weed Flashcards
describe cannabinoid receptors
cannabinoid receptor types 1 and 2: CB1R and CB2R, both GPCRs
CB1R is concentrated in the CNS, mainly found presynpatically at terminals of central and peripheral neurones, typically have inhibitory action on the release of excitatory and inhibitory neurotransmittors
CB2R is found peripherally and acts on the immune system
endogenous ligands: anandamide (AEA) and 2-arachidonoylglycerol (2-AG), both are CB 1 and 2 R agonists
where is CB1R density highest
CB1R density is highest in the hippocampus, prefrontal cortex and basolateral amygdala
how do THC/CBD interact with the endogenous cannabinoid system
THC acts primarily as a partial agonist at CB1R but also at CB2R
CBD has low affinity for CB1R and seems to have a complex range of actions such as attenuation of CB1 agonist effects, reduces cellular reuptake and hydrolysis of AEA in the brain
what are neurobiological changes following acute CB1R agonist exposure
in the PFC: decreased GABA transmission, increased glutamate and noradrenaline, decreased acetylcholine
in the VTA: increased DA cell firing
in the hipp: increase NA, decreased ACh
in the NAc: increased NA, DA, opioid peptides, decreases GABA and Glu
what are cannabis withdrawal symptoms
anger, anxiety, changes in appetite, irritability, restlessness, shakiness, problems with sleep, stomach pain
symptoms tend to be strongest 2-6 days after stopping use, and tend to last up to 14 days
acute administration of THC alleviates these symptoms
describe the effects of cannabis use disorder
cannabis is the most common primary reason for first time entry to european drug treatment
of those who try cannabis at least once, 9% develop addiction which is a lower incidence for alcohol, nicotine, cocaine and heroin
the median time taken to develop CUD is 5 years after first taking it
most users, even frequent users stop using in their 20s
out of users taking cannabis 3 times or more a week 37% experienced CUD within 3 years
are some people at greater risk of CUD than others
in a 3 year study on dutch cannabis users:
current problems such as negative life effects (using cannabis as a coping mechanism) and baseline CUD symptomology is best predictor of CUD
stable vulnerability factors such as childhood adversity and cannabis exposure variables did not predict CUD
also type of weed used may influence addiction rates; with much higher rate for high potency skunk than low potency hash and herbal weed
does CBD alter addiction related processing?
people smoking cannabis containing CBD showed attention away from cannabis related imagery
attentional bias correlates with drug craving and addiction symptomology
cannabis users taking an oral pre dose of CBD did not alter amount of cannabis purchased, rating of intoxication or the rating of cannabis liking
how does cannabis relate to schizo and psychosis
there is an increased risk of psychosis associated with cannabis
large increase in incidence of schizophrenia after having taken cannabis >5 times
the association is robust however the causality is debated
a meta analysis of longitudinal population cohort studies showed the odds of cannabis users compared to never users was 1.4 fold increase to any psychotic event
longitudinal studies adjust for symptoms prior to use however some symptoms naturally develop beyond adolescence thus beyond age of first use
since psychosis is rare and cannabis use is common, what does this imply about a causal link
there is variation in the susceptibility to cannabis related psychosis;
genetic polymorphisms of AKT1 have been identified that confer increased risk of psychosis specifically in cannabis users
C/C genotype carriers were more than twice as likely to experience psychotic disorder compared with users who were T/T carriers
there are risky and less risky cannabis use behaviours, some of which increase psychosis risk more than others
how does cannabis effect cognitive impairement
cannabis robustly impairs verbal memory
according to a meta-analysis study by schoeler et al, cannabis users perform worse on various domains of memory
CBD may protect hippocampal integrity in cannabis users
some studies show IQ test scores may bed reduced in cannabis users
how is cannabis associated with pleasure
CB1R agonists induce similar neurochemical events in the mesolimbic system to those produced by other drugs of abuse:
increased dopamine release, attenuation of evoked GABA and Glutamate release in the nucleus accumbens
the induced increase in opioid peptide release in the nucleus accumbens probably also contributes to the acute rewarding effects of THC
how many cannabis be used medically
there is moderate quality evidence to support the use of cannabinoids for treatment of pain and spasticity
low quality evidence suggesting cannabinoids are associated with improvements in nausea and vomiting due to chemotherapy, weight gain in HIV infection, sleep disorders and tourette syndrome
CBD may be used medicinally to treat: psychosis, epilepsy, anxiety, there is an ongoing trial to see whether it may be used to treat addiction
a study where patients with schizophrenia were either given 1000mg/day of CBD vs control, patients with CBD showed better improvements than control
what proportion of young people in the UK have used weed
11%
