The relationship between these two conditions is so strong that depression is often one of the first conditions healthcare providers look for when diagnosing chronic pain. While the relationship isn’t yet fully understood, researchers are learning more about it all the time.
That means pain and depression aren’t things you just have to live with. You have numerous options for treating and managing both issues, no matter which one came first.
What Is Depression?
More than a feeling of sadness or low mood, clinical depression is a psychological state that causes fatigue, lack of motivation, appetite changes, slowed response time and feelings of helplessness. Depression has physical symptoms as well, including pain and difficulty sleeping.
You can’t just “shake off” clinical depression or “snap out of it.” Sometimes you can point to factors in your life that cause or contribute to depression, such as losing a job or the end of a romantic relationship. Sometimes there’s no identifiable cause, yet the symptoms persist.
In large part, that’s because while depression is characterized by mental and emotional symptoms, it has physiological causes. These include dysregulation of certain neurotransmitters, which are chemicals your brain uses to send signals from one brain cell to another.
What Is Chronic Pain?
Pain becomes chronic when it’s ongoing, whether it’s constant or frequently occurring. Some definitions say it’s chronic if it lasts for more than three months, as in this 2014 research review, while others say six months.1
As with depression, chronic pain sometimes has a cause that you can easily identify, such as arthritis or an injury. Some types of chronic pain, though, have no obvious cause or may be pain that’s lingered abnormally long after damage has recovered.1
Chronic pain is a major health problem, with as many as 20% of people in the United States and Europe living with it.2
Chronic pain can wear on you, mentally and physically. It can disrupt sleep and leave you exhausted and in a foul mood. It can make you unable to do things you enjoy, and it even costs some people their jobs.
Given that, it’s no wonder that people who suffer from chronic pain also have recurrent clinical depression. Scientists estimate that as many as 85% of people with chronic pain are affected by severe depression.2
It makes sense not only from the emotional aspect but from the physical perspective, as well. Your brain has to process every pain signal that’s sent, which means it gets over-worked by chronic pain. Constantly processing pain signals can lead to dysregulation of certain neurotransmitters—the same neurotransmitters involved in depression.
On top of that, researchers have identified at least six regions of the brain that deal with both mood and pain processing.2
Does Depression Cause Pain or Vice Versa?
When pain is a symptom of depression and depression often strikes people with chronic pain, and they both involve some of the same physiological problems, how do you know which one came first? You might not, and that makes the situation especially hard for you and your healthcare provider to figure out and treat.
Going deeper into the physiology, one of the reasons chronic pain and depression are so interwoven is because of the way stress works in the body.
When you’re in pain, the areas of your brain that respond to stress fire up. The brain sends the body into fight-or-flight mode, flooding your system with adrenaline and preparing to fight off or escape whatever is causing the pain. Normally, when the pain goes away, those stress signals turn off and your body goes back to a relaxed state.
When you have chronic pain, though, the fight-or-flight signals never turn off, and the nervous system stays in a constant state of high alert. Too much stress without time off eventually wears the body down.3
That leaves you vulnerable to the physical realities that cause clinical depression, including an inability to produce enough neurotransmitters and stress hormones for your body to cope.4
So if you start out with chronic pain, it can lead to depression, which can increase your pain, which can deepen depression, and it’s a downward spiral. And if you start with depression, it can lead to chronic pain, which can deepen depression, which increases your pain, and so on.
Finding ways to deal with stress and cope with chronic pain can give you a head start in the battle against depression.
You do have treatment options, though, and sometimes, one treatment may target both pain and depression, thanks to their common physiology.
Use of Antidepressants to Treat Depression and Chronic Pain
The class of medications called antidepressants is used for both depression and chronic pain. This confuses a lot of people. They think their practitioner believes their pain is psychological or “all in their heads.”
In reality, though, the use of antidepressants for pain control is scientifically based and has been standard practice for more than 50 years. Even at low doses, these medications cause chemical changes in the brain (those neurotransmitters again) that alter the way pain is perceived and bring relief to a lot of people. So even if you’re not depressed, your healthcare provider may prescribe an antidepressant to treat your pain.
Antidepressants used to treat chronic pain are from three main classes:
- Tricyclics: These drugs increase the amount of two neurotransmitters—serotonin and norepinephrine—that’s available to your brain and block the action of a third neurotransmitter, acetylcholine. The most common tricyclic used for chronic pain is a low dose of Elavil (amitriptyline).
- Selective Serotonin Reuptake Inhibitors (SSRIs): These drugs increase the amount of serotonin available to your brain by slowing down a process called reuptake. Common SSRIs for pain are Celexa (citalopram), Lexapro (escitalopram), Paxil (paroxetine), and Zoloft (sertraline).5
- Serotonin-Norepinephrine Reuptake Inhibitors: These drugs increase the amount of both serotonin and norepinephrine that your brain has available at any given time. A common one used for pain is Cymbalta (duloxetine).6 (A similar drug called Savella (milnacipran) is primary used for treating the pain of fibromyalgia. It’s not approved in the United States for treating depression, but that’s its primary use in numerous other countries.)7
In addition to treating the pain itself, taking antidepressants for pain can stop the cycle that leads to depression before it begins, or at least provide a running start.
Once again, the relationship works both ways—drugs created to treat chronic pain may have an impact on depression, as well.
Research on the common painkiller class of opioids (also called opiates or narcotics) shows promise in treating clinical depression.2 However, given the massive social problem involving opioid abuse and overdose,8 it’s unlikely that these drugs will become widely used for depression.
Psychotherapy is a common treatment for clinical depression, and you might think that it would be ineffective against chronic pain that’s not caused directly by depression. However, some psychotherapy has been shown to help manage chronic pain.
An approach called cognitive-behavioral therapy (CBT) has been shown repeatedly to help people with chronic pain change their behavior and lifestyles in ways that help them manage and cope with their pain. It can also help them become less fearful of and demoralized about their pain.5
With stress playing a role in both chronic pain and depression, learning to manage it can make a big difference. Methods that have been shown to help include:
- Mindfulness meditation
- Deep breathing
- Movement therapies, such as yoga and tai chi
- Guided imagery