Research roundup: Marijuana use and cognitive processes
Marijuana is the third most commonly used drug in the United States after alcohol and tobacco. More than a third of Americans have used it, and roughly 7 percent of the population are “regular users.” Medical marijuana is now legal in 26 states and the District of Columbia, and of those states, recreational use of marijuana is now legal in the District of Columbia, Washington, Colorado, California, Alaska, Massachusetts, Maine, Nevada and Oregon. The trajectory towards decriminalization and increased access may have benefits for medical research, homeopathy and the criminal justice system. However, despite having advantages, cannabis use has the potential to result in abuse, dependence and negative effects on psychological well-being and mental health. Given the likelihood that more people will be regular and heavy users of marijuana, the practice community may need to become better informed about the unique aspects of cannabis use, even for those individuals seeking treatment for a mental health issue other than cannabis use disorder.
The following studies examine how cannabis use can affect cognitive processes that might impact the effectiveness of psychotherapy.
In addition to reviewing the following research summaries, psychologists are encouraged to explore the literature more completely to determine what may be useful to them in practice.
Metrik, J., McGeary, J.E., Rohsenow, D.J., Aston, E.R., Kahler, C.W., & Knopik, V.S. (2015). Marijuana’s Acute Effects on Cognitive Bias for Affective and Marijuana Cues. Experimental and Clinical Psychopharmacology, 23(5), 339-350.
The primary psychoactive ingredient in cannabis, delta-9- tetrahydrocannabinol, has been shown to produce both positive and negative feelings in users. While regular users commonly report using marijuana to reduce negative effects, marijuana can increase stress or social anxiety as well.
The researchers in this study asked 89 non-Hispanic White adults that had self-reported marijuana use at least two days a week for the past month or weekly for the past six months, to abstain from substances for 24 hours. They were then randomly selected to participate in one of two experimental double-blind sessions in which they smoked either an active marijuana or marijuana placebo cigarette. After smoking marijuana, participants completed a pleasantness rating task (7-point scale) of 18 reward, 18 aversive and 18 marijuana-related images. An Emotional Stroop task measured automatic, attentional bias to emotional word stimuli. The participants’ heart rates were recorded at baseline and post-treatment, and each completed a baseline and post-treatment SCID, Marijuana Withdrawal Checklist Diary, Addiction Research Center Inventory-Marijuana Scale, the visual analogue scale Marijuana Rating Form, Marijuana Craving Questionnaire, Timeline Follow-Back Measure (TLFB), and a Positive and Negative Affect Schedule (PANAS) to determine subjective effects.
The study provided evidence that marijuana significantly mediates the affective processing of negative visual stimuli. Participants who smoked the marijuana cigarette had significant delays in response to negative images as compared with neutral images on the pleasantness rating task. However, all participants were significantly slower with negatively associated words than the control words regardless of the drug condition. Only participants who met diagnostic criteria for cannabis use disorder and smoked marijuana showed any evidence of attentional bias towards positive emotional stimuli beyond a delayed response time. Researchers also found significant sex differences: women displayed heightened physiological responses to emotional stimuli and evaluated aversive pictures as more unpleasant and arousing than male participants regardless of marijuana condition. Findings suggest that regular marijuana users allocate greater attentional resources to negative cues without altering the processing capacity of positive emotional cues. Cognitive changes associated with marijuana use may be implicated in the anxiolytic effects common to regular users.
Buckner, J.D., Farris, S.G., Zvolensky, M.J., & Hogan, J. (2014). Social Anxiety and Coping Motives for Cannabis Use: The Impact of Experiential Avoidance. Psychology of Addictive Behaviors, 28(2), 568-574.
Between 25 percent to 30 percent of people with cannabis dependence have social anxiety disorder. The relationship between social anxiety and cannabis dependence can be largely explained by coping-oriented motives for cannabis use. Experiential avoidance may be a mediator between social anxiety and coping motives for marijuana use. Experiential avoidance is a type of emotion regulation that occurs when people circumvent certain internal thoughts or emotions they are uncomfortable with, taking the form of behavioral avoidance, procrastination, distraction/suppression, repression/denial and other mechanisms.
The sample consisted of 103 current cannabis users (confirmed with a drug test) between the ages of 18 and 45 that were not, and had no interest in, substance abuse treatment. The participants completed the following assessments: the Marijuana Motives Measure, the Marijuana Use Form, the Social Interaction Anxiety Scale, the Multidimensional Experiential Avoidance Questionnaire, the Difficulties in Emotional Regulation Scale, and the PANAS.
This study found that experiential avoidance was positively related to both social anxiety and coping motives. Experiential avoidance mediated the relationship between social anxiety and coping motives for cannabis use, reducing the variance ascribed to social anxiety by approximately 98 percent. Upon further analysis, the behavioral avoidance subgroup of experiential avoidance was the only subgroup related to social anxiety and coping motivations after controlling for other variables related to coping motives. Thus, the findings suggest that general experiential avoidance may, at least partially, explain the observed relationship between social anxiety and coping motives for cannabis use. However, it is behavioral avoidance specifically that plays a role in social anxiety’s relation to cannabis use.
Moitra, E., Anderson, B.J., Christopher, P.P., & Stein, M.D. (2015). Coping-Motivated Marijuana Use Correlates with DSM-5 Cannabis Use Disorder and Psychological Distress Among Emerging Adults. Psychology of Addictive Behaviors, 29(3), 627-632.
Current emerging adults have the highest rate of marijuana use compared to all other age cohorts and are indicated as the most accepting of its legalization and recreational use. This cohort also consistently reports the highest rates of stress and social anxiety. This study examined the association of motivations (social, enhancement (“I like the feeling”), and coping) for using marijuana in emerging adults with four measures of marijuana-related problem severity and psychological distress: meeting DSM-5 criteria for cannabis use disorder; marijuana-related problem severity; depressive symptomatology; and perceived stress.
Two-hundred eighty-eight participants between 18 and 25 years old that reported using marijuana in the last 30 days completed the Marijuana Problem Scale; the Patient Health Questionnaire–9; the Perceived Stress Scale–4; an adapted Reasons for Drinking Measure redesigned for marijuana use; a SCID using the DSM-5; and the TLFB. The participants were coded by severity of Cannabis Use Disorder, ranging from none (zero symptoms) to severe (6+ symptoms).
This study found that use of marijuana to cope with stress among emerging adults is significantly associated with having a DSM-5 cannabis use disorder. Using marijuana with the motivation of enhancement or social purposes wasn’t associated with cannabis-related problems like coping-motivated use. Specifically using marijuana to cope with negative emotions is correlated with psychiatric symptoms, such as severe perceived stress and depression.
These studies suggest that marijuana use is associated with cognitive changes in affective processing, experiential avoidance of negative affect, and increased psychiatric symptoms for those who use marijuana as a coping method. Moreover, emerging adults and women who use marijuana may be particularly susceptible to these effects.
Clinicians working with patients who use marijuana to cope with negative emotions face the challenge of confronting misconceptions about the perceived benefit of using marijuana to “treat” stress or negative affect. These studies suggest that the opposite may be occurring — those who use marijuana to avoid painful feelings and stressful situations are then unable to cognitively process these experiences and in turn experience more stress and depression. Additionally, while causation cannot be determined from these studies, the higher incidence of psychiatric symptoms or cannabis use disorder indicators is correlated with users who are trying to cope with undesired emotions suggesting greater risk for future difficulties for this population. Assessing marijuana use and its relationship to current symptoms, coping and functioning will be increasingly important as use continues to increase.