Question: What properties in drugs make them addicting?

Frances Shiely answered on 11 Nov 2019:

The science behind addiction is so complex that scientists have been studying addiction since about 1875. When a brain’s reward pathway has repeated exposure to an addictive drug, it can drive the compulsion to continue seeking more of that drug due to the way that part of the brain is designed. When receptor-active drugs such as opioids are consumed, their molecules (tiny particles) look just like natural molecules (tiny particles) in our brain. Drug molecules bind to certain receptors in the human brain, causing it to activate and trigger a response in the cell. With opioids (a class of drug like Heroin), these drug molecules are of specific opioid receptors, triggering feelings of euphoria and happiness when they bind together. These drugs are structured in such a way that they mimic natural molecules create a natural feeling, like happiness, but in a much stronger way. This is how the “high” of opioid drugs is best explained.

These terms and the science behind them may sound confusing, but a good way to imagine this is by using an analogy of a key and a lock. Think of the natural molecules in your brain as the “master key” to the cell in your brain, which is the lock. These natural molecules are naturally present in your body, so when you are happy and content, those keys naturally fit into the locks and open the door to a natural happy feeling. Drug molecules are a “spare set” of keys. They are just like the master key, only slightly irregular and they will still open the “door” of the cell to create the same feelings of happiness, but unnaturally, and often much more intensely