History Of Cannabis Use Research Articles

Cannabis use and bone mineral density: NHANES 2007-2010.

Cannabis is the most widely used illegal drug in the USA, and its recreational use has recently been approved in several US states. Cannabinoids play a role in bone homeostasis. We aimed to determine the association between cannabis use and BMD in US adults. In the National Health and Nutrition Examination Survey 2007-2010, 4743 participants between 20 and 59 years old, history of cannabis use was categorized into never, former (previous use, but not in last 30 days), light (1-4 days of use in last 30 days), and heavy (≥5 days of use in last 30 days). Multivariable linear regression was used to test the association between cannabis use and DXA BMD of the proximal femur and lumbar spine with adjustment for age, sex, BMI, and race/ethnicity among other BMD determinants. Sixty percent of the population reported ever using cannabis; 47% were former users, 5% were light users, and 7% were heavy users. Heavy cannabis users were more likely to be male, have a lower BMI, increased daily alcohol intake, increased tobacco pack-years, and were more likely to have used other illegal drugs (cocaine, heroin, or methamphetamines). No association between cannabis and BMD was observed for any level of use (p≥0.28). A history of cannabis use, although highly prevalent and related to other risk factors for low BMD, was not independently associated with BMD in this cross-sectional study of American men and women.

The Differential Binding of Antipsychotic Drugs to the ABC Transporter P-Glycoprotein Predicts Cannabinoid-Antipsychotic Drug Interactions.

Cannabis use increases rates of psychotic relapse and treatment failure in schizophrenia patients. Clinical studies suggest that cannabis use reduces the efficacy of antipsychotic drugs, but there has been no direct demonstration of this in a controlled study. The present study demonstrates that exposure to the principal phytocannabinoid, Δ9-tetrahydrocannabinol (THC), reverses the neurobehavioral effects of the antipsychotic drug risperidone in mice. THC exposure did not influence D2 and 5-HT2A receptor binding, the major targets of antipsychotic action, but it lowered the brain concentrations of risperidone and its active metabolite, 9-hydroxy risperidone. As risperidone and its active metabolite are excellent substrates of the ABC transporter P-glycoprotein (P-gp), we hypothesized that THC might increase P-gp expression at the blood-brain barrier (BBB) and thus enhance efflux of risperidone and its metabolite from brain tissue. We confirmed that the brain disposition of risperidone and 9-hydroxy risperidone is strongly influenced by P-gp, as P-gp knockout mice displayed greater brain concentrations of these drugs than wild-type mice. Furthermore, we demonstrated that THC exposure increased P-gp expression in various brain regions important to risperidone's antipsychotic action. We then showed that THC exposure did not influence the neurobehavioral effects of clozapine. Clozapine shares a very similar antipsychotic mode of action to risperidone, but unlike risperidone is not a P-gp substrate. Our results imply that clozapine or non-P-gp substrate antipsychotic drugs may be better first-line treatments for schizophrenia patients with a history of cannabis use.

The positive link between executive function and lifetime cannabis use in schizophrenia is not explained by current levels of superior social cognition

There has been a growing link between a history of cannabis use and neurocognitive performance in patients with schizophrenia. Fewer neurocognitive deficits may be a marker of the superior social cognition needed to obtain illicit substances, or cannabis use may indicate a distinct path to schizophrenia with less neurocognitive vulnerability. This study sought to determine whether the relationship of cannabis use and executive function exists independently of social cognition. Eighty-seven patients with schizophrenia were administered measures of social cognition and executive function. Social cognition was assessed using the Bell-Lysaker Emotion Recognition Test to measure affect recognition, and the Eyes and Hinting Tests to measure theory of mind. Executive function was assessed by the Mental Flexibility component of the Delis-Kaplan Executive Functioning Scale. The relations between the variables were examined with structural equation modeling. Cannabis use positively related to executive function, negatively related to affect recognition, and had no relationship with theory of mind. There were no indirect effects of other illicit substances on amount of regular cannabis use. Alcohol use was related to worse affect recognition. The relationship between cannabis use and better executive function was supported and was not explained by superior social cognition

Medicinal versus recreational cannabis use: Patterns of cannabis use, alcohol use, and cued-arousal among veterans who screen positive for PTSD

IntroductionThe present study is the first to test whether veterans who use cannabis specifically for the purposes of self-medication for their reported PTSD symptoms differ from veterans who use cannabis medicinally for other reasons, or recreationally, in terms of patterns of cannabis use, use of alcohol, and reactivity to written combat trauma reminders. MethodsAssessment measures were administered online to a sample of veterans with a history of cannabis use (n=1971). Cued arousal was assessed pre/post via a prompt about combat experiences. Hypotheses were tested using a series of Bonferroni corrected one-way analyses of variance, t-tests, bivariate and partial correlations, and a Chi-square test. ResultsCompared to recreational users, veterans who identify as medicinal cannabis users reported greater combat exposure (d=0.56), PTSD symptoms (d=1.02), subjective arousal when cued (d=0.25), and cannabis use (dfrequency=0.40; ddensity=0.42), but less alcohol use (d=0.28). Few differences were observed between medicinal users who reported using for PTSD versus those who reported using for other reasons. ConclusionsCompared to those who use cannabis recreationally, veterans who report that they use cannabis medicinally use more cannabis and endorse significantly more symptoms of arousal following a prompt about combat trauma experiences.

Cannabis use among Canadian Armed Forces Veterans

Introduction: Despite rapidly changing cannabis use regulations in Canada, including health care support for Canadian Armed Forces (CAF) Veterans, the prevalence of and reasons for cannabis use in this population have not been studied. Methods: An online 28-item anonymous survey was used to examine the prevalence of cannabis use among CAF Veterans who reported undergoing treatment of PTSD ( N=120). We aimed to estimate the prevalence of cannabis use among CAF Veterans, as well as to explore the reasons for cannabis use in this population. We also examined the relationships between cannabis use and other aspects of health in CAF Veterans, namely other substance use, PTSD symptom severity, and chronic pain severity. Results: Approximately half of the respondents reported a history of cannabis use. Of these, approximately 35.5% reported beginning cannabis use before a military-related trauma, 23% reported beginning after a traumatic event, and 42% reported beginning after release. Participants stated that they used cannabis primarily for relaxation and emotional calm, and for pain management. Only 10% reported its use specifically for PTSD-related symptoms and anxiety. Chronic cannabis users (i.e., one or more years) endorsed a greater number of cannabis abuse symptoms than acute users (i.e., one time to less than three months). Cannabis users were also more likely to use both prescription and non-prescription drugs. No relationships were found between cannabis use and military-related PTSD symptom severity or pain severity. Discussion: Cannabis use, along with other substance use, is common among CAF Veterans, and the reasons for cannabis use vary greatly. Cannabis use does not appear to have an impact on PTSD- and pain-related symptom expression; however, further study is recommended.

The genetic basis of the comorbidity between cannabis use and major depression.

While the prevalence of major depression is elevated among cannabis users, the role of genetics in this pattern of comorbidity is not clear. This study aimed to estimate the heritability of cannabis use and major depression, quantify the genetic overlap between these two traits and localize regions of the genome that segregate in families with cannabis use and major depression. Family-based univariate and bivariate genetic analysis. San Antonio, Texas, USA. Genetics of Brain Structure and Function study (GOBS) participants: 1284 Mexican Americans from 75 large multi-generation families and an additional 57 genetically unrelated spouses. Phenotypes of life-time history of cannabis use and major depression, measured using the semistructured MINI-Plus interview. Genotypes measured using ~1M single nucleotide polymorphisms (SNPs) on Illumina BeadChips. A subselection of these SNPs were used to build multi-point identity-by-descent matrices for linkage analysis. Both cannabis use [h2 =0.614, P=1.00×10-6 , standard error (SE)=0.151] and major depression (h2 =0.349, P=1.06×10-5 , SE=0.100) are heritable traits, and there is significant genetic correlation between the two (ρg =0.424, P=0.0364, SE=0.195). Genome-wide linkage scans identify a significant univariate linkage peak for major depression on chromosome 22 [logarithm of the odds (LOD)=3.144 at 2centimorgans (cM)], with a suggestive peak for cannabis use on chromosome 21 (LOD=2.123 at 37cM). A significant pleiotropic linkage peak influencing both cannabis use and major depression was identified on chromosome 11 using a bivariate model (LOD=3.229 at 112cM). Follow-up of this pleiotropic signal identified a SNP 20kb upstream of NCAM1 (rs7932341) that shows significant bivariate association (P=3.10×10-5 ). However, this SNP is rare (seven minor allele carriers) and does not drive the linkage signal observed. There appears to be a significant genetic overlap between cannabis use and major depression among Mexican Americans, a pleiotropy that appears to be localized to a region on chromosome 11q23 that has been linked previously to these phenotypes.

Cannabis, Psychosis, and Mortality: A Cohort Study of 50,373 Swedish Men.

The authors assessed 1) the overall risk of death among cannabis users compared with nonusers and the extent to which psychosis affects excess mortality; 2) mortality among persons with psychotic disorders and the extent to which cannabis use affects excess mortality; and 3) the interaction effect of cannabis use and diagnosis of psychotic disorders on mortality. This was a longitudinal study of 50,373 Swedish male military conscripts (ages 18-19) who were followed in the National Cause of Death Register up to around age 60. Cox proportional hazard modeling was used to assess risk of death in relation to baseline cannabis use and diagnosis of psychotic disorders. Subjects with a baseline history of heavy cannabis use had a significantly higher risk of death (hazard ratio=1.4, 95% CI=1.1, 1.8) than those without such a history. The authors found an excess mortality among subjects with psychotic disorders, but the level did not differ between those with a history of cannabis use (ever users: hazard ratio=3.8, 95% CI=2.8, 5.0; heavy users: hazard ratio=3.8, 95% CI=2.6, 6.2) and those without such a history (hazard ratio=3.7, 95% CI=3.1, 44). No interaction was observed between cannabis use and diagnosis of psychotic disorders with regard to mortality. The results suggest that individuals with an early history of heavy use of cannabis are at a higher risk of death than those with a history of no use of cannabis. Although the authors adjusted for several confounders at baseline, the results should be interpreted with caution because of a lack of information on confounders in the period after conscription.

Cannabinoid hyperemesis syndrome

Case reportA 25-year-old man was attended in multiple times at Emergency Department by referring abdominal pain and vomiting. No organic disease was found and he was referred to Psychiatric Emergency to assess him. He had history of cannabis use (4–5 times/day) during last 5 years. He referred recurrent episodes of abdominal pain and vomiting since 4 years ago, he had found that having hot showers alleviate his symptoms. Urine screening was positive for THC and negative for other drugs. In results of blood tests, abdominal X-ray, abdominal ultrasonography, abdominal tomography and fibrogastroscopy didn’t find any abnormality. He was diagnosed from suffering a somatoform disorder. Treatment with Setraline 50 mg/day was prescribed and cannabis abstinence was recommended. He was referred to Mental Health outpatient service. He maintained cannabis abstinence for 1 month and some symptoms disappeared. However, 2 months later, he relapsed in cannabis use and all symptoms reappeared. Later he achieved cannabis abstinence again and he got full recovery, then he was diagnosed from cannabinoid hyperemesis syndrome.ConclusionCannabinoid hyperemesis syndrome is characterized by recurrent nausea, vomiting and colicky abdominal pain in patients with long-term cannabis use. These symptoms have been reported to be alleviated temporarily by taking a hot shower or more permanently by abstaining from the use of cannabis. The phenomenon of cannabinoid hyperemesis and clinical diagnosis remained obscure until recently. For this reason, it is necessary to take it into account in order to recognize it and help provide these patients early and better approach.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Evaluating the relationship between cannabis use and IQ in youth and young adults at clinical high risk of psychosis

Among people with psychosis, those with a history of cannabis use show better cognitive performance than those who are cannabis naïve. It is unknown whether this pattern is present in youth at clinical high risk (CHR) of psychosis. We evaluated relationships between IQ and cannabis use while controlling for use of other substances known to impact cognition in 678 CHR and 263 healthy control (HC) participants. IQ was estimated using the Vocabulary and Block Design subtests of the Wechsler Abbreviated Scale of Intelligence. Drug and alcohol use severity and frequency were assessed with the Alcohol and Drug Use Scale, and we inquired participants' age at first use. CHR were further separated into early and late age at onset of cannabis use sub-groups, and low-, moderate- and high-frequency sub-groups. No significant differences in IQ emerged between CHR or HC cannabis users vs. non-users, or between use frequency groups. CHR late-onset users showed significantly higher IQ than CHR early-onset users. Age at onset of cannabis use was significantly and positively correlated with IQ in CHR only. Results suggest that age at onset of cannabis may be a more important factor for IQ than use current use or use frequency in CHR.

Interaction between cannabis consumption and childhood abuse in psychotic disorders: preliminary findings on the role of different patterns of cannabis use.

Several studies have suggested that lifetime cannabis consumption and childhood abuse synergistically contribute to the risk for psychotic disorders. This study aimed to extend existing findings regarding an additive interaction between childhood abuse and lifetime cannabis use by investigating the moderating role of type and frequency of cannabis use. Up to 231 individuals presenting for the first time to mental health services with psychotic disorders and 214 unaffected population controls from South London, United Kingdom, were recruited as part of the Genetics and Psychosis study. Information about history of cannabis use was collected using the Cannabis Experiences Questionnaire. Childhood physical and sexual abuse was assessed using the Childhood Experience of Care and Abuse Questionnaire. Neither lifetime cannabis use nor reported exposure to childhood abuse was associated with psychotic disorder when the other environmental variable was taken into account. Although the combination of the two risk factors raised the odds for psychosis by nearly three times (adjusted OR = 2.94, 95% CI: 1.44-6.02, P = 0.003), no evidence of interaction was found (adjusted OR = 1.46, 95% CI: -0.54 to 3.46, P = 0.152). Furthermore, the association of high-potency cannabis and daily consumption with psychosis was at least partially independent of the effect of childhood abuse. The heavy use of high-potency cannabis increases the risk of psychosis but, in addition, smoking of traditional resin (hash) and less than daily cannabis use may increase the risk for psychosis when combined with exposure to severe childhood abuse.

Views of schizophrenia patients on the effects of cannabis on their mental health

Background . Cannabis use may trigger or perpetuate clinical features of schizophrenia in vulnerable individuals, thereby contributing to the morbidity of schizophrenia and its burden of disease. These findings have mostly not considered the views of schizophrenia patients on cannabis use and its effect on their mental health. Methods . A semi-structured 16-point opinion-type questionnaire was formulated from the results of a previous qualitative study on schizophrenia patients’ opinions about cannabis use. The questionnaire was applied to 60 participants from an inpatient schizophrenia population at Weskoppies Hospital, Pretoria, South Africa, who had a Diagnostic and Statistical Manual of Mental Disorders , 4th edition (text revision) (DSM-IV-TR) diagnosis of schizophrenia and a documented history of cannabis use. Results . According to participants’ responses, 61.7% admitted to suffering from a mental illness, 95.0% admitted to using cannabis in the past, and 20.0% of participants admitted to the current use of cannabis. Over half (51.7%) of the participants responded that cannabis had adverse effects on their mental health, 26.7% that their mental illness was caused by using an illicit drug other than cannabis, 26.7% that only impure cannabis had adverse effects on their mental health, and 48.3% that only using too much cannabis had bad effects on their mind. A high percentage (58.3%) of participants responded that cannabis use helped reduce tension, 56.7% that it helped reduce anxiety, 66.7% that it helped to lift their mood, 63.3% that it helped them to relax, 60.0% that it helped to relieve their boredom, 43.3% that it helped them feel more energetic, 58.3% that it helped them sleep better, 13.3% that it helped reduce auditory hallucinations, and 31.7% that the beneficial effects of cannabis outweighed its negative effects. Conclusion . Most of the participants who responded that they were not using cannabis currently had positive views about its effects on their mental health, despite responding that cannabis may have adverse effects on their mental health. This is a worrisome outcome, since those participants who feel that cannabis has more beneficial than detrimental effects might not remain abstinent.

Cannabis use in early adolescence: Evidence of amygdala hypersensitivity to signals of threat

Cannabis use in adolescence may be characterized by differences in the neural basis of affective processing. In this study, we used an fMRI affective face processing task to compare a large group (n=70) of 14-year olds with a history of cannabis use to a group (n=70) of never-using controls matched on numerous characteristics including IQ, SES, alcohol and cigarette use. The task contained short movies displaying angry and neutral faces. Results indicated that cannabis users had greater reactivity in the bilateral amygdalae to angry faces than neutral faces, an effect that was not observed in their abstinent peers. In contrast, activity levels in the cannabis users in cortical areas including the right temporal-parietal junction and bilateral dorsolateral prefrontal cortex did not discriminate between the two face conditions, but did differ in controls. Results did not change after excluding subjects with any psychiatric symptomology. Given the high density of cannabinoid receptors in the amygdala, our findings suggest cannabis use in early adolescence is associated with hypersensitivity to signals of threat. Hypersensitivity to negative affect in adolescence may place the subject at-risk for mood disorders in adulthood.

Medical Cannabis in Arizona: Patient Characteristics, Perceptions, and Impressions of Medical Cannabis Legalization

Many advances have been made toward understanding the benefits of medical cannabis. However, less is known about medical cannabis patients themselves. Prior research has uncovered many important patient characteristics, but most of that work has been conducted with participants in California, who may not represent medical cannabis patients throughout the United States. Furthermore, it is unknown if medical cannabis legalization, which typically imposes strict regulations on cannabis cultivation and sale, impacts patients’ experiences acquiring and using cannabis. The goal of this study was to address these limitations by (1) examining the characteristics, perceptions, and behaviors of medical cannabis patients in Arizona; and (2) questioning participants with a history of cannabis use regarding their experiences with cannabis before and after legalization. Patients in Arizona share many characteristics with those in California, but also key differences, such as average age and degree of cannabis consumption. Participants also had positive perceptions of the effect of medical cannabis legalization, reporting that feelings of safety and awareness were higher after legalization compared to before. The results are discussed in relation to evidence from patients in other states and in terms of their potential policy implications.

Age at first tobacco use and risk of subsequent psychosis-related outcomes: A birth cohort study.

Compared to the substantial body of research examining links between cannabis use and psychosis, there has been relatively little attention to the role of tobacco as a potential risk factor for psychosis. This study explored the association between age at first tobacco use and psychosis-related outcomes in a birth cohort. This study is based on a large birth cohort (the Mater-University Study of Pregnancy). At approximately 21 years of age, cohort members (N = 3752) were assessed for three psychosis-related outcomes (International Classification of Diseases non-affective psychosis, the presence of any hallucination and total count of delusional-like experiences) with the Composite International Diagnostic Interview and the Peters Delusional Inventory. Associations between age at first tobacco use and psychosis-related outcomes were examined using logistic regression in a model (a) adjusted for sex and age and (b) in a second model excluding all respondents who had a history of past problematic and current cannabis use. When adjusted for age and sex, those who commenced tobacco at 15 years of age or younger were significantly more likely to (a) have non-affective psychosis, (b) be in the highest quartile of total score of the Peters Delusional Inventory and (c) report hallucinations. After excluding all those with a history of a cannabis use disorder, or who were current (last month) cannabis users, a significant association between age at first tobacco use and the presence of hallucinations persisted. There is an association between age at first tobacco use and subsequent psychosis-related outcomes in young adults. While the findings cannot be used to deduce causality, it adds weight to the hypothesis that early tobacco use may contribute to the risk of developing psychosis-related outcomes.

Views of schizophrenia patients on the effects of cannabis on their mental health

<p><strong>Background</strong>. Cannabis use may trigger or perpetuate clinical features of schizophrenia in vulnerable individuals, thereby contributing to the morbidity of schizophrenia and its burden of disease. These findings have mostly not considered the views of schizophrenia patients on cannabis use and its effect on their mental health. </p><p><strong>Methods</strong>. A semi-structured 16-point opinion-type questionnaire was formulated from the results of a previous qualitative study on schizophrenia patients’ opinions about cannabis use. The questionnaire was applied to 60 participants from an inpatient schizophrenia population at Weskoppies Hospital, Pretoria, South Africa, who had a <em>Diagnostic and Statistical Manual of Mental Disorders</em>, 4th edition (text revision) (DSM-IV-TR) diagnosis of schizophrenia and a documented history of cannabis use. </p><p><strong>Results</strong>. According to participants’ responses, 61.7% admitted to suffering from a mental illness, 95.0% admitted to using cannabis in the past, and 20.0% of participants admitted to the current use of cannabis. Over half (51.7%) of the participants responded that cannabis had adverse effects on their mental health, 26.7% that their mental illness was caused by using an illicit drug other than cannabis, 26.7% that only impure cannabis had adverse effects on their mental health, and 48.3% that only using too much cannabis had bad effects on their mind. A high percentage (58.3%) of participants responded that cannabis use helped reduce tension, 56.7% that it helped reduce anxiety, 66.7% that it helped to lift their mood, 63.3% that it helped them to relax, 60.0% that it helped to relieve their boredom, 43.3% that it helped them feel more energetic, 58.3% that it helped them sleep better, 13.3% that it helped reduce auditory hallucinations, and 31.7% that the beneficial effects of cannabis outweighed its negative effects. </p><p><strong>Conclusion</strong>. Most of the participants who responded that they were not using cannabis currently had positive views about its effects on their mental health, despite responding that cannabis may have adverse effects on their mental health. This is a worrisome outcome, since those participants who feel that cannabis has more beneficial than detrimental effects might not remain abstinent.</p>

Interaction Between Functional Genetic Variation of DRD2 and Cannabis Use on Risk of Psychosis.

Both cannabis use and the dopamine receptor (DRD2) gene have been associated with schizophrenia, psychosis-like experiences, and cognition. However, there are no published data investigating whether genetically determined variation in DRD2 dopaminergic signaling might play a role in individual susceptibility to cannabis-associated psychosis. We genotyped (1) a case-control study of 272 patients with their first episode of psychosis and 234 controls, and also from (2) a sample of 252 healthy subjects, for functional variation in DRD2, rs1076560. Data on history of cannabis use were collected on all the studied subjects by administering the Cannabis Experience Questionnaire. In the healthy subjects' sample, we also collected data on schizotypy and cognitive performance using the Schizotypal Personality Questionnaire and the N-back working memory task. In the case-control study, we found a significant interaction between the rs1076560 DRD2 genotype and cannabis use in influencing the likelihood of a psychotic disorder. Among cannabis users, carriers of the DRD2, rs1076560, T allele showed a 3-fold increased probability to suffer a psychotic disorder compared with GG carriers (OR = 3.07; 95% confidence interval [CI]: 1.22-7.63). Among daily users, T carrying subjects showed a 5-fold increase in the odds of psychosis compared to GG carriers (OR = 4.82; 95% CI: 1.39-16.71). Among the healthy subjects, T carrying cannabis users had increased schizotypy compared with T carrying cannabis-naïve subjects, GG cannabis users, and GG cannabis-naïve subjects (all P ≤ .025). T carrying cannabis users had reduced working memory accuracy compared with the other groups (all P ≤ .008). Thus, variation of the DRD2, rs1076560, genotype may modulate the psychosis-inducing effect of cannabis use.

Cannabinoid Hyperemesis Syndrome: A Paradoxical Cannabis Effect.

Despite well-established antiemetic properties of marijuana, there has been increasing evidence of a paradoxical effect in the gastrointestinal tract and central nervous system, given rise to a new and underrecognized clinical entity called the Cannabinoid Hyperemesis Syndrome. Reported cases in the medical literature have established a series of patients exhibiting a classical triad of symptoms: cyclic vomiting, chronic marijuana use, and compulsive bathing. We present a case of a 29-year-old man whose clinical presentation strongly correlates with cannabinoid hyperemesis syndrome. Despite a diagnosis of exclusion, this syndrome should be considered plausible in the setting of a patient with recurrent intractable vomiting and a strong history of cannabis use as presented in this case.

Cannabis use and anxiety: is stress the missing piece of the puzzle?

Objective: Comorbidity between anxiety and cannabis use is common yet the nature of the association between these conditions is not clear. Four theories were assessed, and a fifth hypothesis tested to determine if the misattribution of stress symptomology plays a role in the association between state-anxiety and cannabis.Methods: Three-hundred-sixteen participants ranging in age from 18 to 71 years completed a short online questionnaire asking about their history of cannabis use and symptoms of stress and anxiety.Results: Past and current cannabis users reported higher incidence of lifetime anxiety than participants who had never used cannabis; however, these groups did not differ in state-anxiety, stress, or age of onset of anxiety. State-anxiety and stress were not associated with frequency of cannabis use, but reported use to self-medicate for anxiety was positively associated with all three. Path analyses indicated two different associations between anxiety and cannabis use, pre-existing and high state-anxiety was associated with (i) higher average levels of intoxication and, in turn, acute anxiety responses to cannabis use; (ii) frequency of cannabis use via the mediating effects of stress and self-medication.Conclusion: None of the theories was fully supported by the findings. However, as cannabis users reporting self-medication for anxiety were found to be self-medicating stress symptomology, there was some support for the stress-misattribution hypothesis. With reported self-medication for anxiety being the strongest predictor of frequency of use, it is suggested that researchers, clinicians, and cannabis users pay greater attention to the overlap between stress and anxiety symptomology and the possible misinterpretation of these related but distinct conditions.

A preliminary comparison of cannabis use in subsyndromal gamblers: select neurocognitive and behavioral differences based on use.

Cannabis and gambling are 2 common forms of impulsive behavior among young adults. Although both cannabis use and gambling have been associated with specific cognitive deficits on tasks related to decision making, no studies to date have examined the possible effects on neurocognition in those who simultaneously gamble and use cannabis. To address this question, the present study analyzed 214 subsyndromal gamblers from a larger study on impulsivity. Of these subjects, 64 (29.9%) were current cannabis users (last use within the last 3 months) and 150 (70.1%) had no history of cannabis use in the last 3 months, along with 163 healthy controls. Participants were assessed on various cognitive and clinical measures, including measures for gambling severity and impulsivity. Subjects using cannabis had higher rates of current alcohol use disorders and more frequent gambling behavior per week. Gamblers who used cannabis also exhibited significantly greater scores on one measure of attentional impulsivity. Both gambling groups differed from healthy controls on all clinical and select neurocognitive variables, consistent with previous research. These results indicate that cannabis use in young adults who gamble is associated with nuanced behavioral differences, although causality could not be determined. Longitudinal research should examine cannabis use in subsyndromal gamblers over time to characterize whether these findings are causative.

Functional magnetic resonance brain imaging of executive cognitive performance in young first-episode schizophrenia patients and age-matched long-term cannabis users

Converging evidence from epidemiological, clinical and neuropsychological research suggests a link between cannabis use and increased risk of psychosis. Long-term cannabis use has also been related to deficit-like “negative” symptoms and cognitive impairment that resemble some of the clinical and cognitive features of schizophrenia. The current functional brain imaging study investigated the impact of a history of heavy cannabis use on impaired executive function in first-episode schizophrenia patients. Whilst performing the Tower of London task in a magnetic resonance imaging scanner, event-related blood oxygenation level-dependent (BOLD) brain activation was compared between four age and gender-matched groups: 12 first-episode schizophrenia patients; 17 long-term cannabis users; seven cannabis using first-episode schizophrenia patients; and 17 healthy control subjects. BOLD activation was assessed as a function of increasing task difficulty within and between groups as well as the main effects of cannabis use and the diagnosis of schizophrenia. Cannabis users and non-drug using first-episode schizophrenia patients exhibited equivalently reduced dorsolateral prefrontal activation in response to task difficulty. A trend towards additional prefrontal and left superior parietal cortical activation deficits was observed in cannabis-using first-episode schizophrenia patients while a history of cannabis use accounted for increased activation in the visual cortex. Cannabis users and schizophrenia patients fail to adequately activate the dorsolateral prefrontal cortex, thus pointing to a common working memory impairment which is particularly evident in cannabis-using first-episode schizophrenia patients. A history of heavy cannabis use, on the other hand, accounted for increased primary visual processing, suggesting compensatory imagery processing of the task.