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Cannabis and Schizophrenia. Major Constituents of Cannabis. The two major substances found in cannabis include tetrahydrocannabinol (THC) and cannibidiol (CBD) THC is the major psychoactive substance found in cannabis
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Major Constituents of Cannabis • The two major substances found in cannabis include tetrahydrocannabinol (THC) and cannibidiol (CBD) • THC is the major psychoactive substance found in cannabis • THC acts as an agonist while CBD acts as an antagonist by having the same effect as neuroleptics
THC • THC effectively acts as a dopamine agonist, thus blocking the reuptake of dopamine and L-DOPA (which stimulates the synthesis of dopamine) • Produces an overactivity of dopaminergic synapses in the nucleus accumbens • Dopaminergic neurons are involved in reinforcement.
Areas of The Brain Most Affected by THC • Basal Ganglia, and the Cerebellum (Motor Tasks) • Hippocampus (Short-Term Memory) • Cannabinoids inhibit the transmission of neural signals
Correlation Between THC and Schizophrenia • A relatively small proportion of cannabis users develop psychosis • Explained by the amount and duration of the consumption of cannabis, its strength, and also the age at which individuals are exposed to cannabis • Genetic factors – COMT (catechol-O-methyl transferase)
Those Most at Risk of Developing Schizophrenia • Users under the age of 21, as the human brain has not fully matured • Users under the age of 15 are 4.5 times more likely to develop psychosis by the age of 26 • An increase in the concentration of dopamine in a developing brain increases the likelihood of developing schizophrenia in early adulthood
CBD • Cannabidiol (CBD) represents up to 40% of cannabis extracts • Found to reduce schizophrenic symptoms by blocking dopamine receptors • Prevents the storage of monoamines in synaptic vesicles • Cannabidiol has no affinity for CB1 receptors • http://www.youtube.com/watch?v=gAfs_No8lE8