Executive function is an umbrella term for mental processes enabling us to plan, focus attention, remember, and switch between multiple tasks. Impairments of these functions are prevalent in chronic pain patients and patients rate potential impairments as debilitating for their everyday lives.

Current medical knowledge does not allow for describing differences in executive dysfunction between pain types, as most studies only include heterogeneous, poorly defined pain conditions. For example, a recent review cited no real comparison of executive functioning between pain types, despite clinical experience which argues for substantial contrasts in cognitive difficulties between pain conditions. One example of this is that clinicians often observe that fibromyalgia (FM) patients present more problems with executive functioning than those with neuropathic pain (PNP).

Fibromyalgia patients do indeed rate cognitive decline and its consequences as one of the most significant limitations to everyday life, but so do patients with neuropathic pain. However, PNP patients reporting cognitive dysfunction appear to receive little attention. For example, available computerized cognitive training (CCT) programs are based solely on results from patients with musculoskeletal disorders, despite study-highlighted potential differences in executive dysfunction between pain conditions.

Let’s look at the differences between the two disorders. PNP arises as a direct consequence of a localized lesion or disease affecting the somatosensory system. FM on the other hand is a centrally driven pain condition. But, according to the Neurocognitive Model of Attention to Pain, any executive dysfunction in chronic pain is the result of the interplay between the attention paid to peripheral input and the goal-directed activity of the brain. As such, the Model hypothesizes that there would be differences in executive functioning driven by varies inputs to and from the brain. However, this is a notion which is yet to be tested among chronic patients.

Going a step further in the pathology of the two chronic pain disorders, when comparing FM and NP patients on executive functioning it is also argued that FM is a pain condition of “unknown origin.” As such, it lends itself less to a pathophysiological understanding. This potentially drives greater analysis about “why” a FM patient experiences pain. We know that such thinking taxes attentional resources in the patient. Over time this could drive differences in executive functioning from sustained cognitive activation.

Why is evaluating the difference between cognitive function within specific chronic pain disorders important? Differing between pain types is important as executive functioning is crucial when performing goal-directed behavior and problem-solving, the two building blocks of cognitive-behavioral therapy (CBT). And illuminating differences in executive functioning within pain categories could help evolve a more targeted CBT for chronic pain, potentially improving its therapeutic effects.

As a point of comparison three core components of executive function that are functionally separable were selected to measure. These are inhibition (inhibitory control and interference control), updating or working memory (the ability to maintain accurate representations of information that changes over time), and cognitive flexibility (switching attention from one thing to another and monitoring current internal and external states). Moreover, in studies of heterogeneous chronic pain conditions, insomnia is shown to worsen working memory performance. Both patients with FM and PNP report higher levels of severe insomnia when compared to other pain conditions. In addition, both depression and pain medication can influence executive dysfunction.

The aim of the study was to evaluate whether there were differences between FM, PNP or healthy controls (HC) on four tests of executive functioning. Three of the tests reflect the core components in executive functioning, and the fourth tested attention-demanding cued recall. The hypotheses were that:

(1) FM patients would demonstrate executive dysfunctions beyond HC and patients with PNP on the three executive functions of inhibition, updating and flexibility;

(2) that PNP patients would perform significantly worse on an attention-demanding cued-recall task compared to FM patients and HC.

Results and full study details can be found here.