Mindfulness physical therapy, pain management, rehabilitation

Pain, the Amygdala and Mindfulness

The amygdala is a component of the limbic system and plays a central role in attaching emotional-affective content to sensory input.1,2 The amygdala is active in the emotional-affective aspects of pain and in pain modulation.1,2 Rodent studies show increased amygdala activity in models of muscle pain, visceral pain, monoarthritis and chronic neuropathic pain.2 In addition, increasing amygdala activity through exogenous means can exacerbate or generate pain behaviors in rodents in the absence of tissue damage.2

Human neuroimaging studies demonstrate amygdala activation in response to mechanical compression, thermal stimulation and capsaicin application.3 In addition, increased amygdala activity has been identified in patients diagnosed with osteoarthritis, IBS and fibromyalgia compared to matched controls.3

The medial prefrontal cortex (mPFC) exerts a regulating influence on the amygdala through top-down mechanisms.1,2 Through this neural circuitry, the mPFC contributes to the cognitive modulation of emotional dimensions of pain processing.1,2 Increases in amygdala activity result in an inhibition of neuronal activity in the mPFC.1,2 The resulting loss of mPFC cortical output, in turn, impairs mPFC-modulated inhibitory mechanisms within the amygdala.1,2 This reduction in inhibitory mechanisms contributes to an increase in activity of the amygdala.1,2 Researchers conclude “controlling abnormally enhanced amygdala activity is a desirable goal for pain management.”2

Mindful awareness is characterized by present moment attention and attitudes of acceptance, friendless and curiosity. Training in mindful awareness supports the ability of an individual to calmly observe both internal and external events in a non-reactive and non-judging manner and has been shown to contribute to improvements in perceived stress, anxiety, depression, pain and quality of life.4,5 In a systematic review of evidence of the effect of mindfulness training techniques on brain structure and function, the amygdala showed decreased functional activity, improved functional connectivity with the PFC and earlier deactivation after exposure to emotional stimuli.6 Although further research on chronic pain populations is warranted, the results of this review invite consideration of mindful awareness training as a pain management treatment to potentially address abnormally enhanced amygdala activity associated with the experience of pain.

1Neugebauer V. Amygdala pain mechanisms. Handb Exp Pharmacol. 2015;227:261-284.
2Thompson JM, Nuegebauer V. Amygdala plasticity and pain. Pain Res Manag. 2017;2017:8296501.
3Simons LE, Moulton EA, Linnman C, et al. The human amygdala and pain: evidence from neuroimaging. Human Brain Mapp. 2014 Feb;35(2):527-38.
4Gotink RA, Chu P, Busschbach JJ, et al. Standardised mindfulness-based interventions in healthcare: an overview of systematic reviews and meta-analyses of RCTs.PLoS One. 2015;10(4):e0124344.
5Hilton L, Hempel S, Ewing BA, et al. Mindfulness meditation for chronic pain: Systematic review and meta-analysis. Ann Behav Med. 2017;51(2):199-213.
6Gotink RA, Meijboom R, Vernooij, et al. 8-week Mindfulness Based Stress Reduction induces brain changes similar to traditional long-term meditation practice – A systematic review. Brain Cogn. 2016;108:32-41.