Conference Coverage

‘Fibro-fog’ confirmed with objective ambulatory testing



– Individuals with fibromyalgia had worse cognitive functioning than did a control group without fibromyalgia, according to both subjective and objective ambulatory measures.

For study participants with fibromyalgia, aggregate self-reported cognitive function over an 8-day period was poorer than for their matched controls without fibromyalgia. Objective measures of working memory, including mean and maximum error scores on a dot memory test, also were worse for the fibromyalgia group (P less than .001 for all).

Objective measures of processing speed also were slower for those with fibromyalgia, but the difference did not reach statistical significance.

These findings are “generally consistent with findings from lab-based studies of people living with [fibromyalgia], Anna Kratz, PhD, and her coauthors wrote in a poster at the scientific meeting of the American Pain Society. The study, they explained, extends laboratory-based work on cognitive dysfunction in fibromyalgia to a real-world setting by using smartphone-based capture of momentary subjective and objective cognitive functioning.

In a study of 50 adults with fibromyalgia and 50 matched controls, Dr. Kratz and her colleagues at the University of Michigan, Ann Arbor, had participants complete baseline self-report and objective measures of cognitive functioning in an in-person laboratory session. Then, participants were sent home with a wrist accelerometer and a smartphone; apps on the smartphone administered objective cognitive tests as well as subjective questions about cognitive function.

Both the subjective and objective portions of the ambulatory study were completed five times daily (on waking, and on a “quasi-random” schedule throughout the day), for at least 8 days. Day 1 was considered a “training day,” and data from that day were excluded from analysis.

To assess subjective cognitive function, patients were asked to give a momentary assessment of how slow, and how foggy, their thinking was, using a 0-100 scale. These two questions were drawn from the PROMIS Applied Cognition – General Concerns item bank. Objective measures included processing speed, captured by a 16-trial exercise of matching symbol pairs. Also, working memory was tested by completing four trials of remembering the placement of three dots in a 5x5 dot matrix.

Among the participants, 88% were female. The mean age was 45 years, and about 80% of the subjects were white. Fibromyalgia patients had more pain than did their matched controls and had poorer baseline performance on four neurocognitive tasks drawn from the National Institutes of Health Toolbox. For a flanker test, a list sorting task, a dimensional change card sort test, and a pattern comparison task, mean scores for participants with fibromyalgia ranged from 39.08 to 49.76; for the control group, mean scores ranged from 43.78 to 57.36 (P less than .05 for all).

Some people with fibromyalgia report subjective diurnal variation in cognitive function, so Dr. Kratz and her coauthors were interested in tracking performance on the ambulatory cognitive tasks over the course of the day. “Diurnal patterns and associations between objective/subjective functioning were similar across the groups,” said the authors, with no hallmark diurnal pattern for the participants with fibromyalgia. Generally, participants in both groups had the highest subjective and objective levels of performance in the morning, a dip at the first reporting time, and a gradual recovery to a level somewhat below the first morning test point by the end of the day.

Dr. Kratz and her colleagues found that in both groups, “significant associations were observed between within-person momentary changes in subjective cognitive functioning and processing speed.” This association did not hold true for working memory, however.

The findings were overall generally consistent with lab-based testing of cognitive function in individuals living with fibromyalgia, the authors said.

Dr. Kratz and her colleagues reported no outside sources of funding, and reported no conflicts of interest.

SOURCE: Kratz A et al. APS 2019, Poster 117.

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