So.... you have chronic pain and the stupid doctors keep trying to put you on an antidepressant. WTF? You keep saying, "I'm NOT depressed."
Here is why.
We really don't understand the brain very well. The brain is really really complicated and essentially we have stone age tools. We use them because that's all we have.
And.... we know that there are similarities in the brain in depression and chronic pain. Serotonin is low in the brain between the cells in both depression and chronic pain. Serotonin is a neurotransmitter. The delightful thing is that there is more than one receptor for serotonin and we don't actually know what it does in the cells. It does something. There is a rat neuron that has been studied and has 300 different kinds of receptors for one neurotransmitter. The scientists figured out how to block one of the 300 types. The rats then acted obsessive compulsive. However, we don't know what the other 299 do or what combinations do. That's why I think we are in the stone age regarding the brain.
Things that lower serotonin between the cells and other cell receptors include:
Things that raise serotonin between the cells and other cell receptors in the brain:
the other antidepressants (tricyclics, SNRIs, and the weird outliers)
So we primary care doctors, when confronted with chronic pain and trying to figure out if we can fix it, will give an antidepressant. Not to make the person less depressed. We are trying to increase the intracellular serotonin in the brain because that lowers chronic pain levels. The tricyclics seem to be the best for this. They are old drugs, have side effects, and an overdose is bad.* However, studies show over and over that they work the best for reducing chronic pain if you can convince a patient to use them. Patients in studies tend to be pretty motivated and anyhow, they have signed about half a million consents, so they are committed. The fun thing about studies is that in cholesterol studies the placebo patients have a drop in their cholesterol TOO, because they know they are going to be tested again. It's the Big Brother Effect or possibly the Nagging Effect. I just made those up. I hope the Nagging Effect goes viral.
Why don't we just give opiates? Well a) they are addictive and b) they don't work. The brain has evolved (or is designed) to pay attention to pain. If you block the receptors with opiates the brain says "Gaaakkk! The pain receptors are dead! Change the cells!" The brain then cranks up the sensitivity to pain until it feels it. The brain considers pain to be important information that helps us survive and actually it is correct. The patient then notices that they are hurting again and the doctors (at least in the United States) were trained to Give Them More. Then the brain does it again until the person croaks from an overdose or is addicted or state laws change, leaving them in withdrawal. This has made buckets of money for drug companies who happily put out More and Stronger opiates and now Drugs To Fix Opiate Addiction. I have asked how long it takes to get hooked. The National Institute of Health website and Manchild in the Promised Land (by Claude Brown) agree that one use of heroin is pretty compelling. An older doctor who had worked in a pain clinic said that some folks get hooked after a week of continuous pain pill use. The UW Pain Clinic said that "By six months some patients' brains have changed." Our local pain and addiction specialist says that 20% of chronic pain patients are hooked. Why aren't they all hooked? It turns out that our brains are different. How amazing.
And that is why your doctor will ask you to take an antidepressant to reduce chronic pain.**
*doctor talk for "can kill you".
**if doctors weren't so dense, we would call them "chronic pain lowering medicines" instead of antidepressants