Marijuana's health risks, benefits still hazy

Karen Bouffard
The Detroit News
In this Tuesday, Oct. 2, 2018, photo, a clerk reaches for a container of marijuana buds for a customer at Utopia Gardens, a medical marijuana dispensary, in Detroit. Michigan and North Dakota, where voters previously authorized medical marijuana, will decide now if the drug should be legal for any adult 21 and older. They would become the 10th and 11th states to legalize so-called recreational marijuana since 2012.

If Michigan voters approve November's ballot initiative to legalize marijuana, little is definitively known about how it would affect the health of users in the state because cannabis research is scarce and still developing.

Researchers fear that people under 25 years old who regularly ingest or smoke pot over a long time eventually could hurt their brain development, among other issues. By contrast, some scientists are excited about marijuana's potential to relieve pain, treat post-traumatic stress disorder and aid in the recovery from opioid addiction. 

More:Barriers to marijuana research keep scientists in the dark on health effects

Legalizing the recreational use of marijuana would make it easier for adults to use the drug in the privacy of their homes, but not in public. While teens and youngsters still would be banned from using the product in Michigan, national studies have shown pot use increasing among teens and young adults.

Passage of Proposal 1 would ensure that no changes could be made to the law without approval by two-thirds of the state Legislature — a prospect that worries some critics who fear that unintended consequences of legalization could be hard to fix. 

"The biggest issue is that there's a whole lot we don’t know, from an objective standpoint," about the health effects of marijuana, said Charles Pollack, director of the Lambert Center for the Study of Medicinal Cannabis and Hemp at Thomas Jefferson University in Philadelphia.

"The biggest challenge we face is just getting more data."

Supporters say marijuana is no more dangerous for adults than alcohol and should be regulated in much the same way, while critics contend legalization would lead to more motor vehicle accidents, addiction and increased marijuana use by teens. 

Little funding is available for marijuana research, said Pollack, whose research team is looking at the use of cannabis for pain relief and as a treatment for patients with sickle cell anemia. Most studies are funded by the National Institute on Drug Abuse and focus on addiction and the negative effects of cannabis.

The main health concerns for adults, he said, include the sleepiness, decreased short-term memory and impaired perception and motor skills that can affect driving, But legalization would have broader implications.

"In terms of addiction potential, maybe 10 to 15 percent (of users) may develop cannabis use disorder," Pollack said. "The biggest concern is regular long-term use by people under 25, when cannabis use can result in impaired brain development."

A 2016 study conducted by the National Academies of Sciences, Engineering and Medicine found about 2.5 percent of the U.S. population or about 6 million people have a marijuana addiction or disorder and that it is "strongly and consistently associated with other substance use and mental health disorders." Men are twice as likely to get the disorder as women, and it largely goes untreated.

Marijuana use trends

Marijuana use significantly increased nationwide in 2017 for 8th, 10th and 12th graders combined, according to the Monitoring the Future study, now in its 43rd year by researchers at University of Michigan's Institute for Social Research. Use of illicit drugs other than marijuana declined in 2017, the UM researchers found. 

An increase in cannabis use was expected by researchers since historically marijuana use has increased as adolescents perceive less risk in using it, said Richard Mech, the principal investigator for Monitoring the Future. 

At the same time, state-level data released by the National Survey on Drug Use and Health in 2017 showed that adolescent marijuana use in Colorado fell to the state's lowest level in a decade after recreational marijuana became legal there in 2014.

Just over 9 percent of Colorado 12- to 17-year-olds used marijuana monthly in 2015 and 2016, the lowest rate of monthly use by teens since 2007 and 2008.

In this Dec. 31, 2013 file photo, partygoers smoke marijuana during a Prohibition-era themed New Year's Eve invite-only party celebrating the start of retail pot sales, at a bar in Denver. Colorado is on the brink of becoming the first state with licensed pot clubs.

More Michigan teens smoked pot that year than in Colorado, with 14.4 percent of 12- to 17-year-olds reporting use in 2015 and 2016, according to the federal survey. It was higher than the national average of 12.3 percent.   

Teen rates of alcohol, tobacco and heroin use also declined, according to the federal survey.

“We are very intent in making sure that this initiative is only for people 21 and older, and (state licensing officials) will have a lot of power to regulate businesses and make sure they’re not marketing to kids," said Josh Hovey, spokesman for the Coalition to Regulate Marijuana like Alcohol, the group behind Michigan's marijuana initiative. 

"There will be the same penalties we have today for selling (alcohol) to minors. Our mission is to keep it out of the hands of kids as best as possible, and we think a regulated system will do a better job of that then what’s happening today, which is kids accessing it through the black market." 

Health risks: 'It's scary'

The Colorado law has undergone tweaks since passage to adjust for unforeseen consequences of legalization, said Dr. Sandy Fritsch, medical director of the Pediatric Mental Health Institute at Children’s Hospital of Colorado and an associate professor at University of Colorado School of Medicine.

"One of the things that happened when it was first legalized was they were actually marketing it as ‘candy,’ " Fritsch said, pointing to research that found a two-fold increase in children accidentally poisoned by marijuana in states where the drug is legal. 

"At Children’s Hospital, we had little kids coming to the hospital, toddlers, having ingested THC-laden gummy bears," she said.

"Legislatively now, products ... can’t be called candy, and they can’t be shaped like an animal or a figure.  It’s a lesson learned, I think."

Dr. Sandy Fritsch

Under Michigan's ballot initiative, no marijuana processor would be allowed to make or sell edible marijuana-infused candy in shapes or packages that are attractive to children, or that could be confused with commercially sold candy. Marijuana products would have to be contained in opaque, resealable, child-resistant packages. 

Colorado law now prohibits edibles shaped like candy, and limits have been placed on the potency of products like granola and drinks.  Manufacturers still are allowed to flavor edibles and present them as chocolates, baked goods or lolly pops, and there are no limits on the THC content of high-potency cannabis products, Fritsch said. 

Beyond risks to toddlers, Fritsch said marijuana can impair brain development in children and young adults. It also has been associated with mental illness, including depression, anxiety and psychosis. 

Legalization minimizes those health risks and implies that using pot is safe, she said. 

"It's scary, very scary," Fritsch said. "If I could wave my magic wand ... I would say that nobody in their life would use high potency marijuana products until they're 25, because the brain continues to grow and change until about age 25.

"Early use can lead to reduced connections in the brain, reduced brain volumes that can effect memory, decision-making, impulse control and motor function."

Marijuana poses an additional risk to teens who are learning to drive, Fritsch said. And studies have shown that about four of seven adolescent users will develop a cannabis use disorder or addiction. 

Gov. Rick Snyder signed into law Oct. 17 a measure to bar the use, possession or sale of marijuana-infused beer, wine, liquor and mixed drinks that could potentially exacerbate intoxicated driving. 

"Parents and schools are having that conversation with kids all the time, about not using drugs and staying away from alcohol and tobacco, and all of those things," said Hovey of the Coalition to Regulate Marijuana like Alcohol.

"What we don’t want to do is continue to criminalize adults who are using responsibly in their own home."

Michigan's ballot proposal would place no limit on the potency of marijuana products available to consumers, said Scott Greenlee, president of Healthy and Productive Michigan, the ballot committee opposing the recreational marijuana plan. Marijuana-related traffic deaths increased 151 percent compared with 35 percent for overall traffic deaths in Colorado after recreational pot was legalized there, according to a report released in September.   

"There is road side testing for drunk driving, but there is no road side testing for drugged driving. So the police have no way of knowing when they pull somebody over how impaired they are from marijuana," Greenlee said. 

"When you start getting into the 99 percent THC edibles, it’s a very dangerous prospect to have somebody behind the wheel if they just loaded up on one of those." 

Pain relief and treatment

Cannabis has been used to treat scores of conditions from seizures and muscle spasms to glaucoma and Crohn's disease. But university researcher Pollack said scientists are years away from comprehensively understanding marijuana's health effects. 

In January 2017, the National Academies of Sciences, Engineering and Medicine published a report on the existing research related to cannabis, from its therapeutic effects to its risks for causing certain cancers, diseases, mental health disorders, and injuries.

"Despite the extensive changes in policy at the state level and the rapid rise in the use of cannabis both for medical purposes and for recreational use, conclusive evidence regarding the short- and long-term health effects (harms and benefits) of cannabis use remains elusive," the authors wrote. 

A woman who was part of a protest about the dangers of marijuana walks away after moving a sign in Vancouver, on Wednesday, Oct. 17, 2018. Canada became the largest country with a legal national marijuana marketplace as sales began early Wednesday.

Still, a study published in the November 2014 edition of JAMA Internal Medicine, found that legalization of medical marijuana was associated with a 24.8 percent decrease in opioid overdose deaths in multiple states. 

Decriminalization would improve access for people reluctant to acquire the drug under Michigan's medical marijuana law, said legalization advocate Hovey, who pointed to the case of an 80-year-old Clare County grandmother who was jailed in June for possessing a small amount of marijuana.

Delores Saltzman was arrested after a deputy visited her home to return a family member's lost identification card and phone, and smelled marijuana. She admitted to smoking pot to relieve pain and perk up her appetite, but her medical marijuana card had expired.

Saltzman turned over four joints and a small amount that she kept in a jar, and was arrested for the first time in her life.  She was released the next morning, and the charges against her were dismissed after she renewed her medical marijuana card. 

"People will say 'Why do we need this? We still have medical marijuana,'" Hovey said. "Well, we’re still arresting a lot of people every year, we’re wasting all these resources."

Teen marijuana use 

An annual study by the University of Michigan has been tracking marijuana use trends for 44 years.

* Marijuana use among school-age youngsters and teens reached a peak in the mid-1990s. More than 18 percent of 8th graders used pot at least once a year in 1996, while nearly 35 percent of 10th graders did so in 1997 and 38.5 percent of high school seniors used marijuana in 1997.

*After a dip, pot use was back on the rise in 2017. A little over 10 percent of 8th graders used it annually, compared with 25.5 percent for 10th graders and 37.1 percent for 12th graders.

*Marijuana use is also increasing among young adults. Nearly 6 percent of high school seniors used marijuana daily or near daily in 2017, while 7.8 percent of adults aged 19-28 was a daily or nearly daily user. Daily users are most likely to suffer health risks over the long term, according to medical researchers.

Source: Monitoring the Future

Health effects

A review of more than 10,000 cannabis studies in 2017 found:

  • Patients treated with cannabis or cannabinoids were more likely to experience a significant reduction in pain symptoms.
  • Multiple sclerosis patients treated with oral cannabinoids reported a reduction in muscle spasms.
  • Cannabis use prior to driving increases the risk of being involved in a motor vehicle accident.
  • Evidence suggests smoking cannabis does not increase the risk for cancers often associated with tobacco use — such as lung and head and neck cancers.
  • Some evidence suggests that cannabis smoking may trigger a heart attack.
  • Cannabis use is likely to increase the risk of developing schizophrenia, other psychoses, social anxiety disorders and, to a lesser extent, depression. 
  • There is some evidence that smoking cannabis during pregnancy is linked to lower birth weight; the relationship with other pregnancy and childhood outcomes is unclear.

Source: National Academies of Sciences, Engineering and Medicine

Twitter: @kbouffardDN