Straight Dope

The Research on Marijuana Safety

(Part 4 of 4) by Gary Stimeling

 

Copyright 2005 Psychotropics Cornucopia, Inc. All Rights Reserved.

 

The Chronic Mind

Beginning in 1988, internal cannabinoids (endocannabinoids) and receptors for them have been found throughout the nervous system and several parts of the immune system.([1]) They regulate the activity of many and perhaps all other neurotransmitters and hormones. Two cannabinoid neurotransmitters are known: arachidonylethanolamide (anandamide), the first one discovered, and 2-arachidonylglycerol, which is 170 times more abundant. There are probably others. In the brain, the endocannabinoids play many roles, often by calming the firing rate or activation threshold of neurons. They are especially prevalent in areas that control pain, sensory awareness, memory, coordination, and right-hemisphere spatial-intuitive functions. They also seem to oil the hinges on the doors of perception, helping to increase the flow of input and thoughts into consciousness. The whole system is extremely varied and complex, comprising dozens of chemical interactions in multilevel feedback loops. In general, THC has about three times the receptor-activating power of the body’s own cannabinoids, and synthetic derivatives have been created that are hundreds of times as potent.

Found in all multicellular animals, the endocannabinoid system has been evolving for 600 million years and seems to be a fundamental mechanism for self-healing. To take just one example, it may help undo phobias and posttraumatic stress syndrome. Beat Lutz and coworkers at the Max Planck Institute of Psychiatry in Munich found that a plentiful supply of internal cannabinoids in the brain’s fear center, the amygdala, reduces the effect of traumatic memories. The researchers conditioned two groups of mice to associate a specific musical tone with a painful electric shock. Cannabinoid receptors in the amygdalas of one group had been deactivated by a genetic mutation. Later, when the scientists began playing the sound without giving the shock, the damaged mice took six times as long to unlearn the association and jettison their fear. The normal mice did so in a few days, and showed unusually large amounts of cannabinoids in the fear center.([2])

Harry Anslinger’s tales of reefer madness return every so often in claims that smoking pot makes people more likely to develop schizophrenia or makes the symptoms worse in people who already have it. A statistical association has been found, particularly in a survey conducted in the Swedish army.([3]) However, rates of schizophrenia don’t vary with rates of cannabis use,([4]) symptoms tend to precede use,([5]) and many schizophrenics say weed helps them feel better,([6]) but they tend to smoke more before psychotic episodes.([7]) All this begins to make sense in light of recent findings about the internal cannabinoids. Schizophrenia is accompanied by, and perhaps caused by, an extreme overproduction of dopamine in parts of the brain. Since the endocannabinoids help regulate the dopamine supply, researchers expected that they would be found in larger amounts, but not enough to control the tremendous excess of dopamine—and sure enough, when they tested the spinal fluid of schizophrenics, they found twice the normal amounts of anandamide. This suggests that pot-smoking schizophrenics try to make up the difference with THC, but it doesn’t work well enough because it’s not specific to the abnormal dopamine-producing regions.

Chemical balancing problems might also develop from the outside in. When men are given regular shots of testosterone, their testes make less of it. External corticosteroids cause the adrenal cortex to produce less of them and eventually wither away. So concern naturally arises whether continual use of cannabis might downregulate the internal cannabinoid system. This obviously does not happen to any gross degree or it would have been noticed long ago among heavy users, but the question of subtle impairments is still legitimate and appropriate. So far, there is no convincing evidence for them.([8]) Since the brain and body go through their final stages of maturation during adolescence, and since many teenagers use cannabis, it would be especially good to know whether the drug affects their development. However, all pertinent research so far has been done on adults; none of any real value has been done on teens.

The one study purporting to show permanent memory deficits in the young is actually an example of scientific sleight of hand. It was conducted on ten pot-smoking teenagers committed to a “therapeutic community” by their parents. The doctor in charge, who had previously written a hysterical note of the Nahas type,([9]) gave them seven tests of short-term memory on admission and again six weeks later. He used two control groups, one of teens remanded for other reasons and one of teens from the outside—the second one to control for the fear and depression that are common among prisoners. The paper’s abstract claims a significant memory shortfall among the smokers on one of the seven tests after six weeks without dope, but the data page (once a labeling error is corrected) and the accompanying chart both show that their scores were in fact identical to those of the inmate control group. Some of the cannabis teens had also been users of PCP, which definitely can cause long-term cognitive problems and may have reduced scores that otherwise would have exceeded those of the controls. The only significant deficit was between both groups of inmates and the outside group,([10]) so the asylum atmosphere may have been the culprit after all.

There is one report that deserves careful follow-up. An MRI and PET-scan study of 57 adults found that, on average, those who had started smoking grass at age 16 or earlier weighed less, had smaller brains, and had less gray matter in proportion to white matter.([11]) This suggests that marijuana might stunt growth at a certain age—but does not prove it. Alarmists have cried wolf at too many sheep in wolves’ clothing, and the number of people tested was too small for anyone to jump to a definite conclusion. Moreover, all of those who used weed regularly at that age had used other drugs then, too. Then again, data might be saying more about the division of students into stereotypically conformist jocks and stereotypically rebellious “weedy” heads, unbalanced on both sides of the fence, that so often happens in high school.

At least until we know more, regular recreational use of cannabis by adolescents is likely not a good idea, any more than regular use of alcohol, coffee, or tobacco. NORML has taken a strong position against it,([12]) but occasional experimentation is probably not something to go nuts about, if only to avoid driving it further into secrecy along with sex.

As you might expect, that paper has become a favorite among drug warriors clamoring for ever harsher penalties against adults “for the sake of the children.” One could at least credit them with sincerity if they worried as much about dosing kids with an array of pharmaceuticals to get them to sit still in their seats, despite the fact that some of these drugs may increase the risk of murder and suicide—not to mention the ubiquitous caffeine in soft drinks that definitely contributes to their restlessness. Showing more genuine concern, Claudia Jensen, a California mother and pediatrician, has listened to the many teenagers who’ve told her that marijuana actually helps them concentrate in school. She now recommends it in minimal, subeuphoriant oral doses under a physician’s guidance for genuine cases of attention deficit disorder.([13])

Attempts to find structural or functional brain damage from cannabis in adults have had little success. Most kinds of mental impairment are hard to detect in animals, and no functional deficits have been found from bombarding them with marijuana,([14]) although large amounts for long periods of time do change their EEGs.([15]) In looking for permanent effects in humans from long-term use, scientists generally use a “battery” of standard tests, which can smooth over the flaws of any individual measure. Traditional cannabis-tolerant societies have been excellent “living laboratories” for several studies.

In 1972, research sponsored by the National Institutes of Mental Health compared 30 Jamaican ganja users with 24 similar nonusers. The users had smoked an average of 20 spliffs a day for at least 10 years. None of the 15 tests of memory, learning ability, reaction time, and perception showed any difference between the two groups. The scientists concluded that this very heavy marijuana smoking had produced “no impairment of physiological, sensory and perceptual performance, concept formation, abstracting ability and cognitive style, and memory.”([16])

Another project in Jamaica compared 30 abstaining men matched with 30 men who had smoked ganja every day for an average of 17 years on 47 tests of intelligence and neurological function. Four of the measurements showed some differences, a number to be expected by chance in such a large group of tests—including one that indicated the smokers had better memories than the nonsmokers. In summary, the researchers found, “Cannabis is smoked over a longer period in heavier quantities with greater THC potency than in the United States without deleterious social or psychological consequences.”([17])

Later in the 1970s, a similar study in Greece found only a few minor differences between chronic heavy hash smokers and abstainers on a large number of tests of cognitive function.([18]) In India two groups of psychiatrists recorded some lower scores among heavy users,([19]) but three other groups using similar test batteries did not.([20]) Likewise, in the United States, two studies reported memory deficiencies among chronic heavy cannabis smokers([21]), but three others did not.([22]) The American researchers uniformly found no marijuana-related deficits in abstract reasoning, verbal ability, problem solving, or other aspects of mental life. In three of the studies, the pot smokers scored higher on some measures.([23])

Another research group compared 41 nonusing Costa Rican men with 41 matched users who had smoked an average of 9 large joints a day for an average of 17 years. This group used several dozen tests, including a long IQ test and many measures of memory, coordination, and reaction time. There were no significant differences between the two groups.([24]) Follow-ups on the same men found very small differences on a few new tests, but the differences did not appear on the same tests from one follow-up to the next, so they probably were random variations.([25])

Other scientists gave a dozen neurologic and intelligence exams to 10 members of the Ethiopian Zion Coptic Church, for whom cannabis is a sacrament. All of them had smoked at least 2 to 4 huge spliffs per day, each containing one-fourth to one-half ounce of ganja mixed with a lesser amount of tobacco, for as long as 50 years. All results were a few percent above or below national averages. “The most impressive thing,” the researchers noted, “was the true paucity of neurological abnormalities.”([26]) This study has been criticized for its small sample size and lack of controls, but the heroic level of intake would seem to offset these deficiencies.

In 1993, two anesthesiologists at the University of Iowa reported that heavy users had lower scores than nonusers on one test each of math, word usage, and memory, out of 17 tests. The experiment was controlled by matching users and abstainers according to their scores on a fourth-grade IQ test taken at least 10 years before. There’s a red flag, however: The differences became statistically significant only after the authors redefined their usage categories to isolate the worst performers. And they neglected to use urinalysis to make sure the daily smokers weren’t high during the exams. It’s also interesting that, on a test of recognizing family relatedness by facial patterns, intermediate users (5 or 6 times a week) did much better than abstainers or light or heavy users.([27])

A few years later, two Harvard psychiatrists claimed heavy-use deficits in 8 out of a large series of tests, compared with light use and non-use.([28]) The number of differences was within the number predicted by chance, and most of them were tiny. For example, in memorizing lists of random words, heavy users recalled an average of 14.9; light users, 15.3. Moreover, the heavy users’ lower scores on all but one of the tests disappeared when the results were compared by gender, so at least some of the findings probably were caused by genetic or social differences between men and women, not by cannabis.

A team of scientists recently completed a thorough review and reanalysis of 15 studies of residual effects from cannabis. They concluded that “there might be” an extremely small decline in memory and learning ability but that seven other cognitive abilities are unaffected.([29])

The selective serotonin uptake inhibitors (SSRIs), such as Prozac, Zoloft, and Paxil, as well as other antidepressants, appear to reduce many people’s emotional capacity. This change in brain function can be horrifying to those who experience it, and it can be permanent, lasting many years after use is discontinued.([30]) Perhaps because investors profit handsomely from these drugs, the effect is of little concern to regulators or interest to researchers. By contrast, the effort to prove at least some minor long-term effects from marijuana remains intense.

It would be surprising if daily use of a psychoactive drug did not have some long-term effect on the mind, and the newest hope for proving real changes from cannabis comes from several relatively new tools for studying the brain. From the point of view of those who desire the worst, however,  the results still have been equivocal at best.

Three separate CAT-scan studies of a total of 43 long-term heavy marijuana smokers found no irregularities whatsoever.([31]) Brain cells die at a fairly constant rate, and the brain shrinks slightly as we age. As a result, the ventricles, three chambers filled with cerebrospinal fluid, enlarge. Contrary to expectation, an MRI study found smaller ventricles in regular pot smokers than in age-matched nonusers, suggesting that cannabis may have a protective effect on neurons,([32]) possibly related to an antioxidant protective effect of cannabinoids against the aftereffects of strokes.([33])

Studies of cerebral blood flow (CBF) support the idea that constant use may downregulate the internal cannabinoid system, at least in some areas of the brain. The cerebellum contains a lot of cannabinoid receptors and plays a major role in the sense of time, and three research groups have found a lower metabolic rate([34]) and lower CBF([35]) there among chronic heavy marijuana smokers when they were not stoned. Since cannabis increases heart rate and blood flow, reduced sensitivity in cerebellar receptors may produce the desire to constantly renew a large dose, a sign of true dependence that manifests itself among a minority of users.

Event-related potentials (ERPs) are specific brain waves that appear on an electroencephalograph (EEG) in response to specific stimuli. Several studies of long-term heavy cannabis users have found what scientists are pleased to call “deviant” brain waves. For example, in one series of experiments, investigators asked test subjects to pick out one target sound among several types of irrelevant tones played at intervals through headphones. The target would be heard in one ear rather than the other and would differ from the irrelevant ones by no more than a major third in pitch and only one-twentieth of a second in length. Unstoned chronic users made more mistakes on this test than nonusers, and their EEGs showed slower responses. They also showed similar “comparing waves” after both target and irrelevant tones, indicating that they had trouble discriminating between the two.([36]) A processing-negative (PN) wave—which means, “Nope, not that one”—was larger in the users, probably meaning it took them more effort to decide that a sound was irrelevant. The longer the use, the larger the PN, indicating a real effect of pot. The P300, or initial attention wave, took longer to appear in all users, regardless of length of use. Some, though not all, of these brain-wave changes persisted for at least two years after the last cannabis high in those who had quit. Similar results have been obtained using lights instead of sounds. No one has studied brain-wave differences with meaningful tasks.

Studies of another ERP get into “deviance” in earnest. The P50 wave appears 50 milliseconds after an instantaneous stimulus, like a click or flash of light. In response to two such stimuli in rapid succession, the brain subdues the second P50 to continue processing the first one. Since it seems as though a mental gate has temporarily closed, this process is called gating. Schizophrenics, people with posttraumatic stress syndrome, and others who suffer intrusive thoughts show reduced P50 gating in their EEGs. So do long-term heavy cannabis users.([37])

Most ERP researchers assume that reduced gating on the EEG corresponds to an increased flow of thought and perception, which may be true, and that an increased flow of thought and perception is always a bad thing, which certainly is not true. It is the most basic element of spiritual experience, for example. Every mystical and shamanic tradition cultivates methods for “opening wide the doors of perception,” as William Blake and Aldous Huxley put it, often with the aid of gate-unlocking drugs. Several psychologists and historians have argued that restrictive definitions of madness are in fact a pathology of civilization that impoverishes the consciousness and experience of those defined as sane by the relative narrowness of their mental gates.([38]) Poets have been dramatizing this idea at least since the anonymous ballad masterpiece “Tom o’ Bedlam’s Song” of about 1600.([39])

Most findings of “deviant” brain waves from marijuana vary a great deal from lab to lab, but there is one that all investigators agree on. Alpha waves, 7 to 12 cycles per second, predominate during states of relaxed attention or meditation. They increase in strength during the marijuana high or any period of euphoria. People who have ingested cannabis pretty much every day for a decade or so have more powerful alpha waves in their frontal cortex even when not stoned, and these waves are more coherent than most people’s, meaning that they are more likely to be produced in synchronized patterns from the right and left hemispheres together.([40]) Beta waves, choppy bursts of electrical activity at 12 to 17 cycles per second, are rarely coherent. They predominate during hectic, routine daily life. In other words, regular marijuana smokers tend to be deviantly calm, even without the herb. The meaning of alpha-wave coherence is not known. It may mark an integrative process between right-brain intuition and left-brain logic.

Nearly all emphasis in cannabis science is on the heaviest, longest-term users for the greatest chance of finding adverse effects. Research on them indicates that there may (or may not) be some trade-off. This may involve a small but possibly permanent loss of speed and dexterity in multitasking, in juggling so-called high level cognitive tasks in a logical, syntactically organized way. In return, there may be a tilt toward direct sensory perception in a mellower, more intuitive style of thinking that emphasizes associations across the usual syntactic boundaries. Perhaps the average lifetime cannabis user is slower to jump to conclusions—about deviant brain waves, for example.

One unusual group of psychologists studied originality in their subjects rather than speed and single-mindedness in processing nonsense. Regular marijuana smokers, while sober, exceeded nonusers on 8 of 11 tests.([41]) This may be the real reason for the usual diagnoses of difficulty concentrating. This kind of brain damage could be a benefit, a valuable corrective in a culture where brute logic has led to the brink of disaster. The commonly reported feeling of oneness with nature while high suggests that a truly broad-minded science might even study cannabis as a treatment for the Expediency Complex,([42]) under whose dictates shortsighted profiteers are eating the earth out from under us all. Senator Orrin Hatch recognized this when he said one of the warning signs for parents that their kids might be smoking pot is “excessive preoccupation with social causes, race relations, environmental issues, etc.”([43])

 

Government Experts Are Unanimous

            Numerous physicians and researchers have reviewed the medical literature on cannabis for professional journals.([44]) From time to time, governments of several nations have convened blue-ribbon panels to study these reviews and the original papers in order to assess marijuana’s possible dangers. All of them have recommended reducing or eliminating penalties for personal and medical use. Here are some of their conclusions regarding health and safety.

 

“Moderate use of hemp drugs is practically attended by no evil results at all.”([45])

 

“There is no evidence that [marijuana] has any appreciably deleterious influence on the individual using it.”([46])

 

Even heavy cannabis smoking “produces no effect upon motivation or performance.”([47])

 

“It is important to note that neither the ingestion of marihuana nor the smoking of marihuana cigarettes affects the basic outlook of the individual except in a very few instances and to a very slight degree. … The sociological, psychological, and medical ills commonly attributed to marihuana have been exaggerated.”([48])

 

“Long term consumption of cannabis in moderate doses has no harmful effect.”([49])

 

“Physical dependence to cannabis has not been demonstrated.”([50])

 

“The physiological effects of the use of cannabis are of a relatively harmless nature.”([51])

 

“There is little proven danger of physical or psychological harm from the experimental or intermittent use of natural preparations of cannabis. [It] does not constitute a major threat to public health.”([52])

 

“The costs to a significant number of individuals, the majority of whom are young people, and to society generally, of a policy of prohibition of simple possession are not justified by the potential for harm of cannabis….”([53])

 

“Penalties against drug use should not be more damaging to an individual than the use of the drug itself. Nowhere is this more clear than in the laws against the possession of marijuana in private for personal use.”([54])

 

“One of the most striking facts concerning cannabis is that its acute toxicity is low compared with that of any other drugs. No major health effects have manifested themselves in the community.”([55])

 

“Marijuana has been accused of causing an array of anti-social effects. These beliefs have not been substantiated by scientific evidence.”([56])

 

“Nearly all medicines have toxic, potentially lethal effects. But marijuana is not such a substance. There is no record in the extensive medical literature describing a proven, documented cannabis-induced fatality. Simply stated, researchers have been unable to give animals enough marijuana to induce death. In practical terms, marijuana cannot induce a lethal response as a result of drug-related toxicity. In strict medical terms marijuana is far safer than many foods we commonly consume. Marijuana, in its natural form, is one of the safest therapeutically active substances known to man.”([57])

 

“An objective consideration of marijuana shows that it is responsible for less damage to the individual and society than are alcohol and cigarettes.”([58])

 

“Given the large population of marijuana users and the infrequent reports of medical problems from stopping use, tolerance and dependence are not major issues at present.”([59])

 

“Australia experiences more harm, we conclude, from maintaining the cannabis prohibition policy than it experiences from use of the drug.”([60])

 

“The risks of cannabis use cannot be described as ‘unacceptable.’”([61])

 

“The smoking of cannabis, even long term, is not harmful to health. Leaving politics aside, where is the harm in decriminalising cannabis? There is none to the health of consumers. Sooner or later politicians will have to stop running scared and address the evidence: cannabis per se is not a hazard to society, but driving it further underground may well be.”([62])

 

“New Zealand politicians and the public should accept that cannabis has become part of our culture. Whatever harms are associated with cannabis are magnified by driving its use underground.”([63])

 

“Cannabis was the only drug put in the least dangerous category.”([64])

 

“The analysis concludes not only that the amount of dope smoked worldwide does less harm to public health than drink and cigarettes, but that the same is likely to hold true even if people consumed dope on the same scale as these legal substances.”([65])

 

“If cannabis does cause harm to a small proportion of users, then it is preferable that those people have access to treatment without fear of stigmatization or criminalization.”([66])

 

“The Federal Commission unanimously recommends [regulated legalization] with clear provisions for the protection of the young….”([67])

 

The law “damages individuals in terms of criminal records and risks to jobs and relationships to a degree that far outweighs any harm that cannabis may be doing to a society.”([68])

 

“We believe that [legalizing possession of up to one ounce] will result in greater availability of resources to respond to more serious crimes without any increased risks to public safety.”([69])

 

“The Commission…is of the view that whatever health hazards the substance poses to the individual…, these do not warrant the criminalization of thousands of Jamaicans for using it in ways and with beliefs that are deeply rooted in the culture of the people.”([70])

 

Illegal Facts

            The suppressionists keep buying new research. The question is: Why? It never comes out the way they want. And they don’t need it. They already control the law, the lawmakers, the federal executive, all state and local governments, the courts, the prisons, the police, the schools, the research money, the drug companies, and the media in every country in the world except Holland. Saying, “Don’t confuse me with the facts,” they have proven themselves immune to embarrassment, evidence, and reason.

It may be that no amount of knowledge will ever change the law. Even some scientists consider euphoria (“good feeling”) a harmful side effect and favor control of all herbs, especially psychoactive ones, by pharmaceutical companies through their regulatory hirelings.([71]) To counteract the actual undesirable side effects of pure synthetic THC, some suggest combining it with synthetic cannabidiol.([72]) This foretells an even more grotesque situation—an artificial simulacrum of the “crude drug” dispensed for profit while users of the plant that does the same thing better for free rot in jail by the millions.

            This intransigence has other health consequences besides incarceration. It seems that lies obey the Second Law of Thermodynamics: For every deception there is an equal and opposite misconception. Having been lied to so often about the dangers of ganja, many users assume that it must be completely safe in any amount. But no drug is entirely benign for all users in all situations. Routine overuse of cannabis, as of any other substance, will make problems for some people, although what constitutes overuse for an individual cannot logically be decided by law. It wastes in two senses of the word. It wastes supply, as tolerance develops to the desired effects. And it wastes mind. Dwelling always in one state of consciousness may be counterproductive, whereas alternation and interplay increase power, as in a reciprocating engine. Mindless consumption is the goal and trademark of McCapitalism. On the other side of the Second Law, the intolerant forget that no one is trying to force anyone to use any amount of cannabis.

            After all the studies have been sifted and weighed, the upshot is this: It may be that no lunch is completely free, but of all psychoactive drugs, marijuana offers by far the most benefit for the least payback. In response to super-natural levels of stress, it yields super-natural levels of relief without appreciable harm to anyone.

Notes

 

            I wish to acknowledge my debt to the authors of the following four books, without whose herculean efforts in assessing the enormous literature of cannabis science this short summary would not have been possible. These sources appear repeatedly in the endnotes and are cited in abbreviated form:

            Earlywine: Mitch Earlywine, Understanding Marijuana: A New Look at the Scientific Evidence, Oxford University Press, New York, 2002. Earlywine has made a comprehensive review of the research that is eminently fair and always perceptive. He lets the evidence speak for itself, draws no hasty conclusions, and argues quietly yet forcefully for cannabis liberty.

            Grotenherman and Russo: Franjo Grotenherman and Ethan Russo, eds. Cannabis and Cannabinoids: Pharmacology, Toxicology, and Therapeutic Potential. Haworth Press, 10 Alice Street, Binghamton NY 13904-1580, 2002. This is the most comprehensive recent survey of research on marijuana’s risks and medical benefits to be found in one place. Much of the information is unavoidably technical but each section has been well introduced and edited so that nonscientists can follow much of it, at least with medical and chemical dictionaries handy. Contributors run the gamut from advocates of freedom to crypto-suppressionists.

            Iversen: Leslie L. Iversen, The Science of Marijuana, Oxford University Press, New York, 2000. Iversen calmly demolishes the fears and pseudo-science that have demonized cannabis. While clearly pointing out that smoking is one aspect of its use about which a major safety question remains, he emphasizes the therapeutic research more than either Earlywine or Zimmer and Morgan.

            Zimmer and Morgan: Lynn Zimmer and John P. Morgan, Marijuana Myths, Marijuana Facts, Lindesmith Center, New York, 1997. Though now ripe for an update, this is still the most readable and most penetrating analysis of marijuana research, scrupulously impartial but with zero tolerance for junk science.