Originally Posted by
Upsetnneedhelp 
The title of this thread just caught my eye and brings up a lot of emotions. To the OP, why did you not pick obesity or heart disease? My son went to over a dozen treatment centers. Just as some people don't beat cancer despite the most aggressive treatment. Not everyone can get clean and sober even when they want to more than anything in the world.
That is the saddest part; there are people who want it more than anything but they are unable to attain it. This link from National Institute of Drug Abuse might be helpful to you:
Drugs and the Brain | National Institute on Drug Abuse
Chronic exposure to drugs of abuse disrupts the way critical brain structures interact to control and inhibit behaviors related to drug abuse. Just as continued abuse may lead to tolerance or the need for higher drug dosages to produce an effect, it may also lead to addiction, which can drive an abuser to seek out and take drugs compulsively. Drug addiction erodes a person's self-control and ability to make sound decisions, while sending intense impulses to take drugs.