An addict’s life is ruled by cravings ? to the exclusion of all else ? caused, in part, by changes to the path of neurons within the brain, referred to as the ‘reward circuit’ or ‘pleasure system’.
Experiments carried out, on rodents with significantly similar biochemical processes to humans, had conclusive results. Electrodes were attached to points in the brain, corresponding to the ‘reward circuit’. When the rodents pressed a lever in their cage, a small electrical current travelled, via the electrodes, directly to the rodent’s reward circuit. Significant numbers of the rodents pressed the lever compulsively, thousands of times, until they finally collapsed with exhaustion.
Similarly, in humans, repeated use of drugs or alcohol produces an overpowering urge to drink or use drugs, thus changing what was previously a voluntary behavior into an involuntary one.