Chronic pain is defined as ongoing pain that lasts longer than three to six months. It is a complex and deeply personal experience. Recent clinical studies have provided substantial evidence for a correlation between pain and cognitive impairment. However, the pain management community is reticent to embrace this body of research–citing confounding factors such as the effect of pain relief medications on the central nervous system, as well as comorbid anxiety, depression, and other chronic diseases.
Understanding the Connections
The relationship between pain, cognition, and comorbid disorders is complicated but interconnected. When it comes to patients, both in studies and in the clinic, there may often be confounding variables that make it difficult to isolate a specific correlation.
A meta-analysis by Berryman et al1 found correlations between pain and cognitive domains such as working memory. However, their report included a caveat: many studies did not screen for psychiatric disorders such as post-traumatic
stress disorder (PTSD) and depression, which are associated with working memory deficits. Thus, the researchers could not conclusively say that the identified effects on working memory were due to pain alone.
Other researchers have sought to address these limitations by statistically controlling for confounding variables. A study by Ferreira et al2 determined that cognitive deficits in patients living with chronic pain were independent of comorbidities such as depression, anxiety, hypothyroidism, and medication use. The authors concluded that, “the relationship between chronic pain and cognitive deficits represents a genuine reality not to be neglected in the daily routine of physicians who work with pain management.”2
As medical researchers continue to seek answers, practitioners have an obligation to consider the effects of chronic pain on cognition.
Conducting a Three-Part Assessment
Dr. Kevin C. Fleming, an internist at the Mayo Clinic, advises doctors to view chronic pain as a triangle. The triangle features pain at the top and emotion and cognition on either side (see previous page). It also demonstrates that the relationships between pain, cognition, and emotion are bidirectional. Cognitive symptoms linked to chronic pain may include impaired focus and poor executive function. Emotional effects of chronic pain may include irritability, anger, feelings of helplessness, or comorbid depression and anxiety.
Cognitive impairment also may impact the patient’s perception of pain. In their study, He et al3 found that cognitive dysfunction in patients with trigeminal neuralgia was linked to augmented pain perception. The patients with trigeminal neuralgia showed increased attentional bias toward pain-related stimuli.
There is still debate among practitioners on whether impaired cognition increases or decreases sensitivity to pain. Even within the field of dementia, consensus is lacking. In a review in Pain by Defrin et al,4 Parkinson’s disease may be associated with increased sensitivity to pain, whereas Huntington’s disease correlates with decreased perception.
Emotional status is tightly linked to the conceptualization of pain, according to Lumley et al.5 Anxiety and fear have been shown to increase pain perception. In contrast, positive emotional states have the effect of dampening pain, also known as “affective analgesia.” Knowing this, practitioners should work to educate patients on causes of their pain, answer questions, and address any mental health concerns. Clinicians could couple this with suggestions to promote affective analgesia, which include listening to pleasing music and thinking fondly about a loved one.
Keeping these relationships in mind, when a practitioner sees a chronic pain patient for the first time, it is important to assess not only pain level, but also the patient’s cognitive and psychological status to consider whether multiple parts of the triangle need to be addressed.
Currently, the primary standard of care among new chronic pain patients does not necessarily require a cognitive or emotional assessment unless a patient has a mental deficit. This is largely due to testing time and expense, as well as the need for referral to a trained neuropsychologist. Lack of insight into a patient’s cognition, however, may deprive the practitioner of a holistic view of the patient’s condition.
Therefore, a combination of an in-depth interview, a depression measure such as the PHQ-9, and a brief cognitive assessment may help the physician obtain a more accurate picture of the chronic pain patient. What many may not realize is that even mild cognitive impairment may be associated with poor treatment compliance and poor outcomes. A study of elderly Japanese patients by Okuno6 of the University of Tsukuba, for example, pinpointed cognitive impairment as a predictor for noncompliance and suggested compensating for this impairment with frequent communication and extra support.
Factoring in Prior Noncompliance
As part of any initial assessment, a patient’s history of treatment compliance or noncompliance must be obtained as well. In the case of the latter, it is important to investigate why a patient may have failed to adhere to medication regimens in the past. Some conditions, such as fibromyalgia, are associated with cognitive dysfunction that may cause accidental neglect or misunderstanding of the treatment plan. Additionally, if a patient has previously been promised a “fix” for chronic pain that did not pan out, they might be skeptical and negatively biased toward the next suggested medication.
Practitioners may improve future compliance by ensuring that the patient understands the expectations of the treatment plan. A report on cognitive and emotional control of pain from Bushnell et al7 noted that negative expectations of pain relief could completely undermine the effects of analgesics.
On the other hand, positive expectations of an analgesic may result in pain relief, even when the medication prescribed is a placebo. By managing expectations effectively, practitioners can greatly improve treatment outcomes.
Modeling Future Assessments
Some recent advances in digital testing technologies have made it possible to routinely and cost-effectively screen cognition in patients without the need for a specialist. By assessing potential problematic relationships between cognition, emotional factors, and pain perception and pain treatment outcomes, these technologies hold the potential to reform pain management practice. One example is PainScale, an app that allows chronic pain sufferers to log their symptoms, access educational resources related to their condition, and communicate with their physician. This technology helps patients identify what activities worsen their symptoms, which leads to a better understanding for both the patient and physician.
According to Robiner et al,8 there were 1,002 board certified clinical neuropsychologists in the United States as of 2015. This number stands in stark comparison compared to the number of Americans living with mental disorders: 43.6 million, according to the Substance Abuse and Mental Health Administration.9Digital assessments may democratize cognitive assessments both in terms of access and cost. With the current strides in machine learning and the ability to capture cognitive data at scale, there is an unprecedented ability to model the effect of cognition across pain and other disease states.
As these technologies evolve, practitioners should explore the available technologies. It is important to read the scientific literature to confirm that the application or device is based on solid research. Additionally, customer reviews can provide insight into whether the technology is user-friendly and intuitive to promote patient usage. If the system is too complicated for the average person to figure out, then it may be best to find an alternative. Overall, these technological advancements have potential to empower both the patient and the practitioner to determine the best treatment plan based on increased insight into the patient’s condition.
- Berryman C, Stanton TR, Bowering KJ et al. Evidence for working memory deficits in chronic pain: A systematic review and meta-analysis. Pain. 2013;154:1181–1196.
- Ferreira K, Oliver GZ, Thomaz DC et al. Cognitive deficits in chronic pain patients, in a brief screening test, are independent of comorbidities and medication use. Arq. Neuro-Psiquiatr. 2016;74(5). San Paulo, Brazil.
- He C, Yu F, Zhao-Chai J et al. Fearful thinking predicts hypervigilance towards pain-related stimuli in patients with chronic pain. Psych J. 2014:3(3);189-200.
- Defrin R, et al. Experimental pain processing in individuals with cognitive impairment: current state of the science. Pain. 2015;156(8);1396-1408.
- Lumley MA, et al. Pain and emotion: a biopsychosocial review of recent research. J Clin Psychol. 2011;67(9), 942-968.
- Okuno J, Yanagi H, Tomura S. Is cognitive impairment a risk factor for poor compliance among Japanese elderly in the community? Eur J Clin Pharmacol. 2001:57(8);589-594.
- Bushnell MC, Čeko M, Low LA. Cognitive and emotional control of pain and its disruption in chronic pain. Nat Rev Neurosci. 2013:14(7);502-511.
- Robiner, W. N., & Fossum, T. A. To Be or Not to Be Board Certified? A Question of Quality and Identification for Psychologists. J Appl Biobehav Res. 2017:22(3).
- SAMHSA. Behavioral health trends in the United States: Results from the 2014 National Survey on Drug Use and Health. HHS Publication No. SMA 15–4927, NSDUH Series H-50 (2015), Rockville, MD.