Huh???

All drugs can cause tolerance if used regularly, especially opiates.  The dopamine receptors are NOT destroyed.....that's completely erroneous.  What happens is it takes more med/drug to get the dopamine boost the more one uses and the transient dopamine increase  is what causes the high in the first place.  It's like the thermostat is reset.  Abstinence can cure the problem, though, and then the dopamine level goes back to normal, so abstinence does make the mind grow finer...  If the dopamine receptors were destroyed, it would result in a severe acute Parkinsonian syndrome, not a heart attack or respiratory failure (which don't result from damage to the dopamine receptor anyways, that I know of).    To date, there is only one drug known to do just that, and that is/was heroin laced with MPTP.  It caused a severe acute Parkinsonian syndrome in people who "chased the dragon", ie inhaled the fumes of cooked  heroin.  The adulterant MPTP has been purified and is currently very much in use in Parkinsons research, creating animal models of various syndromes and to help with pharmaceutical testing.  Sounds like your rehab people need to do a little more study before they give such "information".   I take a very dim view of some of the rehab programs, from what I've read about them, but I hope you are doing well, and that it is helping you out.   Scare tactics and mis-information tend to ruffle my feathers though. 

This is just a snippet taken from Wikipedia on bio mechanisms of addiction.   The receptors available are decreased because there are too many bound with dopamine (since the dopamine level is higher as I mentioned above), but they are not destroyed.    Big difference.  

The human body has a natural tendency to maintain homeostasis, and the central nervous system is no exception. Chronic elevation of dopamine will result in a decrease in the number of dopamine receptors available in a process known as downregulation. The decreased number of receptors changes the permeability of the cell membrane located post-synaptically, such that the post-synaptic neuron is less excitable- i.e.: less able to respond to chemical signaling with an electrical impulse, or action potential. It is hypothesized that this dulling of the responsiveness of the brain's reward pathways contributes to the inability to feel pleasure, known as anhedonia, often observed in addicts. The increased requirement for dopamine to maintain the same electrical activity is the basis of both physiological tolerance and withdrawal associated with addiction.