Now this is an interesting little article that looks at the theory of 'the hijacked brain' and whether addiction is 'disease or choice'.
Me personally I believe drug use is a choice. There is a difference between using drugs and being addicted to drugs ....however when a human body is experiencing physical addiction and goes through the stage of withdrawal I believe that the brain will override any 'choice' you maybe making unless you really are choosing to continue to go through withdrawal. But if in the back of your mind your thinking 'I actually like using drugs and I probably will do it again sometime soon" then your 'choice' may change from 'not using drugs' to 'stop the physical pain'.
It is complicated, however the only people who really know are the people that are using drugs the rest of the commentators are just theorising or using information that they got from people who use drugs
So lets give credit where it is due and stop using stupid language like 'Hijacked Brain' as a way to dismiss an individuals right to choose.