ABSTRACT

There is now a good evidence that heavy and long-term use of marijuana can result in subtle impairments of memory, attention and executive function and that the functioning of prefrontal cortical, hippocampal and cerebellar regions can become compromised. Human research has used increasingly sophisticated and sensitive techniques to examine the cognitive consequences of marijuana use and their neural concomitants, improving upon the methodology that produced equivocal results in past studies. The discovery of the endogenous cannabinoid system, a decade ago spurred a vast amount of animal research on the effects of cannabinoids on receptor and overall brain function. This research has demonstrated alterations in the functioning of the brain in regions and in neuromodulator systems (e.g. dopaminergic and cholinergic) that are crucial for cognitive processes. Further research is required to elucidate the parameters of human use that may lead to clinically significant dysfunction and to investigate individual susceptibilities to impairments. There is evidence that the alterations in cognition and brain function may persist following cessation of use but the extent to which they might recover with prolonged abstinence has yet to be determined. This chapter reviews the literature pertinent to marijuana and cognitive function with a focus on the most recent animal and human research.