Marijuana and Other Drugs Cause Brain Damage, Linked to Mental Illness


Study strengthens marijuana brain damage case

A new Australian study says long-term, heavy cannabis use causes brain damage that is equivalent to mild-traumatic brain injury or premature aging.

The research is published today in the journal Archives of General Psychiatry. The study also found that all users are at risk, and the more you smoke, the more your brain shrinks. Doctors have known for years there is nothing "soft" about the drug cannabis. Professor Jon Currie is the director of addiction medicine at St Vincent's Hospital in Melbourne.

"This is a very exciting study because it proves for the first time what we have been really worried out. That brain problems are real and that people who smoke cannabis over a long term do get problems." he said.
The study conducted at the University of Melbourne took MRI pictures of the brains of 15 men who had smoked more than five joints daily for more than 10 years.

It found the parts of their brains that regulate memory and emotion, the hippocampus and the amygdala, were significantly smaller than those of non-users.

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The abnormalities were equivalent to those caused by a mild traumatic brain injury or premature ageing.
Researchers found the men aged in their late-30s had the memory function of men in their mid-50s.
The amount of damage corresponded directly to the amount of cannabis smoked.


And the researchers say the results show that cannabis can adversely affect all users, not just those in high risk categories like the young or those susceptible to mental illness, as previously thought.
Professor Currie says the results reflect what he sees in practice.

"If you've got heavy cannabis use over a period of time, you don't have to have pre-existing diseases. It is not just for people who have got schizophrenia, everyone who smokes cannabis for a long period of time, is at risk," he said.
But the executive director of the Australian National Council on Drugs, Gino Vumbaca, approaches the study with caution because of its apparently small sample size.

"I think in scientific studies we need to see this sort of work repeated and the results verified again in other studies," he said.

Mr Vumbaca says while studies like this are helpful, cannabis use has already halved in the last decade, reflecting what he sees as a recognition among users that the drug is harmful.

"It has gone down from people aged over 15. It was peaking at around 17, 18 per cent 10 years ago and it is down to just over 9 per cent now," he said.

"A lot of people don't see cannabis as a benign drug anymore. They understand that all drugs cause problems. Particularly if they are used on a regular or a heavy basis, that you are going to encounter problems with those drugs."
But Professor Currie still hopes this study will provide new impetus for people to quit.
"My hope is that this can be used as a very, very clear warning to people. Get help, seek medical help, try and stop smoking, " he said.

Adapted from a 7.30 Report story by Jane Cowan.

New ground-breaking research shows long-term, heavy cannabis use causes significant brain abnormalities resulting in psychotic symptoms and memory loss equivalent to that of patients with a mild traumatic brain injury.

The study, conducted by researchers at the University of Wollongong, is the first to show that long-term cannabis use can adversely affect all users, not just those in the high-risk categories such as the young, or those susceptible to mental illness, as previously thought.

The research was published 4 June 2008 in the prestigious American journal Archives of General Psychiatry.
A collaboration with researchers at the ORYGEN Research Centre and Melbourne Neuropsychiatry Centre at the University of Melbourne, used expertise there to undertake brain image analysis.

They used brain imaging to demonstrate for the first time that the hippocampus and the amygdala, brain regions thought to regulate memory and emotional processing, were significantly reduced in cannabis users compared to non-users by an average of 12 per cent and 7 per cent, respectively.

According to lead researchers Dr Murat Yücel and Dr Nadia Solowij (School of Psychology, UOW) the new evidence plays an important role in further understanding the effects of cannabis and its impact on brain functioning.

“The study shows that long-term cannabis users were more prone to a range of psychotic experiences, such as persecutory beliefs (paranoia) and social withdrawal,” said Dr Yücel from ORYGEN Research Centre and Melbourne Neuropsychiatry Centre at the University of Melbourne.

“It also demonstrates that these long-term users had progressed the loss of memory by around 15 years. With an average age of 39, the trial group had the memory capabilities of a 55 year-old. This loss of memory could be likened to the damage suffered by patients with mild traumatic brain injury”, Dr Solowij said.

“Although growing literature suggests that long-term cannabis use is associated with a wide range of adverse health consequences, many people in the community, as well as cannabis users themselves, believe that it is relatively harmless and should be legally available. Given that cannabis is the most prevalent illicit drug in our community, there is a clear need to conduct robust investigations that highlight the possible long-term dangers,” Dr Yücel said.

The testing involved high-resolution structural magnetic resonance imaging on 15 men (average age 39 years) who smoked more than five joints daily for over 10 years. Their results were then compared with images from 16 individuals (average age 36) who were not cannabis users. All participants also took a verbal memory test and were assessed for subthreshold (below the standard of disease diagnosis) symptoms of psychotic disorders, which include schizophrenia and mania.

The more cannabis used, the more these individuals were likely to show reduced brain volume, particularly of the hippocampus, as well as sub-threshold psychotic symptoms and significant memory loss.

“These findings challenge the widespread perception of cannabis as having limited or no harmful effects on brain and behaviour,” said Associate Professor Dan Lubman, an Addiction Medicine specialist at Orygen Youth Health and co-investigator on the study.

“Young people in particular, need to be aware of the strong relationship between cannabis and mental health problems. That is why, in partnership with the National Cannabis Prevention and Information Centre, we are currently developing guidelines and resources for young people, teachers and their parents to help address this issue.”
“Although modest use may not lead to significant neurotoxic effects, these results suggest that heavy daily use might indeed be toxic to human brain tissue,” Dr Yücel said.

“Further research is required to determine the degree and mechanisms of long-term cannabis-related harm and the time course of neuronal recovery after abstinence.”

Cannabis smoke 'worse' than tobacco

Many people think smoking cannabis is safe. Smoking pure cannabis is more harmful to lungs than tobacco, a health charity is warning. A study by the British Lung Foundation found that just three cannabis joints a day cause the same damage as 20 cigarettes.

It is vital that people are fully aware of the dangers so they can make an educated decision and know the damage they may be causing

Dr Mark Britton

And when cannabis and tobacco are smoked together, the effects are dramatically worse.

Evidence shows that tar from cannabis cigarettes contains 50% more cancer causing carcinogens than tobacco.
Dr Mark Britton, chairman of the British Lung Foundation, said: "These statistics will come as a surprise to many people, especially those who choose to smoke cannabis rather than tobacco in the belief it is safer for them.

"It is vital that people are fully aware of the dangers so they can make an educated decision and know the damage they may be causing."

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Dr Britton emphasised that the British Lung Foundation report - called A Smoking Gun? - was "not about the moral rights and wrongs of cannabis".

But, he said, they simply wanted to make sure people were completely clear about the respiratory health risks involved.


Surveys carried out earlier this year showed that 79% of children believed that cannabis was 'safe'.
Only 2% understood correctly that there are health risks associated with smoking the drug.

The British Lung Foundation report also shows that the health dangers of cannabis have substantially increased since the 1960s.

That means that clinical studies carried out in the sixties and seventies may well underestimate the ill effects of smoking the drug.

This is due to increased amounts of THC - or delta-9 tetrahydrocannabinol, the major active chemical compound - in the cannabis consumed today.

Pleasure receptors

In the brain, THC connects to specific sites called cannabinoid receptors on nerve cells and thereby influences the activity of those cells.

Many cannabinoid receptors are found in the parts of the brain that influence pleasure, memory, thought, concentration, sensory and time perception, and coordinated movement.

Dame Helena Shovelton, chief executive of the British Lung Foundation, said: "Puff and inhalation volume with cannabis is up to four times higher than with tobacco - in other words you inhale deeper and hold your breath with the smoke for longer before exhaling.

"This result in more poisonous carbon monoxide and tar entering into the lungs."

The British Lung Foundation is calling for the government to implement a public health education on the health risks of cannabis.

The charity will also be pushing for further research into cannabis and the lungs and its potential link with the development of chronic obstructive pulmonary disease.

ScienceDaily (Feb. 13, 2005) — ST. PAUL, Minn. – People who smoked marijuana had changes in the blood flow in their brains even after a month of not smoking, according to a study published in the February 8 issue of Neurology, the scientific journal of the American Academy of Neurology.

The findings could explain in part the problems with thinking or remembering found in other studies of marijuana users, according to study authors Ronald Herning, PhD, and Jean Lud Cadet, MD, of the National Institute on Drug Abuse in Baltimore, Md.

The study involved 54 marijuana users and 18 control subjects. The marijuana users volunteered to take part in a month-long inpatient program. The blood flow velocity in brain arteries was tested with transcranial Doppler sonography in all participants at the beginning of the study and again at the end of the month for the marijuana users.

The blood flow velocity was significantly higher in the marijuana users than in the control subjects, both at the beginning of the study and after a month of abstinence from marijuana use. The marijuana users also had higher values on the pulsatility index (PI), which measures the amount of resistance to blood flow. This is thought to be due to narrowing of the blood vessels that occurs when the circulation system's ability to regulate itself is impaired.

"The marijuana users had PI values that were somewhat higher than those of people with chronic high blood pressure and diabetes," Herning said. "However, their values were lower than those of people with dementia. This suggests that marijuana use leads to abnormalities in the small blood vessels in the brain, because similar PI values have been seen in other diseases that affect the small blood vessels."

The PI values for light and moderate marijuana users improved over the month of abstinence. There was no improvement for heavy marijuana users. The light users smoked two to 15 joints per week. The moderate users smoked 17 to 70 joints per week, and the heavy users smoked 78 to 350 joints per week.

The American Academy of Neurology, an association of more than 18,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, and multiple sclerosis.

For more information about the American Academy of Neurology, visit its Website at

Marijuana Smokers Face Rapid Lung Destruction -- As Much As 20 Years Ahead Of Tobacco Smokers

ScienceDaily (Jan. 27, 2008) — A new study finds that the development of bullous lung disease occurs in marijuana smokers approximately 20 years earlier than tobacco smokers.

A condition often caused by exposure to toxic chemicals or long-term exposure to tobacco smoke, bullous lung disease (also known as bullae) is a condition where air trapped in the lungs causes obstruction to breathing and eventual destruction of the lungs.

At present, about 10% of young adults and 1% of the adult population smoke marijuana regularly. Researchers find that the mean age of marijuana-smoking patients with lung problems was 41, as opposed to the average age of 65 years for tobacco-smoking patients.

The study "Bullous Lung Disease due to Marijuana" also finds that the bullous lung disease can easily go undetected as patients suffering from the disease may show normal chest X-rays and lung functions. High-resolution CT scans revealed severe asymmetrical, variably sized bullae in the patients studied. However, chest X-rays and lung functions were normal in half of them.

Lead author Dr. Matthew Naughton says, "What is outstanding about this study is the relatively young ages of the lung disease patients, as well as the lack of abnormality on chest X-rays and lung functions in nearly half of the patients we tested."

He added, "Marijuana is inhaled as extremely hot fumes to the peak inspiration and held for as long as possible before slow exhalation. This predisposes to greater damage to the lungs and makes marijuana smokers are more prone to bullous disease as compared to cigarette smokers."

Patients who smoke marijuana inhale more and hold their breath four times longer than cigarette smokers. It is the breathing manoeuvres of marijuana smokers that serve to increase the concentration and pulmonary deposition of inhaled particulate matter – resulting in greater and more rapid lung destruction.
This paper is published in the January 2008 issue of Respirology.

Marijuana Smoke Contains Higher Levels Of Certain Toxins Than Tobacco Smoke

ScienceDaily (Dec. 18, 2007) — Here's another reason to "keep off the grass." Researchers in Canada report that marijuana smoke contains significantly higher levels of several toxic compounds -- including ammonia and hydrogen cyanide -- than tobacco smoke and may therefore pose similar health risks.

David Moir and colleagues note that researchers have conducted extensive studies on the chemical composition of tobacco smoke, which contains a host of toxic substances, including about 50 that can cause cancer. However, there has been relatively little research on the chemical composition of marijuana smoke.

In this new study, researchers compared marijuana smoke to tobacco smoke, using smoking machines to simulate the smoking habits of users. The scientists found that ammonia levels were 20 times higher in the marijuana smoke than in the tobacco smoke, while hydrogen cyanide, nitric oxide and certain aromatic amines occurred at levels 3-5 times higher in the marijuana smoke, they say. The finding is "important information for public health and communication of the risk related to exposure to such materials," say the researchers.

The study, "A Comparison of Mainstream and Sidestream Marijuana and Tobacco Cigarette Smoke Produced under Two Machine Smoking Conditions," is scheduled for the Dec. 17 issue of ACS' Chemical Research in Toxicology.

As you learned in the lectures on cell assemblies, most of our thoughts and perceptions depend on (1) the inborn nerve pathways that mediate early reflexive behavior, and (2) the new pathways, called cell assemblies, that develop when we have learning experiences. Both the inborn and learned neural pathways can be affected by drugs -- recreational, over-the-counter, and prescription. Drugs that affect the brain alter some of the synapses and neurotransmitters that operate at the synapses. Depending on the drug and the synapses it affects, all sorts of different and unusual things can occur, including hallucinations, distorted perception, happy emotions, "bad trips," euphoria, confused thinking, memory loss, addition and hysteria.

Many of John's students have been interested in learning more about the effects of drugs on the brain. Here are some bits of information that may be of interest. The topics covered in the lengthy document below are summarized in this "Table of Contents" (which is organized chronologically, based on the date when the research was publiced.).

Ecstasy Impairs Memory

MDMA (or ecstasy) is known to cause memory problems. Volunteers who took the drug for a long period of time underwent memory tests and most aspects of the MDMA users' memories got worse during the year that they were taking the drug and being tested for memory capacity. Marijuana and cocaine are known to hamper thinking, but MDMA hampers memory.

REFERENCE: 10 April 2001, Neurology, by Drs. Zakzanis & Young.

SD to Memory-CA Triggers Drug Craving

This study used rats that had been addicted to cocaine then forced to "go clean." After the rats had "kicked the cocaine habit," stimulation to the memory area of the rat's brain triggered drug cravings and the rats went back to seeking cocaine. Interestingly, stimulation to the area of the brain that produces the "high" feelings associated with cocaine use did not induce drug cravings or attempts to find cocaine.

REFERENCE: 11 May 2001, Science, vol 292, page 1039.

This and the next paragraph suggest that the cravings of addiction are based memory systems, such as the cell assemblies we develop through learning.


Addition is based on the same neurotrophic factors that affect learning and memory. Both alter the formation or loss of dendritic spines and other alterations at synapses. As people get addicted to a drug, they are inducing long lasting neural changes in their brain; and this makes them more prone to relapses even after years of abstinence. The more a person uses addictive drugs, the more their brain develops a "memory" of that drug. Later, relapses can be triggered by any SD's (stimuli that are "keys to memory") that activate the long lasting memories of the drug.
REFERENCE: 22 June 2001, Science, vol 292, pp 2266-2267.

The implication is clear. Avoid additive drugs and you can avoid developing long-lasting brain memories of them. The fewer "memories" of that drug you have, the less likely you are to be to relapse and fall back into craving that drug at some later point in life. The more you use a drug, the harder it is to get off the drug and stay off it.


Males are 2.5 times more likely to use marijuana. Smoking marijuana causes some of the same problems as smoking tobacco, and smoking marijuana exposes the lungs to 3-4 times more tar than do cigarettes. THC, the active ingredient in marijuana, reduces the bodies defenses needed for fighting infection (such as pneumonia) and cancer. Driving while under the influence of marijuana is dangerous, since the user is intoxicated. A study of airplane pilots found that they had delayed reaction times even 24 hours after smoking pot. Older smokers tun the risk of a five fold increase of having a heart attack. This is especially serious of a person who has a disease (such as diabetes) that puts them at heightened risk of cardiovascular problems.
REFERENCE: LA Times, July 9, 2001, pp S1 and S4.

Crystal Meth

Crystal methamphetamine causes a powerful high with sexual arousal. It makes many users sexually insatiable. When people get high on crystal, they often feel invincible and they have no fear of sexually transmitted diseases. When people come down from the high, they often become very depressed and paranoid -- and eager to get more crystal in their bodies. Many users are contracting HIV (the virus that causes AIDS) because they do all sorts of sexual activities (including anal sex, the most dangerous form of sex) while high.

Crystal causes the release of dopamine and other chemicals in the brain; and these chemicals cause the emotional high and sexual arousal. Crystal has a half-life of about 12 hours, so people still have enough to feel a high some 24 hours after taking the drug. But when the drug wears off, the depression feels to bad that it feels like an eternity. So here is a drug that hits the reinforcement and punishment systems in the brain, producing an amazing high followed by a painful low.

There is no remedy (such as methadone maintenance) to help people get off crystal; so it is very addictive. Many a person has not been able to kick this drug, and it can ruin any chance a person might have had to have a normal life.
REFERENCE: LA Times Magazine, October 7, 2001, pages 12-15 and 29-30.

Drug That Elicit Pleasure

An article in the highly respected journal, Science, helps us understand the effect of pleasure-eliciting drugs. Drugs that feel good are primary reinforcers, and they are addictive because they co-opt both memory and motivation systems, not just pleasure systems in the brain. Their use causes short-term surges in dopamine and other neurotransmitters that trigger pleasure and reward. However, the brain quickly adapts to this deluge of pleasure, and the pleasure circuits desensitize-- producing tolerance to the drug. At this point, people need to use more of the drug to get the same "high" that they got at first. This leads to addition, even if the drugs no longer bring much pleasure.

Addiction is based on the learning and memory systems of the brain. Through Pavlovian conditioning, the stimuli that are present just before using pleasure- inducing drugs become CSs for positive drug-related pleasure emotions. In the future, the presence of these CSs can cause drug cravings; and this is a big part of the addition process.

Some of the CSs for drug cravings operate at the unconscious level, contributing to the compulsive aspects of addiction. If a person happens to perceive one of the drug-related CSs, the drug craving can pop up, even if the person has no conscious awareness of the presence of the CS. Even subtle context cues can become CSs for compulsive drug urges. Just being in a room that resembles a room where the person took drugs in the past can be enough of a CS to elicit strong drug urges. Hence, "many recovered drug users say they fight cravings for the rest of their lives."

"Although each drug of abuse has its idiosyncratic effects, all specialize in bombarding the brain's dopamine-mediated reward circuits. Long-term abuse can wear out these pathways, reducing the number of receptors that respond to dopamine." Even people who have been drup free for months do not have a complete recovery of their dopamine pathways. The loss of dopamine receptors interferes with motivation and pleasure. The loss also interferes with learning and movement, creating memory problems and damage to motor coordination.

Also, the loss of dopamine receptors causes the brain to become less sensitive to natural reinforcers, such as the "pleasure of seeing a friend, watching a movie, the curiosity that drives exploration." So people turn ever more to drugs (as the other reinforcers lose their power). This is when people start neglecting their friends, families, jobs and health. The article says: "It isn't that the crack-addicted mother does not love her children. She just loves drugs more."

There is a great picture on page 984 that shows how cocaine causes the extra growth of dendrites and dendritic trees on nerve B. Thus people who use cocaine, develop these extra large number of dendrites that makes the brain extra hungry for cocaine. They are the drug receptors that increase an individual's sensitivity to drugs, while the damage to the dopamine-mediated reward circuits (described in the pior two paragraphs) destroys the brain's ability to experience pleasure from the drugs.

When people "go off" a pleasure-inducing drug, they experience withdrawal symptoms (since their body has become dependent on the drug). The psychological feelings of withdrawal are closely akin to the dark feelings associated with extended mourning for the loss of pleasure and security. These feelings can be intense mood drops that cause a spike in irritability, depression or other negative emotions.

REFERENCE: Science, Vol 294, November 2, 2001, pages 983-984.

Psilocybin, or Hallucinogenic Mushrooms

An article written by Ladan Moeenziai explains the behavior of a student on psilocybin, a hallucinogenic mushroom. At about 8:35 pm, during dead week, December, 2001, a 19-year-old UCSB student, Christopher Miller reportedly began running naked from IV to campus. When reaching Mesa Road, Miller ran into the side of 3 moving cars, bouncing off each one and continuing to run. Miller was struck by a 4th car when he jumped out in front of it. He sustained only minor injuries and remained conscious. He was using psilocybin, a hallucinogenic mushroom. He was taken to Cottage Hospital. The driver of one of the cars said, "The whole time I was thinking, did I hit someone or did someone hit me?"

REFERENCE: Daily Nexus, vol 82, no 49, Dead Week, Fall 2001, p 1.

Biological Psychology

The Department of Psychology offers a couple of courses on biological psychology that go into wonderful detail on the brain and include lots of nice scientific data on the effects of drugs on the brain. The book listed below is used in one of the classes, and it contains a whole chapter (ch #4) on drugs, neurotransmitters and behavior. The topic of prenatal exposure to drugs is covered in a separate chapter, pages 204-205.

REFERENCE: Mark Rosenzweig, Marc Breedlove, and Arnold Leiman (2002). Biological Psychology (3rd edition). Sunderland, MA: Sinauer Associates, Publishers.

Ecstasy Causes Brain Damage

Long known to disrupt neurons that communicate via the neurotransmitter serotonin, Ecstasy now appears to have even more potential for roughing up the dopamine system. Ecstasy heightens sensations, gives a euphoric rush, and creates feelings of warmth and empathy, apparently by causing neurons to spurt huge quantities of serotonin. Afterward, the CNS is drained of serotonin, making one depressed and unable to concentrate. The amount of ecstasy used in one all-night "rave" may be enough to induce permanent brain damaged and make a person more vulnerable to Parkinson's disease, which is caused by a loss of dopamine-producing neurons. The axons of affected nerves become damaged, reducing their ability to communicate to other nerves.

REFERENCE: George A. Ricaurte and colleagues (2002). "Drug Find Could Give Ravers the Jitters." Science, 27 September, pp 2185-2187 and 2260-2263.

Brain Shrinkage

As people age (after age 30), their brains shrink and lose weight if they do not do regular cardiovascular exercise. The loss of brain size and weight is matched by declines in cognitive performance. People who swim, walk, job or cycle at least 20 minutes a day, several days a week, show less decline in brain mass than do people who do less cardiovascular exercise. So it is wise to adopt good habits of cardiovascular exercise as soon in life as possible and maintain those habits through all your remaining years.

REFERENCE: Science, 7 March, 2003, page 1511.

Nicotine Accelerates Things

In the brain, nicotine sparks activity in the neurons, especially the acetylcholine synapses. The excited neural activity makes smokers feel good, even euphoric; and it is also what makes them crave more. Now we are learning that nicotine also speeds up activity in tumor cells, which can make cancer cells grow faster. (Scientists usually blame all sorts of the other chemicals found in cigarettes -- and not nicotine -- as the causes of cancer; but nicotine can make cancer cells divide faster.) Nicotine also accelerates the again of skin cells, since it has the capacity to accelerate cell activity and cell division. That is why smokers' faces age faster than do nonsmokers.

REFERENCE: Science News, 22 March 2003, pages 184-186.

Pregnant Women Using Marijuana

Various studies have suggested that children born to women who had used marijuana while pregnant suffered from memory problems and hyperactivity. A recent study on rats provides laboratory evidence that is in line with the prior studies. Female rats were exposed to a marijuana-related drug during pregnancy. Their offspring produced less glutamate (an essential neurotransmitter) in the hippocampus, which is a memory-processing center in the brain. The researcher says, "Our findings suggest that both pregnant and lactating women should avoid using marijuana."

REFERENCE: Science News, 5 April 2003, pages 220-221.

GABA Helps Old Brains Think Like Younger Brains

As the brain ages, people often experience increased amounts of "cross-talk" between CAs all over their increasingly well-conected brains (as CAs keep hooking up with each other). This "cross-talk" can interfer with logical and clear thinking. Research on primates suggests that adding regular doses of GABA (Gamma-aminobutyric acid) to the brain may help reduce the random "noise" in the brain, due to too much "cross-talk," and this helps old individuals think more clearly. GABA is the brain's major inhibitory neurotransmitter, and it usually declines with age, allowing for the indiscriminant firing of irrelevant neurons. GABA renews powers of discrimination and sensory-information processing that younger individuals have--but which are often lost with advanced age. "Anything that can show a reversal in the effects of aging is really exciting and potentially beneficial" says Julie Mendelson, a neuroscientist at the University of Tolonto. GABA helps the brain extract information from a noisy environment.

REFERENCE: Science, May 2, 2003, page 721-2; and Newsweek, May 12, 2003, page 10.
Marijuana's Effects

A recent study compared 704 long-term marijuana users with 484 nonusers and found that there was only difference in a series of different measures that were taken. The long-term marijuana users showed no decrement in language skill, reaction time, motor skills, perceptual capacity or reasoning abilities. There was only one difference: The marijuana users had a small decrement in their ability to learn new information.

REFERENCE: Journal of the International Neuropsychological Society, July, 2003.

Cocaine and Amphetamines Retard Brain Development

Speed-type drugs stunt the growth of brain cells. During normal learning, dendrites grow more branches and spines (the tiny receptor sites on the dendrites); but cocaine and amphetamines greatly inhibit the formation of new dendrite branches and spines. Bryan Kolb, the head scientist on the project said, "It may be that the drug exposure has altered [the subjects'] ability to learn from their experience" -- which would make them a lot like human addicts. This is the first study to show that drugs can block the effects of learning experience at the anatomical level in the brain.

REFERENCE: Proceedings of the National Academy of Sciences, end of August, 2003.

Beliefs About Marijuana Are Confused

January 5--Marijuana is very deceptive because it is extremely slow acting. Very little of its active ingredient, THC, has reached the brain at the time of the "high." Hence the drug appears to the user to be mild.
However, the user does not realize that it has an appreciable effect on his body for over a month.

About 40% of the THC is stored in the body fat and is then slowly released into the blood over many weeks. Each joint adds to the supply of THC that the body is storing, thereby increasing the level of it in the blood. When a person smokes regularly, the THC in his blood is sufficient to sedate him all the time.

Not Like Alcohol:

As they experiment, kids play with pot because they hear from many sources that it is no more harmful than alcohol. Therefore, they reason, "If my parents can drink alcohol, I can smoke pot." As they experiment, the pot appears to be mild, and so they try it again and again. The THC builds up in their bodies and it steadily drags them into a state of continual sedation. Their minds become confused, and their drug use escalates. They usually start drinking alcohol heavily also. In time their brains become so confused that many graduate to the use of cocaine and heroin, drugs they would never have taken before being caught in the marijuana trap.

It is often claimed that marijuana is not harmful because it is not an "addictive drug." The basis for this claim is that physical withdrawal symptoms are mild when one abruptly stops smoking it. However, the reason for mild withdrawal symptoms is that the body has been storing the THC in the body fat and has its own supply of THC.

Prior to 1970, most of the pot had about 1% THC or less, and the best stuff had 3%. Because of the enormous demand for marijuana since the 1960's, a strong effort was expended to develop new varieties. Today, practically all of the street pot has about 12%, and some has as much as 25%. Thus the marijuana available today is about ten times as potent as in the 1960's.

Brain is Damaged:

Dr. Robert Heath of Tulane Medical School did extensive studies of the effect of marijuana on the brains of monkeys. He was world-renowned for his research on the brain, and he was the head of the departments of psychiatry and neurology at five hospitals in the New Orleans area.

A typical experiment performed by Dr. Heath was to allow a monkey to smoke the equivalent of a human's smoking two joints of pot per day containing 2.5% THC, five days per week for six months. The monkey was allowed to recover for six months and then was killed. Brain waves were measured from electrodes embedded in the brain. The brain waves had become severely distorted after two months of smoking, and remained severely distorted until the monkey was killed.
The cells in the brain, which were examined under an electron microscope, showed serious damage, particularly in a deep part of the brain called the limbic system, which is the center of emotion. All of the brain cells of the limbic region showed strong structural changes. For monkeys that smoked only 40% of this amount, the damage was much less but was still observable.

The level of marijuana use by the monkey is equivalent to the smoking of two joints per week of modern pot with 12% THC, by a teenager weighing 130 pounds. We can expect serious long-term brain damage from this level of marijuana use. We can also expect detectable brain damage in a teenager smoking half this level, i.e., one joint of 12% THC per week.

About 1980, this monumental research was cancelled by the National Institute of Drug Abuse, which is the U.S. federal agency that sponsors research on drugs. It buried the results of this research.

Other Damage to the Body:

Regular marijuana use at levels generally assumed to be moderate can seriously damage the chromosomes, the immune system, the hormones, the reproductive system, the sex organs, the sex drive, the lungs, and, as we have seen, the brain. Some of it is as follows.

- - It causes severe damage to the T-lymphocytes, which are the primary white blood cells associated with the immune defenses of the body, according to studies performed in the early 1970's. The damage to these cells caused by other drugs such as alcohol, cocaine, and heroin is insignificant in comparison to marijuana. These are the blood cells of the immune system that are primarily damaged by AIDS.

- - The chromosomes of mice are also severely damaged, according to studies performed by Dr. Susan Dalterio of the University of Texas. Severe abnormalities were caused in newborn mice from use by the grandfather, even with no marijuana use by the grandmother, father or mother.

- - The effect on the reproductive system can be severe. Regular use of the drug by children who have not reached puberty can retard and even permanently inhibit sexual maturity. Its use can destroy the sperm and egg cells and thereby cause sterility. Pot smoking is particularly harmful to girls because their ovaries do not produce new egg cells.

Why Are Beliefs About Marijuana So Confused?

If the scientific case against marijuana is so strong, why are there such strong beliefs that it is relatively harmless? The primary answer is that powerful economic forces are working to keep the marijuana issue confused.

Hundreds of billions of dollars are being made from cocaine and heroin each year. We can expect that much of this money is being spent every year in disguised advertising and influence to help support the trade. As long as the kids believe that marijuana is relatively harmless, many of them will play around with it, and this generates a steady supply of cocaine and heroin addicts.

We were making progress when the National Institute of Drug Abuse supported excellent research on marijuana in the 1970's. However, new leadership took control about 1980, and all of this was cancelled. Since then, the Institute has not supported any significant responsible research on marijuana. In 1988 the United States government sponsored the White House Conference for a Drug-Free America which recommended that an independent evaluation of the National Institute on Drug Abuse be conducted.

No action was ever taken on this recommendation. Nevertheless our federal government spends billions of dollars every year in a fruitless War on Drugs, which attempts to keep drugs from entering our country.

Medical Use of Marijuana:

The attempts to legalize it for medicinal purposes are an indirect means of achieving the total legalization of the drug. Even more important, the message that is being spread concerning the medical use of marijuana is very effective advertising to convince kids that marijuana is not very harmful. This advertising is many, many times more effective than the "Joe Camel" ads by the tobacco companies, which lure kids to smoke tobacco.

We have seen that marijuana severely damages the immune system. How then can we justify telling unfortunate AIDS patients that they should smoke marijuana to lessen their pains? Instead we should be shouting, "With your weak immune systems, you should consider marijuana to be the worst form of poison."

It's also being used by some cancer patients, but it's just as bad for them. Although chemotherapy can cause severe nausea and THC is very effective in combating nausea, the last thing a cancer chemotherapy patient needs is marijuana, which would weaken his immune system further.

There is probably enough common sense in our country to keep us from falling for the phony plea to legalize medical marijuana. However the primary harm from this campaign is its associated propaganda. This propaganda is convincing countless youngsters that marijuana is harmless.

Implications of Fat Solubility of THC:

The reason that marijuana is much more dangerous than alcohol is because the alcohol is water-soluble and it dissolves readily into the blood. It is absorbed from the stomach and stays in the blood until it is metabolized by the liver. The blood carries the alcohol to the brain, where it performs its numbing effect.

In contrast, the THC that is found in marijuana is not soluble in water and so cannot dissolve in the blood.
When a person smokes marijuana, no more than 25% of the THC is absorbed into the blood. About 40% of the THC that enters the body is stored deeply in body fat. The fat releases the THC into the blood with a half-life of one week, which means that if a person stops smoking pot it takes one week for the stored THC to drop to 1/2, two weeks to drop to 1/4, etc. Every week the THC is stored in the fat, it decreases by one-half.

The blood in the brain is separated from the main blood supply by the blood-brain barrier, which is a sieve that helps to protect the brain from toxic substances. Since the THC molecules stick to this sieve, they pass through the blood-brain barrier very slowly. This delays the flow of THC to the brain. By the time an appreciable amount of THC has worked its way through the blood-brain barrier, there is little THC left in the blood. Consequently the peak concentration of THC in the brain blood is very small. It is only 1/2 of one percent of the initial THC concentration in the main blood supply.
At the time of the "high," the peak concentration of THC in the blood of the brain is about 1/1000 of the THC in the marijuana joint, spread over the blood supply of the body.

THC is extremely potent. It is one million times more potent than alcohol. Marijuana appears to be mild because THC acts very slowly, over a period of many weeks.

The more often one smokes marijuana, the more THC is stored in the body fat. The THC stored in body fat is released steadily into the blood. Although the blood-brain barrier delays the flow of this THC to the brain, it does not reduce the amount of THC in the brain because the fat releases THC slowly and steadily. When a person smokes one marijuana joint per day, the peak change of THC concentration in the blood of his brain after smoking a joint is only 3 times the steady THC concentration. He builds up tolerance to the steady THC level, and so he does not feel a strong "high" when smoking a single joint.

The regular pot smoker is constantly sedated from the steady THC level, and so he sinks into a state of continual sedation. His mind becomes confused, he becomes lazy and sloppy, and he has a strong urge to feel "high." Since he is tolerant to the steady THC in his blood, he often turns to other drugs to get "high." Nevertheless, he continues to smoke pot as he takes the other drugs, because smoking marijuana makes him "feel good all the time."

One of the drugs that marijuana smokers take frequently is alcohol. Those who smoke pot usually drink much more alcohol and drink much harder than those who do not. Normally a young person becomes sick and vomits when he drinks excessive alcohol. However THC strongly inhibits nausea, and so a young pot smoker can easily consume a lethal dose of alcohol without vomiting. For someone who does not smoke pot, it normally takes many years of hard alcohol drinking before one builds up sufficient alcohol tolerance to hold down a lethal dose of alcohol without vomiting.

Our society is deeply troubled by the smoking of cigarettes by teenagers. Yet nobody seems concerned that nearly as many teenagers smoke marijuana as smoke cigarettes. How do you convince a teenager to stop smoking cigarettes when he is smoking pot ?

Relationship to Crime:

Individuals directly involved in prosecuting criminals are well aware of the strong relation between crime and drug abuse. One district attorney stated that most of the criminals in our jails were so confused by drugs when they committed their crimes they cannot even remember the crimes for which they are bring punished. Marijuana is the seed from which the scourge of drug abuse grows. If we stop the marijuana, we will stop the rest of the drug abuse, and with it the crime.

The marijuana presently being smoked by our kids is ten times as potent as in the 1960's. When we realize how much marijuana is being used by our teenagers, and how extremely potent it is, it is frightening to think of the damage that this marijuana must be doing to the brains of these innocent children. None of us should be surprised by the violence in our schools today.

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