Chronic pain is pain that lasts or keeps returning for more than three months. The ICD-11, the World Health Organization’s diagnostic system, also recognizes chronic primary pain, which is linked to emotional distress or disability (Treede et al., 2015). It is common. In a 2016 national survey, Dahlhamer and colleagues (2018) found that about 20% of U.S. adults had pain on most days, and about 8% had pain that limited work or daily activities.
Doctors use the term treatment-resistant depression for depression that has not improved after at least two adequate antidepressant trials. The first awareness day devoted to it shows that more people are now looking for reasons why some patients do not recover. Untreated or undertreated chronic pain is one of the reasons worth checking.
Why chronic pain and depression so often appear together
The two conditions overlap more than most people expect. In a review of the literature, Bair and colleagues (2003) found that on average about two thirds of people with depression also reported pain. Depression was also common among people attending pain clinics, and considerably more common there than in primary care.
Part of the explanation is that pain and low mood use some of the same brain regions and chemical messengers, including serotonin and norepinephrine. Hooten (2016) reviewed this shared biology, along with the epidemiology and the treatment implications. The relationship probably runs in both directions. Pain can lead to depression, and depression can make pain feel stronger and harder to tolerate.
Most of the evidence is observational, so it cannot show that one condition causes the other in a particular person. In practice the order of events matters less than the fact that both conditions are present. Treating only one of them often leaves the other untouched.
Consider a man in his fifties with lower back pain after years of warehouse work. He tried two antidepressants and felt little change. He was sleeping four hours a night because of the pain and had stopped walking because he feared making it worse. His mood began to improve only when the pain, the sleep and the inactivity were treated as part of the same problem.
How pain makes depression harder to treat
Pain disturbs sleep, and poor sleep worsens both pain and mood. Pain also reduces activity. People stop seeing friends, stop exercising and stop doing the things that used to give them satisfaction. Each of these changes is a known contributor to depression, and each is a common result of living with daily pain.
Thinking patterns matter as well. Many people with chronic pain begin to expect the worst, avoid movement out of fear of harm, and see the pain as a sign of damage. These patterns are linked to more disability and lower mood. They can be changed with treatment, and they are a main target of psychological therapy for pain.
When depression does not improve with treatment, pain should be assessed and treated as part of the same plan.
Bair and colleagues (2003) also reported that more severe pain was associated with poorer outcomes of depression treatment. This is an association, not proof of cause. Still, it supports a simple clinical rule. If a person with depression is not getting better, the doctor should ask about pain, and a person with chronic pain should be screened for depression.
Medication choices deserve care. Opioids relieve short-term pain, but they are not an antidepressant, and long-term use carries risks, including dependence. Some antidepressants, such as duloxetine and low doses of amitriptyline, are also used for certain types of chronic pain. Whether one of them suits you depends on your diagnosis, other medicines and health, so it is a decision to make with your prescriber.
Practical steps to take with your doctor
Tell your doctor about both the pain and your mood, even if you came for only one of them. Many people mention only the symptom they think the visit is for. Say how long the pain has lasted, how it affects sleep and daily tasks, and whether you have lost interest in things you used to enjoy.
Keep a simple daily record for two weeks. Write down a pain rating from 0 to 10, your mood, the hours you slept and what you did that day. Patterns often appear that are hard to remember in an appointment, such as worse pain after a bad night or better mood on days when you walked.
Ask about psychological treatment. In a Cochrane review of psychological therapies for chronic pain in adults, Williams and colleagues (2020) found small benefits of cognitive behavioral therapy for pain, disability and mood. The certainty of the evidence was low to very low, so the benefits are modest. They are still worth having, because these therapies carry little physical risk and can be used with medication.
Increase physical activity slowly and on a schedule rather than waiting for a good day. Short walks that you lengthen by a small amount each week are often more manageable than occasional long efforts. A physical therapist can help you set a safe starting level. Keep regular times for going to bed and getting up, and avoid using alcohol to sleep, since it disrupts sleep later in the night.
If depression has not improved after two adequate treatments, ask whether pain, sleep problems or another condition is limiting the response. If you ever have thoughts of ending your life, contact a doctor, go to the nearest emergency department, or call the Suicide and Crisis Lifeline. Help for both pain and depression is available, and the two are best treated together.
References
- Bair, M. J., Robinson, R. L., Katon, W., & Kroenke, K. (2003). Depression and pain comorbidity: A literature review. Archives of Internal Medicine, 163(20), 2433-2445.
- Dahlhamer, J., Lucas, J., Zelaya, C., Nahin, R., Mackey, S., DeBar, L., Kerns, R., Von Korff, M., Porter, L., & Helmick, C. (2018). Prevalence of chronic pain and high-impact chronic pain among adults, United States, 2016. Morbidity and Mortality Weekly Report, 67(36), 1001-1006.
- Hooten, W. M. (2016). Chronic pain and mental health disorders: Shared neural mechanisms, epidemiology, and treatment. Mayo Clinic Proceedings, 91(7), 955-970.
- Treede, R.-D., Rief, W., Barke, A., Aziz, Q., Bennett, M. I., Benoliel, R., Cohen, M., Evers, S., Finnerup, N. B., First, M. B., Giamberardino, M. A., Kaasa, S., Kosek, E., Lavand’homme, P., Nicholas, M., Perrot, S., Scholz, J., Schug, S., Smith, B. H., … Wang, S.-J. (2015). A classification of chronic pain for ICD-11. Pain, 156(6), 1003-1007.
- Williams, A. C. de C., Fisher, E., Hearn, L., & Eccleston, C. (2020). Psychological therapies for the management of chronic pain (excluding headache) in adults. Cochrane Database of Systematic Reviews, 2020(8), CD007407.
