Thread: What causes physical dependancy on drugs during misuse?

What causes the body to become physically dependant on drugs during drug abuse/misuse (this could be prescription medication, illegal drugs, alcohol, nicotine etc.)? What causes a person to become physically dependant on drugs and then suffer physical withdrawal symptoms after they cease taking them?

What exactly do these drugs do to the body that causes it to become dependant - a problem much more severe than psychological addiction. Psychological dependancy is caused by an addiction to the feeling the drug instigates, but physical dependancy is clearly something more complex.

Thank you

There are many mechanisms which result in physical dependence, mainly due to either up regulation or down regulation of pathways which are changed due to the presence of the drug. For example – opiates which act on the mu receptor in the CNS to produce the euphoria (all addictive drugs result in a “reward” due to increased dopamine release in the mesolimbic pathway) by stopping the breaking mechanism of this system. Action of opiates also result in up regulation of certain pathways in the CNS (and peripherally but I’m not sure on what exactly) cAMP in the locus coeruleus being one, which results in physical withdrawal. One example of many.


The bottom line is that taking any drug changes the body’s natural physiology, alters pathways which the body can adapt too. Then when the drug is stopped, the adaptation to accommodate the drug is still there.


For example (out of my head – but relevant I think) a drug, such as opiates again, which by whatever mechanism slows GIT movement, results in an adaptation of physiology, e.g. hyper movement. Then if the drug is removed, the body is still in the hyper digestion state but the drug is no longer slowing down the system so we see symptoms.

I don’t think it’s possible to put one explanation on all drug withdrawal but the bottom line is the same principle.