Cannabis remains a controversial drug even as broad acceptance accelerates. Vocal factions advocate for cannabis as a virtual panacea, a remedy for a range of problems from anxiety and depression to chronic pain and relief from other addictions, with often misleading comparisons with other harmful substances such as alcohol and tobacco. While cannabis may be relatively low-risk and even helpful for many, for others it can be life-altering in a negative way.

Given the potential risks, many advocate for caution regarding claims of marijuana’s health benefits and safety—especially for the developing brain and for those at risk for psychotic illness and mood-cycling disorders (Wainberg et al, 2021). Genetic associations predict an increased risk of four domains of psychotic symptoms: auditory hallucinations, visual hallucinations, persecutory delusions, and delusions of reference (thinking things like signs and messages on media are about oneself or directed toward oneself when they are not).

Research has found that cannabis use is associated with existing bipolar disorder and PTSD (Botsford et al., 2020; Lowe et al., 2019). While marijuana may alleviate negative emotions short-term (e.g. depression), and the endocannabinoid system is a ripe target for potential therapeutics (e.g. Huang et al., 2016), there is no solid evidence that marijuana is an effective treatment for depression. On the contrary, research finds an elevated risk for depression and suicidality among adolescent marijuana users (e.g. Gobbi et al., 2019), with a neutral impact on anxiety. A prospective study (Metrik et al., 2022) of veterans with PTSD found marijuana use linked with the worsening of intrusive thoughts. In addition, cannabis use is increasingly linked to the generation of both schizophrenia and bipolar disorder.

About 1 in 10 people who use marijuana will develop a cannabis use disorder, rising to 1 in 6 among those who start before the age of 18, according to statistics reported by SAMSHA (the Substance Abuse and Mental Health Services Administration), and is associated with reduced IQ among those who start early.

A Hazy Picture

Compounding concerns is the availability of increasingly potent varieties and insufficient standardization and regulation. This makes it difficult for people to know what they are taking, whether it actually is cannabis or has been adulterated with other substances. In addition, levels of the marijuana-high component, tetrahydrocannabinol (THC), tend to be increasing while the non-psychedelic component cannabidiol (CBD) can be highly variable.

Given the increasing popularity, significant risk, and strong industry motivation to paint a benign picture,¹ understanding risk factors for problematic marijuana use, including the role of personality traits, is imperative to inform policy and decision-making.

Cannabis and the Big Five

How might personality traits affect predisposition to problematic marijuana use? Researchers Winters, Malouff, and Schutte, in the journal Personality and Individual Differences (2022), published a meta-analysis of studies looking at associations between the Big Five personality factors of Openness to Experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism and risk for excessive cannabis use.

Five papers met the criteria for sufficient quality and statistical power and were included in the analysis. Altogether, they included over 5,300 participants and valid and reliable measures of personality, problematic marijuana use (e.g. the PUM Problematic Use of Marijuana scale; the CUDIT Cannabis Use Disorder Identification Test; the CAST Cannabis Abuse Screening Test, and others), the DIS Diagnostic Interview Schedule for substance use and psychiatric disorders, and related measures.

All of the Big Five traits, except extroversion, were associated with increased risk for problematic cannabis use with significant statistical effect sizes. Neuroticism (or emotional instability) accounted for 11.2 percent of the variability in cannabis risk scores; lower conscientiousness and agreeableness each contributed 8.4 percent, and openness to experience 3.2 percent.

Unpacking Personality and Cannabis Use

Neuroticism:People with higher neuroticism tend to worry more and use worry to cope, are more self-conscious, and experience greater vulnerability and insecurity, characterized by greater emotional instability. They may find marijuana appealing to self-medicate negative emotions, given that it can have a short-term euphoric, mood-elevating effect, which, however, can be followed by dysphoria (a negative emotional state), irritability, cognitive impairment, and other symptoms.

Rather than using problem-solving and cognitive reappraisal, more neurotic individuals may lean on less adaptive coping strategies. Combined with the potential for synergistic psychotic reactions (e.g. feeling persecuted), especially with super-potent strains available today and less regulated dosing with street products, neurosis and marijuana may not mix well. The research reviewed here also found that chronic cannabis use may increase neurosis, compounding the issue over time.

Conscientiousness: Lower conscientiousness is associated with reduced motivation and persistence (less grit), impulsivity, and disorganization. Study authors point out that lower conscientiousness is associated with poorer self-care (reduced “health-promoting behavior”) and that marijuana use may further undermine motivation for some users. Once a cannabis use problem gets established, less conscientious individuals may therefore have more difficulty stopping.

Agreeableness: Reduced agreeableness is associated with the Dark Triad personality traits of narcissism, Machiavellianism, and psychopathy. These traits, in turn, have been shown to be associated with reduced well-being and health, social difficulties, work- and performance-related problems, and an array of other difficulties. Given the negative impact of low agreeableness, the short-term mood-enhancing effects of cannabis may be appealing. Yet, as with neuroticism and conscientiousness, over the longer run, negative effects of cannabis may further undermine social relationships, impairing interpersonal skills and further eroding agreeableness for some users.

Openness to Experience:Though the statistical effect was low, for some people with high trait openness to experience, a preference for novelty and creativity may make marijuana appealing because of its psychedelic effects. While this may enhance experiences for many users (driving recreational use) for some, cannabis use may substitute for other types of enjoyable, original experience—preventing people from trying new things. Especially if other traits like higher neuroticism and lower conscientiousness get in the way, marijuana may appear to be a familiar, safe way to experience open-mindedness, a reliable companion.

Extroversion: Notably non-significant in this review, the introversion-extroversion dimension did not contribute to marijuana misuse. Social factors are likely to be related to other factors including neuroticism and agreeableness. Marijuana is not typically described as a “social lubricant” in the same way that alcohol is—whether one is more social or more withdrawn may depend on individual and contextual factors, including increasing societal acceptance paving the way for cannabis as a drug used in social settings.

Making Good Decisions

While many other factors go into determining whether someone will develop problematic substance abuse, understanding the personality traits associated with marijuana misuse arms individuals and clinicians with insights about how personality may interact specifically with cannabis, and can inform policy around legalization and messaging about cannabis risk—to include explicit warnings similar to those on tobacco and alcohol packaging, and restrictions on access based on age.

For people struggling to reduce or stop marijuana use, understanding where personality plays a role can empower positive change—for example, identifying neurotic coping approaches allows for greater self-awareness in the moment, and ultimately the possibility of opting for more effective coping strategies.

Future work on therapeutics to help those suffering from marijuana use disorders can target personality change and look at whether doing so improves outcomes. Those at increased risk for problematic marijuana use can choose to avoid marijuana completely.

Emerging clinical research on how to most effectively use marijuana can guide treatment decisions; such research remains scant and is often industry-driven, requiring caution in interpreting data. People seeking to use marijuana therapeutically, or those with a likelihood of problematic use, are advised to seek appropriate clinical consultation to avoid negative outcomes.

Originally published in Psychology Today on April 4, 2022

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