Principles of Addiction Medicine

Addictions can also be viewed through a social and political lens.[1]

  • Stimulants (dance) - cocaine, amphetamine, Ecstasy, crystal meth, GHB
  • Alcohol (chill) - alcohol, benzodiazepines
  • Hallucinogens (outer space) - Marijuana, LSD, PCP, magic mushrooms, mescaline
  • Opiates (numbing) - (opiates) heroin, morphine

Physiological Tolerance

Physiological tolerance is best understood using the example of opioids:

  • When the brain is chronically exposed to elevated levels of opiates, two things develop: (1) opioid tolerance and (2) opioid dependence. Tolerance is the need to take more of the same substance to achieve the same effect, and dependence is being susceptible to opioid withdrawal symptoms. You can only develop withdrawal symptoms if you develop tolerance first.[2]
  • When morphine binds to opiate receptors, it triggers the inhibition of adenylate cyclase, which triggers cytokines to fire impulses. With repeated activation of the opiate receptor by morphine, the enzyme adapts so that morphine no longer cause changes in cell firing. Thus, the effect of a given dose of morphine or heroin is diminished.

Environmental (Learned) Tolerance

Tolerance can also be learned or developed through environmental exposure. This is much like Pavlovian conditioning (Pavlov's Dogs), where environmental stimuli can trigger innate physiological responses. For example, for a heroin user who frequently injects in his bathroom at home, his body will adapt to develop increased tolerance to opiates at that time. If, however, he decided to go rehab, and not use for several weeks, and then injected in a a foreign location, his body develop this same learned tolerance, and thus this makes him more susceptible to an overdose.[3] Cases have been reported of patients overdosing due to Pavlovian conditioning.[4]