photo by: AP Photo/Richard Vogel, File

In this May 20, 2019, file photo, marijuana plants sit in a grow room under green lights that are used to not wake the plants during their night cycle at Loving Kindness Farms in Gardena, Calif. (AP Photo/Richard Vogel, File)

What are the health consequences of using marijuana, America’s most commonly used illicit drug?

To find out, the Journal-World talked to two experts and read the results of a major study in an attempt to compile nonpartisan information on the effects of marijuana use.

One expert, Richard Yi, is the director of The University of Kansas’ Cofrin Logan Center for Addiction Research and Treatment. Yi has a doctorate in psychology and teaches in the psychology department at KU. As director of the addiction research center, Yi said he has to know a little bit about everything in the discipline of substance use.

The other expert, Lauren Dutra, is a research scientist at RTI International, a nonprofit research institute. She is a doctor of science and holds a master’s degree in mental health and behavioral medicine. Dutra’s research involves public health policy and the social epidemiology of tobacco use, cannabis, and health disparities.

The report, titled “The Health Effects of Cannabis and Cannabinoids,” comes from the National Academies of Sciences, Engineering, and Medicine. A committee reviewed research published since 1999 regarding what is known about the health effects of cannabis and cannabis-derived products. More than 10,000 abstracts were considered before the committee reached its nearly 100 conclusions.

Here’s what they said:

Does marijuana have therapeutic effects?

Reports have concluded that marijuana can be helpful for nausea, said Dutra, and it may also have benefits in dealing with chronic pain.

Yi also listed nausea relief as a therapeutic effect of marijuana.

He explained that cannabis, the plant from which marijuana comes, contains many kinds of cannabinoids. Cannabidiol (CBD) and tetrahydrocannabinol (THC) are the two most prominent. THC is the part that gets people high. CBD aids in digestion. The ratio of cannabinoids matters, Yi said — in the ’60s and ’70s, the amount of CBD and THC was nearly even, but today most marijuana is higher in THC and lower in CBD.

According to the report, there is substantial evidence that short-term use of certain “oral cannabinoids” relieves pain from muscle spasms due to multiple sclerosis or chemotherapy-induced nausea or vomiting.

What are the effects of using marijuana and driving?

It’s complicated, Dutra said, calling the research “conflicted.”

Smoking marijuana within three hours of driving will affect reaction times. But Dutra said there is also a debate as to whether these slower reaction times are compensated for by the fact that people who are high tend to drive more slowly.

Dutra’s research also shows that people who live in states with legal marijuana are less likely to report driving high in the past 30 days and are more likely to report that they consider driving high to be dangerous. Traffic data, however, suggests that people living in states with legal marijuana are more likely to drive high.

Overall, “I would say the main message is don’t drive high, because why would you take the risk?” she said.

Yi said there is “good evidence that if you’re high on marijuana, that it does impact your decision making.” This would also apply to decisions one makes when driving, he said.

The report found that cannabis use before driving increases the risk of a car accident.

How does marijuana affect mental health?

People with mental health issues are more likely to use drugs in general, Yi said, which leads to a chicken-and-egg question: Does substance use cause mental health issues, or do mental health issues cause substance use?

“It’s very difficult to disentangle what causes what,” he said.

However, Yi said he would not recommend that people with depression use cannabis.

The report found that heavy cannabis users are more likely to report suicidal ideation and that individuals with bipolar disorder who use cannabis may experience more pronounced symptoms of that disorder.

Dutra mentioned that if a person has a genetic predisposition to schizophrenia and also uses marijuana, that that person might be more likely to develop a disorder like schizophrenia.

Can marijuana use increase a person’s risk of cancer?

According to the report, smoking cannabis does not increase the risk for cancers associated with tobacco use. But both Yi and Dutra were cautious about the effects on one’s lungs from smoking anything.

“What I can say is that whenever you are combusting something — lighting something on fire — and you’re inhaling it, it is going to cause lung damage,” Dutra said, and that may contribute to a higher risk of cancer.

“If you’re going to consume, if there’s a way to consume without combusting the bud, that would be the ideal way to consume,” she said.

Yi also said that the way one consumes marijuana makes a difference, and that smoking through a pipe or other device might be less harmful than smoking a premade cigarette, which has other chemicals in it as well.

But in short, “you’re taking smoke into your lungs,” Yi said. And that smoke is “not supposed to be there.”

Is marijuana a gateway drug?

It’s complicated, and it depends on what you mean by “gateway drug,” Yi said.

It is the case that for those who partake in substance use, marijuana tends to be one of the first drugs they use, along with alcohol and tobacco. That’s because those drugs are the easiest to access, Yi said.

But does smoking marijuana cause someone to escalate to using other drugs such as opioids? “It’s not clear,” Yi said.

According to the National Institute on Drug Abuse, the majority of people who smoke marijuana do not go on to use “harder” drugs.

Will a child be affected if a parent smokes marijuana during pregnancy?

Dutra urges people not to use cannabis if they are pregnant or breastfeeding. It could make the baby too sleepy or sedated, she said, which could cause the baby to be underweight and could affect brain development.

Yi put it shortly: “Anything you ingest into your body when you’re pregnant can affect your child.”

The report shows that smoking cannabis during pregnancy is linked to a lower birth weight for the child. The report, however, found no substantial evidence that a child whose parents used cannabis during pregnancy would have an increased risk of developing cancer.

Are there long-term health effects of smoking marijuana?

Dutra said one thing she’s looked at in terms of long-term effects is that “there is a concern that marijuana use in the teenage years might contribute to lower educational outcomes.” That is, instead of getting a master’s degree, people might get an undergraduate degree. Or instead of getting an undergraduate degree, they might get an associate degree.

Yi said that smoking marijuana when one’s brain is still developing could have negative effects on cognitive development. But he said it’s also the case that brains can be resilient. If someone smoked when they were young and then stopped, he said, that doesn’t necessarily mean they will be cognitively impaired, as the brain is able to recover somewhat.

Regarding effects on the immune system, the report states that there is not enough data to conclude anything decisively. There is limited evidence, however, that suggests regular exposure to cannabis smoke may have anti-inflammatory effects.