Common mechanisms of pain and depression: are antidepressants also analgesics?

Abstract

Neither pain, nor depression exist as independent phenomena per se, they are highly subjective inner states, formed by our brain and built on the bases of our experiences, cognition and emotions. Chronic pain is associated with changes in brain physiology and anatomy. It has been suggested that the neuronal activity underlying subjective perception of chronic pain may be divergent from the activity associated with acute pain. We will discuss the possible common pathophysiological mechanism of chronic pain and depression with respect to the default mode network of the brain, neuroplasticity and the effect of antidepressants on these two pathological conditions. The default mode network of the brain has an important role in the representation of introspective mental activities and therefore can be considered as a nodal point, common for both chronic pain and depression. Neuroplasticity which involves molecular, cellular and synaptic processes modifying connectivity between neurons and neuronal circuits can also be affected by pathological states such as chronic pain or depression. We suppose that pathogenesis of depression and chronic pain shares common negative neuroplastic changes in the central nervous system (CNS). The positive impact of antidepressants would result in a reduction of these pathological cellular/molecular processes and in the amelioration of symptoms, but it may also increase survival times and quality of life of patients with chronic cancer pain.

Pain, depression and sleep disorders in patients with diabetic and nondiabetic carpal tunnel syndrome: a vicious cycle

“…A decrease in noradrenaline levels is one of the characteristic properties of depression. Increased glutamate expression is a basic stage in central sensitization of chronic pain and depression 24 . Using common mechanisms, a vicious circle is created of chronic pain leading to depression and depression leading to pain sensitivity.…”

Can We Use MDDScore for the Identification of Comorbid Major Depressive Disorder (MDD) in Patients with Chronic Pain?

“…The prevalence of patients with chronic pain who display depressive symptoms is quite high, with depression potentially an integral component of centralized pain [4][5][6]. Patients with chronic pain and depression have worse health outcomes than those with chronic pain alone [7][8][9].…”

Pharmacological Pain Management: For Better or for Worse?

“…Newer classes of antidepressants, duloxetine and venlafaxine (serotonin and norepinephrine reuptake inhibitors SRNIs), may be less analgesic but they have less adverse effects although fatigue is frequently reported. Depression and chronic pain share a number of common mechanisms (Nekovarova et al 2014 ;Blackburn-Munro 2001 ;Chou 2007 ), and depression may precede or follow after chronic pain. Chronic pain and depression are both conceptualized as stress and all three modulate brain and synaptic plasticity.…”