Correlation does not prove causation. It should be no surprise that people with mental and emotional problems self-medicate with all manner of intoxicants.
“New research continues to reveal the multiple health consequences of smoking cannabis, [yet] there is still a dangerous lack of public awareness of quite how harmful this drug can be,” said Dame Helena Shovelton, BLF chief executive.
“Young people in particular are smoking cannabis unaware that each cannabis cigarette they smoke increases their chances of developing lung cancer by as much as an entire packet of 20 tobacco cigarettes.” She called for a public health campaign to “dispel the myth that smoking cannabis is somehow a safe pastime”.
The reason why cannabis is more dangerous than tobacco, per cigarette, is thought to be related to the way it is smoked. Cannabis smokers inhale more deeply and hold it longer than tobacco smokers.
Cannabis smoking has been linked with a wide range of respiratory problems, while the concentration of tetrahydrocannabinol (THC) – the drug’s psychoactive ingredient – has doubled since the 1990s, according to analysis of samples from police seizures. THC has been linked to an increased heart attack risk and suppression of the immune system.
Antiemetic (anti-nausea) use
Early on, THC had been shown to be effective for some patients who suffered nausea from cancer chemotherapy treatments. However, the narrow window between the anti-emetic dose and that which caused unwanted psychic effects made THC difficult to use.3 In some studies, negative side effects occurred in up to 81% of patients.4 In one of the few studies using smoked marijuana, 20% of patients dropped out of the study, while another 22% reported no relief of nausea symptoms.5 The advent of serotonin 5-HT3 receptor antagonists as new and more powerful anti-emetic drugs that were free of unwanted psychic effects has made cannabinoid use less attractive. For this reason, physicians virtually never prescribe marijuana or THC as an antiemetic for use by chemotherapy patients.6
Multiple sclerosis
Studies have shown that cannabis can relieve muscle pain and spasticity in patients suffering from multiple sclerosis7 and can control tremors in multiple sclerosis animal models.8 However, a study in ten patients with spastic multiple sclerosis showed that smoking marijuana further impaired posture and balance in those patients.9 In addition, MS patients who used marijuana had a greater number of psychiatric diagnoses and a slower mean performance time on standard neurological tests.10 Some randomized, double-blind, placebo-controlled, parallel group crossover trials have found no significant improvement of MS symptoms during cannabis plant extract use. However, in some trials patients did show an increase in aggressive behavior and paranoiac tendencies in a standard psychological test.11 Another placebo-controlled study, examining the effect of a cannabis extract on spasticity in MS, found a positive partial relief of symptoms in 40% of patients.12 A 10-week, placebo-controlled study of MS patients found that 42% withdrew due to lack of efficacy, adverse events and other reasons. Patients reported 292 unwanted effects, of which 251 were mild to moderate, including oral pain, dizziness, diarrhea, nausea. Three patients suffered five serious adverse events, including two seizures, one fall, one aspiration pneumonia, one gastroenteritis. Four patients had first-ever seizures. A minority of patients received some relief of symptoms.13 So, overall, studies show that a minority of multiple sclerosis patients can receive some symptom relief through the use of marijuana extracts or THC, although a significant percentage of patients suffer unwanted adverse effects.
http://www.godandscience.org/doctrine/medical_marijuana_review.html
Analgesia (pain relief)
Some clinical studies have indicated that THC has some analgesic activity in patients with cancer.18 However, there is a narrow therapeutic window between doses that produce useful analgesia and those that produce unacceptable central nervous system effects. Several studies have shown improvement of pain at higher doses,19 while others have shown no effect or a negative effect at higher doses compared with placebo.20
Medical marijuana summary
The use of marijuana or cannabis extracts for medical treatment has been extensively studied over the last 20 years. Initial enthusiasm for THC as an antiemetic or to reduce intraocular pressure has waned with the advent of new medications that provide superior medical benefits with fewer adverse effects. The main success of THC has been found in patients suffering from AIDS-related wasting syndrome and in some cases in which patients are suffering from intractable pain. However, nearly all of these studies involved the use of controlled doses of purified cannabinoids, bypassing the adverse effects associated with smoking marijuana. Dr. Robert L. DuPont, Georgetown University School of Medicine, says that most opponents of the medical use of smoked marijuana are not hostile to the medical use of THC, while “most supporters of smoked marijuana are hostile to the use of purified chemicals from marijuana, insisting that only smoked marijuana leaves be used as ‘medicine,’ revealing clearly that their motivation is not scientific medicine but the back door legalization of marijuana.”21
A 38-year study of more than 1,000 New Zealanders found that adolescents who used marijuana at least four days per week lost an average of eight IQ points between the ages of 13 and 38.43 Those people who began heavy smoking of marijuana only in adulthood did not suffer a loss of IQ. Loss of IQ was not reversible once marijuana use was ceased.43
Some marijuana users can suffer from cannabis psychosis when they take large doses over a period of time, with symptoms characteristic of paranoid schizophrenia.44 A recent study found that marijuana use significantly increased the risk of developing mental health problems among those young people who possessed a genetic high risk for schizophrenia (familial risk factors).45 Among cannabis users who developed cannabis-induced psychosis, 44.5% developed schizophrenia-spectrum disorders, with about half of those being diagnosed more than a year after seeking treatment for their cannabis-induced psychosis.46 A study using a sample of 880 adolescents in Melbourne, Australia found that lifetime cannabis use and the frequency of cannabis use in the last year were associated with psychotic-like experiences (primarily the experience of auditory and visual hallucinations).47 Another study examined the association between cannabis use and psychosis in 3,800 participants involving a subset analysis of 228 sibling pairs over a 21-year period of time. The results showed that early use of marijuana was associated with psychosis-related outcomes in young adults.48
Another study examined the associations between cannabis use and the development of mood and anxiety disorders.49 The study found no association between cannabis used and the development of anxiety disorders, although there was a significant correlation with the development of depression and bipolar disorder.49 Another study found an association between cannabis use and the development of panic attacks.50
Studies have suggested that smoking marijuana increases the risk of both oral cancers81 and lung cancer.82 This is because marijuana smoke contains carcinogenic materials, including vinyl chlorides, phenols, nitrosamines, reactive oxygen species, and various polycyclic aromatic hydrocarbons, including Benzo[a]pyrene, which is present in marijuana tar at a higher concentration than in tobacco tar.83 Ammonia was found in marijuana smoke at levels up to 20-fold greater than that found in tobacco.84 Hydrogen cyanide, NO, NO x , and some aromatic amines were found in marijuana smoke at concentrations 3-5 times those found in tobacco smoke.
Mental health issues linked to cannabis increase by half in four years
The number of cannabis users suffering serious mental or behaviour disorders has increased by half in just four years.
The sharp rise has coincided with growing concerns over the increased prevalence of so-called “super skunk”, a particularly strong form of the drug.
In 2008, leading psychiatrists warned people who smoked super strength were 18 times more likely to suffer a psychotic episode.
Figures released to MPs show that the number of hospital admission for mental or behavioural issues due to cannabis rose from 651 in 2008/09 to 1,003 in 2011/12.
Mary Brett, who chairs the campaign group Cannabis Skunk Sense (CanSS), said: “’Despite many warnings over the years the rise in admissions must surely be truly alarming.
“However, this 54 per cent increase in episodes of cannabinoid-induced mental or behavioural issues should come as no surprise.