Depression, Emotion, and Physical Pain

Harvard Health describes pain, and chronic pain in particular, as something more than a physical sensation. They call it an emotional condition, a complicated experience that reaches into thought, mood, and behavior, and one that can leave a person isolated, unable to move freely, and at risk of leaning on drugs. Pain and depression tend to travel together. One can trigger the other, and depressive symptoms can sharpen pain that already exists. Researchers have put a number on it: someone living with chronic pain carries roughly three times the usual risk of developing a mood or anxiety disorder. The reverse holds too, with depressed patients facing about three times the normal odds of ending up with chronic pain.

Several of the drugs that psychiatrists already rely on turn out to do double duty, easing mental health symptoms while also quieting physical pain. SSRI antidepressants, mood stabilizers, and anticonvulsants can all take the edge off anxiety, depression, and bodily discomfort at once. Two broad families of antidepressant come up most often here. Tricyclics are one; selective serotonin reuptake inhibitors, the SSRIs, are the other. Amitriptyline, sold as Elavil, is a tricyclic that doctors frequently reach for as a painkiller, partly because its sedating effect helps with the pain complaint itself. SSRIs like fluoxetine (Prozac) and sertraline (Zoloft) tend to come with fewer side effects, though they do not relieve pain as reliably. Some clinicians split the difference, giving a patient an SSRI through the day and amitriptyline at night.

Why would both classes work on pain at all? According to Harvard Health, each acts inside brain pathways that govern mood and the way pain is perceived. Tricyclics push up the activity of two neurotransmitters, norepinephrine and serotonin, while SSRIs work more narrowly on serotonin alone. A newer so-called dual-action drug, venlafaxine (Effexor), hits both chemicals hard, and certain researchers and clinicians argue it beats both the tricyclics and the SSRIs for pain. The evidence, as Harvard Health put it, remains inconclusive.

Migraines show up in this picture as well. People wrestling with depression and anxiety often report them, and the numbers back up the link. Depression touches more than 10% of Americans. One study tracked people over two years and found that a person with a past bout of major depression was three times likelier than average to suffer a first migraine attack, while someone with a history of migraine was five times likelier than average to have a first stretch of depression. Given how thoroughly depression can throw the nervous system off balance, pain reads as a reasonable thing to expect.

Harvard Health lays out the mechanics of that overlap. Signals between body and brain run both directions. Ordinarily the brain shunts aside messages of physical discomfort so attention can stay on the outside world. Let that shutoff falter and physical sensations, pain among them, start crowding to the front of the mind. The pathways that take in pain signals, including the limbic region where emotion lives, draw on some of the same neurotransmitters that steady mood, serotonin and norepinephrine chief among them. When that regulation breaks down, pain grows worse and so do sadness, hopelessness, and anxiety. Chronic pain, much like chronic depression, can rewire how the nervous system behaves and keep itself going.

So patients handed a diagnosis of depression routinely report chronic pain, and patients fighting chronic pain routinely report feeling depressed. The study of how the two intertwine is still young, but it is picking up backing from medical work that documents real changes in the brain and nervous system. Diagnoses of depression keep climbing, and so do reports of pain, which is reason enough for research to keep digging into this mind-body connection and to settle on the best way to treat both ends at the same time. Because psychiatric medication can do something for pain, psychiatrists and pain management specialists both stand to benefit from ongoing training that prepares them to address the medical and the psychological together.