Mindfulness physical therapy, pain management, rehabilitation

Stress Weakens Prefrontal Cortex Networks

The prefrontal cortex (PFC) plays a central role in our cognitive abilities, including generating thoughts, modulating attention, regulating emotions and initiating actions.1,2 In addition, the PFC is responsible for bringing about mental representations necessary for abstract thought and flexible, goal-directed behavior.1,2

In rodent studies, sustained stress induces a loss of dendrites and spines in the PFC.3 This loss correlates with weaker attentional flexibility and impaired working memory.1,2 In addition, chronic stress increases dendritic growth and excitability in the amygdala, contributing to an imbalance in PFC – amygdala function.4,5

In human studies, chronic stress has been shown to weaken PFC functional connectivity and the PFC regulation of the amygdala.6,7 In addition, a decrease in PFC grey matter has been correlated with the experience of adverse events.8 Researchers propose these stress-associated changes impair the top-down functions of the PFC and, simultaneously, strengthen emotional circuitry.1,2 This, in turn, leads to a shift from a thoughtful, reflective regulation of behavior to a more primitive, reactive condition.1,2 For an excellent summary, please see the 5 minute slide show by researcher Amy Arnsten, PhD. on this topic.

This research suggests that, in theory, for those who experience chronic pain as an uncontrollable, persistent stressor, stress-associated changes in the PFC could occur and promote emotional reactions and habitual behaviors while impairing thoughtful, flexible, goal-directed behaviors. Mindfulness training may offer a treatment strategy to address stress-associated cortical changes. Mindfulness training has been shown to increase prefrontal cortex activity, connectivity and volume in stressed, anxious and healthy participants.9 Although not yet studied in patients with chronic pain, this evidence identifies a possible mechanism for consideration when examining the role of mindfulness training in the treatment of pain. Further research is needed in chronic pain populations.

1Arnsten AF. Stress weakens prefrontal networks: molecular insults to higher cognition. Nat Neurosci. 2015;18(10):1376-85.
2Arnsten AF, Raskind MA, Taylor FB, et al. The effects of stress exposure on prefrontal cortex: translating basic research into successful treatments for post-traumatic stress disorder. Neurobiol Stress. 2015;1:89–99.
3Liston C, Miller MM, Goldwater DS, et al. Stress-induced alterations in prefrontal cortical dendrite morphology predict selective impairments in perceptual attention set-shifting. J Neurosci. 2006;26(30):7870-4.
4Vyas A, Mitra R, et al. Chronic stress induces contrasting patterns of dendritic remodeling in hippocampal and amygdaloid neurons. J Neurosci. 2002;22(15):6810-8.
5Rosenkranz JA, Venheim ER, Padival M. Chronic stress causes amygdala hyperexcitability in rodents. Biol Psychiatry. 2010;67(12):1128-36.
6Listen C, McEwen BS, Casey BJ. Psychosocial stress reversibly disrupts prefrontal processing and attentional control. Proc Natl Acad Sci. 2009;106(3):912-7.
7Kim P, Evans GW, Angstadt M, et al. Effects of childhood poverty and chronic stress on emotion regulatory brain function in adulthood. Proc Natl Acad Sci.2013;110(46)18442-18447.
8Moreno GL, Bruss J, Denburg NL. Increased perceived stress is related to decreased prefrontal cortex volumes among older adults. J Clin Exp Neuropsychol. 2017;39(4):313-325.
9Gotink 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.