Neurocognitive Disorders: Pain Expression in the Face of Mental Deficits
There are an estimated 35 million people with dementia worldwide.1 This figure is expected to increase to 100 million by the year 2050.2 More compelling for pain practitioners is that the rate of dementia is known to rise with age to over 50% in those 90 years of age or older,3 and the prevalence of chronic pain is 72% in those 85 years or older.4
The most common cause of dementia is Alzheimer’s disease, but dementia due to vascular, frontotemporal, and Lewy bodies are also prevalent.1 In all subtypes of dementia, specific neuropathological changes are responsible for the decline in function, cognition, and other symptoms, such as behavioral disturbances, psychological problems, and the breakdown of language and communication. Those with pain and dementia often express their pain through behavioral disturbances, such as agitation, screaming, and aggression.1
In the current Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), the chapter on neurocognitive disorders (NCD) begins with delirium, followed by the syndromes of major NCD (previously dementia), mild NCD, and their etiological subtypes due to Alzheimer’s disease; vascular, Lewy bodies, Parkinson’s disease, frontotemporal, traumatic brain injury, HIV infection, substance/medication-induced, Huntington’s disease, prion disease, multiple etiologies, and other medical conditions.5 The primary clinical deficit that these disorders have in common includes cognitive dysfunction that is acquired rather than developmental.5
Setting the Stage for Neurocognitive Pain Management
The prevalence of delirium in the community is low (1–2%) but increases with age, rising to 14% among individuals older than 85 years.6 Overall prevalence estimates for major NCD are approximately 1–2% at age 65 years and as high as 30% by age 85 years.7 Estimates of the prevalence of mild NCD among older individuals are fairly variable, ranging from 2-10% at age 65 and 5-25% by age 85.8
The prevalence of mild NCD based on their etiological subtypes are as follows:
- Alzheimer’s disease ranges from about 60-90%, depending on the setting and diagnostic criteria9
- Vascular-related conditions range from 0.2% in the 65–70 years age group to 16% in individuals 80 years and older10
- Lewy bodies range from 0.1-5% of the general elderly population, and from 1.7-30.5% of all dementia cases11
- Parkinson’s disease steadily increases with age from approximately 0.5% between ages 65 and 69 to 3% at age 85 years and older12
- Conditions originating in the frontotemporal region are in the range of 2–10 per 100,00013
- Traumatic brain injury-associated disability is about 2% of the general population14
- HIV infection affects approximately one-third to over one-half of individuals depending on the stage of the disease15
- Substance/medication-induced disorders are more likely to arise in those who are older and have a history of longer drug use, and/or have other risk factors such as nutritional deficits16
- Huntington’s disease in North America, Europe, and Australia is 5.7 per 100,00017
- The prevalence of prion disease is unknown
Keep in mind that several of the NCDs frequently coexist in patients with dementia.
Attending to the Comorbidity of Pain and Dementia
Scientific interest in the comorbidity of pain in NCD is relatively new. The literature indicates that the prevalence rate of patients with dementia that are regularly in pain varies from around 20% to higher than 50%.18 Evidence reflects that around 60-80% of individuals with NCD in dependent-care (nursing home) settings regularly experience pain, usually related to musculoskeletal, gastrointestinal, cardiac conditions, genitourinary infections, pressure ulcers in the skin, and/or orofacial pain.19-20
There have been few studies on pain in different subtypes of NCD, such as dementia due to vascular, frontotemporal, and Lewy bodies. Approximately 35% of stroke patients suffer from post-stroke central neuropathic pain, which also occurs in vascular dementia.21 The prevalence of some type of pain (musculoskeletal, dystonic, radicular-neuropathic, and central neuropathic pain) in Parkinson’s disease ranges from 68-85%.22 In terms of traumatic brain injury-associated disabilities, the prevalence of chronic pain is about 52% among civilians23 and at least 42% among veterans with comorbid post-traumatic stress disorder (PTSD) and persistent post-concussive symptoms.24
How do neuropathological changes in NCD affect pain?
Current theory states that the areas of the brain involved in pain processing can be divided into two networks, the medial and lateral pain systems. The medial pain system is the pathway that mediates cognitive-evaluative and motivational-affective aspects of pain and is comprised of the amygdala, medial thalamus, hippocampus, anterior cortex cinguli, and prefrontal cortex. The lateral pain system is a pathway that mediates the sensory-discriminative aspects (localization, intensity, and quality of pain), which is comprised of the primary somatosensory areas and the lateral thalamic nuclei.25 There may be an overlap between the two systems in the insula (the region of the brain that separates the frontal and parietal lobes from the temporal lobe).
There is conflicting evidence from neuropathological, neuroimaging, experimental, and clinical research regarding the impact of NCD on pain processing. However, support exists for decreased, unchanged, or increased pain processing in patients with dementia.26 In addition, there is speculation that atrophy of the gray matter may lead to an increase in pain tolerance, while white matter lesions appear to decrease pain tolerance.1 Thus, there still remains a great deal of uncertainty regarding the effects of neuropathological changes in NCD. For information on the influence of NCD on motivation-affective and sensory-discriminative aspects of pain see Table 1.27
How is the diagnosis different now in the DSM-5?
The NCD was referred to in the previous DSM-IV as dementia, delirium, amnestic, and other cognitive disorders. The DSM-IV diagnoses of dementia and amnestic disorder are under the newly named major NCD, which is consistent with the rest of medicine and remains distinct to capture the care needs for this group.
New to the DSM-5 is the less severe level of cognitive impairment, mild NCD, which was subsumed under “cognitive disorder not otherwise specified” in the DSM-IV. Its presence is consistent with other fields of medicine, notably in Alzheimer’s disease, vascular disease, HIV infection, and traumatic brain injury-associated disability. In addition, distinct diagnostic criteria were added for major or mild NCD due to Lewy bodies, Parkinson’s disease, frontotemporal, traumatic brain injury, HIV infection, substance/medication-induced, Huntington’s disease, prion disease, multiple etiologies, and other medical conditions.5
How is pain assessed in neurocognitive disorders?
Musculoskeletal pain can be identified through gentle, guided movements.28 Self-reports of pain (visual analog, numeric rating, and faces pain scales) are possible in individuals with NCD depending on the patient’s memory, expectations, and capacity, but may become more challenging as neuropathological decline progresses.29
In cases of more advanced dementia, a proxy rater or a primary caregiver who is familiar with the patient’s usual behavior should be included in the pain assessment. Examples of caregiver rating scales are the Pain Assessment for the Dementing Elderly and the Pain Assessment Instrument in Noncommunicative Elderly.
The American Geriatrics Society published guidelines outlining the various behavioral expressions of pain in the elderly, including facial expressions, body movements, and vocalizations, which have been instrumental in the development of assessment tools for dementia.30 Examples of these tools include:
- Cohen-Mansfield Agitation Inventory
- Discomfort Scale for Dementia of the Alzheimer’s Type
- Checklist of Nonverbal Pain Indicators
- Pain Assessment in Advanced Dementia
- Facial Action Coding System
- Observational Pain Behavior Assessment Instrument
- Dementia Care Mapping
- Elderly Pain Caring Assessment-2
- Behavioral Pathology in Alzheimer’s Disease Scale
However, it has been suggested that instruments using observation and detection of pain-related behavior may require further validation in people with NCD and assessment of their utility in clinical practice.31 The value of biomarkers of pain, particularly inflammation, should be considered as an enhancement of a pain assessment in patients with NCD.19
What do the treatments for neurocognitive disorders look like?
Healthcare providers are not sufficiently prepared to handle difficulties in establishing good pain management practice for patients with NCD. For example, the behavioral expression of pain in persons with NCD can be extremely distressing for both the patient and their caregiver, which can lead to inappropriate prescribing of antipsychotic medication instead of adequate pain treatment.1
Providing a low dosage of pain medication seems to occur consistently in NCD patients in medical care, potentially due to the scarcity of pharmacological studies and the uncertainty in effective dosing with limited or no feedback from the patient.32 Thus, there is a need for this to be added to medical education in order to improve healthcare providers’ competency in distinguishing pain behaviors from other behavioral symptoms.33 Research has shown that verbal agitation (eg, complaining, negativism, repetitious sentences and questions, constant request for attention, and/or cursing/verbal aggression) responded well to medication management of pain, while restlessness and pacing were sensible to analgesics.34 The literature supports the value of stepped-care approaches of analgesia administration—from acetaminophen to opioids—to people with dementia.19 The consensus among experts is that a multidisciplinary approach to pain management, including pharmacological and non-pharmacological therapies, seem to offer the most benefit in relieving persistent pain among individuals with NCD despite there being no research data available to support such claims.30
With regard to non-pharmacological options to lessening pain, there is a modicum of evidence that exercise and some complementary and integrative medical practices, such as reflexology and music therapy, may be effective in lessening pain in some patients with NCD. Moderate physical activity, such as walking, has been shown to provide a double benefit in these patients by offering both pain relief35 and improved cognitive function.36
Research in reflexology, the application of pressure to the feet and hands with specific hand techniques without the use of lubrication, has also provided some evidence of a reduction in pain experienced by individuals with NCD.37 Interestingly, music therapy, a process by which music and all of its facets are employed to help patients improve their physical and mental health, has shown some promise.38 It appears that music therapy may be useful in providing a distraction from pain, promoting relaxation, and changing the patient’s attitude or improving mood. Music has been employed for procedural pain, postoperative pain, cancer pain, and arthritis pain. When engaged in music therapy, its effectiveness was greatest when patients were encouraged to tap out a rhythm, sing, and dance, as well as to have the volume and length of the music intervention controlled by patient preference.
Due to the complexities involved when treating chronic pain in patients diagnosed with NCD, the collaborative expertise of multiple disciplines, including neuropsychologists or practices that provide neurocognitive testing, may prove necessary and beneficial when working with this population.
In the next installment of Mental Health Series A to Z, the author will discuss obsessive-compulsive disorders and pain.
