The world of legal recreational cannabis has many people worried about how safe this drug can be. Many claim that since it is natural it cannot be as harmful as other drugs as well as providing other claims as to its safety. However, a new study by a group of researchers at Northwestern University seeks to demonstrate that there are some negative effects of cannabis use in adolescents that mimic changes in the brain that are similar to schizophrenia especially with their effects on memory.
This is quite an interesting new area to explore, especially with the new push for legalization in many states. This is because since legalized recreational use of Cannabis in some states is so recent there has not been much time or as much access to data on the effects of usage on adolescents and teens.
This lack of time form recreational legalization for easier study has not prevented some research from being done. Some of the result of previous research on Cannabis use on memory show that adolescents and young adults that have used Cannabis tend to score lower on long term memory tests than non users by about 18 percent. This deficit tends to be associated with episodic memory which is the type of memory that involves being able to recall specific things about your own past. However, the understanding of why these deficits in memory occur has not been fully explored which is why these researchers at Northwestern carried out their study.
To determine the effect of Cannabis on memory the researchers chose to examine the area known to be associated with long term memory, the Hippocampus. This area of the brain has also been known to be affected by many neurological conditions such as Schizophrenia.
To test whether or not adolescent cannabis use has similar effects on the brain the researchers decided to use Magnetic Resonance brain mapping to see if there were any structural differences in the hippocampus between past users of Cannabis to non users as well as schizophrenic users and non users of Cannabis. The researchers found that the same areas of the hippocampus that are deformed as a result of schizophrenia are also the same areas affected in the hippocampus of adolescent users of Cannabis that suffer memory deficits. The main effect that was seen with relation to the structure of the hippocampus was that it became less ridged and became smoother decreasing the overall surface area. This change, seen below, is what the researchers believe to be the cause of decreased memory. In addition, the results of this study also agree with the results of a 2013 study linking Cannabis use with relation to likelihood of mental disorders such as schizophrenia since it demonstrates that there are similar brain changes.
Figure 1 from Smith et al 2015
This figure shows the change in hippocampus structure between control hippocampus vs cannabis use hippocampus (row 1) schizophrenic vs control (row 2) and schizophrenic vs cannabis use.
With such strong evidence relating adolescent Cannabis use to severe hippocampus structure changes mimicking schizophrenia it makes sense that many people want stronger restrictions on recreational usage of Cannabis. Many try to claim that the access that adults have to recreational Cannabis will affect the usage of adolescents, therefore the access adults have to Cannabis should be restricted. However, the use of other drugs such as alcohol, during adolescence has also been shown to be detrimental to brain function in adulthood. This suggests that it is maybe not solely cannabis that is the major harm to adolescent brains but rather the use of any drug that affects the brain on one that is still developing. This would cause the stress of drug management to go from prohibiting all drugs, to ensuring that relatively safe drugs such as tobacco, alcohol, and some would argue cannabis, are only being used by adults whose brains are developed enough to handle such drugs without suffering major changes.
For more information on this topic check out the sources below:
Drug Use in Adolescents
Chambers, R. (n.d.). Developmental Neurocircuitry of Motivation in Adolescence: A Critical Period of Addiction Vulnerability. American Journal of Psychiatry, 1041-1052.
Cannabis and Schizophrenia
Smith, M. (2015). Cannabis-Related Episodic Memory Deficits and Hippocampal Morphological Differences in Healthy Individuals and Schizophrenia Subjects.Hippocampus. Retrieved March 12, 2015, from http://onlinelibrary.wiley.com/enhanced/doi/10.1002/hipo.22427/
Chadwick, B., Miller, M., & Hurd, Y. (n.d.). Cannabis Use during Adolescent Development: Susceptibility to Psychiatric Illness. Frontiers in Psychiatry.