62°F
weather icon Partly Cloudy

Is marijuana a ‘gateway’ drug? Most scientists still aren’t sure

Discussions of legalizing the use of marijuana often revolve around the contention that pot functions as a “gateway drug” — a substance that can lead individuals to abuse “harder” substances like cocaine or heroin.

That assertion, which has been raised in connection with Nevada’s Question 2 on the Nov. 8 ballot, has some support in the scientific community, but experts say a lack of definitive research on the subject leaves plenty of room for argument.

“There’s not enough evidence to prove (it) one way or another,” said Nathan Gillespie, an assistant professor of psychiatry at Virginia Commonwealth University who has done research on drug use and genetics.

Marijuana, the most commonly used illicit substance in the country, is legal in Nevada for medicinal purposes and would become legal for recreational use if voters approve Question 2, which was narrowly leading in the most recent Review-Journal poll on the measure.

Though most people who abuse substances like cocaine or opioids try marijuana first, there is no proven causal relationship between use of marijuana and other illicit drugs, according to the National Institute on Drug Abuse.

The issue from a scientific perspective is that a typical pattern of progression isn’t the same as establishing that Behavior A causes Behavior B, Gillespie explained. For example, he said, studies have shown that hard drug users also frequently drank alcohol and consumed nicotine before moving on to more dangerous and addictive drugs.

“(But) just because there’s a temporal order doesn’t mean there’s causality,” he said.

SOME SCIENTISTS ARE PERSUADED

A commonly cited 2015 article on marijuana’s potential “gateway” properties in The International Journal on Drug Policy, based on responses to a national survey on use of alcohol and other mind-altering substances, found that about 45 percent of adults who used cannabis at some point progressed to use of at least one other illicit drug.

The strong correlation between marijuana use and use of harder drugs found by that study and similar research has supported the belief of some scientists that the link is real.

In an April opinion piece in The New York Times titled “Marijuana Has Proven to Be a Gateway Drug,” Robert L. DuPont, president of the Institute for Behavior and Health and a past director of NIDA, argued that legalizing marijuana would expand the country’s drug abuse problem.

“Like nearly all people with substance abuse problems, most heroin users initiated their drug use early in their teens, usually beginning with alcohol and marijuana. There is ample evidence that early initiation of drug use primes the brain for enhanced later responses to other drugs,” he wrote.

A series of studies on animals have bolstered the gateway theory, finding that tetrahydrocannabinol, the active ingredient in marijuana, can increase the risk for addiction to nicotine and opiates, though other published studies have cast doubt on the opiate claim.

Critics of the gateway argument in regard to marijuana say the animal studies fall short of establishing a causal connection and more studies of marijuana’s effects on humans are needed.

They also note that similar correlations have been found with alcohol and nicotine. A 2011 journal article in Science Translational Medicine, for instance, found that nicotine also altered the brain, making it easier for users to become addicted to cocaine.

Some researchers believe environment and accessibility play primary roles in people’s progression from marijuana to harder substances, according to the NIDA website.

Instead of a gateway-type theory proposing that marijuana leads to use of harder substances, proponents of this theory believe the movement from drug to drug is predicated on outside factors like genetics or environment.

“An alternative to the gateway-drug hypothesis is that people who are more vulnerable to drug-taking are simply more likely to start with readily available substances like marijuana, tobacco or alcohol, and their subsequent social interactions with other substance users increases their chances of trying other drugs,” NIDA says.

A third theory indicates use of the drugs is a mixture of gateway effects, genetics and other factors.

Because marijuana is listed as a Schedule I controlled substance by the U.S. Drug Enforcement Agency, research involving the substance has been tightly controlled in the past. However, the DEA announced in August it would allow more approved growers to distribute the drug to authorized institutions to foster research. That, in turn, could pave the way for comprehensive studies that could put the debate to rest.

Gillespie said a lengthy study of twins could definitively answer the question.

Such a study would allow scientists to control for factors like genetics and environment, Gillespie said, and demonstrate once and for all what role marijuana use plays, if any, in leading a user down the path to addiction.

“The correct models have never been properly or adequately tested,” he said.

Contact Pashtana Usufzy at pusufzy@reviewjournal.com or 702-380-4563. Follow @pashtana_u on Twitter.

Don't miss the big stories. Like us on Facebook.
Politics Videos
Democratic National Convention postponed - VIDEO
The Democratic National Convention was set to take place over four days in the middle of July. Democratic officials have now confirmed the convention will take place the week of Aug. 17. (Las Vegas Review-Journal)
Henderson allows immediate sale of alcohol with curbside pickup - VIDEO
The city of Henderson decided Thursday evening to allow alcohol to be sold by restaurants as part of their curbside pickup service during the COVID-19 crisis. (James Schaeffer / Las Vegas Review-Journal)
Sisolak signs order banning any gathering of 10 or more people - VIDEO
Gov. Steve Sisolak on Tuesday signed a new order banning any gathering of 10 or more people in Nevada in another step the state has taken to slow the spread of the new coronavirus. (James Schaeffer / Las Vegas Review-Journal)
Takeaways from the president's daily briefing on coronavirus - VIDEO
RJ Washington correspondent Debra Saunders talks about today's daily White House news conference regarding the coronavirus outbreak, Friday, March 20, 2020. (Renee Summerour/Las Vegas Review-Journal)
Judicial Department 5 Debate - Video
The Las Vegas Review-Journal hosts a debate between the 3 candidates running for Department 5 in Clark County District Court. Participating are Veronica M. Barisich, Terry A. Coffing and Blair Cowan Parker.
Trump cancels Las Vegas trip because of ‘coronavirus outbreak’ - VIDEO
President Donald Trump canceled planned travel to Las Vegas ‘out of an abundance of caution’ amid virus outbreak. (James Schaeffer / Las Vegas Review-Journal)
Trump signs $8.3 billion coronavirus package - VIDEO
President Trump signed a bill providing $8.3 billion in emergency funding to combat the coronavirus outbreaK, Friday, March 6, 2020. (Las Vegas Review-Journal)
Sen. Rosen supports Judge Togliatti - VIDEO
Sen. Jacky Rosen shows her support for Nevada Judge Jennifer Togliatti to be appointed to the federal bench. (Sen. Jacky Rosen)
Sen. Cortez Masto shows support for Judge Togliatti - VIDEO
Sen. Catherine Cortez Masto shows her support for senior state District Court Judge Jennifer Togliatti to be appointed to the federal bench in Nevada. (Sen. Catherine Cortez Masto)
MSNBC’s Chris Matthews resigns following series of controversies - VIDEO
The "Hardball" host announced his departure Monday night, March 2, 2020, effective immediately. The anchor recently came under fire for comparing Sen. Bernie Sanders’ victory in the Nevada caucasus to the Nazi conquest of France in 1940. (Las Vegas Review-Journal)
Candidates file for office in Clark County - VIDEO
Amy Klobuchar drops out of 2020 presidential race - VIDEO
On March 2, campaign officials announced Amy Klobuchar’s decision to suspend her presidential bid. The news comes on the eve of Super Tuesday and just one day after Pete Buttigieg also announced his decision to depart from the race. (Las Vegas Review-Journal)
Activist shouts warnings at Nevada Democratic chairman's home - VIDEO
A Southern California activist and supporter of Sen. Bernie Sanders spent nearly an hour shouting warnings and condemnations of the Democratic Party through a megaphone at the home of Nevada Democratic Party Chairman William McCurdy II on the eve of last week’s presidential caucuses, prompting him to call the police. (Maria Estrada)
The Nevada caucus in photos
Best shots from the Review-Journal photo staff's coverage of the Nevada Caucus, Saturday, February 22, 2020.
Bernie Sanders announces his Nevada caucus win to supporters in Texas
At a rally in San Antonio, Texas, Bernie Sanders announces winning the Nevada Democratic caucus.
Joe Biden addresses supporters in Las Vegas
Joe Biden energizes a crowd of supporters at the IBEW Hall in Las Vegas after the Nevada Democratic caucus.
Tweet highlights from the 2020 Nevada Democratic caucus
Confusion, flaring tempers and misinformed volunteers highlighted Review-Journal tweets during the Nevada Democratic caucus.
Voters comment on Nevada Democratic caucus - VIDEO
Nevada caucusgoers comment on the process from locations across the Las Vegas Valley, Saturday, Feb. 22, 2020. (Las Vegas Review-Journal)
Doolittle Community Center hosts caucuses - VIDEO
The Doolittle Community Center hosted six precincts in one room for the Nevada Democratic caucuses, and voters engaged in debate and discussion about who to lead each precinct, Feb. 22, 2020. (James Schaeffer / Las Vegas Review-Journal)
Desert Oasis High School has wait for caucus check-in - VIDEO
James Strange has been waiting in line to caucus for the first time for 45 minutes and some said they have been waiting for an hour at Desert Oasis High School for the Nevada Democratic caucuses. (Las Vegas Review-Journal)
Conservative guru encourages Republicans to vote in Democratic caucuses - VIDEO
Republican activist Chuck Muth encourages his fellow GOP members to change party affiliation for a day to elect Bernie Sanders. (K.M. Cannon/Las Vegas Review-Journal) @KMCannonPhoto
Nevada Congresswoman Susie Lee at Desert Oasis High School - VIDEO
Rep. Susie Lee, D-Nev., stopped by the Nevada Democratic caucus at Desert Oasis High School in Las Vegas, Saturday, Feb. 22, 2020. (Al Mancini/Las Vegas Review-Journal)
Caucus day in Summerlin - VIDEO
Out-of-state caucus observer Ken Valz speaks about the Nevada Democratic caucuses at Palo Verde High School, Saturday, Feb. 22, 2020. (Las Vegas Review-Journal)
Doors open for Nevada Democratic caucuses - VIDEO
Caucusgoers are lining up Saturday morning to take part in the Nevada Democratic caucuses across the state (Renee Summerour/Las Vegas Review-Journal)
Caucus day at East Last Vegas Community Center - VIDEO
Registration begins at the East Las Vegas Community Center for the Nevada Democratic caucuses, Saturday, Feb. 22, 2020. (Las Vegas Review-Journal)
It’s caucus day in Nevada - VIDEO
Democrats will gather at over 250 locations across the state to declare their presidential preferences in the Nevada caucuses, Saturday, Feb. 22, 2020. (Las Vegas Review-Journal)
Democratic caucus-goers lined up to register at Liberty High - VIDEO
Democratic caucus-goers lined up to register at Liberty High in Henderson, Saturday, Feb. 22, 2020. (Bizuayehu Tesfaye/Las Vegas Review-Journal) @bizutesfaye
Elizabeth Warren holds rally with Julian Castro
Elizabeth Warren held her Get Out the Caucus Block Party with Secretary Julián Castro at the Clark County Government Center Amphitheater.
Trump caps western swing with campaign rally in Las Vegas
President Trump speaks to an enthusiastic crowd of thousands gathered at the Las Vegas Convention Center during a tour across the western United States.
Anti-Trump Protestors at LVCC Rally - Video
President Trump speaks at a Keep America Great rally as a small group of protesters gather outside the Las Vegas Convention Center.
Thousands gather for Trump rally
Thousands showed up for President Donald Trump’s rally Friday morning, forming a line that stretched nearly a quarter mile around the Las Vegas Convention Center.
Trump supporters camp outside the Las Vegas Convention Center
Trump supporters camp outside the Las Vegas Convention Center on Thursday, Feb. 20, 2020, where President Trump will held a rally on Friday in Las Vegas. (Bizuayehu Tesfaye/Las Vegas Review-Journal) @bizutesfaye
President Trump lands in Las Vegas - VIDEO
Donald Trump landed in Las Vegas on Tuesday, Feb. 18, 2020, as part of a four-day western state swing. (James Schaeffer/Las Vegas Review-Journal)
Democratic candidates Elizabeth Warren and Tom Steyer talk pay for child care workers - Video
Elizabeth Warren and Tom Steyer talk to care in action about the importance of Medicare for All, paid leave and child care. (Nathan Asselin/Las Vegas Review-Journal)
Election 2020: Nevada Caucus and Early Voting - Video
AARP's Nevada Caucus discussion with Steve Sebelius about the Nevada Caucus and early voting.
Election 2020: Nevada Caucus - Video
AARP's Nevada Caucus Discussion with Steve Sebelius. Join us as we discuss the Nevada Caucus process.
Las Vegas ready to enforce homeless camping ban - VIDEO
Las Vegas police will begin enforcing a controversial camping ban on city streets on Saturday, but officials say they expect to impose the penalties available under the new ordinance only in rare instances. (James Schaeffer / Las Vegas Review-Journal)
Yvanna Cancela Speaks on Supporting Biden - Video
The RJ Politics podcast crew sits down with Nevada State Senator Yvanna Cancela to discuss why she is supporting former Vice President Joe Biden in the 2020 presidential race.
Tom Steyer on Donald Trump and the economy - Video
Tom Steyer joins the RJ Politics podcast to talk about his campaign presence in Nevada and how he plans to take Trump on when talking about the economy. (Las Vegas Review-Journal)
Las Vegas City Council Votes On Homeless Ordinance - Video
The Las Vegas City Council on Wednesday will discuss expanding on a controversial camping and sleeping ban aimed at deterring the homeless from bivouacking on city streets to include hours when public sidewalks are being cleaned.
THE LATEST
Trump tempers officials dark coronavirus assessments with optimism

The U.S. surgeon general said Sunday that Americans should brace for levels of tragedy reminiscent of the Sept. 11 attacks and the bombing of Pearl Harbor, while the nation’s infectious disease chief warned that the new coronavirus may never be completely eradicated from the globe.

 
New York gets ventilators from China; Trump wants more thanks

In a sign of the disorganized response to the global crisis, Gov. Andrew Cuomo praised the Chinese government for its help in securing the shipment of the breathing machines.