eli5 what exactly is happening to the brain during opiate withdrawal and how does it translate into the most horrific feeling throughout literally the entire body and mind?
In: Chemistry
The human brain is made up at a network of cells that communicate with each other. One part of that communication is the release of chemicals that aid on the sending of signals from cell to cell.
Opioids mimic the chemicals that aid in sending signals. Specifically, they mimic the signal these cells use to recognize “pleasure”, and block those that recognize “pain”. So when a person takes opioids, their brain feels little pain (which is why they are used in medicine) and a lot of pleasure (which is why they are used recreationally).
However, the brain has mechanisms that recognize when things are out of balance. If you take opioids regularly, the brain grows a lot more pain receptors. This results in “habituation” – the user now needs more opioid to have the same effect … because the brain now acts as if having opioids is normal. In short, the brain ‘wants’ to get back into balance (obviously not consciously) do that it experiences the ‘right’ balance of pain and pleasure – because these are signals that are useful for survival (they reinforce useful actions).
The brain is capable of growing or taking away receptors. The problem with this is that there is a long lag time either way. The brain doesn’t adjust right away.
So, if a user of opioids who is ‘habituated’ by having a lot of pain receptors (because their brain is usually awash with opioids) suddenly has no more opioids – why then, the brain of that user, which now is loaded with pain receptors, acts as if it is getting tons of pain signals. The user feeds, well, very bad.
This lasts until the brain recognizes it is messed up – out of balance yet again. The brain starts shrinking pain receptors. If the user can stand going through this ‘cold Turkey’ phase, their brain can, eventually, return to the pre-opioid state.
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