With cannabis now legal in many parts of the world, an increasing number of people count as regular users of the drug, many even chalking up daily usage.
A frequently voiced concern has been that this heavy usage of cannabis may affect brain function, especially in those who start consuming the drug young. However the evidence for this is actually pretty flimsy, and a couple of new research studies don’t raise any huge new concerns.
The first study, published July, was an observational one looking at the effect of cannabis on cognitive function in medicinal users of the drug. In this case the researchers hypothesized that brain function may actually improve over the course of the study (given that cannabis medicines can improve pain levels and general quality of life), and they were correct.
Specifically, what the researchers observed in medicinal cannabis patients was a significant improvement on measures of executive function (the ability to plan, focus, remember instructions, and multi-task), with verbal learning and memory performance remaining roughly stable.
The second study, published August and conducted in a Dutch population, was an imaging study designed to compare the fine structure of white matter in the brain between cannabis and non-cannabis users. One group consisted of 39 near-daily cannabis users, and the other contained 28 controls, who were roughly matched on age, alcohol and cigarette use.
The study found no significant differences in white matter between the two groups.
The authors of this second study did however introduce some caution, saying that while their findings suggested that long-term near-daily cannabis use does not necessarily affect white matter microstructure…” vulnerability may be higher during adolescence”.
They added that further studies should investigate whether earlier cannabis use onset has more impact on the brain.