COUNTERPOINT: But chronic use is harmful.
Marijuana doesn’t meet standards to be considered a medicine.
There’s a massive lack of standardization in the product. Compounds have very different, in some cases opposing, effects. Potency varies depending on the strain and how it was prepared.
There’s also no standardization around administration. Smoking or inhaling marijuana – the most common routes speed drug uptake and the effects of cannabinoids on reward processing, which increases addictiveness.
Smoking marijuana is carcinogenic and causes lung damage. Yes, a study suggested twice-a-month use doesn’t really change your lung capacity, but that changed with daily, frequent use. The typical use pattern is about four times per day, daily, in medical patients.
Pain studies looked at acute use of cannabis for a week or so. They haven’t looked at chronic effects. We don’t know the impact of tolerance and dependence in patients with chronic pain, or the effect of constant activation of reward circuits by marijuana on new behavior patterns over time. That’s typically what you have trouble with in chronic pain patients – getting them up, getting them going, getting them back into life. Marijuana could make that more difficult.
Dr. Jodie Trafton
A meta-analysis of 18 randomized, double-blind, controlled trials of cannabis for chronic pain found a greater effect with cannabis than with placebo, but this was not huge. If a patient starts out with a pain score of 8 out of 10, it will drop to about 7.4 – a 7.5% reduction in score. We’re talking about going from severe to a little less severe pain. Patients on cannabis were much more likely to have alterations in perception, motor function, and cognitive function (Pain Med. 2009;10:1353-68).
In the crossover study of 23 patients that Dr. Abrams cites, low-dose and high-dose THC decreased pain, but there was no difference in the middle doses, compared with placebo. And look at the levels of pain scores: You’re going from an average of 6.1 to 5.4, from moderate pain to moderate pain. That’s less than 1 point on a 10-point scale, and you’re getting all of the adverse effects and behavioral changes in conjunction with that. Is that worth it?
The 28-patient crossover study he cites started with 34 patients. There were some serious cannabis-related issues, including acute psychosis and intractable cough, in the patients who didn’t complete it. One patient started using methamphetamine again. This is not a particularly low rate of problems.
We don’t have a lot of data to say what happens to patients with chronic pain who use marijuana over time. There are more data on what happens when people in the general population use marijuana chronically. The best characterized chronic effects include a motivational syndrome, poor concentration, attention and judgment, impaired social skills, introversion, deteriorating personal habits and depersonalization, mood disorders, anxiety disorders, insomnia, increased risk of schizophreniform illness and psychosis, more negative life events, and withdrawal.
Studies have found functional impairments related to chronic marijuana use. People who use marijuana over long periods of time develop at least partially persistent problems on neuropsychological tests – problems that don’t go away even if they stop using marijuana.
There’s also evidence of a relationship between cannabis and mood disorders. Cross-sectional studies show that people who use cannabis daily or near-daily are 3.4 times more likely to have major depression. Longitudinally, if you are diagnosed with cannabis dependence, you have a 6.4-fold increased chance of being diagnosed with major depression within a 12-month time period.
It appears that cannabis is inducing the mood disorders, not the mood disorders driving cannabis use. A Dutch study of 3,854 adults with no history of mood disorders found that cannabis use at baseline was associated with a doubling in risk for developing any mood disorder, a 60% increased risk for major depression, and a five-fold increased risk for bipolar disease (Addiction 2007;102:1251-60).
If cannabis use makes people tend toward mood disorders, and chronic pain patients tend toward mood disorders, how much harder are you making it by suggesting they try marijuana to get that 1-point decrease in pain?
Frequent marijuana use is associated with development of dependence. Withdrawal symptoms occur whenever drug levels start to decrease over time. Withdrawal starts within 2-4 hours, and symptoms last for weeks. Symptoms include irritability, anger or aggression, nervousness or anxiety, sleep difficulty, decreased appetite or weight loss, restlessness, depressed mood, and a variety of physical symptoms causing significant discomfort.
The main reasons that people say they want to use medical marijuana are to treat nervousness, anxiety, insomnia, and depressed mood. All of these potentially are withdrawal symptoms.
One study showed a vast majority of California patients seeking a physician’s recommendation for medical marijuana – well over 95% were already self-medicating with marijuana. We would expect that population to be dependent.
A separate study confirmed that 10 of the 15 "clinical benefits" reported by 1,746 medical marijuana users were the easing of problems that can be found on a list of withdrawal symptoms (J. Psychoactive Drugs 2011;43:128-35).
Chronic pain patients already have high comorbidity with depression, functional problems, and high rates of disability. Recommending medical marijuana increases risk in an already at-risk population.
Jodie Trafton, Ph.D., is director of the Program Evaluation and Resource Center in the Office of Mental Health Operations, Veterans Affairs Palo Alto (Calif.) Health Care System. The views expressed are those of Dr. Trafton and do not necessarily represent those of the Department of Veterans Affairs. She declared having no financial disclosures.