Medical cannabis doesn’t impair cognitive function – study

A new study suggests that cannabis, when used as prescribed to manage a chronic health condition, does not negatively impact cognitive function.

These new findings are said to contribute a vital piece to the puzzle in assessing the safety and efficacy of medical cannabis treatment, especially with respect to cognitive function.

Researchers at Swinburne University of Technology’s Centre for Human Psychopharmacology in Australia, conducted an open-label trial, in which 40 patients with various health conditions self-administered a standard dose of prescribed medical cannabis as directed by the label.

Participants were prescribed a range of products including orally administered oils and flowers for vaporisation. The most common indication for which cannabis was prescribed was chronic non-cancer pain, followed by sleep disorder and anxiety.

The researchers assessed cognitive performance using the Cambridge Neuropsychological Test Automated Battery (CANTAB) and Druid app, as well as subjective effects before and after consumption. 

Patients chose from adjectives such as ‘stoned’, ‘sedated’, ‘relaxed’, ‘comfortable’, ‘anxious’ and ‘confident’ to describe the effects. 

The results showed that participants’ performance improved over time on the CANTAB Multitasking Test and Rapid Visual Information Processing test, while all other cognitive performance measures were non-significant. 

Vaping was associated with significantly stronger subjective feelings of ‘stoned’ and ‘sedated’ compared to oils. 

Commenting on the findings, lead researcher on the study, Dr Thomas Arkell, said: “We already know that non-medical cannabis can impact memory and attention. However, our findings show that patients prescribed medical cannabis by a doctor don’t experience the same effects.

“This could indicate that patients develop tolerance over time, akin to what we see with other psychoactive medications like antidepressants and benzodiazepines.”

The research also found that patients might become tolerant to the potentially impairing effects of delta-9-tetrahydrocannabinol (THC), the primary psychoactive component of cannabis.

“It could also mean that patients experience some alleviation of their symptoms, such as pain, after using medical cannabis, which might lead to a normalisation of cognitive function,” Dr Arkell continued.

While this research marks a critical step in understanding the impact of prescribed medical cannabis on cognitive function, the results cannot be generalised to non-medical cannabis or non-prescribed medical cannabis use.

The study emphasises the distinction between prescribed medical cannabis and its non-medical or non-prescribed counterparts.

Dr Arkell added: “This is only a small study and further research is needed. However, these findings have real implications for the many thousands of Australians who are now prescribed medical cannabis to manage a chronic health condition.”