Pubdate: Thu, 14 Apr 2016
Source: San Diego Union Tribune (CA)
Copyright: 2016 Union-Tribune Publishing Co.
Contact:  http://www.utsandiego.com/
Details: http://www.mapinc.org/media/386
Note: Seldom prints LTEs from outside it's circulation area.
Author: Paul Sisson

NEW MARIJUANA RESEARCH OUTLINED

The topic of marijuana got a serious scientific treatment Wednesday 
at the University of California San Diego, where researchers outlined 
the latest evidence about the drug.

The federal government estimates that 22.2 million Americans use 
cannabis today, an increase of about 4.4 million since 2002. The rise 
comes amid a growing medical marijuana movement that has culminated 
with full legalization in Colorado, Alaska, Oregon, Washington state 
and Washington, D.C.

California could join those ranks in November if the state's voters 
approve marijuana for recreational use.

Science is trying to catch up with the public's growing acceptance 
and use of a plant that contains 400 chemical compounds, including 
more than 60 cannabinoids known to act directly on specialized 
receptors in the brain.

Understanding just how these compounds work - how they influence 
issues such as addiction, pain relief and even control of severe 
childhood seizures - is an evolving effort.

Wednesday's symposium started with a presentation on marijuana's 
prenatal impact.

The speaker was Larry Parsons, a member of the Committee on the 
Neurobiology of Addictive Behavior at The Scripps Research Institute 
in La Jolla. Parsons explained that THC, a cannabinoid that gives 
marijuana its psychotropic effects, clearly affects brain development 
before birth and can cause lasting effects into adulthood.

Research on mice and observation in humans have shown that THC 
influences neuron development and signaling, potentially increasing 
the risk of memory problems, addiction and perhaps schizophrenia later in life.

Also weighing in was Christina Chambers, director of the Center for 
Life Course Research, part of UC San Diego's Clinical and 
Translational Research Institute.

She said studies of children whose mothers used marijuana during 
pregnancy suggest that the drug elevates the risk of hyperactivity, 
attention deficit disorder, lack of motor coordination and poor 
academic achievement during the first two decades or so of life.

However, all of these results came from relatively small studies - 
and many of those studies are decades old. Larger, newer clinical 
trials are necessary to prove marijuana's imprint on childhood development.

"The sample sizes are so small. There is a critical need for more 
data," Chambers said.

As it happens, UC San Diego is in the thick of a massive research 
project that is expected to yield unprecedented insight into how the 
adolescent mind is affected by marijuana and many other factors.

The university is coordinating the Adolescent Brain Cognitive 
Development Study, which is tracking 10,000 children across the 
nation for a decade.

Annual testing, which will include highly sensitive brain imaging, is 
expected to help researchers map how life events of all kinds shape 
brain development.

"To be able to study kids longitudinally, starting at age 9 and 10, 
is going to transform our understanding," Chambers said.

Adults also got attention during Wednesday's event.

Researchers said studies indicate that medical marijuana is most 
effective at fighting muscle spasms caused by multiple sclerosis and 
at combating the neuropathic pain that cancer patients often suffer.

There is also evidence, though less robust, of cannabis' effects on 
nausea caused by chemotherapy, in promoting weight gain for 
HIV-infected patients and in easing sleep disorders.

On the flip side, cannabis can cause nausea, dizziness, impaired 
driving, addiction and a reduction in cognition.

Meanwhile, the cognitive effects of marijuana are thought to be less 
severe in adults than in children and adolescents.

Scientists continue trying to determine the proper dosing for 
conditions where marijuana shows promise. Sometimes, the right answer 
can be a bit counter-intuitive.

For example: Dr. Barth Wilsey, an associate physician of psychiatry 
at UC San Diego, cited research that shows marijuana with a THC 
concentration of only 1.3 percent is just as effective at controlling 
neuropathic pain as varieties with more than twice the potency.

"You don't need a very high concentration to bring about relief," Wilsey said.

One topic concerning children that did not get much attention 
Wednesday was the increasing use of low-THC hemp oil to treat 
epileptic seizures.

Media coverage and social-media stories of sometimes-miraculous 
decreases in seizure activity for some kids treated with the oil has 
prompted many states to legalize its use.

But more recent studies have found, again in small numbers of 
children, that the oil is not a panacea.

Dr. Kevin Chapman, who works in the pediatrics department at 
Children's Hospital Colorado, co-authored a 2015 study showing that 
only a third of 75 kids in his state treated with cannabis oil saw a 
50 percent or greater reduction in seizures.

And researchers discovered that 44 percent of the test subjects 
suffered adverse events, including an increase in seizures for 13 
percent of the participants.

This observational study has limited value because it did not control 
for factors such as the children using different doses and types of 
hemp oil, Chapman said Wednesday in a phone interview.

He noted that British drug company GW Pharmaceuticals is about to 
release results of the world's first double-blind, placebo-controlled 
study of cannabidiol compounds in children with a rare form of epilepsy.

Seen as the gold standard of medical research, this type of clinical 
trial should shed brighter light on the question of just how much 
marijuana might help or hurt kids suffering from seizures, Chapman said.

Until the debate is fully settled in scientific circles, he advised 
families to use high-cannabidiol hemp oil, often called CBD, as a last resort.
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MAP posted-by: Jay Bergstrom