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The legal landscape around marijuana is rapidly changing. Several decades ago, when I was in college, it was a regular social event to toke up and then go to the theater and watch Reefer Madness, a crazy movie from the 1930s vilifying marijuana. Back then, marijuana was illegal everywhere and the war on drugs was in full force. Recently, marijuana legalization was on the ballot in multiple states and passed everywhere it was introduced. There are now 15 states that legalized recreational use of marijuana and 40 states will have legalized it by the end of the year. Also, the U.S. House of Representatives passed a bill to decriminalize marijuana possession at the federal level and to expunge some past convictions for legal violations involving marijuana.
All of this movement on the legal landscape can lead to confusion about whether marijuana is safe to use and the side effects might be. Is marijuana safe or harmless? Is it a dangerous gateway drug that leads to addiction? How does someone decide whether to use it?
How does marijuana work in the brain?
The active ingredient in marijuana is tetrahydrocannabinol or THC. THC binds to receptor sites in the hippocampus. In the brain, the hippocampus is involved in interpreting new experiences and determining what should be stored in long-term memory. Messages from the hippocampus are stored in the frontal cortex of the brain. This is not particularly a problem when adults over the age of 25 use marijuana because the frontal cortex is fully developed. An adult brain tends to have about 72 hours of reduced cognitive functioning after ingestion but then returns to normal functioning.
Light, occasional use of marijuana by mature adults is of little concern.
How does marijuana affect adolescent brains?
The frontal cortex of the human brain does not fully develop until around age 25. When an adolescent or young adult regularly ingests THC, the frontal cortex may not develop normally, and many of the differences in brain structure don’t go away even when the person stops using marijuana. Risks include a significant drop in intelligence, difficulties with memory, problems in emotional regulation, and ineffective decision-making ability. In addition, the risk of developing psychotic disorders such as schizophrenia is double for young marijuana users, particularly for those aged 15 or younger. This is a greater concern with families who have some genetic risk for psychosis or schizophrenia.
Limiting use of marijuana to mature adults is critically important.
What are the long-term effects of heavy, habitual use of marijuana?
As more THC is available in the body, the cannabinoid system gets the message to turn down production of anandamide and increase production of fatty acid amide hydrolase (FAAH). This results in lowering the body’s natural ability to calm itself. When THC is not present a regular marijuana user is likely to experience more anxiety and agitation. In turn, the user is likely to increase their use of marijuana.
Is marijuana a gateway drug that leads to using more serious drugs?
A majority of marijuana users do not progress to using other drugs. These results are likely confounded by marijuana’s legal status. It is possible that the illegal status of marijuana is, in part, responsible for a small number of users who do go on to other drugs. Once you break the law, you may be more likely to continue breaking the law. This is no longer an issue if marijuana is legally obtained and legally used.
There are several possible immediate short-term effects on functioning when using THC:
- When someone is high, memory consolidation is impaired. This results in lower recall from reading. It’s a bad idea to study while high.
- Some people experience anxiety, paranoia, or panic attacks while high.
- There is a risk of psychotic symptoms while high, particularly for people who have some genetic vulnerability.
- Reactions times, judgment and motor coordination are impaired while high. Driving will be impaired while someone is high.
- There is a slight increase in risk of heart attack and stroke when high.
- Sexual dysfunction can occur, particularly in males.
In contrast to these risk factors, many studies provide evidence for positive effects of marijuana. THC and its cousin, the non-psychotropic compound cannabidiol (CBD), can reduce the nausea caused by chemotherapy for cancer patients. There is some evidence that THC can help in the process of recovering from trauma. CBD can reduce seizures, and both THC and CBD can reduce chronic pain. Researchers are finding that THC can be helpful with MS, ALS, and Parkinson’s. Ironically, THC can actually help improve memory for people with Alzheimer’s. Research on THC and CBD is a relatively new area and we will undoubtedly learn more in the coming years.
One of the most exciting research results with CBD has been the dramatic improvements for children with Dravet syndrome, a seizure disorder. Children with Dravet syndrome may have more than 100 grand mal seizures per month. A variety of marijuana that is very low in THC and high in CBD, called Charlotte’s Web, can dramatically reduce or eliminate seizures. For these children and their families, this strain of marijuana is lifesaving.
There are some increased legal risks in particular populations, including immigrants, students, and student-athletes.
For immigrants and people applying for permanent residency or citizenship, marijuana possession can be particularly damaging. Marijuana use and possession remains a federal crime and can prevent eligibility for residency or the ability to obtain or extend visas.
As of now, at the federal level, marijuana is a Schedule 1 banned controlled substance. Most universities and colleges receive some federal funding and therefore ban marijuana use on campus, even if the campus is in a state that has legalized recreational marijuana. Every campus has its own rules and regulations and it is important to know the rules and potential consequences for violations of those policies.
For student-athletes, marijuana remains a banned substance and THC is typically part of the standard urine screen. Testing positive can result in loss of scholarship and even removal from school. While the World Anti-Doping Agency (WADA) explicitly allows the use of CBD, the NCAA does not address this. CBD is not listed as a banned substance, but the NCAA policy also states that any substance not on the list that is chemically related to an item that is on the list is also banned. Since THC is on the list and is chemically related to CBD, that means the latter is also likely prohibited.
Hopefully, this information can help you and your family make informed decisions about using marijuana. For mature adults using lightly and occasionally, and avoiding driving while using marijuana, there are few adverse consequences. For people with some medical conditions, marijuana can be helpful. For adolescents, there is far more potential for long-term adverse effects.
