June 8, 2010 – Hartford, CT—Subjects exhibit virtually identical psychomotor skills on a battery of driving simulator tests prior to and shortly after smoking marijuana, according to clinical trial data published in the March issue of the Journal of Psychoactive Drugs.

Investigators from Hartford Hospital in Connecticut and the University of Iowa Carver College of Medicine assessed the simulated driving performance of 85 subjects in a double-blind, placebo controlled trial. Volunteers responded to various simulated events associated with automobile crash risk — such as avoiding a driver who was entering an intersection illegally, deciding to stop or go through a changing traffic light, responding to the presence of emergency vehicles, avoiding colliding with a dog who entered into traffic, and maintaining safe driving during a secondary (in-the-car) auditory distraction. Subjects performed the tests sober and then again 30 minutes after smoking a single marijuana cigarette containing either 2.9 percent THC or zero THC (placebo).

Investigators reported that volunteers performed virtually the same after smoking cannabis as they did sober and/or after consuming a placebo. “No differences were found during the baseline driving segment (and the) collision avoidance scenarios,” authors reported.

Investigators did note, “Participants receiving active marijuana decreased their speed more so than those receiving placebo cigarette during (the) distracted section of the drive.” Authors hypothesized that subjects’ reduction in speed on this task suggested that they may have been compensating for perceived impairment. “[N]o other changes in driving performance were found,” researchers concluded.

A 2008 driving simulator study published in the scientific journal Accident, Analysis and Prevention also reported that drivers administered cannabis are likely to decrease their driving speed. “Average speed was the most sensitive driving performance variable affected by both THC and alcohol but with an opposite effect,” investigators reported. “Smoking THC cigarettes caused drivers to drive slower in a dose-dependent manner, while alcohol caused drivers to drive significantly faster than in ‘control’ conditions.’”

Previous reviews assessing the crash culpability risk of drivers under the influence of cannabis have reported a positive association between recent marijuana exposure (as typically measured by the presence of active THC in the driver’s blood) and a gradually increased, dose-dependent risk of vehicle accident. However, these studies have consistently found that this elevated risk is below the risk presented by drivers who have consumed legal quantities of alcohol. By contrast, studies have also reported that drivers engaged in the simultaneous use of both cannabis and alcohol can increase their risk of accident compared to the consumption of either substance alone.

NORML’s white paper assessing the impact of marijuana on psychomotor skills, “Cannabis and Driving: A Scientific and Rational Review,” is available online here. Source.

March 12, 2010 – As a supporter of the use of medical marijuana, this topic really throws a spanner in the works – a member of my own family was made dreadfully ill by the recreational use of cannabis (yet other members of my family have been using the stuff for years with no ill effect).

When my son – we’ll call him Jack for the purposes of this piece – was 15 years old he came to me one morning in a dreadful state.  I’ll never forget his words. ‘Mum, I’ve done something really stupid and I think I might be dying.’  As you can imagine I was scared to say the least, and although he wasn’t dying I was right to be scared because that conversation was the beginning of two years from hell.

Jack, who had always been the most tranquil of my children, had developed severe hypochondria and anxiety.  At that time I was working in a general hospital as a health professional and each day I would receive at least 5 calls from Jack, who was convinced his heart had stopped beating.  Yes, it sounds funny now but at the time it was tragic; so tragic in fact that many of my colleagues would break down in tears as they overheard the conversations with my very troubled son.

But that wasn’t all.  Jack suffered severe panic attacks, so severe that he soiled his pants on several occasions.  And he had become so fixated on the idea that his heart might stop beating that I often mislaid my stethoscope, only to find it hidden under his pillow or mattress.  School became impossible and Jack missed all his exams, ending up with no qualifications at all, despite being of above average intelligence.

Cognitive therapy didn’t help and we had very limited success with hypnosis; eventually, after two years, anti-anxiety meds from the family doctor did help.  Today, Jack is 23 years old and happy in his work as the manager of a rather classy hotel but, just occasionally, he still experiences mild panic attacks.

So, how does cannabis lead to anxiety and panic attacks?

Well, although I found plenty of papers confirming that cannabis can cause psychotic experiences such as hallucinations, fantasies, depersonalisation and derealisation (feeling out of touch with yourself or your surroundings), feeling a loss of control, fear of dying, irrational panic and paranoid ideas, I couldn’t find anything that explained exactly why this might be.

What did become very clear in my research is that cannabis alone does not cause psychosis; however, it may contribute to its development.

In theory, cannabis may cause a psychotic reaction in the following ways:

• Taking a high dose may cause a psychotic reaction with hallucinations or confusion, which goes away after the drug is stopped.
• It may lead to a long-term psychosis that does not go away when the drug is stopped.
• Long-term use may induce psychosis that gets a bit better if the drug is stopped.
• Cannabis may be a trigger for serious mental illness, such as schizophrenia (Johns A, 2001, ‘Psychiatric effects of cannabis’, British Journal of Psychiatry, vol. 178, pp.116-122.)

Here are some research findings, along with the relevant references:

• Research in young people suggests that using cannabis as a teenager increases the likelihood of experiencing symptoms of schizophrenia in adulthood, and early cannabis use (by age 15) confers greater risk than using it later on (by age 18). This research suggests that, although the majority of adolescents are not harmed by using cannabis, a small minority are.

(Arsenault L, Cannon M, Poulton R, Murray R, Caspi A, and Moffit TE, 2002, ‘Cannabis use in adolescence and risk for adult psychosis: longitudinal prospective study’, British Medical Journal vol. 325, pp. 1212-1213.)

• Results of a Swedish study suggest that cannabis increases the risk of schizophrenia by 30 per cent. However, this does not appear to be reflected in the figures for schizophrenia in the population in general, which have remained constant over a long period. This study also concludes that cannabis has few harmful effects overall, but that there is a potentially serious risk to the mental health of people who use cannabis, particularly in the presence of other risk factors for schizophrenia.

(Zammit S, Allebeck P, Andreasson S, Lundberg I, Lewis G, 2002, ‘Self reported cannabis use as a risk factor for schizophrenia in Swedish conscripts of 1969: historical cohort study’, British Medical Journal vol. 325, pp. 1199-1201.)

• Researchers who examined further published evidence on cannabis and psychosis in 2004 came to the conclusion that, for any individual, using cannabis doubles the risk of developing schizophrenia in later life, and, for the population as a whole, elimination of cannabis use would reduce the incidence of schizophrenia by about 8 per cent, if you assume that it has a causal effect. Cannabis use alone does not cause psychosis, but it is one of the things that may contribute to its development; therefore, using cannabis increases the risk, and some cases of psychosis could be prevented by discouraging cannabis use among vulnerable young people.

(Arseneault L, Cannon M, Witton J, and Murray R, 2004, ‘Causal association between cannabis and psychosis: examination of the evidence’, British Journal of Psychiatry, vol 184, pp 110-117).

• A response to this report further suggested that adolescents may be more vulnerable to the adverse effects of cannabis than are adults because their brains are still developing.

(Dervaux A, Goldberger C, Laqueille X, and Krebs M-O, 2004, ‘Cannabis and psychosis’, letter, British Journal of Psychiatry, vol 185, p 352.)

• A further study concluded that cannabis use increases the risk of psychotic symptoms in young people, but has a much stronger effect in those with evidence of a predisposition for psychosis (such as a family history of mental illness).

(Henquet C, Krabbendam L, Spauwen J, Kaplan C, Lieb R, Wittchen H-U, and van Os J, 2005, ‘Prospective cohort study of cannabis use, predisposition for psychosis, and psychotic symptoms in young people’, British Medical Journal, vol 330, 1 Jan, pp 11-13)

So, is this uncomfortable reading for a pro-marijuana board? Yes and no.  All the evidence suggests that it is not cannabis per se that causes the problems; rather, it is when cannabis is used by those who are already vulnerable to emotional instability.  However, having seen the effects at first hand, I am uncomfortable at the polarization of the pro and anti-marijuana camps.  With both sides entrenched in their respective positions the problem is unlikely to be sorted soon.  We have to accept that, just sometimes, bad things can happen – hence the uncomfortable post; the ‘opposition’  have to accept that, rather more frequently, positive things can happen too.  Source.