crack

As a rule of thumb, it is profoundly unwise to take crack-cocaine. The brain has evolved a truly vicious set of negative feedback mechanisms. Their functional effect is to stop us from being truly happy for long. Nature is cruelly parsimonious with pleasure. The initial short-lived euphoria of a reinforcer as powerful as crack will be followed by a "crash". This involves anxiety, depression, irritability, extreme fatigue and possibly paranoia. Physical health may deteriorate. An intense craving for more cocaine develops. In heavy users, stereotyped compulsive and repetitive patterns of behaviour may occur. So may tactile hallucinations of insects crawling underneath the skin ("formication"). Severe depressive conditions may follow; agitated delirium; and also a syndrome sometimes known as toxic paranoid psychosis. The neural aftereffects of chronic cocaine use include changes in monoamine metabolites and uptake transporters. There is down-regulation of dopamine D2 receptors to compensate for their drug-induced overstimulation. Thus the brain's capacity to experience pleasure is diminished.