Brain Health Series: Chronic Pain and Brain Function

Brain health in is a topic not discussed often enough, especially within the medical community. The conversation around mental health and access to mental health services has been increasing in recent years, however the aging brain is often left out of the conversation. There are so many questions left unanswered surrounding the decline of brain health associated with aging. The medical profession has made observations about those who ultimately experience brain atrophy and those who don’t, so we are slowly starting to gain clarity. However, there are still many questions left unanswered.

Research has identified some clear correlations and patterns in those who ultimately receive a diagnosis of dementia. Keep in mind, however, that correlation does not equal causation. We know that balance problems and risk of falls increase with increasing severity of cognitive decline. We know poor mental health increases the risk of developing dementia. We know that muscle weakness is associated with greater risk of dementia. What is not entirely clear is why.

This is a series on the connection between the brain and body written from the prespective of a geriatric physical therapist. I feel fortunate to have fallen into a profession where I work with older adults while still in my 30s. It provides me a unique perspective into my future and the future of my loved ones, leaving me in a unique position to try to put the puzzle of cognitive decline together and put forth my best effort to prevent it before it happens. Unfortunately, I often do not get referred to patients and their families until they are experiencing physical decline in conjunction with mental decline, leaving me in a position to trace backwards to form a clear picture of what that person was like before they had dementia.

The first area to highlight is the connection between chronic pain and brain health. One recent area of study is the impact of chronic pain on the aging brain. Up to 50% of older adults experience chronic pain, making pain an area of high impact in terms of aging. Chronic pain has multiple levels of influence on brain health including changing the brain itself, increasing the incidence of depression, and the use of medications for pain management which impair mental function. These multiple levels of impact make studying chronic pain in terms of brain health complicated.

Let’s explore these complexities further. By unraveling the connections between pain and brain health we can shine light on the issues and open up the discussion on brain health and aging. And most importantly, knowledge is power and we will show you how to use this information to make your health the best it can be!

Most Importantly, Sometimes Pain is Normal…

Whether we want to believe it or not, acute pain serves a useful purpose to our body. No one likes to be in pain, however acute pain is a signal to us that an area of our body is in need of attention. If the problem is a priority, your brain will bring awareness to it using the pain signal pathway to cause you to take the appropriate action to address the issue. For example, if you sprain your ankle by stepping off the curb the wrong way while crossing a street, you experience pain. The pain you feel keeps you from walking, which allows the damaged tissue in your ankle to heal.

It sounds simple enough, however the pain response is complicated. More complicated than just tissue damage equals immediate pain. To explain this further, let’s take a closer look at the nervous system. Our nervous system consists of nerves that run from tissues to the brain that contain sensory receptors (sensory nerves), nerves that run from the brain to our muscles (motor nerves), and the brain itself. Sensory nerves takin in information regarding touch, pressure, temperature, and pain. Put your hand too close to a hot stovetop and react by pulling your hand away from the heat before you even realized what was happening? Thank your sensory nerves. These nerves relay vital information about your environment to the brain to protect you while you move throughout the world.

There might be times when your brain determines an injury is not the main priority at the moment, and will delay the pain response to allow you to address a more pressing issue. For example, what if you sprain your ankle while crossing a street and look up to see a bus coming at you? You forget about the ankle so you can get out of the way of the bus as quickly as possible! After all that adrenaline, you likely won’t feel the ankle pain for a few hours after all is calm.

So what happened here?

The brain receives information from these nerves all over the body all day, among all the other jobs it performs. The brain prioritizes this information to determine what needs to be acted on in that moment, and suppresses information that can wait until later. So back to the example of crossing the street while the bus is coming… getting out of the way of the bus in order to save your life is the main priority. The ankle damage can wait until later.

We can compare the pain cycle to an alarm system. In the case of the ankle, the alarm is going off for a reason. Chronic pain is a completely different picture. In many cases, the alarm continues to go off long after there is no longer the threat of tissue damage. Over time, chronic pain impacts different areas of the nervous system than acute pain. Research has shown in cases of chronic pain the area of the body in pain is over-represented in the brain. Furthermore, the pain receptors in that area of the body both increase in quantity and become more sensitive to stress hormones. All of these changes combined drastically lower a person’s pain threshold in that area of the body, making something that would normally not be painful cause an awful lot of pain. This recent revelation about chronic pain drastically changed the approach to treating chronic pain for the better.

So, now that we have the basic information about pain response covered let’s take a closer look at what research on chronic pain related to brain health found.

Chronic Pain Changes the Brain’s Resting State

Under normal circumstances, the brain has an organized pattern of activity during the resting state. Studies have shown this pattern is disrupted in autism, Alzheimer’s disease, depression, and ADHD. Chronic pain not only alters these patterns in a similar manner, but also increases depression, anxiety, and inhibits sleep further compounding the changed resting state of the brain. This disruption contributes to altered mental status in those with chronic pain.

Chronic Pain Impacts Emotional and Memory Systems in the Brain

Over time, chronic pain becomes more integrated with the emotional and memory systems of the central nervous system. Fear-avoidance patterns of movement become evident in many of those who have experienced pain for some time. Anyone who has experienced an episode of pain in the past knows how emotional the experience can become. This impact on these systems leads to greater risk of long term detrimental changes within the brain.

Chronic Pain Impairs Attention

Acute pain, which is well studied, disrupts thought patterns. Attention is thought to decrease in cases of chronic pain because pain is occupying working memory areas of the brain which leads to less available attention for for other tasks. Even tasks not related to movement or pain.

Chronic Pain Impairs Neuropsychological Performance

Neuropsychological performance declines futher with increasing pain severity. Neurophysiological performance mediates the relationship between pain and physical performance. The lower the score in neurophysiological performance, the worse the physical performance. Increasing pain severity decreases performance in body position sense, mental flexibility, and manual dexterity.

Chronic Pain Increases Brain Atrophy

Patterns of brain atrophy have been identified in older adults with disrupted sleep, depression, and anxiety. Brain atrophy has also been identified in older adults with chronic pain. However, the brain atrophy identified in chronic pain is different than brain atrophy in older adults with chronic depression or anxiety. To further complicate this aspect of brain health, depression and anxiety increase the risk of dementia, and we also know that chronic pain increases the incidence of depression and anxiety. It also appears chronic pain on its own impacts the brain in a different way.

Pain Medications

No discussion of how chronic pain impacts the brain would be complete without mentioning pain medications. Medications are a topic that can be covered for hours on end, however we will just briefly mention them. Research has found the opioid medications are commonly prescribed in cases of chronic pain and have been connected with a decline in brain health. Older adults respond differently to strong pain medications which can make impairments in the brain more difficult to identify and link to the use of pain medication.

So What Can You Do?

We don’t want to leave everyone with this picture of doom and gloom! Now that we covered the latest research, let’s talk about what you can do to improve both your levels of pain and boost your brain health.

As stated above, chronic pain has multiple levels of impact on the brain. With the change in treatment approach to chronic pain came so many more options for treating chronic pain. Anything from physical therapy, to dietary changes, and meditation can improve quality of life and pain levels in anyone experiencing chronic pain. Check out our overview of chronic pain to further explore all the treatment options. Just know that pain does not have to be your normal!

The next part of this series will explore the connection between muscle strength and brain health. We hope we cleared up some of the mystery surrounding the connections between brain health, aging, and movement.

 

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