I am well aware that high dopamine release causes addiction because it activates the reward centres in the brain... Like with heroin, opioids causes dopamine release (via the disinhibition of GABA) and that causes activation of reward centres in the brain... You get addiction... With amphetamines it is the same story... They cause dopamine release and they cause addiction... But I am a bit confused about some of the drugs... I was learning about Parkinsons disease medication today and got a bit confused... Levodopa - it is the precursor of dopamine and it is used in order to treat parkinson's disease... It travels through the blood brain barrier, where it is decarboxylated to form dopamine - and yet this increase in dopamine levels in the brain but it is not addictive... Bromocriptine is a dopamine receptor agonist... It is given when levodopa is no longer effective... Since it activates the same receptors are dopamine - surely this would make it addictive?... But levodopa and bromocriptine don't seem to be addictive as far as i know... so anyway, does anyone know why they aren't addictive?