A lateralized model of the pain-depression dyad

Abstract

Chronic pain and depression are two frequently co-occurring and debilitating conditions. Even though the former is treated as a physical affliction, and the latter as a mental illness, both disorders closely share neural substrates. Here, we review the association of pain with depression, especially when symptoms are lateralized on either side of the body. We also explore the overlapping regions in the forebrain implicated in these conditions. Finally, we synthesize these findings into a model, which addresses gaps in our understanding of comorbid pain and depression. Our lateralized pain-depression dyad model suggests that individuals diagnosed with depression should be closely monitored for pain symptoms in the left hemibody. Conversely, for patients in pain, with the exception of acute pain with a known source, referrals in today's pain centers for psychological evaluation should be part of standard practice, within the framework of an interdisciplinary approach to pain treatment.

Keywords: Depression; Lateralization; Nociception; Pain.

Figure 1.

Lateralized model for pain-depression dyad. A. Classic pain-depression dyad: there is increased risk (intersection) for comorbid pain and depression compared to the lower risk for pain or depression, separately. B. Depression leading to lateralized psychogenic pain: widespread abnormal active properties of the RH induce incongruent right S1 signals and pose higher risk (darker arrow) for left-sided pain compared to lower risk (lighter arrow) from localized passive property changes in LH resulting in right-sided pain. C. Lateralized pain leading to depression: combination of pain in left/right hemibody that alters active RH/passive LH properties, respectively, pose higher risk (darker parenthesis) for depression compared to lower risk (lighter parenthesis) from combination of pain in left/right hemibody that alters passive RH/active LH properties, respectively.