For those who smoked a little pot in high school or college who plan to return to the habit now that it’s legal in Connecticut, today’s cannabis is not the marijuana of their youth. While research shows it can help with nausea that some cancer patients experience as a side effect of chemotherapy, scientists who study cannabis say there’s more evidence of harm than benefits. And there are limited studies of cannabis’ effect on humans, with many saying more research is needed.
As of July 1, recreational use of marijuana became legal in Connecticut, making it the 18th state, plus the District of Columbia, to legalize its use for adults 21 and older.
The four major areas of health concern are:
- the harm to developing fetuses when mothers consume marijuana while pregnant — some 7 percent of pregnant mothers reported marijuana use for nausea;
- damage done to the developing adolescent and young-adult brain, which isn’t fully developed until about age 25 or 26;
- the increased potency and number of regular users raises the number of adolescents and young adults at risk of developing schizophrenia and cannabis use disorder;
- and the fact that there are no existing tests police officers can legally administer to determine whether someone is driving while high, increasing the risk to public health.
“I’m worried about adolescent exposure and prenatal exposure,” says Steven G. Kinsey, a UConn professor who researches cannabis. “There’s just not a lot of research out there.”
Researchers at Washington University in St. Louis found that children whose mothers consumed cannabis while pregnant are more likely to have psychopathology in middle childhood, according to a study in JAMA.
The cannabis plant of the 1960s had a maximum 3 percent potency of tetrahydrocannabinol (THC), the mind-altering ingredient, and resin (hashish). However, the commercially produced, genetically modified cannabis of today is far more potent, reports a study in World Psychiatry. The average U.S. potency reached 12 percent by 2014. Meanwhile, the levels of cannabidiol (CBD), which counteract THC’s effects on the brain, have decreased, resulting in a THC-to-CBD ratio of 14 times in 1995 to about 80 times in 2014.
Additionally, since cannabis is illegal at the federal level, little scientific research has been conducted looking at how cannabis interacts with other drugs. “I have some concerns about drug interactions we don’t know about yet,” Kinsey says.
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For those who are over 26, not pregnant or breastfeeding or planning to drive, occasional use has not been shown to have long-term health implications, Kinsey says. About 30 percent of regular cannabis users develop cannabis use disorder, so with more people using the drug, more people will develop a dependency, says Dr. Godfrey Pearlson, director of the Olin Neuropsychiatry Research Center at the Institute of Living in Hartford. Like other recreational drugs, including nicotine and alcohol, some cannabis users develop tolerance, and some increase the dose to attain the same effects, says Pearlson, a Yale School of Medicine professor of psychiatry and neuroscience who serves on the Board of Physicians that advises the state Department of Public Health on appropriate use of medical marijuana.
“If you’ve made it to your 50s or 60s and not developed schizophrenia, the risks of developing it in midlife are minimal, especially if you’re an occasional user of the plant rather than synthetic cannabinoids,” Pearlson says. “The CBD that occurs naturally in the cannabis plant lessens the impact THC has on the brain, but without it, the high is more intense.”
Are there health risks to people over 25 who use cannabis recreationally? “We don’t know,” Pearlson says. “Nearly all the studies have been done on young people. If there are risks, we really don’t know them.” Surveys show the majority of middle-aged people using cannabis are doing it to help with sleep or pain, he says. The main risk is dependence, he says. Eventually about 30 percent develop some degree of cannabis use disorder, according to Dr. Deepak Cyril D’Souza, Yale School of Medicine professor of psychiatry.
Overall, one person in 100 will develop schizophrenia at about age 19 or 20, says Pearlson, whose research specialties are marijuana and psychosis. “The odds of developing schizophrenia if you smoke a lot of cannabis and start early is probably doubled.”
Regarding the roadway, Pearlson’s lab has done studies showing that stoned drivers are about twice as likely to be in an accident as sober drivers, while drunk drivers are about 10 times as likely to have an accident, he reports.
What about benefits?
While large-scale studies need to be done, there’s evidence THC helps chemotherapy-related nausea and appetite loss and helps multiple sclerosis patients with spasticity, Pearlson says. One problem with medical cannabis is that it’s not uniform in its many compounds, the way acetaminophen is, he says. The U.S. Food and Drug Administration has approved two cannabinoid drugs to treat anorexia in patients with AIDS and chemotherapy-associated nausea, reports a study in BMJ Journals. A review of multiple studies found that CBD reduces epileptic seizures by 50 percent and is more effective than a placebo in patients with a treatment-resistant form of epilepsy, the same study reported.
Some people report that CBD helps lessen pain, but again, there’s a dearth of scientific research as to whether the results are from the placebo effect, another ingredient in the CBD cream or whether it’s the cannabinoids themselves. Multiple reports have found CBD to be an anti-inflammatory, but other studies report mixed results.
“It’s a very interesting time we’re in right now. The marketing and the popular opinion of cannabis is way ahead of any research to support what people think it may do,” Kinsey says. “It’s hard to tease apart placebo effects. … It does become a chicken-and-egg argument.”