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What statistics are there for measuring the suffering of families with drug dependent children?

An Ancient Arabic question"

“Say to those who eat hashish in ignorance

The worth of a man is a jewel

The ornament of a man is his mind

Why then you fools do you sell it for a piece of grass?”

It is illuminating to study countries where cannabis has been in use for centuries. The anthropological analysis of cannabis use in certain countries and the social political and/ or historical events surrounding its use, play up very important role in understanding the Western worlds contemporary obsession with drugs.

Throughout its history widespread abuse of cannabis is associated with collective apathy and cultural and economic regression. Anecdotal reports from medieval Islam (1396), India (1878-1972), Egypt (1843-1925) Brazil (1955), Bahamas (1970) and Jamaica (1976) all specified an association between marijuana and mental disturbances ranging from distorted perception to hallucinations, dementia schizophrenia.

If we don't heed the lessons of history then perhaps we should take heed of the following advice

“I know of no better exemplification of the death wish

at the heart of our way of life, than this determination

to bring about the legalisation of hashish so that it

may ravage the West as it has the Middle and Far East.”

Malcolm Muggeridge


Comments about the destructive effects of marijuana are also found in the writings of Jerry Rubin, an ideologue of the 1968 Students' Movement. He claimed that:

“Legalise pot and society will fall apart”.

No two people could be further opposed ideologically and politically than Muggeridge and Rubin. However, both are in agreement that the norms and values of society would be seriously threatened if cannabis use became widespread.

One of the remarkable things I noticed during my years of counselling was that it was often the most sensitive and intelligent young people in particular who were attracted to the mind-altering experience of marijuana. This fact brings into question the possibility of losing some of Australia’s future artists and intellectuals if street drugs become part of our culture

In 1979 at an international scientific conference in Helsinki it was established that marijuana probably had long-term damaging effects on the brain, learning and behaviour, the immune system, reproductive function and foetal development. However, before such damage could be scientifically documented time was needed to carry out long-term studies of marijuana users.

Although experience and common sense dictated that such proof would be established eventually, special interest groups took advantage of the situation to confuse lay people with statements that inferred that until the side-effects of marijuana were scientifically established there was in fact no real evidence of harm associated with the use of marijuana. This was similar to the lies and manipulation that was part of the tobacco controversy: people with ‘vested interests’ defending the indefensible.

The first people to recognise any change in behaviour or the first signs of brain damage are a drug users family and friends. But unfortunately anecdotal material and clinical observations have lost much of their status in the field of research and the invaluable contribution and insight of mothers’ teachers and doctors is often underestimatedestimated. *

Just as legal precedents are an essential part of law, so history provides an important context within which to discuss the role of street drugs in the twenty first century. Pro drug activists are doing their best to convince people of influence i.e. politicians, academics, and even representatives of law enforcement that it is more damaging for society to maintain legal sanctions on street drugs than making them freely available. Very few of their supporters are familiar with the devastating effect that psychoactive drugs have had in various countries throughout history.

The Common Good

The notion that it is the right of the individual to pursue their pleasure in any way they chose is perfectly acceptable. That is unless it is harmful to other people. In other words has a detrimental effect on others in the community. In every other area of Public Health Policy 'the common good' is one of the most important aspect and prevention is absolutely essential. So why is it in this day and age that most health workers fail to understand the significance of primary prevention in the case of drug abuse? Prevention not only discourages young people from taking up street drugs but also targets the next generation of potential drug users. Controlling the number of drug users is critically important. However, lack of informed accurate and up to date information about drugs puts Australian teachers at a great disadvantage when it comes to teaching drug education classes.

It is difficult if not impossible for policy makers to make an informed decision about whether or not to remove legal sanctions if they are not aware of the lessons of history or the reasons why certain drugs were classified as illegal. Positive liberty requires that we have an idea of what is needed for young people to flourish and in my opinion to expose young people to the dangers of street drugs in order to promote political or financial ambitions is morally corrupt.

Interestingly when you look at the history of “the tobacco industry’ it has many parallels with that of marijuana. In the 1950’s much of the research linking cigarette smoke and cancer was statistical. Twenty-four investigations in nine countries surveyed population of cigarettes smokers - noted their smoking habits and in subsequent years ascertained the cause of death.

In Britain Dr. Richard Doll and Prof Austin Bradford Hill made an extensive study of 40,000 British doctors in America Dr. Daniel Horne and Dr. Guyler Hammond surveyed 187,000 American smokers and non-smokers. All these studies concluded that there was an association between the risk of lung cancer and the number of cigarettes smoked.

However in the late 1950s some prominent medical scientists was skeptical of the link between lung cancer and cigarette smoke. Dr. Ian McDonald one of California’s foremost cancer specialist stated before a US Congregational Committee that not only did he believe that cigarette smoking for no relationship to lung cancer, but suggested:

A pack of cigarettes a day will keep lung cancer away.”

It wasn’t so long ago that those of us who knew how advanced the research was on marijuana were absolutely pilloried by the ‘experts’ here in Australia. And remember the main argument put forward as a reason for lifting legal sanctions on marijuana was because the ‘experts’ kept insisting it was a ‘soft drug’. This has turned out to be completely false. Despite the plethora of research that completely discredits their claims, drug law reformers still insist that marijuana has minimal risks and that there is still not enough evidence based research. One wonders what parallel universe they inhabit.

The fact that most people still refer to marijuana, as a 'soft drug' is hardly surprising - it is a cliché that has been used for years to placate people’s concerns about marijuana and it has been repeated so often it has become part of public discourse. And just as in the case of tobacco, research and epidemiological studies on cannabis will continue for years to come. But there is more than enough evidence at this point in time about the damage it can cause to the health and well being of the developmentally immature adolescent to deter us from removing legal sanctions. We just need to remember the debate that raged for eighty years about the health risks associated with tobacco to understand how vested interests will obstruct and pervert the truth. We also need to remember that the prolonged debate about those risks caused unnecessary suffering to many people who were unable to overcome their addiction. This in turn placed an enormous burden on the health system.

The Brain

The brain performs many tasks that interact with each other. It has to understand information, assess it, integrate it with previous information and envisage the consequences. On this basis the brain then decides what action to take. This process requires metabolic energy and proficient communication between nerve cells. The cannabinoids impede these activities.

Consequently, the behaviour and responses of many users are badly affected, and they often display personality traits such as poor social judgment, poor attention span, poor concentration, confusion, anxiety, depression, apathy, passivity and often slow and slurred speech. One of the depressing aspects about marijuana is that it doesn’t differentiate between the deprived and disaffected and the well-educated and well adjusted.

It may be only a few months, but usually it takes years, before family or friends notice any significant changes in the personality and general health of a person affected by marijuana. It is almost impossible for users themselves to detect deterioration of their own mental and physiological processes. Marijuana use produces both acute and chronic effects.

There is a whole range of factors associated with the use of marijuana. Sometimes personality changes occur within weeks or months of starting to use it. Other people maintain their normal lifestyles for many years and the deterioration of potential skills and personality is so gradual, that marijuana is not seen to be associated with these changes. There are also many people who appear to be unaffected, even after many years of continuous use.

There are many middle-aged users who have been smoking marijuana for years and do not show any of the signs or symptoms associated with its use. However in many cases people in this age group have settled into lives limited by their use of the drug, and indicators are likely to be difficulties associated with thinking and failure to make commitments. One thing is clear, the younger a person starts using marijuana the more serious the consequences, and as long as this contemporary obsession with drugs keeps gathering momentum the greater is the risk of younger people becoming involved.

Students will often point to the achievements of artists singers and movie stars who are drug users and claim that their talent are unaffected by drug use However usually the achievement of an outstanding talent has already been developed and practiced before a ‘star’ starts using drugs. On the other hand, we see many examples of talents being diminished because of drug use.

People need particular skills in order to gain knowledge and the first of these is memory. This is necessary in order to compare new experiences with past information. It is also necessary to have a mind that is capable of evaluating and integrating what is learnt.

Short-term memory loss has serious repercussions for students because the accumulation of knowledge is disrupted at a time when previous learning is essential for the understanding of future lessons. These complex developments are impeded if interfered with by mind-altering chemicals.

Loss of short-term memory is often underestimated. I have seen many young men, who were once great achievers, slowly compromising their talents and slipping into mediocrity.

When anyone learns social and intellectual skills, repetition is then necessary in order to store what has been learned in long-term memory. Of course they must also be keen to ‘learn’ more. If this process is interrupted by drug use, their intellectual and emotional development is also stunted. This lack of maturity becomes patently obvious when counseling young pot-smokers. Finally, there must be the reward or reinforcing part of acquiring knowledge.

It became abundantly clear to me that after year of counseling most of my clients, who were in their late teens or early twenties, had the emotional maturity of a twelve-year-old. There is no way of knowing which children will be the most vulnerable to marijuana, who will lose their potential, who will become addicted or who will progress to other illegal drugs.

One of the most impressive men I met during my time in the US was Dr. Robert Gilkeson. He was well ahead of his time in his research on the brain and other scientists have replicated his findings again and again. Sadly, he didn’t live long enough to see how crucial his work was in advancing the knowledge about marijuana. No one was able to express the way in which marijuana affects the brain more elegantly than Doctor Gilkeson in his book, Marijuana Myths and Misconceptions:

“The most important, the most specialised, the most complex and the most fragile cells in the body are the cells of the human brain, the neurons. These cells make huge numbers of connections or synapses.

These connections transmit and associate information arising from outside and inside the body. Internal messages relate the needs of the cells in the body. External messages tell us everything going on in the `outside world'. The brain ‘reads’ these messages, analyses them, then plans and initiates the correct movements, the glandular secretions and the other functions to meet those needs.

To pass accurate messages, sodium, potassium, calcium and the complex messenger chemicals called neurotransmitters must all cross the cell membrane channels in the correct amounts, very rapidly.

The centre of the brain coordinating the interaction of the other brain centres and controlling the amount of brain energy is called the Reticular Activating System (RAS). Since it makes the most connections and is always in operation, it is the most saturated and affected of all the centres.

This centre controls our alertness and our level of consciousness. When the energy of the RAS is decreased, the efficiency of the entire conscious brain is lowered. This activating system turns on and increases, or turns off and decreases, the chemical messages between areas of the brain that regulate the very level and complexity of human thought and behaviour.

It regulates the intensity of messages between the centre for memory, the centre for feelings, and the centre for analysing all the messages from inside and outside the body. This information in turn triggers necessary motor behaviour or glandular activity.”


Most people do not sustain permanent brain impairment from using marijuana. However, as the use of marijuana escalates in Western societies reports of adolescents and young adults suffering varying degrees of impairment are also increasing. Evidence indicates that certain factors cause people to be more susceptible to developing ‘drug burnout’ or chronic young adult psychiatric syndrome. It is medically classified as Post Drug Impairment Syndrome, (PDIS).

Evidence suggests that certain factors may render a person vulnerable to Post Drug Impairment Syndrome:

  • Using drugs for a number of years. i.e. 3 years or more.

  • Commencing at a young age. e.g. 15 years.

  • Heavy consumption – using marijuana with at least one other illegal drug, e.g. magic mushrooms, amphetamines PCP, LSD or designer drugs.

PDIS is believed to be a form of chronic brain syndrome, i.e. a permanent imbalance of the chemical equilibrium of the brain. Symptoms of Post Drug Impairment Syndrome include the inability to maintain patterns of consistency, inability to withstand stress, slowed speech, slowed response to time, superficial interest, instability and unwillingness to carry out former responsibilities.

Such people do not perceive the world as most normal people do; they feel alienated from society and blame others for their problems. They usually have a bland or dull personality and have frequent temper tantrums. Post Drug Impairment Syndrome may vary in intensity from person to person and not all people will exhibit all signs and symptoms. Unfortunately there is neither predictable nor effective treatment for Post Drug Impairment Syndrome. Most will treat these people along traditional psychiatric lines and often such treatment is not effective. According to Doctor Forest Tennant who was the first researcher to identify PDIS:

"The best hope for future PDIS treatment lies in research. With better identification of the precise neurochemical defects in PDIS, it may be possible to select medication that will be specific for the individual. Observations to date indicate that PDIS may involve different patterns of neurochemical impairment so that medication will probably have to be specific, based on differences as diagnosed by laboratory tests."

Clinical Observations

Marijuana-impaired personalities have been clearly defined by psychiatrists since the mid 1970's and the conclusions have since been confirmed and reaffirmed by scientific research ever since. Considering that the first of signs of impairment to the brain is a change in behaviour 'observations' including those of parents, teachers, employers and doctors are of enormous importance. If the Australian 'experts ' had taken all the clinical and scientific research that was available - approximately 10,000 - into account in the 1980' s, many parents would have been saved a great deal of heartache. Instead they were constantly told that there was no association between marijuana and the changes of behaviour they were observing in their children who were smoking it. Instead they were accused of being either neurotic or told that their families were dysfunctional. And meanwhile the general public were subjected to years of lies and misinformation.

Anecdotal evidence

The first part of research is a set of cases sharing the same characteristic. This anecdotal evidence is then evaluated by scientists and if it is deemed to be consistent and reliable, then scientific research is undertaken. Since 1925 there has been an abundance of scientific research to support the original claims.

A good example of the effectiveness of anecdotal evidence was the great antisepsis movement in the mid 19th century that began to bring infectious diseases such as typhoid and cholera under control long before the germs that caused these diseases had been discovered. The movement was based on anecdotal/observation, e.g. that drinking polluted water was associated with the disease. If the provision of clean water had been delayed until the discovery of bacteria, then thousands of preventable deaths would have continued to occur for many years.

When I returned from the U.S. in 1986 I bought with me the following research papers that were written by psychiatrists in the seventies and the eighties.

According to Dr. Doris H. Milman, professor of paediatrics at the State University of New York, “During the past six years, we have seen a clinical entity different from the routine syndromes usually found in adolescents and young adults. Long and careful diagnostic evaluation convinced us that this entity is a toxic reaction in the central nervous system due to regular use of marijuana and hashish. Contrary to what is frequently reported, we have found the effect not merely that of a mild intoxicant which causes a mild exaggeration of usual adolescent behaviour, but a specific and separate clinical syndrome unlike any other variation of the abnormal manifestations of adolescents. We feel there should be no confusion, because regardless of the underlying psychological difficulty, mental changes - hallmarked by disturbed awareness of the self, apathy, confusion, and poor reality testing - will occur in an individual who smokes marijuana on a regular basis, whether he is a normal adolescent, an adolescent in conflict or a severely neurotic individual.”(1)

Drs. Kolonsky and Moore’ documented the following observations:

'The psychological effects of cannabis have been known since antiquity. The most obvious of these effects is, of course, the cannabis-induced psychotic reaction, with delusional symptoms, disorientation, hallucinations, paranoia, and feelings of depersonalisation and derealisation. The psychosis may present acutely or insidiously, may be transient and wholly reversible or it may be prolonged and chronic. When chronic, it is clinically indistinguishable from chronic psychosis of the schizophrenic or paranoid type. The most prominent cognitive effects are impaired recent memory and retrieval, attention deficits, difficulties in central processing, altered time perception, visual distortions and hallucinations. Among emotional effects are mood fluctuations including euphoria, listlessness, apathy, and depression. Other emotional responses include drowsiness, indolence, withdrawal, anxiety and apprehension. Hallucinations, paranoid delusions, and feelings of depersonalisation and derealisation are not uncommon, and are seen in acute intoxicated states as well as in acute or chronic psychoses.” (2)

According to Dr. Donald Ian Macdonald a paediatrician and former President of the Florida Paediatric Society: ‘The use of psychoactive chemicals by children and adolescents leads to a clear-cut and easily recognisable syndrome of behavioural and emotional change. Regardless of the motive for experimenting with mind-altering drugs, once children begin to use drugs for producing good feelings at a time of stress, they are in trouble. As they become chemically dependent, as millions of our youngsters have, their disease progresses in a remarkably predictable downward path.” Dr. Harold Voth who has studied the psychopathology of marijuana since 1972 has this to say: “Based on the observations I have made on the effects of marijuana, it is my opinion that this substance is harmful, especially to the young. I believe marijuana does lead to maladjustment and that it reinforces rebellious, negativistic behaviour and lower the individual's motivation for effective social adaptation. Furthermore, I am completely convinced that marijuana affects psychological processes and personality across a wide spectrum of behaviours and functions”.

My interest in the effects of marijuana began approximately 10 years ago because of its apparent effects on both inpatient and outpatient psychiatric populations. Without any question in my own mind, patients use the substance to facilitate their repressive trends, that is, to assist them in their escape from the responsibilities and stresses of life and to calm their anxieties. Periodic conversations with my psychiatrist colleagues provide support for my observations with only a few exceptions. Some of these exceptions may be related to the fact that some of these psychiatrists use themselves. One psychiatrist of national prominence who disclaims any harmful effects of marijuana has stated publicly that he smokes the substance several times weekly. For the most part, however, colleagues agree that marijuana is harmful.”

Dr. John Meeks, psychiatrist and medical director of the Psychiatric Institute of Montgomery County, Maryland, made the following comments:

“It is striking that most marijuana users – as long as they are actively using the drug – tend to view themselves as undamaged by the chemicals in cannabis. They are often joined in the denial by their parents, teachers and other adults. Obvious evidences of irritability, altered consciousness, volatile moods, paranoid hostility, and impaired social, educational, and economic functioning are dismissed or minimised as `adolescent rebellion’ or cultural protest. This is a transformation of reality that makes simple alchemy a snap by comparison.”

According to Doctor Sidney Cohen who conducted one of the largest adult studies ever done on marijuana users:

“The demotivating potential of potent preparation of cannabis has received renewed attention because of the vast increase in the use of marijuana by young people in many parts of the world where it had never been a part of the dominant life-style. In 1968 the term ‘amotivational syndrome’, in relation to sustained marijuana use, was employed independently by a number of health professionals.”

One of these was Doctor David Smith, who stated that: “Certain younger individuals who regularly use marijuana also develop what I have called the amotivational syndrome in that they lose the desire to work or compete.”

Doctors Mc Glothlin and West, also experienced in the field of drug abuse, describe the syndrome as follows: “Clinical observations indicate that regular marijuana use may contribute to the development of more passive, inward turning, amotivational personality characteristics. For numerous middle class students, the progressive change from conforming, achievement-oriented behaviour to a state of relaxed and careless drifting has followed their use of significant amounts of marijuana.”

Dr. Doris H. Milman published a report in 1982 on a study of adolescents: “The patients and their parents were particularly frightened by flashbacks and the occurrence of delusions. These states evoked unbearable anxiety, fear and agitation requiring sedation with chlorpromazine. Flashbacks lasted up to four months after stopping the drug. Other researchers have found that marijuana can induce LSD, mescaline or PCP flashbacks in patients who have taken these drugs. The total of eleven instances out of twenty-four of schizophrenia and borderline schizophrenic personality was extremely high in relation to the absence of these categories in the pre-drug state. Personality traits and features also included a new finding of paranoia in addition to an increased incidence of depressive features.”

In 1989 Doctor Richard Schwartz of Georgetown University described the results of an exceptionally well controlled study of persistent American, middle class adolescents. Their median age was 16 and they had at least eight years of education. Their performance was compared with that of a group of controls matched for age and I.Q. Schwartz began his study after he noticed that marijuana-dependent adolescents who had just entered a rehabilitation program experienced difficulties in recalling newly learned rules as well as remembering conversations and exchanges in their group therapy sessions. These adolescents reported that such memory deficits persisted for at least three to four weeks after their last use of marijuana: When initially tested, the marijuana-dependent group compared unfavourably on short term memory tests with the control group. After six weeks of supervised abstention from intoxicants they still presented short-term memory deficits. Marijuana use hits hardest those teenagers who do poorly in school. “For them, remedial teaching without concurrent abstention from marijuana is ineffective. While the brightest might compensate for a while, the average hardly gets by, and the low I.Q. groups are devastated by it.”

These are only a few documented studies from the thousands that were available in the early eighties. Can you imagine the difference if Australian parents had been aware of this research at the time? Parents and friends don’t have to be scientists or health professionals to realise that their children’s personalities deteriorate when they use marijuana. They don’t need to know the data or statistics. They live with the consequences.

As the years went by scientific research confirmed the clinical observations of the 1980’s. Recently I was ridiculed for using so called 'old' research. Such a comment alerted me yet again to the fact that the 'elites' do not understand the character and force of the drug epidemic and studiously ignore historical precedence. Of course evidenced based scientific research plays a vital in acquiring data but it cannot be created in a vacuum. It is just one of the building blocks. No matter how 'old' research is - it is an important part of ongoing studies.

Further research is available on these websites:

Surgeon General Report: on Addictions: can be accessed via accessed January 8, 2017.

The Surgeon General Report on Coexisting disorders and Cannabis use: can be accessed via accessed January 8, 2017.

The evidence for health risks of Marijuana use accessed marijuana-threat-assessment-part-one-July 2017

Short Term Effects

The short-term effects of cannabis use on brain function can include things such as problems with memory and learning, difficulty in thinking and problem solving, loss of coordination. Long-term effects include permanent memory impairment and overall slower cognitive function. Importantly, Chambers (2003) and Pistis (2004) found the adolescent brain, while still under development, was particularly vulnerable to the ill effects of substance abuse, including cannabis.

Researchers have concluded that repeated exposure to cannabis as an adolescent was related to abnormalities in the development of the specific fibres associated with higher aspects of language auditory functions (Ashtari, 2005). Giedd et al (1999) also discusses the development of the adolescent brain which does not reach physical maturity until the mid-twenties, and warned drug abuse could alter the normal course of brain growth. He later specifically looked at regions of the brain that control impulse and risky behaviours; reconfirming his previous findings that cannabis use on a developing adolescent brain can negatively affect overall and specific brain functions.

In a study of brain abnormalities in schizophrenics as compared to the brain abnormalities presenting in adolescents frequently using cannabis, Kumra (2007) concluded the deficiencies were the same and in that part of the brain which develops during adolescence – emotional associations and other higher cognitive functions such as language, perception, creativity and problem solving. Most recently, Medini et al (2008) confirmed the adverse brain impact of adolescent cannabis use in a study presented to the American Academy of Pediatrics. The research team found that the chronic use of cannabis during adolescence – a critical period of ongoing brain development – slowed psychomotor speed, led to poorer complex attention, verbal memory and also planning ability. Perhaps, most startlingly, these impacts continued after one month’s abstinence from cannabis use.

Recent evidence on cannabis and cognitive functioning also comes from Greece (Messinis et al, 2006) where they found that those who smoked at least four joints per week for several years performed significantly worse than non-users in several areas, particularly verbal learning (the ability to remember previously learned words) and executive functioning (organising and coordinating simple tasks). Further, Ranganathan (2006) reviewed the literature on the acute effects of cannabis on memory, concluding that cannabinoids impair all stages of memory (including encoding, consolidation and retrieval).

Conclusive evidence shows that heavy marijuana use for five years or more may impair memory and slow cognitive function (Lambros, 2006; Ashtari, 2005; Robbe, 2006; Karila, 2005; Lundqvist, 2005; Fisk 2008; Solowij, 2008), with specific research completed on impaired driving ability (Kurathaler, 1999; Menetry, 2005; Drummer, 1994, 1998, with Gerostamoulos, 1999).

Solowij et al (2002) examined the effects of the duration of cannabis use on specific areas of cognitive functioning among users seeking treatment for cannabis dependence. Their results also confirmed that long-term heavy cannabis users show impairments in memory and attention, that in fact endure beyond the period of intoxication and with increasing years of regular cannabis use. Bolla (2002) found a dose-response relationship in that the more cannabis used, the worse they performed in cognitive testing, especially memory. It is very clear that regular cannabis use is associated with impaired functioning – both by objective measures and by the admission of users themselves (Pope Jr, 2004) Alternate studies (Niveau & Dang, 2003; Howard & Menkes, 2007) also looked at the effects of cannabis use upon neural mechanisms controlling impulse and found a connection with acts of violence and aggression. Additionally, the latest evidence of brain abnormalities in long-term, chronic cannabis users further confirms that heavy daily use exerts harmful effects on brain tissue (Yucel, 2008) and in similar ways to those seen after long-term abuse of other major drugs (de Fonseca, 1997).

Specific research on the impacts of cannabis on driving ability has increased of late. Drummer (1994; 1998; with Gerostamoulos, 1999) has done significant research on the issue and found road fatalities related to cannabis intoxication have steadily increased over the last ten years. Consistent with Drummer’s findings, past research examining the effects of THC on driving ability indicate it impairs both car control (Moskowitz, 1985) and the driver’s awareness of the vehicle’s position in traffic (Ramaekers et al, 2000). Hansteen et al (1976) also found THC intoxication is more likely to result in collision with obstacles on a driving course than when not intoxicated. Studies by Papfotiou (2001, 2005) found that driver errors occurred more frequently when the driver was under the influence of both cannabis and alcohol. Since the two are frequently taken together, it is to note that a 2005 study (Laumon et al) found the risk of accident when cannabis was combined with alcohol was 16 times higher than when using either drug alone.

These findings indicate that cannabis impairs driving ability and given the prevalence of cannabis use (upward of 300,000 Australians smoke it daily; 750,000 smoking it weekly) this poses a significant risk on our roads.

Physical Harms

Cannabis smoke contains many of the same known carcinogens as tobacco smoke. In fact, studies have found the tar from cannabis contains 50% more of some of the carcinogens found in tobacco, notably benzopyrene, a potent carcinogen and key factor in the development of lung cancer (Hoffman et al, 1997; Tashkin et al, 1997; Novotny et al, 1976; Leuchtenberger et al, 1983) and so it should not be surprising to see cannabis use as a factor in a wide range of adverse physical conditions, including lung cancer, chronic obstructive pulmonary disease, increased risk of heart or stroke due to adverse impacts on the cardiovascular system, weakened immune system and birth defects. Cannabis cigarettes also have a higher combustion temperature than tobacco cigarettes.

There is research to support the connection between cannabis use and cancer of the digestive and respiratory tracts (Hall, 2002), lung cancer (Berthiller 2008), lung (Sridar, 1994) and breast (McKallip, 2005). Aldington (2007; et al, 2008) found that long term cannabis use specifically increased the risk of lung cancer in young adults, particularly in those who started smoking cannabis at a young age. Tashkin (2006) explains that cannabis smokers typically hold their breath four times longer than tobacco smokers, allowing more time for particles to be deposited in the lungs. In addition, cannabis is usually smoked without an adequate filter.

Researchers have interviewed lung cancer patients in seeking to identify the main risk for the disease, such as smoking habits, family history and occupation (Tetrault et al, 2007). The patients were questioned about cannabis consumption and results showed lung cancer risk rose by 5.7 times for patients who had smoked a joint a day for 10 years, or two joints a day for five years, and after adjusting for cigarette smoking.

A study in 2006 (Terris et al) reported that, of 52 men with transitional cell bladder cancer, 88.5% had a history of smoking cannabis and almost 31% were still using the drug. Terris et al found that cannabis metabolites have a half-life in urine about 5 times greater than tobacco metabolites and warned smoking cannabis may be a more potent stimulant than tobacco smoking of malignant cell transformation, a hallmark of cancer.

In relation to chronic obstructive pulmonary disease (COPD), the period of cannabis use seems to play an important role, particularly in regard to lung emphysema and various other respiratory complications such as asthma, dyspnea, pharyngitis and chronic cough (Tetrault et al, 2007). Beshay (2007) researched emphysema in young adults and agreed the period of cannabis use was influential. A further study Tan (2007) on people aged 40 and over found that smokers were two and a half times as likely as non-smokers to develop COPD and that adding cannabis to tobacco increased the risk again by one third.

With regard to the body’s cardiovascular system, the harms of cannabis use are again significant. At first, the intoxication produced by cannabis causes an increase in heart rate of between 20% and 50% (Huber et al, 1988; Jones, 1984) as THC increases the production of chemicals which stimulate the heart.

The increase in heart rate caused by cannabis is additive with the increased heart rate caused by nicotine in tobacco. THC is also found to have analgesic properties, lessening chest pain which Jones (1982, 1984) argues may delay the seeking of treatment, decrease the supply of oxygen to the heart and place it under greater strain. Maykut (1984) also found a rise in blood pressure if the person is sitting or lying, but upon standing drops drastically, in some cases causing the person to faint.

It must be added that tolerance can develop quickly to the acute cardiovascular effects of cannabis, with people receiving daily doses by mouth developing tolerance within 7 to 10 days, in a possible explanation of why effects can sometimes be missed (Benowitz & Jones, 1975; Nowlen & Cohen, 1977; Jones, 1984).

Supporting research as to the cardiovascular harms of cannabis use are found in Herning et al (2001), who used sound waves to measure cerebral artery blood flow resistance and found that prolonged cannabis use in 18 to 30 year olds increased the resistance in arteries and restricted blood flow to the brain; in Geller et al (2004) who detail an incident in which three teenagers, aged 15 to 17, “binge smoked” cannabis and suffered strokes from which two later died; and, in Mittleman (2001) who interviewed 3,882 patients of heart attacks and found the risk of myocardial infarction rose almost 5 times in the hour following the smoking of a joint.

We still do not know the long-term effects of exposure to cannabis smoke on the cardiovascular system over extended periods, but experience with the problems of tobacco smoke should urge caution. Jones (1984) suggests “after years of repeated exposure, there may be lasting, perhaps even permanent alterations of the cardiovascular system function. There are enough similarities between THC and nicotine’s cardiovascular effects to make the possibility plausible” and this is supported by a multitude of research (Mukamal et al, 2008; Lindsay, 2005; Fisher et al, 2005; Korantzopoulos, 2008).

There is also significant supporting research on the effects of cannabis use during pregnancy on newborns, with THC readily crossing the placenta (Bada, 2006; Cornelius, 1995; Bailey, 1987) – Bluhm (2006) discusses an increased risk of neuroblastoma; Robinson et al (1989) identified an eleven-fold increase in leukemia; and there are multiple abnormalities in physical appearance, size, weight and hormonal functions discussed by Fried, 1980 and 1984; Zimmerman, 1991; Zuckerman, 1989; Barnett, 1983; El Marroun 2008; Mendelson, 1985 and 1986).

A paper by Klonoff-Cohen et al (2006 studied the effects of cannabis use on the outcomes of IVF and GIFT fertility treatments and concluded cannabis use lowered the prospects of successful treatments. They found females produced fewer eggs and the child once successfully conceived had a significantly lower birth weight.

The risk of miscarriage of ectopic pregnancy of women smoking cannabis in the early stages of pregnancy is highlighted in recent research by Day (2006). THC was found to mimic anandamide and its control over embryo development, disrupting the process and creating cell abnormalities in mice. Day also concluded that, “Prenatal exposure to marijuana, in addition to other factors, is a significant predictor of marijuana use at age 14”.

This study’s findings warrant further attention to puberty as a sensitive period in an individual’s development. With regards to prevention, there is a need to understand more about the pathways between pubertal development, child behaviour and substance and cannabis use (Hayatbaksh, 2009).

A review by Huizink & Mulder (2006) came to the conclusion that pre-natal exposure to cannabis use is related to some common neuro-behavioural and cognitive outcomes, including symptoms of ADHD such as inattention and impulsivity, decreased general cognitive functioning and deficits in learning and memory tasks.

Barros and colleagues, writing in The Journal of Paediatrics in January 2007, found that marijuana-exposed infants born to adolescent mothers scored differently on measures of arousal, regulation and excitability compared to non-exposed infants, where they displayed subtle changes in the first few days of life, i.e. they cried more, startled more easily and were more jittery. The authors said this may also interfere with mother-child bonding.

Harkany et al. (2007) found that endocannabinoid signalling modulates central nervous system patterning, so that “pharmacological interference with endocannabinoid signals during foetal development leads to long-lasting modifications of synaptic structure and functioning. Marijuana abuse during pregnancy can impair social behaviours, cognition and motor functions in the offspring with the impact lasting into adulthood.”

Another paper in May 2007 had similar findings. Endocannabinoids in the human body play a vital role in the development of a baby’s brain in that they are responsible for controlling how the complex system of nerves develop in the embryonic brain. Dr. Ann Rajnicek states “Smoking cannabis could interfere with the signals that are being used in the brain to wire it up correctly in the first place. As the brain develops further, there will be functional problems – potential brain damage” (Berghuis et al. 2007).

The reason for the late appearance of this damage is assumed to be that the functions involved are “executive” cognitive functions that are not taken into use until the child is four to six years old. Another long-term study shows similar associations between exposure during the foetal stage and relatively late (at age 6 and 10 respectively) behavioral disturbances (Ramstrom, 2003).

The harms of cannabis use on the user’s mental health have been well documented and include specific research into the onset of schizophrenia (see Boydell, 2006; Solowij, 2007; Fergusson, 2005; Ferdinand, 2005, Veling 2008) and other mood disorders including depression, bi-polar disorder and amotivational syndrome (see Bovasso, 2001; Hayatbakhsh, 2007; Corcoran 2008). Research has also explored the links to suicide, especially in young people (Dervaux, 2003; Greenblatt, 1998; Beautrais, 1999 Firstly, severe mental disturbances, such as momentary short-term psychosis or the long-term illness of schizophrenia, have been linked to cannabis use and especially so when cannabis use begins in adolescence. As a stimulant of the dopamine system, cannabis offers the user a pleasurable ‘high’; however, this ‘high’ can become dangerous when dopamine levels become excessive. Murray (2005) discusses the impact of early cannabis use on the developing adolescent brain and specifically dopamine receptors, indicating early cannabis use may damage these receptors permanently, leaving a young cannabis user at a much higher risk of developing schizophrenia or experiencing psychosis.

A significant study in Sweden (Andreasson, 1987) examined, over fifteen years, the link between heavy cannabis use and schizophrenia in 50,087 members of the Swedish Army and conclusively found schizophrenia occurred more frequently in heavy consumers of cannabis.

The results were re-analysed and replicated in additional studies (Zammit, 2002; Ferguson, 2003) with the British Medical Journal (BMJ) reporting in 2002 heavy consumers of cannabis at age 18 were over 600% more likely to be diagnosed with schizophrenia over the next fifteen years than those who did not use cannabis. The BMJ report also clarified that it was cannabis use and not other drugs that was associated with schizophrenia.

Moore et al concluded in2007 that “there is now sufficient evidence to warn young people that using cannabis could increase their risk of developing a psychotic illness later in life”. In fact, Moore et al found, in a review of 35 longitudinal studies, that cannabis use increased the risk of developing a psychotic illness, such as schizophrenia, by 40%. This figure was doubled for frequent or heavy users. Reports by Hollis et al (2008); Henquet (2005) and Konings (2008) have found a significant positive association between cannabis use and mental health disturbance in young people who are genetically predisposed to mental health problems, such as schizophrenia.

Interestingly, Ramstrom (2003) demonstrated the association between adolescent cannabis use and adult psychosis persists even after controlling for many potential confounding variables, such as low IQ and education levels, unemployment, social integration, gender, age, ethnic group, tobacco smoking and previous psychotic symptoms. This finding was supported by recent studies of Finnish adolescents (Jouku et al, 2008) which showed an association between cannabis use and psychosis symptoms not caused by other drug use, family background or behavioural problems.

Further research in Spain recently found a strong and independent link between cannabis use and the onset of psychosis at a young age, reporting that compared with nonusers, the age of psychotic onset was lowered by 7, 8.5 and 12 years among users, abusers and dependents respectively. These results are supported by multiple studies (Fergusson, 2005; Ferdinand, 2005; Solowij, 2007) and all highlight the notion of the younger the user, the worse the effects.

A second mental health issue frequently associated with cannabis use is depression and numerous studies support the connection: For example, an Australian study of 3,239 young adults, from their birth to the age of 21, found a relationship between early initiation to and frequent use of cannabis and depression (Hayatbaksh, 2007); a 16-year study of individuals not initially suffering depression, but who then frequently used cannabis, were found to be four times more likely to develop depression at follow up (Bovasso, 2001); and Fergusson (2002) studied 1,265 children over a 21-year period and concluded that cannabis use, particularly heavy or regular use, was associated with a later increase in depression and suicide. Recent articles in The Age newspaper (September 29, 2008) discuss Australian statistics showing that cannabis’ toll on mental health, expressly causing depression, is more prevalent than that caused by the well-known impact of amphetamines.

Thirdly, cannabis use can induce amotivational syndrome, a mental state characterised by apathy, an inability to carry out plans, deal with frustration or concentrate for any length of time (Cohen, 1982). While equivocal, amotivational syndrome strikes a chord in that it aptly describes the ‘personality’ of a chronic cannabis smoker and is supported by numerous studies (Newcomb & Bentler, 1988, Tunving, 1987; Cohen, 1982). Musty & Kaback (1995) maintain that amotivational syndrome exists and is a manifestation of depression.Finally, multiple studies have linked cannabis use with suicide.

A study of Beautrais et al (1999) examined and found a relationship between cannabis abuse and suicide. Greenblatt (1998) found that young people, aged 12 to 17 who smoke cannabis weekly are three times more likely than non-users to have thoughts about committing suicide, and this ratio was confirmed by Lynskey et al (2004). Dervaux (2003) examined the link between cannabis abuse and the suicide attempts of schizophrenics, finding a close correlation. Consider the enormous national health debt incurred by the use of tobacco and alcohol. Why would any rational government legalise an activity that would increase the national debt?

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