High-Potency Marijuana Linked to Psychosis

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People who consume high-potency marijuana or other forms of cannabis may have increased chances of developing new symptoms of the highly disabling mental state called psychosis, according to new findings from a group of British researchers.

Marijuana/cannabis is a plant-based drug known for its ability to trigger addiction and psychosis, particularly in heavy and habitual consumers. In a study published in February 2015 in the journal The Lancet Psychiatry, researchers from the United Kingdom’s King’s College London gauged the impact that consumption of high-potency marijuana/cannabis has on the odds that any given person will experience new psychosis-related symptoms. These researchers concluded that intake of high-potency forms of the drug clearly increases psychosis risks, especially in daily users.

Potency of Marijuana

The potency of any batch of marijuana is directly related to that batch’s level of THC (tetrahydrocannabinol), the main mind-altering ingredient in all forms of cannabis (including hashish and hashish oil). Two to three decades ago, the average batch of marijuana in the U.S. had a THC content of roughly 4 percent, the National Institute on Drug Abuse reports. By the year 2012, the THC content in the average batch of marijuana had almost quadrupled to 15 percent. Potential consequences of this drastically increased potency include heightened chances of developing a marijuana/cannabis addiction (especially among teenagers and daily or near-daily users) and increased chances of developing serious drug reactions that result in a need for emergency hospitalization. Currently, no one knows all of the potential short- or long-term consequences of the steep rise in marijuana potency.

Marijuana and Psychosis

Psychosis is not a separate mental health disorder. Instead, professionals in the field define the mental state as a collection of highly destabilizing symptoms that can appear in people affected by certain mental illnesses, as well as in people not affected by any other diagnosable mental health issues. The core symptoms of a psychotic state are a deeply and persistently illogical or irrational state of mind (i.e., a delusional state of mind) and the onset of hallucinations that alter the normal input of at least one of the five senses. Psychosis can also involve highly disordered thought processes, highly disordered patterns of speech and/or thought processes that “skip” between subjects that have no discernible connection to each other.

Researchers are well aware that people who use marijuana/cannabis have statistically increased chances of experiencing psychosis symptoms. Risks for psychosis generally appear to be substantially higher in people who use the drug heavily on a daily or near-daily basis, as well as in people who have a particular genetic variation affecting the chemical environment of the brain’s pleasure center. Adolescent users of marijuana/cannabis also apparently have heightened psychosis risks during adulthood when they have another genetic variation that alters the brain’s chemical environment.

Increased Potency-Related Risks

In the study published in The Lancet Psychiatry, researchers used information collected from 780 adults to help determine if the use of high-potency marijuana/cannabis increases the odds that an individual will experience symptoms of psychosis for the first time. Four hundred ten of the study participants had experienced an initial episode of psychosis at some point between the middle of 2005 and the middle of 2011; the remaining 370 participants acted as a comparison group of people unaffected by any history of psychosis during the same timeframe. Some of the study participants were consumers of high-potency “skunk” marijuana/cannabis, while others consumed lower-potency cannabis or no cannabis at all.

The researchers concluded that, when compared to adults who have never used marijuana/cannabis, consumers of high-potency forms of the drug are substantially more likely to develop symptoms of psychosis for the first time. The highest increase in risk (fully 200 percent) appears among individuals who use high-potency marijuana/cannabis essentially every day. Generally speaking, the study participants in the psychosis-affected group did not have a higher lifetime rate of cannabis intake than the participants in the non-psychosis-affected group. However, the participants in the psychosis-affected group did have a higher rate of daily consumption of the drug, as well as a history of using high-potency forms of the drug.

The authors note that, among the study participants, the experience of a first episode of psychosis was also linked to initiating marijuana/cannabis use before age 16 and an increased likelihood of having consumed at least 100 cigarettes over the course of a lifetime.

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