The aging body is predisposed to developing pain. Osteoarthritis of the neck and lower back, chronic joint pain, and musculoskeletal pain are some of the most common complaints among the elderly. However, the complex links between chronic pain, opioid use, depression, dementia, and pseudodementia are decidedly difficult to study among advanced age patients. The following summary of recent literature outlines several interactions with which anesthesia providers should be familiar.
Nociception undergoes age-related changes. Notably, the thresholds for low and high intensity pain become dampened with age. That is to say, sub-threshold nociceptive stimuli may not illicit a pain response from the elderly. However, once perceived, the response to noxious stimuli may be exaggerated and complicate pain control.1 This decay in pain tolerance may be due to alterations in the central inhibitory pathways and neuronal plasticity. Taken together, these altered mechanisms can work to increase an elderly person’s susceptibility to developing chronic pain after an injury.
Although the use of opioid medications may impart many risks to chronic users, deleterious cognitive effects associated with long-term use have not been observed in large studies. One prospective cohort study of patients over 65 years of age found little to no association between total opioid consumption and development of dementia or Alzheimer’s in a ten-year follow-up.2 Moreover, a meta-analysis of studies on opioid prescriptions for cognitively-intact versus cognitively-demented patients found evidence for undertreatment of pain in the cognitively impaired.3 These data underscore the challenge of detecting and managing pain in patients who struggle to communicate and express their subjective experiences.
Age-related changes in the central nervous system, notably the development of amyloid plaques, neurofibrillatory tangles, and amyloid angiopathy, can be observed upon autopsy in patients with dementia.4 The extent to which neural injury from chronic pain contributes to these pathologic processes is uncertain. However, a past study found that patients with chronic pain demonstrate poor performance in several neuropsychological testing domains, suggesting that cognitive decline coincides with pain in the elderly.5 More recently, a longitudinal cohort study of over 10,000 patients aged over 62 years found that persistent pain hastens measurable impairments in everyday living.6 In fact, persistent pain accelerated memory decline, inability to manage personal finances, and the probability of developing dementia by roughly 10%.
Anesthesia providers should be aware of the associations between chronic pain and dementia. Elderly patients, especially those with dementia, may be more prone to inadequate treatment with analgesics as outpatients. Regional anesthesia and multimodal analgesia models should serve as the cornerstone for perioperative pain control. Diminishing the propensity for developing chronic pain after surgery continues to be a burgeoning area of research.
References:
- Paladini et al. Chronic Pain in the Elderly: The Case for New Therapeutic Strategies. Pain Physician. 2015;18(5):E863-76.
- Dublin et al. Prescription Opioids and Risk of Dementia or Cognitive Decline: A Prospective Cohort Study. J Am Geriatr Soc. 2015;63(8):1519-26.
- Griffioen et al. Prevalence of the Use of Opioids for Treatment of Pain in Persons with a Cognitive Impairment Compared with Cognitively Intact Persons: A Systematic Review. Curr Alzheimer Res. 2017;14(5):512-522.
- Love S. Neuropathological investigation of dementia: a guide for neurologists. J Neurol Neurosurg Psychiatry. 2005 Dec;76 Suppl 5:v8-14.
- Landrø et al. The extent of neurocognitive dysfunction in a multidisciplinary pain centre population. Is there a relation between reported and tested neuropsychological functioning? Pain. 2013;154(7):972-7.
- Whitlock et al. Association Between Persistent Pain and Memory Decline and Dementia in a Longitudinal Cohort of Elders. JAMA Intern Med. 2017;177(8):1146-1153.
