COVER STORY Research in the last decade illustrates that patient-reported attention deficits have risen with the incidence of chronic pain In clinical parameters, cognition is defined by domains such as attention, perception, memory, motor skills, exec-utive functioning, and verbal and lan-guage skills. 2 There is current evidence that pain has a direct effect on neuro-plasticity, the brain’s ability to change neuronal connections in response to newer information. Chronic pain and hypersensitivity, or hyperalgesia, can influence these neuronal connections and thereby influence long-term mem-ory. More specifically, when an individ-ual experiences chronic pain, they may develop alternate responses to pain at the biochemical level; it is in this con-text that neuroplasticity may be exert-ing changes to one’s pain cycle. 2 Re-search in the last decade illustrates that patient-reported attention deficits have risen with the incidence of chronic pain. 2 Majority of the clinical studies examining cognition includes partici-pants with chronic pain conditions such as fibromyalgia, migraine, chronic back pain, rheumatoid arthritis, diabetic neuropathy, osteoarthritis, CRPS, pe-ripheral neuropathic pain syndromes, and multiple sclerosis. 2 With respect to neuroplasticity resulting from chronic pain, human studies highlight there is a decreased hippocampal volume, a brain region responsible for behaviour regu-lation, stress modulation, learning consolidation and short-term memory. 2 Congruent with this evidence are find-ings in which the majority of patients with chronic pain report poor memory, recall, and concentration in their daily activities. 2 Confirming that pain can affect cog-nition and cognitive domains, when pain is reversed, it has been found that cognition can be retrained. A study by Noorani et al. (2022) observed 61 pa-tients with trigeminal neuralgia. What was common amongst the pain resolu-tion group after surgical treatment was the recovery and normalization of the hippocampal volume as opposed to those who did not find significant pain resolution post-surgery. 7 Although the study was small, this finding suggests that chronic pain can contribute to hippocampal burden and atrophy, and resolution of pain can contribute to the neuroplasticity of the hippocampus. Thus, treatment and investigation of pain should not be overlooked when working with patients exhibiting cogni-tive decline. Addressing sources of pain and mit-igating inflammatory processes should be a central focus in combination with psycho-social interventions. Interrupt-ing the pain catastrophization cycle and reinterpreting the sensations of pain has been a cornerstone in the lit-erature showing reduced pain severity. 5 Based on research conducted by Suarez-Roca et al. (2021), afferent stimulation of the vagus nerve de-creases chronic pain scores. Vagus nerve stimulation delivers analgesic effects; some of these analgesic effects are brought by modulation of inflam-matory pathways. 8 Vagal tone activa-tion can be achieved by mechanical methods such as auricular acupunc-ture, or electrical stimulation such as transcutaneous electrical nerve stimu-lation (TENS). 6 One study that inves-tigated the impacts of vagal elec-trostimulation highlighted the reduction of pro-inflammatory cy-tokines in vitro, and significantly miti-gated pain severity in rheumatoid ar-thritis patients. 6 Thus, researchers deduced electrical stimulation of the vagus nerve activates the parasympa-thetic nervous system and decreases pain via proposed biochemical mecha-nisms including cytokines. Applying these principles to patients, treatment options that mitigate inflammation may dually impact the pain cycle, and cognition. Curcumin may display an-ti-inflammatory properties by blocking TNF directly in in vitro and in vivo studies, and in various types of cells. 9 In vivo and in vitro studies of Boswellia serrata suggest interception of inflam-matory mediators and may slow the progression of inflammatory, and conditions associated with pain, in-cluding osteoarthritis. 10 Observation and identification of pain in patients is crucial, followed by prevention and treatment of pain in its early stages. Influencing pain patterns and pathways can be achieved in pri-mal stages of chronic pain, prior to neuroplasticity influences on brain re-gions and the subsequent cognitive domains. Effective pain management requires a holistic approach, encom-passing interventions involving symp-tomatic reduction, structural align-ment, modulating inflammation, co-factors and nutrients for repair and structure, rehabilitation, and psycho-social and emotional support. REFERENCES 1. Goldberg, D. S., & McGee, S. J. (2011). Pain as a global public health priority. BMC public health, 11, 770. https://doi. org/10.1186/1471-2458-11-770 2. Khera, T., & Rangasamy, V. (2021). Cognition and Pain: A Review. Frontiers in psychology, 12, 673962. https://doi. org/10.3389/fpsyg.2021.673962 3. Mills, S., Nicolson, K. P., & Smith, B. H. (2019). Chronic pain: a review of its epidemiology and associated factors in population-based studies. British journal of anaesthesia, 123(2), e273– e283. https://doi.org/10.1016/j.bja.2019.03.023 4. Raja, S. N., Carr, D. B., Cohen, M., Finnerup, N. B., Flor, H., Gibson, S., Keefe, F. J., Mogil, J. S., Ringkamp, M., Sluka, K. A., Song, X. J., Stevens, B., Sullivan, M. D., Tutelman, P. R., Ushida, T., & Vader, K. (2020). The revised International Association for the Study of Pain definition of pain: concepts, challenges, and compromises. Pain, 161(9), 1976–1982. https://doi. org/10.1097/j.pain.0000000000001939 5. Garland E. L. (2012). Pain processing in the human nervous system: a selective review of nociceptive and biobehavioral pathways. Primary care, 39(3), 561–571. https://doi. org/10.1016/j.pop.2012.06.013 6. Suarez-Roca, H., Mamoun, N., Sigurdson, M. I., & Maixner, W. (2021). Baroreceptor Modulation of the Cardiovascular System, Pain, Consciousness, and Cognition. Comprehensive Physiology, 11(2), 1373–1423. https://doi.org/10.1002/cphy.c190038 7. Noorani, A. Hung, P. SP., Zhang, J. Y., et al. (2022). Pain Relief Reverses Hippocampal Abnormalities in Trigeminal Neuralgia. The Journal of Pain, 23(1); 141-155. 8. Chakravarthy, K., Chaudhry, H., Williams, K., & Christo, P. J. (2015). Review of the Uses of Vagal Nerve Stimulation in Chronic Pain Management. Current pain and headache reports, 19(12), 54. https://doi.org/10.1007/s11916-015-0528-6 9. He, Y., Yue, Y., Zheng, X., Zhang, K., Chen, S., & Du, Z. (2015). Curcumin, inflammation, and chronic diseases: how are they linked?. Molecules (Basel, Switzerland), 20(5), 9183–9213. https://doi.org/10.3390/molecules20059183 10. Bannuru, R. R., Osani, M. C., Al-Eid, F., & Wang, C. (2018). Efficacy of curcumin and Boswellia for knee osteoarthritis: Systematic review and meta-analysis. Seminars in arthritis and rheumatism, 48(3), 416–429. https://doi.org/10.1016/j. semarthrit.2018.03.001 Mathur, V. A., Khan, S. A., Keaser, M. L., Hubbard, C. S., Goyal, M., & Seminowicz, D. A. (2015). Altered cognition-related brain activity and interactions with acute pain in migraine. NeuroImage. Clinical, 7, 347–358. https://doi.org/10.1016/j. nicl.2015.01.003 Polaski, A. M., Phelps, A. L., Kostek, M. C., Szucs, K. A., & Kolber, B. J. (2019). Exercise-induced hypoalgesia: A meta-analysis of exercise dosing for the treatment of chronic pain. PloS one, 14(1), e0210418. https://doi.org/10.1371/journal.pone.0210418 8 Chiropractic and Naturopathic Doctor May/June 2022 www.Cndoctor.ca
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