Study: cannabis exposure improves working memory in rats

Most of the studies conducted on cannabis and memory show that memory is negatively affected by cannabinoids and in particular THC. Against all odds, a recent study conducted by the University of Florida and published in the journal Neurobiology of Learning Memory concluded that cannabis has a positive effect on memory performance under certain conditions. The study was carried out on rats, and unlike most studies of this kind, which use injections, the chosen method of administration was inhalation, the most common route of administration in humans.

The study

The rats were subjected to memory tasks with food rewards. The first test sessions took place while the rats were sober, after which some male (15) and female (16) rats were exposed to cannabis smoke and others to smoke without cannabis (placebo). Surprisingly, exposure to cannabis had no effect on the working memory of the male rats, but improved memory accuracy in the female rats. However, the researchers did not conclude that there was a gender difference, pointing out that the females had already performed more poorly when sober.

Exposure to cannabis smoke had the same effect on a sub-group of males who had lower performance levels, similar to those of sober females. So it seems that it's when performance is less than optimal that cannabis takes effect, and has the capacity to make it better. These results are corroborated by certain studies which show that cannabis has positive effects on memory in the elderly and that certain cannabinoids have neuroprotective properties. On the other hand, numerous studies also show that regular cannabis use in young people leads to poorer cognitive performance. A recent study found that these effects faded after a week or more of abstinence.

Taking the placebo did not result in performance impairment, suggesting that cannabinoids do indeed have an effect on working memory. On the other hand, follow-up experiments showed that the administration of THC or a molecule with a similar modus operandi, in large doses and by a route other than smoking, did indeed lead to a deterioration in memory performance. According to the researchers, this suggests that differences in mode of administration, exposure time or dose cause different effects on cognition, and recommend that these differences be studied in greater depth.