Health benefits of marijuana—myth, fact, or something in between?
August 2, 2019

Photo courtesy Leafly
Medical marijuana may be prescribed for such conditions as cancer, glaucoma, Alzheimer’s disease, epilepsy, and chronic pain.

By Eva Hofmann

It is official.

Governor JB Pritzker has signed the bill legalizing recreational marijuana for adult use, beginning in January 2020. Marijuana for medical use under a doctor’s prescription already is legal in Illinois.

This is the second in a three-part series of articles to help inform Gazette Chicago readers about the pros and cons of legal cannabis. Here, we focus on the drug’s health aspects.

Treating pain and disease

What are cannabinoids? The chemicals in marijuana are known as cannabinoids, and the two main cannabinoids of medical interest are cannabidiol (CBD) and tetrahyrocannabinol (THC). Unlike THC, CBD does not make people high. Researchers continue to explore uses of THC, CBD, and other cannabinoids for medical treatment.

Cancer. According to the American Cancer Society, several small studies found smoked marijuana helped treat nausea and vomiting from cancer chemotherapy. Other studies have shown smoked or vaporized marijuana can help treat pain caused by damaged nerves and improve food intake.

More recently, scientists reported THC and other cannabinoids such as CBD slow growth or cause death in certain types of cancer cells growing in lab dishes. Some animal studies suggest certain cannabinoids may slow growth and reduce the spread of some forms of cancer.

Researchers have conducted some early clinical trials of cannabinoids in treating cancer in humans, with more planned.

Alzheimer’s. While THC is said to slow Alzheimer’s disease’s progression, the Alzheimer’s Association states more research is needed. “Marijuana, like many supplements and alternative treatments, is not regulated, so we can’t guarantee its purity or safety,” said Rebecca Edelmayer, PhD, the association’s director of scientific engagement. “It has not undergone testing, review, or scientific scrutiny, so we do not have enough rigorous trial data to predict a benefit.

“We also don’t know if marijuana interacts with medically approved prescriptions, so we are approaching the issue with caution until research is done,” Edelmayer added. The Alzheimer’s Association has sponsored research in this area, “but without scientific data to back up efficacy, we cannot take a position to advocate for its use,” she said, adding that people can take other steps to prevent and treat Alzheimer’s.

“We’ve seen research suggesting that incorporating multi-component changes into your daily habits could decrease your risk,” she said. The Alzheimer’s Association advocates lifestyle choices—including healthful diet, exercise, and cognitive and social stimulation—to help decrease risk of cognitive decline and dementia.

Glaucoma. Marijuana reduces pressure inside the eye caused by glaucoma, which can injure the optic nerve and cause loss of vision. According to the Glaucoma Research Foundation, however, marijuana’s effect on eye pressure lasts only three to four hours, meaning someone would have to smoke six to eight times throughout the day to lower eye pressure around the clock. Researchers have investigated using eye drops containing THC or related compounds but have not been able to formulate an eye drop that can introduce the drug into the eye in concentrations high enough to be effective.

Pain relief. A growing body of research and anecdotal evidence suggests marijuana or its compounds may help relieve some types of pain. While marijuana lacks enough strength to ease severe pain, it is quite effective for chronic pain. Safer than opiates, it can take the place of pain relievers such as Advil and Aleve if people cannot take them due to gastrointestinal or kidney problems. An online survey featured in the Journal of Alternative and Complementary Medicine showed marijuana could promote sleep and reduce pain and inflammation, which can help relieve symptoms for people with rheumatoid arthritis. In the study, researchers found Sativex, a cannabinoid-based pain medicine, helped patients feel less pain and sleep better just two weeks after taking the drug.

Epilepsy. According to the Epilepsy Foundation, scientists have studied marijuana’s role in treating epilepsy and other neurological conditions for a number of years. In 2018, the FDA approved a drug, Epidolex, to treat seizures associated with two epilepsy syndromes—Lennox-Gastaut syndrome and Dravet syndrome—in people age two or older.

Photo courtesy Breath of Life
A worker harvests cannabis for medical use. Medical marijuana is available in Illinois with a medical marijuana card provided by a doctor.

Concern over adolescent use

While the new law stipulates legal marijuana use for adults age 21 and older, some worry legalization will make it easier for teens and young adults to access the drug.

Adolescent marijuana use may alter neuron function in brain areas engaged in decision making, planning, and self-control, according to researchers at the University of Illinois at Chicago (UIC). “Substance use as a teenager has the potential to disrupt the normal developmental trajectory of the prefrontal cortex, with potentially long-term consequences for decision making,” said Jamie Roitman, UIC associate professor of psychology and study co-author.

Physician and Bridgeport resident Irene O’Neill, MD, also has concerns. “Marijuana is a gateway drug, especially with the strength of the marijuana being used today,” she said.

O’Neill said the dangers of using marijuana increase greatly in people younger than 25, as their brains have not reached full development. “The less developed the brain, the higher the risk of addiction,” said O’Neill.

According to the National Institute on Drug Abuse (NIDA), people who begin using marijuana before age 18 are four to seven times more likely to develop a marijuana use disorder.  This demographic faces a higher risk of addiction and moving on to other drugs as well as greater risk of psychosis, schizophrenia, depression, anxiety, and other psychiatric

Baby boomers are at it again

The 2016 National Survey of Drug Use and Health showed a ten-fold increase in cannabis use among adults beyond age 65. Some older users reported positive outcomes when using cannabis for pain as opposed to taking prescription opioids.

A Colorado study published in the May 2019 issue of Drugs and Aging showed cannabis use among older adults is growing faster than for any other age group. “Older Americans are using cannabis for a lot of different reasons,” said Hillary Lum, MD, PhD, assistant professor of medicine at the University of Colorado School of Medicine, who co-authored the paper. “Some use it to manage pain while others use it for depression or anxiety.”

Researchers found some felt reluctant to ask their doctors for a medical marijuana card. Instead, they chose to pay more for recreational cannabis. Lum said this behavior could stem from self-consciousness about asking a doctor for cannabis.

“From a physician’s standpoint, this study shows the need to talk to patients in a non-judgmental way about cannabis,” said Lum. “Doctors should also educate themselves about the risks and benefits of cannabis and be able to communicate that effectively to patients.”

Is marijuana addictive?

According to NIDA, cannabis can lead to marijuana use disorder, in which a person feels withdrawal symptoms when not taking the drug. People who use marijuana frequently report irritability, mood and sleep difficulties, decreased appetite, cravings, restlessness, and various forms of physical discomfort that peak within the first week after quitting and last up to two weeks.

It is possible to be dependent without being addicted. Marijuana use disorder becomes addiction when the person cannot stop using even when it interferes with aspects of daily life. Studies suggest 9% of people who use marijuana will become dependent on it. That number rises to about 17% in those who start using in their teens.

Regulated cannabis is better

The good news is that legalization leads to better cannabis products, according to Jonathan Loiterman, an Illinois attorney and cannabis entrepreneur at Green Star Growing. “People have been buying marijuana on the black market for decades,” he said, citing possible contaminants in unregulated, black-market cannabis products, which could include mold, heavy metals, and pesticides. “Legal cannabis will be safer because it’s being tested,” said Loiterman. “We can debate about whether cannabis is good for pain. Legalization gets that research to happen.”

For the Alzheimer’s Association, log on to For the Epilepsy Foundation, see Log on to for the Glaucoma Research Foundation. For Green Star Growing, log on to For Lum, call (720) 848-3400, and for Roitman email Log on to for the National Institute on Drug Abuse.

Editor’s note: This is the second in a Gazette Chicago three-part series of articles on the advantages and disadvantages of legalized cannabis in Illinois. The third installment in the series will focus on public health and safety related to cannabis legalization.