Four Questions: Chronic Pain and How It Affects the Brain

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Alexis Blue, Chris Richards photo

Chronic pain affects an estimated 100 million Americans, and its impact goes beyond physical discomfort.

Research led by University of Arizona psychologist Stephen Cowen illustrates how chronic pain may impact cognitive abilities, such as decision-making, as well.

Cowen and UA professor of pharmacology Frank Porreca, along with their collaborators at Eli Lilly, investigated how pain impacts cognitive flexibility, or the ability of the brain to learn new information. The study, published in the journal Pain, revealed that the ability to adapt to changing situations may be hindered in those with chronic pain.

“Cognitive flexibility is a broad term, but overall, it’s your ability to adapt to new information, being flexible with your learning,” says Cowen, an assistant professor in the UA Department of Psychology. “For example, you might initially learn one route to work, and you do that day after day, and then the next two days in a row there’s construction. You should be able to reroute yourself and not, out of habit alone, keep going down that path that always makes you late for work.”

In Cowen’s study, rats with neuropathic pain were able to learn a basic task — pulling a designated lever to receive a food reward — at the same rate as control groups. However, they were much slower than rats without pain to adapt when conditions changed, and a new lever was introduced that produced more food.

The findings provide insight into how pain may hinder cognitive flexibility in humans, Cowen says.

Q: What motivated you to look at chronic pain as it relates to decision-making? 
A: Traditionally, what we’re mostly concerned about with chronic pain is the pain itself — the emotional component of the pain or the physical feeling of pain. Those are the things we usually focus on, and rightly so, but there are also other consequences of having chronic pain that affect your ability to learn and make decisions, and that’s what we focused on with this study. We wanted to see what types of learning deficits or alterations in your ability to adapt to new information are affected by chronic pain, and that’s something that’s very rarely been looked at in the field.

Q: What are the implications of your findings for people suffering chronic pain?
A: If you’re suffering from chronic pain, your ability to make good decisions or adapt to new information might be compromised. You might not realize it, but your friends and others might notice that you’re sticking to what you know. You’re not venturing out, you’re not trying new things, you’re not learning new information. You’re kind of on autopilot. 
So this might be an unforeseen consequence of chronic pain that we don’t study enough. In the past, we’ve focused more on the immediate effect of just the pain itself, which is very important, but some of the more detrimental consequences may be in the poor decisions that are made.
With most of the therapies we test for chronic pain, nobody looks at the effects on treating the cognitive or learning deficits that perhaps are accompanying chronic pain. In our study, we found maybe we should start looking at that. 

Q: Why do we see the connection between chronic pain and cognitive flexibility, and what are the next steps for this research? 
A: I study the frontal cortex, the frontal part of the brain that we think is so important for decision-making and cognitive flexibility. The frontal cortex is really important for the ability to override our basic instincts, in a sense, and to be more adaptive to new information. 
When you have chronic pain, the neuronal activity in the frontal cortex changes considerably. We thought that these changes would result in an inability to adapt to new information, and, sure enough, that’s what we found. 
We didn’t directly measure frontal activity — we didn’t look at the neuroscience — so that’s what we really would like to do next, and that’s what my lab’s specialty is: recording the activities of neurons in the brain during decision-making and during learning. 

Q: What excites you most about this work? 
A: If I can get a glimpse into how this great machine of ours called the brain works and understand how interactions between groups of neurons lead to a memory, lead to an action, lead to a decision — that’s the most exciting thing. I really want to look under the hood and get a glimpse of what the system is doing. I’m very interested in the translational component too: How do we take what we’re doing and help patients?