By Lidia Wasowicz, UPI Senior Science Writer
Source: United Press International

Natural molecules that act like the primary active ingredient in marijuana apparently play a key part in helping the brain wipe away fearful memories, perhaps averting undue anxiety and panic attacks, researchers report.

The discovery, detailed in the British journal Nature, could lead to the development of psychiatric drugs for the treatment of such fear-based conditions as phobias and post-traumatic stress disorder, they said.

The results of the mouse studies provide clues to the influence on human behavior of so-called "endocannabinoids," naturally occurring molecules related to the psychoactive ingredient in cannabinoids such as pot and hashish that have been used for medicinal and recreational purposes for some 3,000 years.

The ingredient, called delta9-tetrahydrocannabinol or delta9-THC, affects the nerve cells in the brain, producing its signature mind-altering effects by attaching itself to a protein on the surface of each cell. The protein, called the CB1 receptor, also provides a critical hook-up point for the endogenous cannabinoids -- the cannabinoids naturally produced by the body. Without it, the chemicals cannot do their prescribed job.

The five-year study, by Beat Lutz of the Max Planck Institute of Psychiatry in Munich, Germany, and his German and Italian colleagues, revealed a previously unknown component of that job -- snuffing out terrifying memories as part of the body's fear-coping mechanism.

"Our work shows an involvement of the endogenous cannabinoid system in extinction of fear memory for the first time," Lutz told United Press International.

"We really had no idea before that this system might be involved in erasing of particular types of memories," neuroscientist Pankaj Sah of Australian National University in Canberra, Australia, who wrote an accompanying commentary, told UPI.

"Although we understand how fearful memories are stored in the brain, how they are extinguished remains a mystery. The answers may lie with the cannabinoid compounds our bodies produce," he added. "The finding might have implications for treating anxiety disorders in humans."

Anxiety disorders are the most common of all mental health diseases, costing the United States some $46 billion a year in direct and indirect health-care expenses. Social phobia, the No. 1 anxiety disorder, affects some 5.3 million Americans annually. The persistent, irrational fear of social interactions leads to a compelling desire to avoid them at any cost. Specific phobias, of animals, objects or situations, touch more than one out of every 10 persons in the United States.

Another 5.2 million Americans suffer from post-traumatic stress disorder, characterized by emotional numbness and denial in the wake of extreme psychological stress brought on by war, violence, childhood abuse, sexual attack or serious accident, followed by months or years of recurring nightmares, "flashbacks," short-term memory problems, insomnia or heightened sensitivity to sudden noises.

Estimated cases of panic disorder -- sudden, repeated, intense feelings of terror and impending doom -- range between 3 million and 6 million a year. Twice as many women as men suffer the disorder that renders them sweaty, weak, faint, dizzy, trembling, numb and believing they are losing their mind or facing imminent death.

Such exaggerated reaction to a perceived threat -- be it a social engagement or an animal encounter -- is a legacy left humans by their earliest ancestors. This evolutionary inheritance includes instincts to stay alert in potentially dangerous situations, including binding or boundless spaces, lofty heights or impending confrontations with creatures perceived as repulsive or threatening, such as spiders or snakes.

Guarding against possible hazards is as important as recognizing false alarms. When the prospect of danger fails to materialize, most humans sigh with relief and relax. But there are those, termed phobics, who cannot adapt and remain on high alert even in the absence of any threat. Examples include the uncontrollable over-reaction that leads to panic attacks or the emotional scars from accidents, war experiences or other traumatic experiences that fail to heal with time. The new findings point to the endogenous cannabinoid system of the brain as a key prop in this delicate balancing act.

In the experiments, normal mice and those lacking the cannabinoid receptor CB1 heard a tone, then felt an electric shock to the foot. Over the next few days, the researchers sounded the tone without administering the shock. The normal rodents soon started to regard the sound as benign and stopped responding by freezing in fear. The mutants, on the other hand, continued for a much longer time to react to the tone as if it portended terrible things to come.

"All animals showed a remarkable fear reaction during the first re-exposure to the tone," Lutz explained. "With repeated tone presentations, control mice quickly recovered from this fear reaction. CB1-deficient mice, in contrast, showed only a weak reduction of fear."

To wipe away frightful recollections, endocannabinoids flood the amygdala -- the brain's almond-shaped center of threat recognition, fear and aggression -- where they dampen the action of its nerve cells, helping to dismantle terrifying associations.

Drugs that boost the chemicals' activity in this region of the brain might help sufferers of post-traumatic stress disorder, phobias, panic attacks and certain forms of chronic pain, scientists told UPI.

"The finding that the endocannabinoids contribute to extinction raises the possibility that drugs that target these molecules and their receptors could be useful new treatments for anxiety disorders," Sah said.

Once thought of as character flaws, these conditions are now recognized as having biological and psychological components. Treatment often combines medication with psychotherapy.

"To my mind (the study) raises issues about why people use cannabis in the first place," Sah told UPI. "We all take aspirin for headaches and toothaches -- of course, aspirin does not have the same gamut of cognitive actions as cannabis. But it's worth considering that people (who) constantly use cannabis may be doing it for other reasons than just to 'get high' -- perhaps they are experiencing some emotional problems which taking cannabis alleviates. Much the same way as some people drink alcohol to relieve anxiety."

Sah concluded, "This work tells us that the cannabinoid system is very old and plays roles in evolutionarily quite old behaviors. This, I suppose, fits with the very long history of use of cannabis in human society. It tells us that trying to work out how cannabinoids act is a very useful exercise whose outcome could have important medical benefits in the future."

From the Science & Technology Desk

Source: United Press International
Author: Lidia Wasowicz, UPI Senior Science Writer
Published: July 31, 2002
Copyright 2002 United Press International
Website: United Press International - News. Analysis. Insight.™ - 100 Years of Journalistic Excellence
Contact: United Press International - News. Analysis. Insight.™ - 100 Years of Journalistic Excellence

Related Article & Web Site:

Medical Marijuana Information Links
Medical Marijuana Information Links

Natural High Extinguishes Bad Memories in Brain
cannabisnews.com: Natural High Extinguishes Bad Memories in Brain

CannabisNews Medical Marijuana Archives
cannabisnews.com: medical related topics

(For the link and additional comments, cannabisnews.com: Pot-Like Chemical Helps Beat Fear)

Also, there is research being done into a synthetic fear-blocking chemical called "propranalol." After successfully treating many people, including war veterans who suffer from panic attacks, the White House suddenly suspended all propranalol research for "bio-ethical reasons," claiming that this drug was somehow involved in erasing memories. However, according to the limited data, no memories were erased nor was there any permanent psychological damage inflicted on participants in the propranalol studies. This conflict between the White House's position and the available research data was highlighted in a special on the TV show "60 minutes."

Propranolol, The Memory Pill
November 26th, 2006

Propranolol is a beta blocker that is sometimes used in the treatment of hypertension and migraines. The Sixty Minutes segment The Memory Pill looked at its use for treating post-traumatic stress syndrome. Apparently, one of its effects is to lessen the intensity and immediacy of traumatic memories. Various patients were interviewed, all of whom showed astounding improvement after years– even decades– of suffering from severe PTSD following car accidents, physical debilitation, and rape.

Although the results are more than promising– there seem to be few side-effects– research in the US was effectively shut down after a White House bioethics report questioned the ethics of “altering memory.” Research continues in Canada, though, and it looks like the U.S. Military is going to start funding that research…