Chronic Pain: The Brain-Body Connection

Pain

What our perceptions tell us about the experience of pain, chronic or otherwise

Pain is universal, subjective, and one of the leading causes of disability. Culture, temperament, mental state, memory, cognitive beliefs, expectations, co-occurring health conditions, gender, age, and other biopsychosocial, sensory, and emotional experiences form our perception and responses to pain.

According to a recent study conducted in 2016 by the National Health Interview Survey, approximately 20 percent of U.S. adults reported chronic pain, while 8 percent experienced high-impact pain (pain lasting more than three months and restricting at least one significant life activity.) 

People with high-impact pain also experience a higher frequency of healthcare utilization, mental health problems, and difficulty caring for themselves than individuals with chronic pain.

Individuals with chronic pain are four times more likely to have depression or anxiety than those who are pain-free. In a National Health Interview Survey (NHIS) from 2015-2017, the researchers found: 

  • An estimated 10.3 million U.S. adults with arthritis reported anxiety, depression, or both. 
  • The prevalence of pain was substantially higher among younger adults than among older adults with arthritis.
  • The incidence of anxiety exceeded that of depression. Fewer adults with anxiety reported taking medication than those with depression.
  • Disability and inability to work resulted in higher rates of anxiety and depression than those who were employed. Adults 18-64 years reported a higher incidence of each than those > 65 yrs.
  • One out of five persons with arthritis and major depression admitted suicidal ideation within the past year, and only half received treatment for anxiety.
  • Mental health conditions and arthritis are among the top two causes of work disability among adults 18-64 years in 2011-2013.

Frequent Chronic Pain Conditions with Mental Health 

Osteoarthritis: Depression often occurs due to pain, decreased activity level, and impaired joint mobility. OA results in decreased independence with daily living activities, isolation, and frustration with the inability to meet life’s demands. 

Rheumatoid Arthritis: An autoimmune disease, chronic inflammation leads to permanent joint damage. An individual experiences pain, difficulty with activities of daily living, social isolation, and depression ensues.

Psoriatic Arthritis: The immune system attacks the body, causing inflammation and pain; joints, connective tissue, and the skin are affected. Specific mood and anxiety disorders occur at higher rates with PsA.

Fibromyalgia: A chronic, multi-system disease where the brain and spinal cord process pain signals differently. FM is associated with widespread pain in the muscles and bones. Alterations in pain perception occur with areas of tenderness and fatigue. FM affects 2 percent to 3 percent of the population; however, more than 90 percent of the patients are women. FM affects energy and general health. Anxiety, especially obsessive-compulsive disorder (OCD), is five times higher in women with FM than the general population.

Multiple Sclerosis: Damage to the myelin of nerves disrupts communication between the brain and body. Anxiety, depression, and pseudobulbar affect- pathological laughing and crying are the three most common mental health concerns. Generalized anxiety disorder (GAD) appears to be the most common anxiety disorder among persons with MS. Panic disorder, and OCD may occur more frequently among MS patients than the general population.

Back/Neck Pain: In a study of 190,585 participants ages 18 or older across 43 countries, the data analysis revealed that people with back pain were more than twice as likely to experience anxiety, depression, psychosis, stress, and sleep deprivation compared with those without back pain. A chronic painful condition also increases the duration of depressive symptoms.

Chronic Migraines: Evidence suggests that chronic migraines and mental health conditions frequently co-occur with an increased prevalence of major depression and anxiety. Individuals with migraine are 2 to 3 times more likely to be diagnosed with generalized anxiety disorder (GAD), agoraphobia, panic disorder or PTSD than individuals without migraine. Conversely, individuals with anxiety are predisposed to developing migraines. Neuroimaging studies indicate both chronic pain and anxiety activate overlapping brain areas (thalamus, PFC, ACC). Migraines are associated with poorer health-related outcomes such as disabilities, restricted activities, and an increase in mental health care services.

Bidirectional Relationship Between Pain and Mental Health Disorders

Chronic pain and mental health disorders are common in the general population. Epidemiological studies indicate that a bidirectional or two-way relationship exists between these two conditions with shared neural mechanisms. In addition to depression, anxiety, and substance use disorder, individuals with chronic pain are at risk for suicide, nicotine addiction, and many have sustained sex violence.

Functional imaging studies support the bidirectional relationship between pain and depression. Various chronic pain conditions, including fibromyalgia, abdominal pain and low back pain are associated with functional imaging alterations in brain regions responsible for processing emotional stimuli, the anterior cingulate cortex (ACC), and the prefrontal cortex (PFC). In depressed adults, emotional processing in the insula shifts toward an insular region associated with processing pain stimuli in healthy individuals.

Like depression and anxiety, a two-way relationship exists between chronic pain and substance use disorder. The estimated incidence of chronic pain in individuals with substance use disorder (SUD) ranges from 27 percent to 87 percent. Individuals with chronic pain are more likely to develop a SUD, and individuals with SUD are approximately 1.5 times more likely to develop chronic pain.

Chronic pain is an independent predictor of depression, and if depression is untreated or inadequately, there is an increased risk for developing chronic pain syndrome. Post-Traumatic Stress Disorder (PTSD) is associated with an increased risk of developing pain. Early childhood trauma and stress can predispose an individual to developing pain later in life.

Chronic Pain and Severe Mental Illness

Individuals with bipolar disorder type 2 are three times more likely to experience migraines than the general population. Musculoskeletal conditions such as low back pain, arthritis, and hip problems are more prevalent among bipolar disorder than the general patient population at the Department of Veteran Affairs.

Researchers at Boston University examined the associations between clinical pain and global functioning in a sample of 898 participants with schizophrenia or schizoaffective disorder, bipolar disorder, and major depressive disorder (MDD) receiving treatment. The results found that more than one-half demonstrated some measure of pain interference ranging from moderate to severe reported by 33 percent of the participants. 

The participants with MDD reported increased pain interference with daily living activities in the past month compared with those with bipolar or schizophrenia. The researchers concluded that individuals with serious mental illness need screening for pain and potential targeted interventions to decrease the effects of it on functioning. Additionally, a critical takeaway from the study is that pain is a significant factor affecting several aspects of life for those with severe mental illness.

Treatment Options

Cognitive Behavioral Therapy (CBT): An evidence-based psychotherapy based on the premise that thoughts, feelings, and sensations are interrelated. CBT helps individuals develop coping strategies and problem-solving approaches for managing health-related problems posed by pain.

Acceptance-Based Therapies: Acceptance and commitment therapy and mindfulness-based stress reduction are two widely used approaches in pain management. The clinical outcomes for acceptance and commitment therapies are mixed. Functional neuroimaging studies suggest that mindfulness meditation reduces activation of the primary somatosensory cortex and enhances brain regions involved in the cognitive regulation and reappraisal of pain.

Multidisciplinary Pain Management (also known as interdisciplinary pain management) is an integrated approach for pain management by a team of healthcare professionals who share common goals. The team consists of physicians, pain specialists, nurses, psychologists, occupational and physical therapists, vocational specialists, and pharmacists. This approach is associated with a significant reduction in pain intensity, functional disability, sustained employment, and reduced medical costs.

Aerobic and strengthening exercises show notable improvements in strength, cardio fitness, and pain perception. Additionally, opioid tapering demonstrates significant reductions in medication costs without compromising treatment outcomes.

Pharmacological Treatments

Serotonin-norepinephrine reuptake inhibitors (SNRIs): The selective reuptake of norepinephrine has an analgesic effect on pain. Venlafaxine is most effective in treating the pain symptoms of depression. SSRIs increase the risk of gastrointestinal bleeding.

Tricyclic Antidepressants (TCAs): These antidepressants are effective in treating neuropathic pain, low back pain, and fibromyalgia. TCAs increase the risk for dizziness, constipation, blurred vision, and difficulty urinating. The most severe side effect is a dangerously abnormal heart rhythm, therefore, contraindicated for those with heart disease.

Anticonvulsants: Several anticonvulsants such as gabapentin treat a wide range of pain and mental health conditions. Gabapentin is effective for fibromyalgia and neuropathic pain.

Lifestyle Changes: Adopting a healthy lifestyle such as exercise, stress management, improved sleep quality, and diet can reduce pain, increase energy, and improve quality of life for those suffering from pain and mental health disorders.

Complementary Approaches: Yoga, tai-chi, qi gong, meditation, progressive muscle relaxation, breathing techniques, acupuncture, hypnosis, massage, spinal manipulation, and supplements such as glucosamine show promise in reducing pain symptoms.

Conclusion

A reciprocal relationship exists between pain and mental health disorders with shared neural mechanisms. Untreated or inadequately treated depression and anxiety predispose an individual to develop pain. Conversely, if pain persists, an individual is at risk for experiencing depression and anxiety. High-impact pain is one of the leading causes of disability, poor health outcomes, and reduced quality of life. It is imperative that healthcare professionals screen for mental health problems among pain patients and pain among patients with mental health conditions to prevent a further decline in quality of life.

References

Chapman, A. (2019). Back pain linked to five mental health conditions: Sufferers find recovery challenging. Express. https://www.express.co-uk/life-style/health/1139173/back-pain-treatment-causes-mental-health-recovery

Cosio, D. (2017). Chronic Pain and Bipolar Disorders: A Bridge Between Depression and Schizophrenia Spectrum. Practical Pain Management, 17(2).

https://www.practicalpainmanagement.com/pain/other/co-morbidities/chronic-pain-bipolar-disorders-bridge-between-depression-schizophrenia

Guglielmo, D., Hootman, J., Boring, M.A., Murphy, L.B., Theis. K.A., Croft, J.B., Barbour, K.E., Katz, P.P., Helmick, C.G. (2017). Symptoms of Anxiety and Depression Among Adults with Arthritis-US 2015-2017. Centers for Disease Control and Prevention. https://www.cdc.gov/mmwr/volumes/67/wr/mm6739a2.htm

Hooten, W.M. (2016). Chronic Pain and Mental Health Disorders: Shared Neural Mechanisms, Epidemiology and Treatment. Mayo Clinic Proceedings, 91(7), 955-970. https://doi/10.1016/mayocp.2016.04.029

Mental Health America (2020). Chronic Pain and Mental Health. https://www.mhanational-or/chronic-pain-and-mental-health

National Institute of Health and Human Services (NIHHS)(2018). Chronic Pain-In-Depth. National Center for Complementary and Integrative Health. https://www.nccih.nih.gov/?health/chronic%20pain-in-depth

Rodriquez, T. (2020). Effect of Pain on Functioning in Serious Mental Illness. Psychiatry Advisor. 

https://www.psychiatryadvisor.com/home/topicsgeneral-psychiatry/connection-between-pain-and-functioning-among-individuals-with serious-mental-illness

Smith, D. (2017). Mental Illness and Chronic Pain. National Pain Report. https://www.nationalpainreport.com/mental-health-illness-and-chronic-pain-8832670.html

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