There has been incredible evidence stemming from animal research which shows that prolonged marijuana exposure especially during the crucial developmental stage has the possibility of causing long term changes on the brain, some of this being adverse effects. Some of these tests have also been carried out on human beings.
The test conducted on rats in different stages of development; before birth, immediately after birth and one during the adolescent period. These results showed notable issues more specifically geared towards memory and learning skills experienced in latter life. Any cognitive challenge experienced in the adult life of the rats was as a result of the rats being exposed to THC at the adolescent stage of development.
Some of the challenges were associated with functional and structural changes happening at the hippocampus. This exposure during the adolescent period has also been associated with any altered reward system which increases the likelihood that the animal will result to self administration of other drugs like cocaine whenever the opportunity presented itself.
When imaging studies of adult human adolescents the results showed that regular marijuana consumers displayed more impairment neurologically in specific regions of the brain. These are more specifically neural connectivity impairment which is involved in functions such as learning, memory and controlling impulses. These images differed greatly from those of non users.
These findings are very useful in explaining results of a big longitudinal survey which was conducted in New Zealand that found frequent and more persistent cannabis users who started using it in adolescence were more likely associated with an average IQ loss of up to 8 points which was measured in their mid adult life. Importantly the same study the same adults who were heavy adolescent users and chose to quit in the adult life did not regain the loss in IQ status.
