018, approximately 192 million people worldwide aged between 15 and 64 used cannabis recreationally.
This is characterised by the persistent desire to use the drug and disruption to daily activities, such as work or education.
This effect seemed to be linked to the age at which people started taking the drug – the younger they were, the more impaired their executive functioning was.
We showed that, while male cannabis users had poorer memory for visually recognising things, female users had more problems with attention and executive functions.
For example, some previous research has suggested that reward and motivation – along with the brain circuits involved in these processes – can be disrupted when we use cannabis.
In our recent study, we used a brain imaging task, in which participants were placed in a scanner and viewed orange or blue squares.
Cannabis use during adolescence has also been reported as a risk factor for developing psychotic experiences as well as schizophrenia.
Assessing 2,437 adolescents and young adults , the authors reported a six percentage points increased risk – from 15% to 21% – of psychotic symptoms in cannabis users without a predisposition for psychosis.
Another study of 780 teenagers suggested that the association between cannabis use and psychotic experiences was also linked to a brain region called the “uncus”.
Cognitive and psychological effects of cannabis use are ultimately likely to depend to some extent on dosage , sex, genetic vulnerabilities and age of onset.