Posted by ed_uk on December 5, 2004, at 5:13:57
In pharmacology at university we are taught that people who are tolerant to the benefits of a drug will always experience withdrawal symptoms and people who experience withdrawal symptoms must have developed at least some tolerance to the therapeutic effects of the drug. In reality, however, the situation seems to be rather more complex. Both tolerance and withdrawal symptoms appear to be due to the brains almost infinite capacity to adapt to the presence of foreign substances. Some people experience withdrawal symptoms from ADs (and APs) despite the absence of any signs of tolerance to the benefits of the drug (Beware! This argument has been used to deny the fact that ADs are associated with physiological dependence). Equally, some people develop tolerance to the benfits of a drug and are consequently able to discontinue without any obvious signs of withdrawal. Some people are unlucky enough to experience both profound tolerance to the benefits of a drug and severe withdrawal symptoms on stopping.
One possible explanation for this could be that the adaptive changes in the brain which are responsible for withdrawal symptoms are not necessarily associated with tolerance to the therapeutic efficacy of the drug. On the other hand, some people may develop adaptive changes which are associated with both therapeutic tolerance and withdrawal symptoms......... and finally some people may develop adaptive changes which are associated with therapeutic tolerance but not withdrawal symptoms. In other words, different people's brains may adapt to the presence of a psychotropic drug in very different ways. YMMV!
What do you think? What is the relationship between tolerance, withdrawal and physical dependence?