Otherwise known as “fibro fog,” dyscognition is the new medical term researchers are using to describe symptoms related to difficulty concentrating, disorganized thinking, memory problems, and inability to stay focused or alert. According to neuro-psychologist Jennifer Glass, Ph.D., at the University of Michigan, “These cognitive symptoms are often more troubling to the patient than other symptoms.”1
Reviewing the research findings for dyscognition in people with FM and CFS/ME, Glass states, “In the past, some controversy existed over whether the perceived cognitive problems could be demonstrated with objective testing. However, enough evidence has now been found to safely say that objective cognitive deficits can be shown in both CFS and FM patients.” Indeed, it is no longer a question of whether you grapple with processes that drain the brain, but rather, the question now being asked is: “What causes dyscognition?”
Glass sites several interesting findings that may form a strong foundation for helping researchers identify the cause of dyscognition in FM patients:
- Tests that evaluate working memory and episodic memory (e.g., the ability to learn and later recall a list of words), as well as those pertaining to verbal fluency (the ability to access stored knowledge of words) show that FM patients perform poorly compared to healthy control subjects.
- Several functional brain imaging studies conducted while subjects are given a painful stimulus show increased activation in the pain processing areas of the brain in FM patients compared to healthy controls. Glass points out that these findings may be relevant to dyscognition because painful stimulation activates some areas of the brain that are also involved in attention-demanding cognitive tasks.
- One small preliminary study comparing 12 FM patients with 9 controls suggests that patients activate more cortical (or brain) areas during a working memory test, but this finding has not been formally published.2
- Memory in FM patients is more disrupted than in healthy controls during conditions involving distractions (i.e., attention is divided while learning and recalling a word list). Commenting further, Glass says, “These findings show that FM patients may have difficulty controlling attention, perhaps due to the attention-capturing properties of pain itself.” Lending some credibility to the notion that pain and cognition are linked is the common self report from patients that when their pain levels are reduced, their cognition improves … but other factors, such as the quality of one’s sleep, could be linked to pain as well.
- Looking at brain waves in response to specific stimuli, such as evoked response potentials (ERPs), FM patients tend to show a reduction in focused cognitive effort (as measured by size of the brain waves in response to specific auditory stimuli).
- Why is it that neuroimaging evidence shows an increased pattern of brain activation in FM patients, while ERP studies show a reduction in focused cognitive effort? Glass says that further research will be needed to sort this out, adding that “the increased areas of neural activation seen in the imaging studies may reflect an attempt at neural recruitment when a more efficient focused increase in activity is not possible.” In other words, the brain may respond by a generalized activation because for some reason it is having difficulty fine-tuning its response to specific stimuli. This phenomenon may also relate to disorganized thinking and inability to stay focused, which are important components of dyscognition.
Glass points out that standard neuropsychological tests were designed to detect overall impairments rather than a pattern of cognitive processes that are specific to FM. “For example, FM patients appear to be quite sensitive to the effects of distraction, but most neuropsychologic testing takes place in a distraction-free environment quite different from the hectic world.” There is also the possibility that the pain itself may be a distracting factor.
If pain is suspected to play a distracting role that produces the dyscognition in FM, what about sleep? Glass points to early studies in CFS patients that failed to correlate levels of fatigue with degrees of self-reported dyscognition, while recent reports show that mental fatigue does correlate with cognitive dysfunction. This highlights the importance of looking at mental “brain” fatigue as opposed to the general symptom of fatigue, in which the latter could pertain to the muscles or post-exertional malaise. Although the majority of FM patients exhibit symptoms of generalized fatigue, mental fatigue, and disturbed sleep, these components of the disease have not yet been assessed for their potential role in generating dyscognition.
1. Glass JM, Curr Rheum Reps 8:425-9, 2006.
2. Bangert A, et al. Arthritis Rheum 48:S90, abstract # 117, 2003.