All Fatigue is Not Created Equal

All Fatigue is Not Created Equal: Why it Matters and What it Means for Pain Management – by  Ian Boggero – April 6, 2017

For people with chronic pain conditions, feelings of fatigue may be the norm rather than the exception. In fact, fatigue is one of the most common symptoms reported by patients with chronic pain and increases as the intensity of the pain increases.

Why does fatigue matter? It predicts low quality of life and poor functioning in a number of chronic pain populations, including cancer and lower back pain.

In our work, we found that fatigue predicts low satisfaction with life in patients with chronic orofacial pain (pain in the head and face), and partially explains why pain is associated with psychological distress.  

In nature, this is exactly what pain is supposed to do, so labeling this distress as “catastrophizing”, as many do, is incorrect.

Our team wanted to take a more nuanced approach and test whether different subtypes of fatigue

• (general fatigue,
• mental fatigue,
• emotional fatigue,
• physical fatigue, and
• vigor), as well as
• total fatigue (as a single symptom),

predicted pain-related interference with social and recreational activities.

First, total fatigue (as a single symptom) significantly predicted pain interference, above and beyond pain intensity, depression, psychological distress, and poor sleep!

Is any pain patient even slightly surprised by this? Why are researchers so surprised? Have they never had pain that lasted more than a partial day?

Why are they all so naive about pain, as though they weren’t just as human as pain patients are?

This suggests fatigue is more than feeling tired or lacking energy and is likely influenced by a number of factors.

In fact, there’s moderately strong evidence for a central governing mechanism that monitors an array of cognitive, emotional, and physiological inputs and produces feelings of fatigue to prevent catastrophic overexertion

A second interesting finding was that the fatigue subtypes did not overlap as much as might be expected (13 – 40% of shared variance).

Most of the variance in any one type of fatigue was not accounted for by the other types, suggesting we can feel emotionally tired but physically energized, just as we can feel mentally tired but generally energized, for example. Think of a long airplane ride.

This is research news?

Examples of being fatigued in one domain but not another abound, but pain research takes a less nuanced approach and treats all of fatigue as one and the same.

The reason this matters – and this is the third interesting finding- is that each of these fatigue subtypes predicts outcomes differently.

In our study, physical fatigue and lack of vigor were the only two significant predictors of pain interference: general, emotional, and mental fatigue were not significantly associated. 

The more physically fatigued people felt, or the less energy they had, the more pain disrupted their social and recreational activities.

Clinically, these findings suggest that perhaps we should be looking at people’s fatigue profiles to target individualized treatment.

Author: Ian Boggero is a clinical psychology graduate student at the University of Kentucky, but is originally from Los Angeles and did his undergraduate studies at UCLA. His research interests involve the psychological and social factors that promote adaptive responses to pain.