The anxiodepressive comorbidity in chronic pain

Chronic pain is often accompanied by mood, sleep and cognitive complications affecting the patient's quality of life. This reviews aims to provide a synthesis of the recent clinical and preclinical findings concerning the chronic pain and mood disorder comorbidity.

The possible mechanisms underlying the presence of anxiety and/or depression in neuropathic pain, chronic widespread pain (fibromyalgia) and inflammatory pain are reviewed based on recent evidences from neuroimaging, anatomical, behavioral, pharmacological, genetic and biochemical studies. Clinical data from patients and preclinical findings from pain models in rodents are considered.

The epidemiological studies report a high prevalence of mood disorders in patients with chronic pain, and these consequences of pain can be preclinically modeled. This comorbidity may be explained by shared morphological and functional alterations observed in both chronic pain and mood disorders. However, mechanistic studies also highlight differences in such alterations depending on the type of chronic pain. Better understanding of the genetic and environmental determinants of pain-induced mood disorders and of the various neurobiological bases of this comorbidity depending on the pain subtype could provide the clinician with important diagnosis and treatment tools. Such progress benefits from translational effort between clinical and preclinical research.