We are all familiar with fibrofog when it comes to fibromyalgia but fibrofog is really just part of the symptoms associated with the cognitive dysfunction of FM.
Article published online July 21 in Arthritis Care and Research has recently looked more in-depth into the symptoms of cognitive dysfunction and where it affects FM. What they looked at was four components of Executive Function:
- Shifting; the ability to shift our attention between tasks.
- Inhibition; the ability to suppress routine responses.
- Updating; replacing outdated information with current relevant information.
- Access; the ability to access long-term memories which is needed for verbal fluency.
The study had 30 participants between the ages of 18 and 70 with a control group of 30 women matching in age group. All participants were involves in 90 minutes of testing that measured pain, anxiety, depression, executive function, memory and working memory. Self-evaluation of cognitive impairment was also measured using Functional Assessment of Cancer Therapy-Cognition Scale (FACT-Cog 2), which can be used with people that do not have cancer because it does not contain any specific references to cancer.
The patients with FM reported a mean pain intensity level of 6.68 (SD, 2.59) on a visual analog scale, suggestive of moderate pain. On the Hospital Anxiety and Depression Scale, patients with FM had a mean total score of 18.2 (SD, 5.8), indicating severe anxiety and depression, compared with a mean of 11.2 (SD, 5.7), or moderate anxiety and depression, among the control participants (P < .0001). Scores of 8 or more suggest clinically relevant levels of anxiety or depression.
On the Digit Scan-Backward test, a measure of updating and working memory, the patients with FM had a mean score of 3.8 (SD, 1.1) compared with a mean of 4.4 (SD, 0.9) for the control group (P = .031). Patients with FM also scored lower on the delayed recall portion of the Rey Auditory Verbal Learning Test, with a mean score of 9.9 (SD, 3.6) compared with a mean of 11.7 (SD, 2.4; P = .033), suggesting impairments in episodic memory.
Attentional shifting was measured using the A and B portions of the Trail Making Test (TMT). There was no significant difference between groups on scores for the TMT-A, in which participants connect numbers ascending from 1 to 25. However, on the TMT-B, which requires the test takers to alternate between numbers and letters, FM patients recorded a mean score of 97.3 (SD, 39.9) compared with a mean of 75.7 for the HC group (SD, 28.6; P = .020).
Working memory was measured with the 1-Back test, in which subjects look at colored blocks on a screen for a given period of time and must then press a keyboard to indicate what they have seen. Reaction time is measured in milliseconds, along with accuracy. There was no difference in accuracy between the groups, but the patients with FM had significantly longer reaction times (mean, 891.2 msec; SD, 185.0) compared with the HC group (mean, 722.4 msec; SD, 131.9; P < .0001).
Patients with FM also showed significantly poorer judgment on all measures of self-perception of cognitive dysfunction, including mental acuity (P = .002 compared with HC participants), deficits noticed by other people (P = .001), verbal and nonverbal memory, verbal fluency, functional interference, and effect on quality of life (P < .0001 for each). (Medscape)
Overall, the more serve the patient’s FM (measured by Fibromyalgia Impact Scale) the greater the self-perception of cognitive impairments (such as attention and concentration or fibrofog). The sample size though was a limitation of this study. “In addition, the authors did not control for pharmacological treatment when enrolling the participants, and they point out that certain medications can have a significant effect on cognitive function. However, they write, “this limitation does not invalidate the main result of the study, which concerns the degree of accordance between subjective and objective reports.””
“[O]ur data indicate that the long-term and working memory, shifting of attention and updating executive functions of FM patients are impaired compared to [HC]s,” the authors conclude. “These impairments are reflected in subjective complaints independently of depressive symptoms.” They recommend inclusion of a self-report questionnaire to assess cognitive impairment in the initial clinical evaluation of patients with fibromyalgia. (Medscape)
Arthritis Care Res. Published online July 21, 2014. Abstract