Chronic Pain and Chronic Stress: Two Sides of the Same Coin?

Abstract

Pain and stress share significant conceptual and physiological overlaps. Both phenomena challenge the body’s homeostasis and necessitate decision-making to help animals adapt to their environment. In addition, chronic stress and chronic pain share a common behavioral model of failure to extinguish negative memories. Yet, they also have discrepancies such that the final brain endophenotype of posttraumatic stress disorder, depression, and chronic pain appears to be different among the three conditions, and the role of the hypothalamic-pituitary-adrenal axis remains unclear in the physiology of pain. Persistence of either stress or pain is maladaptive and could lead to compromised well-being. In this brief review, we highlight the commonalities and differences between chronic stress and chronic pain, while focusing particularly on the central role of the limbic brain. We assess the current attempts in the field to conceptualize and understand chronic pain, within the context of knowledge gained from the stress literature. The limbic brain—including hippocampus, amygdala, and ventromedial pre-frontal cortex—plays a critical role in learning. These brain areas integrate incoming nociceptive or stress signals with internal state, and generate learning signals necessary for decision-making. Therefore, the physiological and structural remodeling of this learning circuitry is observed in conditions such as chronic pain, depression, and posttraumatic stress disorder, and is also linked to the risk of onset of these conditions.

Analgesic effects of ASP3662, a novel 11β‐hydroxysteroid dehydrogenase 1 inhibitor, in rat models of neuropathic and dysfunctional pain

“…Chronic stress is widely known to exacerbate pain in a wide range of conditions (Blackburn-Munro and Blackburn-Munro, 2001;Abdallah and Geha, 2017). Glucocorticoids are a major class of stress hormones that have been reported to participate in stress-induced hyperalgesia (Alexander et al, 2009).…”

Subliminal (latent) processing of pain and its evolution to conscious awareness

“…Potential processes that may be risk factors for the development or association of pain include genetic (Costigan et al, 2010; Estacion et al, 2009; Reimann et al, 2010), psychosocial (Innes, 2005), emotional status (Hasenbring et al, 2001; Pincus et al, 2002; Rosenberger et al, 2006), and chronic stress (Abdallah and Geha, 2017) resilience. We have previously summarized these in a prior paper (George et al, 2016).…”

Coexistence of Chronic Pain and Depression: A Short Review with a Focus on the Antidepressant Effect of Tramadol and Buprenorphine

“…Three common symptoms of depression and chronic pain are emotional symptoms (irritability, anxiety, excessive worry, crying, depressive style of thinking, obsessions), somatic symptoms (sleep and appetite disorders, reduced psychomotor efficiency and life energy, impairment of concentration and attention) and symptoms related (guilt, sadness, loss of interest, suicidal tendencies) [1,3]. Therefore, although chronic pain and depression are separate pathological conditions, they often co-exist and affect each other negatively [18][19][20][21][22][23][24][25][26][27].…”

“…All three standard types of opioid receptors μ, κ and δ are involved in regulating mood [1,3]. The occurrence and development of depression include many neurotransmitter systems that are associated with changes in neuroplasticity.…”

“…According to the definition of pain adopted by the International Association for the Study of Pain, pain, regardless of the triggering factor, is always associated with stress and mental suffering, which may intensify the symptoms of depression [1][2][3].…”