humulene and Learning-Disabilities

Heavy cannabis use has been frequently associated with increased rates of mental illness and cognitive impairment, particularly amongst adolescent users. However, the neurobiological processes that underlie these associations are still not well understood. In this review, we discuss the findings of studies examining the acute and chronic effects of cannabis use on the brain, with a particular focus on the impact of commencing use during adolescence. Accumulating evidence from both animal and human studies suggests that regular heavy use during this period is associated with more severe and persistent negative outcomes than use during adulthood, suggesting that the adolescent brain may be particularly vulnerable to the effects of cannabis exposure. As the endocannabinoid system plays an important role in brain development, it is plausible that prolonged use during adolescence results in a disruption in the normative neuromaturational processes that occur during this period. We identify synaptic pruning and white matter development as two processes that may be adversely impacted by cannabis exposure during adolescence. Potentially, alterations in these processes may underlie the cognitive and emotional deficits that have been associated with regular use commencing during adolescence.

Topics: Adolescent; Animals; Brain; Cannabinoids; Cannabis; Depression; Endocannabinoids; Female; Humans; Learning Disabilities; Memory Disorders; Pregnancy; Prenatal Exposure Delayed Effects; Schizophrenia

Topics: Adult; Airway Resistance; Attention; Blood Pressure; Cannabis; Clinical Trials as Topic; Conjunctiva; Dronabinol; Heart Rate; Humans; Learning; Learning Disabilities; Male; Placebos; Plethysmography, Whole Body; Reaction Time; Self Concept; Time Perception

Cognitive deficits that persist up to a month have been detected among adult marijuana users, but decrements and their pattern of recovery are less known in adolescent users. Previously, we reported cognitive deficits among adolescent marijuana users after one month of abstinence (Medina, Hanson, Schweinsburg, Cohen-Zion, Nagel, & Tapert, 2007). In this longitudinal study, we characterized neurocognitive changes among marijuana-using adolescents across the first three weeks of abstinence.. Participants were adolescent marijuana users with limited alcohol and other drug use (n=19) and demographically similar non-using controls (n=21) ages 15-19. Participants completed a brief neuropsychological battery on three occasions, after 3days, 2weeks, and 3weeks of stopping substance use. Abstinence was ascertained by decreasing tetrahydrocannabinol metabolite values on serial urine drug screens. Verbal learning, verbal working memory, attention and vigilance, and time estimation were evaluated.. Marijuana users demonstrated poorer verbal learning (p<.01), verbal working memory (p<.05), and attention accuracy (p<.01) compared to controls. Improvements in users were seen on word list learning after 2weeks of abstinence and on verbal working memory after 3weeks. While attention processing speed was similar between groups, attention accuracy remained deficient in users throughout the 3-week abstinence period.. This preliminary study detected poorer verbal learning and verbal working memory among adolescent marijuana users that improved during three weeks of abstinence, while attention deficits persisted. These results implicate possible hippocampal, subcortical, and prefrontal cortex abnormalities.

Topics: Adolescent; Attention; Cannabis; Case-Control Studies; Cognition; Dronabinol; Female; Humans; Learning; Learning Disabilities; Longitudinal Studies; Male; Marijuana Abuse; Memory, Short-Term; Neuropsychological Tests; Substance Withdrawal Syndrome; Young Adult

Chronic oral administration of cannabis extract to rats (daily delta 9-tetrahydrocannabinol dose 20 mg/kg) was examined in three experiments for its residual effect on radial-arm maze learning following a 1-month drug-free period. Learning a simple eight-arm maze was significantly impaired in rats treated for either 6 months (Experiment I) or 3 months (Experiment II) with the drug. In Experiment III, animals that received the extract for 3 months exhibited significant learning deficits on a much more difficult 12-arm radial maze. The results demonstrate that the deleterious effects of cannabis on radial-arm maze learning are probably due to a tendency toward increased vigilance and perseveration, possibly combined with an impaired utilization of spatial cues.

Topics: Animals; Body Weight; Cannabis; Dronabinol; Food Deprivation; Humans; Intubation, Gastrointestinal; Learning Disabilities; Male; Plant Extracts; Rats; Rats, Inbred Strains

Topics: Adolescent; Adult; Age Factors; Cannabis; Delusions; Depth Perception; Female; Homosexuality; Hospitalization; Humans; Learning Disabilities; Male; Pregnancy; Psychological Tests; Psychoses, Substance-Induced; Speech Disorders; Substance Withdrawal Syndrome; Substance-Related Disorders; Time Factors