When it comes to the effects of marijuana, there are a lot of negatives. There also are some promising positives.
More than anything, however, there are unknowns. In a state that just made marijuana legal, that’s the most unsettling factor for medical professionals.
“There’s so little we know,” said Dr. Christine Nevin-Woods, the public health director of the Pueblo City-County Health Department. “It’s hard to study something that the federal government says is illegal.”
What that means is that high-level research, which takes years and lots of money, is scarce when it comes to studying marijuana. Smaller studies have been conducted and there is plenty of anecdotal evidence, but more is required.
Some studies have been done in other countries, but they don’t rise to the level of “strict, randomized research” that’s expected in the U.S., Nevin-Woods said.
Nevin-Woods attended a statewide marijuana symposium last May, where doctors and researchers presented their findings.
Among the adverse effects of marijuana use, “Some things that are seeping through are very troubling,” said Nevin-Woods.
An important factor to consider is that marijuana is more potent now than it was 40 years ago. THC is the psychoactive ingredient in marijuana. A study by the University of Mississippi, which included samples of hashish and hash oil, analyzed the THC levels in samples obtained via law enforcement seizures.
In 1983 samples, the THC level averaged 4 percent. In 2007, it was 9.6 percent. Those results are similar to other U.S. studies.
In addition, “There are more strains (of marijuana) and we don’t always know its origin,” Nevin-Woods said.
While pot can make some people feel relaxed, it may have a different effect on others, leaving them anxious and depressed.
Medical professionals do know enough to say that marijuana, like alcohol and other drugs, can be addictive. Those who use it steadily and stop suddenly will experience withdrawal symptoms similar to nicotine withdrawal: restlessness, irritability, sleep problems, cravings and depression.
Long-term use may cause cognitive problems and have a serious effect on learning ability — but, again, greater study is needed to confirm what’s being seen.
Marijuana does affect cognitive and motor skills, as well as reaction time, which means it will affect a user’s driving ability. The Canadian Task Force recommends users not drive for at least three hours after ingesting pot.
In the home
As the public health director, Nevin-Woods is especially concerned about the effect legalized marijuana may have on children whose parents decide to smoke it in the house.
“If you limit it to inside (usage), there’s going to be lots of exposure,” she said.
How will that secondhand smoke affect kids? Again, no long-term research is available, but Nevin-Woods doesn’t see a positive.
She said marijuana use for her generation — people who came of age in the ’60s and ’70s — was usually an experimental thing, something that was tried in college and then left behind.
Today she sees a disturbing trend: Adults who smoke it in the home on a regular basis — around or even with their children — and consider pot a part of everyday life without knowing the long-term consequences.
“Do you take the risk of taking a substance that hasn’t been studied? Do you want to expose your children to that?” said Nevin-Woods. “There won’t be any growing up for a lot of families.”
Does marijuana have beneficial properties? A growing number of people who deal with certain medical issues, including cancer, glaucoma and autoimmune diseases, say yes.
The phrase “potential benefits” gets used a lot in stores about using pot to treat such conditions because even though feedback may be positive, the lack of those big studies keeps the medical community cautious.
“I think many of us would love to see it help certain medical conditions,” said Nevin-Woods.
She believes Colorado’s medical marijuana program is “very well regulated.”
Soldiers suffering from PTSD report that marijuana eases their anxiety, as well as some of the physical pain from injuries. Marijuana has proven helpful for cancer patients, alleviating the nausea and decreased appetite associated with chemotherapy.
It may inhibit the growth of or even shrink certain tumors. It appears to reduce blood and eye pressure and some significant results have been reported in the treatment of seizures, particularly in children (see sidebar).
The observed results aren’t as positive for conditions such as depression and schizophrenia; marijuana use may even amplify symptoms.
One big question will remain unanswered until a body of scientific evidence can be built: Will any short-term benefits be outweighed by long-term effects?
The long haul
What’s the bottom line with pot pros and cons? Everyone is learning as they go.
Nevin-Woods said the Colorado State Health Department hopes to conduct more extensive research with money from the state’s medical marijuana fund. Children’s Hospital also is doing some research to establish the potential harm and benefits to kids.
“It all adds to the knowledge base, but it will take years,” she said. “There are scenarios that haven’t been discussed, much less delved into.
“We won’t know for a generation or two.”