Feeling pain is normal and is one of the body’s protective functions. It alerts us to being unwell or injured, encourages us to seek medical care, and promotes rest and recovery. Pain also serves as a reminder of past harmful experiences and teaches us to avoid them in the future. For example, if you were to burn yourself while using the oven, the pain from the burn would serve as a reminder to be cautious next time the oven is in use. This type of pain, often called acute pain, serves an important purpose. In contrast, chronic pain does not.
What is chronic pain?
When the experience of pain lasts longer than the typical healing time of an injury, or greater than 3 months, it is often referred to as chronic pain. Chronic pain can have a profound impact on a person’s quality of life and function, leading to difficulties managing activities of daily living, loss of productivity and income, and social isolation.
While the physical and psychological impact of chronic pain may seem obvious, what is often overlooked is the effect chronic pain has on a person’s cognitive function.
What is cognitive functioning?
Cognition may be considered an umbrella term that encompasses the mental and neuropsychological functions performed by the brain. These include:
- Focusing, switching, or dividing attention
- Understanding and processing information (including sight, smell, sound, and touch)
- Forming, storing, and recalling memories
- Planning and initiating tasks or actions
- Problem solving and exercising judgement
- Regulating emotions
Chronic pain and cognitive functioning:
It is widely accepted that pain can negatively affect cognitive performance; but why?
There are several factors which have been identified to influence or account for an impairment in cognitive functioning for individuals with chronic pain. For example, pain and cognition share common neural substrates and are known to interact reciprocally¹. So too, poor sleep (as a result of pain) reduces a person’s attention, as well as their learning and information processing ability. Other factors such as age, severity of pain, and the cognitive load/ demand that an individual has to contend with are also thought to impact upon cognitive functioning for individuals with chronic pain.
The use of opioid based medications is another significant contributor to issues with cognitive functioning for individuals with chronic pain. This is because opioid medications act upon the central nervous system, which includes the brain. Research has linked long term use of opioid medications with reduction in psychomotor speed, processing, and working memory². Additionally, people with chronic pain often require long-term opioid use to manage their pain levels which can lead to them developing a tolerance to the opioid medication, and therefore requiring higher doses to achieve the same therapeutic benefit³. Higher doses of the opioid medication then further worsen cognitive function within specific domains including attention, language, orientation, and psychomotor function4.
Chronic pain and cognition also have a bidirectional relationship5, meaning chronic pain and cognitive function interact with each other reciprocally, like a feedback loop. When a person experiences chronic pain, they may develop cognitive issues. In turn, these cognitive issues may then have a negative impact on pain by affecting the person’s capacity to manage the pain or the perception of the pain itself.
Whilst each individual’s experience of both chronic pain and any resultant cognitive impairment is unique, they may experience deficits in their ability with attention, information processing, memory and/ or executive functioning with the impact within each of these cognitive domains discussed below.
Attention:
Attention is the ability to remain focused and direct consciousness. Within the brain, a widespread matrix of interconnected neurons control attention. This matrix overlaps with pain pathway neurons. Due to this overlap, research has suggested that persistent pain impacts upon the ability to sustain attention and ignore irrelevant sensory stimuli, resulting in decreased task performance. It is common for individuals with chronic pain to report attention deficits including difficulties maintaining attention to a task, switching between two tasks, and dividing attention between two tasks. These issues may present in the following ways:
- Becoming easily distracted
- Losing focus/ concentration while reading a book, watching a television show or movie, or within a conversation
- Having difficulty sticking to a task or jumping around between tasks without completing any
- Issues with multitasking
- Difficulty following instructions
Information Processing:
The speed at which information is processed can be reduced for people with chronic pain. This means that it often takes them longer to register and understand sensory information. Common issues with processing include:
- Needing to complete tasks more slowly in order to understand them.
- Difficulty functioning in noisy and busy environments (such as a shopping centre, classroom, or on public transport)
- Understanding verbal or written instructions or information. The person may need to be given one step at a time, or need to re-read something several times in order to understand it.
- Following a lot of information or keeping up in a conversation.
- Getting muddled or confused, going off on tangents, or having difficulty answering questions quickly.
Memory:
In order to form and use memories, the brain must perform a sequence to process information accurately, hold it in short term memory stores, and then convert it to long term memory. These processes occur in several areas of the brain.
Research has shown that the area of the brain responsible for long term memory, known as the hippocampus, may have reduced volume and plasticity for individuals with chronic pain6,7,8. In addition, short term memory processes which occur in the amygdala have also been observed to be impacted by high levels of glucocorticoid (a chemical released by the body in response to stress such as pain).
A person with chronic pain may therefore forget things easily. This can impact upon their function and safety, as they may forget to take their regular medications, forget to pay bills, or forget to turn off appliances when using them. In addition, memory problems may also commonly present as:
- Having difficulty remembering important information such as appointment dates or deadlines.
- Forgetting details of a conversation or instructions.
- Forgetting names, pin numbers, phone numbers.
- Telling someone the same story more than once or failing to recall details of a story.
Executive Functioning:
Executive Functioning includes more complex cognitive functions such as initiation, planning and organising, controlling thoughts, regulating emotions, problem solving and exercising judgement. These functions mostly occur in the frontal lobe area of the brain, where the neural pathways for pain and these cognitive functions overlap. Research has shown that the volume of this area of the brain is decreased for individuals with chronic pain, therefore potentially leading to problems with executive functioning.
Executive functioning problems can have a significant impact on an individual as it may affect their ability to plan and execute their daily routine, and cause extremely poor time management. This can often be incorrectly perceived as laziness and disorganisation when it is actually a result of impaired cognitive functioning. Other ways executive functioning problems present include:
- Difficulty dealing with unexpected problems or changes in plans or daily routine.
- Problems with correcting personal mistakes or exercising good judgement when a problem arises.
- Difficulty with planning the day or week, particularly if there are several conflicting priorities.
- Problems with regulating emotions which can lead to emotional outbursts or acting impulsively based on emotion.
Occupational Therapy, Chronic Pain, and Cognitive Impairment:
Occupational Therapists are experts in evaluating how a person functions within their day-to-day life. For individuals with chronic pain, particular consideration is given not only to the physical impact of the chronic pain, but also cognitive issues and the consequence that deficits in this area might have on their ability to function.
When conducting our assessment, we use a combination of semi-structured interviews, standardised cognitive assessments, observation of functional performance, and self-report questionnaires to thoroughly and accurately identify the cognitive issues experienced by an individual, and to fully understand their impact upon the individual’s functional capacity.
Where relevant, occupation therapy treatment may be recommended to develop person-specific strategies and interventions used to minimise the impact of the cognitive impairment in order to optimise the individual’s ability to function despite their cognitive issues.
When it is considered likely that additional prompting or supervision will continue to be required as a result of the cognitive impairment, recommended supports will be discussed in our medico-legal reports, with associated costs provided.
1 Moriarty, Orla; Finn, David P. Cognition and pain. Current Opinion in Supportive and Palliative Care 8(2):p 130-136, June 2014.
2 Higgins et al (2018) The relationship between chronic pain and neurocognitive function: A systematic review. Clin J Pain. 2018 March ; 34(3): 262–275. doi:10.1097/AJP.0000000000000536.
3 Anand, K. J. S., Willson, D. F., Berger, J., Harrison, R., Meert, K. L., Zimmerman, J., et al. (2010). Tolerance and withdrawal from prolonged opioid use in critically ill children. Pediatrics 125, e1208–e1225. doi: 10.1542/peds.2009-0489
4 Khera T and Rangasamy V (2021) Cognition and Pain: A Review. Front. Psychol. 12:673962. doi: 10.3389/fpsyg.2021.673962
5 Villemure, C., and Bushnell, M. C. (2002). Cognitive modulation of pain: how do attention and emotion influence pain processing? Pain 95, 195–199. doi: 10.1016/s0304-3959(02)00007-6
6 Johnston, I. N., Maier, S. F., Rudy, J. W., and Watkins, L. R. (2012). Post-conditioning experience with acute or chronic inflammatory pain reduces contextual fear conditioning in the rat. Behav. Brain Res. 226, 361–368. doi: 10.1016/j.bbr.2011.08.048
7 Mutso, A. A., Radzicki, D., Baliki, M. N., Huang, L., Banisadr, G., Centeno, M. V., et al. (2012). Abnormalities in hippocampal functioning with persistent pain. J. Neurosci. 32, 5747–5756. doi: 10.1523/JNEUROSCI.0587-12.2012
8 Tajerian, M., Hung, V., Nguyen, H., Lee, G., Joubert, L.-M., Malkovskiy, A. V., et al. (2018). The hippocampal extracellular matrix regulates pain and memory after injury. Mol. Psychiatry 23, 2302–2313. doi: 10.1038/s41380-018-0209-z
