A recently published Australian study suggests when used as prescribed to manage a chronic health condition, cannabis does not negatively impact cognitive function.
Carried out by researchers at Swinburne University of Technology’s Centre for Human Psychopharmacology, the study involved 40 patients who were prescribed a range of products containing the intoxicating cannabinoid delta-9 tetrahydrocannabinol (THC).
A subjective drug effect questionnaire was repeated at 1, 2, and 4 hours after dosing. A Cambridge Neuropsychological Test Automated Battery (CANTAB) was repeated at 3 hours, while the Druid assessment was repeated at 3 and 5.5 hours after dosing. The CANTAB test battery includes six tests:
- Multitasking Test (MTT)
- Pattern Recognition Memory (PRM)
- Reaction Time (RTI)
- Rapid Visual Information Processing (RVP)
- Spatial Span (SSP)
- Spatial Working Memory (SWM)
A range of other assessments were completed and participants also provided blood and oral fluid samples for quantification of THC.
Overall, minimal acute impact on cognitive function was found.
“This could indicate that patients develop tolerance over time, akin to what we see with other psychoactive medications like antidepressants and benzodiazepines,” said lead researcher Dr Thomas Arkell. “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 is a psychopharmacologist with a broad research interest in drugs and their effects on the brain and human behaviour. He also chairs the Cannabis and Driving working group through the International Council for Alcohol, Drugs and Traffic Safety (ICADTS).
The researchers state their findings are consistent with two systematic reviews published in the last year suggesting medical cannabis used regularly and consistently for a chronic health condition may have little if any impact on cognitive function.
While the researchers warn results cannot be generalised to non-medical or non-prescribed medical cannabis use and it was only a small study – with further research needed – Dr. Arkell says the findings have implications for the many Australians who are currently prescribed medical cannabis to manage a chronic health condition.
The study report has been published in the journal CNS Drugs.