Pubdate: Thu, 12 Jan 2017
Source: Los Angeles Times (CA)
Copyright: 2017 Los Angeles Times
Author: Melissa Healy


Researchers combed through more than 10,000 scientific studies to
examine the various health effects of marijuana use.

More than 22 million Americans use some form of marijuana each month,
and it's now approved for medicinal or recreational use in 28 states
plus the District of Columbia. Nationwide, legal sales of the drug
reached an estimated $7.1 billion last year.

Yet for all its ubiquity, a comprehensive new report says the precise
health effects of marijuana on those who use it remain something of a
mystery -- and the federal government continues to erect major
barriers to research that would provide much-needed answers.

If historical patterns are any guide, ballot initiatives that
legalized recreational marijuana in California, Maine, Massachusetts
and Nevada last year will lead to an increase in cannabis use and
drive down public perceptions of the drug's risks. The result could be
a natural experiment on a grand scale, according to the report
released Thursday by the National Academies of Sciences, Engineering
and Medicine.

"This lack of evidence-based information on the health effects of
cannabis and cannabinoids poses a public health risk," a panel of 16
experts concluded in the first comprehensive look at marijuana
research since 1999.

The report, nine months in the making, assessed more than 10,000
studies that examined marijuana's relationship with cancer,
psychiatry, accidents and a host of other health issues. The authors
included physicians, public health experts, neurobiologists and
addiction specialists.

California's Department of Public Health was one of 15 sponsors of the
report. Department spokesman Matt Conens said in a statement that it
hoped "to gather credible information" to protect patients and the
public and guide the state's cannabis-related public health response,
and is reviewing its recommendations.

Some things were clear. The report authors concluded with confidence
that marijuana and products that mimic its psychoactive effects can
provide effective treatment of chronic pain and help some patients
with sleep. Cannabis and cannabinoids, they wrote, effectively ease
chemotherapy-induced nausea in cancer patients and spasticity in those
with multiple sclerosis.

There is "substantial evidence" that women who use marijuana during
pregnancy are more likely to give birth to smaller babies who face a
range of early disadvantages. The report also detailed strong evidence
that long-term pot-smoking is linked to worsened respiratory symptoms
and more frequent episodes of chronic bronchitis. And it found solid
research findings of an overlap between frequent users of marijuana
and those who develop schizophrenia or other psychotic disorders,
though it's not clear whether one causes the other.

At the same time, the authors warned that many of the conditions for
which patients have turned to medical marijuana have little or no
research that demonstrates its effectiveness. Those include the use of
cannabis or cannabinoids for treatment of epilepsy, Parkinson's
disease symptoms and support of abstinence from addictive substances.

Also thin, according to the new report: research that clarifies the
relationship between drugged driving and accidents. The statistical
link between marijuana use and an increased risk of motor vehicle
crashes is "substantial." But that might be because those most likely
to drive under the marijuana's influence -- young men and people who
also use alcohol and other drugs -- are already more likely to get in

While it's possible to measure the concentration of marijuana's active
agent, THC, in the blood of drivers, researchers aren't really sure at
what concentration impairment -- or, for that matter, beneficial
effects -- kicks in, the experts wrote.

That's a crucial research gap for state legislators looking to draft
laws against driving under the influence. Indeed, the panel members
wrote, it's not even clear that measures focusing on marijuana use
alone would save lives.

Overall, the report suggests that, like many drugs, marijuana can be
powerful medicine at some doses and to some people, and potentially
dangerous in other strengths and to other people. The body of
available research doesn't provide a clear guide to who will reap
those benefits or incur those harms, and how dosage or mode of
administration could spell the difference.

"What do we really know for sure? Mainly it's anecdotes or very poor
evidence," said Dr. Marie McCormick, a maternal and child health
expert at Harvard's School of Public Health who chaired the National
Academies panel.

Given the continuing tug-of-war between the states and the federal
government over marijuana policy, it's unlikely that new research will
provide better answers any time soon. Those who wish to investigate
marijuana's effects face high legal and bureaucratic hurdles, the
panel noted.

When most federally funded researchers put marijuana's properties to a
rigorous test, they have one legal source to turn to: a University of
Mississippi facility that has cultivated the plant for the National
Institute on Drug Abuse since 1968.

Commercially available marijuana and derivative products have changed
dramatically since then, becoming more potent, more concentrated and
available in forms that can be consumed and vaped as well as smoked.
These changes aren't reflected at the growing facility; in most cases,
it offers the plant's leaves and flowers in a narrow range of
concentrations. Only in July did NIDA ask researchers how its
marijuana products might better serve their research needs, the panel

Rules governing marijuana research can also be forbidding, the panel

Federally funded marijuana researchers must get an OK from the Drug
Enforcement Agency and in some states, a state board of medical
examiners. The DEA requires researchers to erect elaborate security
measures to limit the number of people who come into contact with
marijuana provided for research.

"This process can be a daunting experience for researchers," the panel

Meanwhile, testing the health effects of marijuana products that are
actually marketed to consumers is illegal, according to the report.
Even as sales of cannabis concentrate (often called "dabs") doubled in
Colorado between 2015 and 2016, federal law prevented biomedical
researchers from conducting research on its benefits or harms, blocked
chemists from examining its safety, and barred neuroscientists from
gauging its effects on the brains even of lab animals.

While marijuana "edibles" are a booming part of the consumer market,
federal law also bars scientists from testing these products for
contaminants, investigating their effects on patients with certain
medical conditions, or administering them to lab animals.

"The federal government continues to enforce restrictive policies and
regulations on research into the health effects or harms of cannabis
products that are available to consumers in a majority of states," the
report said. Those strictures are "leaving patients, health care
professionals and policy makers without the evidence they need to make
sound decisions regarding the use of cannabis and cannabinoids."

Tarek Tabsh, who operates medical marijuana dispensaries in Los
Angeles and Las Vegas, said he's concerned about the dearth of
reliable information about the products his industry sells. In
particular, he said, it's important to understand how the industry's
customers will be affected by the increasingly concentrated products
that are coming on the market.

"I question the value of a lot of current research," said Tabsh, who
hailed the report's call for changes.

"The biggest fear I have has nothing to do with policy or commerce,"
he added. "It has everything to do with science."
- ---
MAP posted-by: Matt