You can often hear that smoking cannabis makes a person distracted and forgetful. Let's see what is really known about this. Will the memory return to a person who smokes it only on public holidays?
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Memory Paradox
For a long time, information about the effect of marijuana on memory was based not on qualitative studies, but on descriptions of isolated cases. The data that have been obtained in recent years have turned out to be unexpectedly contradictory.
Expectedly, immediately after the use of marijuana, short-term memory may be disturbed, its processing in the brain suffers. This is accompanied by a decrease in the ability to concentrate. These effects have been found to last for days or even weeks, and are completely reversible.
At the same time, there is evidence of memory improvement after the use of marijuana and its components for medical purposes in a number of serious illnesses. It has been shown in humans in epilepsy, in animals in Alzheimer's disease.
A Tale of Two Substances
Marijuana contains over 100 cannabinoids. The most important representatives of this group of psychoactive substances for our story are tetrahydrocannabinol (THC) and cannabidiol. These substances can be called a kind of antagonists. The former, by binding to cannabinoids in the brain, produces the euphoric feeling that is characteristic of marijuana use. The second one competes with THC for these receptors: by binding to them, it prevents the onset of drug intoxication. This component of marijuana improved memory in the examples above.
In recent years, there has been a trend towards an increase in the concentration of THC in marijuana. In different varieties, the ratio of THC and cannabidol may vary, affecting its effects.
THC is responsible for the acute memory impairments we wrote about above. It binds to the receptors of those parts of the brain that play an important role in the formation of memory (the hippocampus, amygdala and cortex). The ability to both “hold” new information and recall already known suffers. A study found that high-THC marijuana is responsible for short-term memory impairment in teenagers who use it.
Does age play a role
Another paradox is the beneficial effects of THC on the memory of older mice. Scientists suggest that with age, the structure and function of the connections of neurons in the brain may change. Perhaps in the future we will learn unexpected things about the effects of marijuana on older people. However, today it is difficult to draw firm conclusions about how memory depends on marijuana use at different ages.
The study found that adolescents who use marijuana may experience thinning of the areas of the cerebral cortex responsible for memory. But today there is no qualitative evidence that their memory really suffers irreversibly. Poor academic performance among adolescents who use marijuana can be attributed to their reduced motivation to attend school.
Similarly, very little is known about memory changes in people over the age of 50. There have been studies in this area, but the evidence is mixed.
What happens if you use marijuana for a long time
Studying the effects of long-term effects of marijuana on memory is difficult because it is difficult to take into account all the concomitant factors. For example, if a person, in addition to smoking cannabis, likes to drink, then it is not easy to establish why exactly his memory was impaired. On the other hand, people who use psychoactive substances may exaggerate or underestimate their use because they are prone to false memories (twice as often as non-smokers).
Today's scientific evidence allows to say only that long-term use of marijuana is probably associated with a slight deterioration in memory. With accidental, irregular use, irreversible memory changes do not happen. Scientists suggest that, given the current knowledge, marijuana can no longer be unequivocally blamed for memory impairment. It is necessary to take into account its types and concentrations of various active substances in it.