Marijuana and Strokes: Medical Reality or Scare Story?

Heavy tokers may be at higher risk, but alcohol is the hidden confounder.

Young people don’t suffer from strokes, as a rule. And when they do, at least half the time there is no obvious cardiovascular explanation. So it’s not surprising that drugs are often invoked as the culprit.

A New Zealand study earlier this year once again raised the specter of a possible link between stroke and marijuana smoking. As reported by Maia Szalavitz at Time Healthland, the confounding issue, as is typical of such studies, is the coexisting use of other drugs, like alcohol and cigarettes. As Szalavitz writes:

The stroke study, which incorporated preliminary data, is the first trial of its kind to study a possible connection between marijuana use and stroke. It included 160 patients aged 18 to 55 who had suffered a stroke connected to a blood clot in the brain, and who agreed to have their urine tested for marijuana within 72 hours of the stroke.  These results were compared to those from 160 controls who had not had a stroke but came to the hospital for other reasons. They were matched on age, gender and ethnic background, all of which can also affect the risk for this type of stroke. About 16% of the stroke patients showed traces of marijuana in their urine, compared to 8% of those in the control group, suggesting a doubling of the risk of stroke.

However, because of nicotine and other confounding variables, that study was considered inconclusive. In an earlier study published in Stroke, the journal of the American Heart Association, Valerie Wolff and colleagues from the University of Strasbourg in France searched the medical literature and found 59 cases of stroke in which cannabis could be considered a cardiovascular risk factor. The investigators used only cases that had been confirmed by neuroimaging. The researchers focused on cases where a stroke had occurred while smoking marijuana, or within a half hour after the last joint or bong hit.

But proving a cause and effect relationship is tricky. Assuming, for now, that all of the strokes in question were not caused or compounded by alcohol or drugs other than marijuana, the French scientists postulated several mechanisms that could conceivably account for a cannabis-related ischemic stroke (a stroke caused by obstruction of a blood vessel). These include orthostatic hypotension, altered cerebral vasomotor function, major swings in blood pressure, and cardiac arrhythmias. However, the only solid commonality in cannabis-related strokes was that the users were more likely to be heavy smokers.

In the 50 strokes the researchers were able to confirm by cerebral imaging, the patterns in some patients were similar to those observed in a syndrome called reversible cerebral vasoconstriction syndrome (RCVS). RCVS  is marked by severe headaches, strokes, and brain edema, but symptoms typically resolve in a few months.  “Reversibility of the vasoconstriction within 12 weeks is a key point of this syndrome,” the authors write. “The long duration of stenosis [blockage] argues in favor of a drug-induced immunoallergic vasculitis rather than vasospasm. Our point of view is that this disorder may be considered as a variant of RCVS,” rather than as a garden-variety ischemic stroke triggered by excessive use of cannabis.

According to the French study, “The most frequently presented characteristics of cannabis users who experienced a stroke are young male chronic tobacco and cannabis abusers who have had an unusual high consumption of cannabis and alcohol before stroke.” The most convincing mechanism to explain ischemic strokes in young people, the researchers say, is “reversible cerebral angiopathy involving several arteries, associated with cannabis consumption in association with tobacco and alcohol use.”

And there you have it. Smoke weed, and you appear to have a slight risk of suffering stroke, which, under age 50, is an extremely uncommon medical event.  Add tobacco, and the stroke risk goes up. Add alcohol, and the stroke risk ratchets even higher. By itself, marijuana appears to be a minor factor in strokes—but it appears likely that pot is indeed the culprit at least some of the time.

“Cannabis-related stroke is not a myth,” the scientists conclude, “and a likely mechanism of stroke in most cannabis users is the presence of reversible multifocal intracranial stenosis (MIS) induced by this drug. The reality of the relationship between cannabis and stroke is, however, complex, because other confounding factors have to be considered (ie, lifestyle and genetic factors).”

Wolff V., Armspach J.P., Lauer V., Rouyer O., Bataillard M., Marescaux C. & Geny B. (2013). Cannabis-related Stroke: Myth or Reality?, Stroke, 44 (2) 558-563. DOI: 10.1161/STROKEAHA.112.671347

Graphics Credit: http://www.strokegenomics.org/

Does Marijuana Withdrawal Matter?

What happens to some smokers when they cut out the cannabis.

People who say they are addicted to marijuana tend to exhibit a characteristic withdrawal profile. But is cannabis withdrawal, if it actually exists, significant enough to merit clinical attention? Does it lead to relapse, or continued use despite adverse circumstances? Should it be added to the list of addictive disorders in the rewrite of the Diagnostic and Statistical Manual of Mental Disorders (DSM) currently in progress?

Marijuana fits in fairly well with the existing criteria for clinical addiction—except for one common diagnostic marker. Among the identifying criteria currently used in the DSM, we find: “The presence of characteristic withdrawal symptoms or use of substance to alleviate withdrawal.” Opponents of marijuana’s inclusion as an addictive drug have long insisted that cannabis has no characteristic withdrawal symptoms, but this position has been severely eroded of late, as new research has consistently identified a withdrawal syndrome for marijuana, which includes drug cravings, despite decades of controversy over this basic medical question.

A group of researchers at the University of New South Wales, Australia, along with Dr. Alan J. Budney of the Geisel School of Medicine at Dartmouth, New Hampshire, writing in PLOS ONE, presented evidence that the characteristic withdrawal symptoms displayed by addiction pot smokers are in fact strong enough to be considered clinically significant.
(For more on the marijuana withdrawal profile, see HERE, and HERE. For a bibliography of relevant journal articles, go HERE).

But how does one go about determining if withdrawal reactions rise to the level of clinical significance? The researchers wanted to know whether functional impairment reported during abstinence was clinically significant, whether it correlated with severity of addiction, and whether it was predictive of relapse. 46 survey volunteers who were not seeking any formal treatment for marijuana addiction were recruited in Sydney, Australia. Users ranged in age from 18 to 57, with an average age of 30. After a one-week baseline phase, the participants underwent two weeks of monitored abstinence. Using a “Severity of Dependence Scale” (SDS) to measure variability in functional impairment, the researchers compared a high SDS subgroup to a low SDS subgroup in an effort to tease out whether functional impairments in high SDS participants were predictive of relapse. The researchers noted that earlier work had established that the symptoms most likely to cause impairment to normal daily functioning were: Trouble getting to sleep, angry outbursts, cravings, loss of appetite, feeling easily irritated, and nightmares or strange dreams.” The investigators broke these symptoms into two groups: “somatic” and “negative affect” variables.

The researchers then examined self-reports about the impact of cannabis withdrawal on normal daily activities.  While the common yardstick for withdrawal is typically taken to be intensity of cravings, the authors argue that this reliance on craving “may mask the extent to which symptoms led to functional impairment, as those who maintained abstinence may still have experienced clinically significant negative consequences from cannabis withdrawal (e.g. relationship or work problems resulting from the withdrawal syndrome.”)

As might have been expected, higher levels of cannabis dependence were associated with greater functional impairment. And while the average level of functional impairment caused by cannabis is “mild for most users, it appears comparable with tobacco withdrawal which is of well established clinical significance.”

And certain symptoms were, in fact, correlative: “Increased somatic withdrawal symptoms are predictive of relapse, and…. increased physical tension is a significant predictor of relapse.”

 Physical distress, a “somatic” variable, mattered more, in terms of relapse, than the amount of marijuana smoked, or any other symptom on the roster of functional impairments—including mood and other negative affect variables.

“In conclusion,” the investigators write, “cannabis withdrawal is clinically significant because it is associated with elevated functional impairment to normal daily activities, and the more severe the withdrawal is, the more severe the functional impairment is. Elevated functional impairment from a cluster of cannabis withdrawal symptoms is associated with relapse in more severely dependent users.”

Furthermore: “Targeting the withdrawal symptoms that contribute most to functional impairment during a quit attempt might be a useful treatment approach (e.g. stress management techniques to relieve physical tension and possible pharmacological interventions for alleviating the physical aspects of withdrawal such as loss of appetite and sleep dysregulation.)”

As with most studies, there are limitations. As noted, the participants were not in a formal cessation program. And while urine tests were used, there was no external corroboration of the self reports.

Allsop, D., Copeland, J., Norberg, M., Fu, S., Molnar, A., Lewis, J., & Budney, A. (2012). Quantifying the Clinical Significance of Cannabis Withdrawal PLoS ONE, 7 (9) DOI: 10.1371/journal.pone.0044864

Graphics Credit: http://www.addictionsearch.com/