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Background: Cognitive dysfunction is a signature feature of fibromyalgia. Many who develop cognitive problems in their middle years are concerned that it is prodromal to Alzheimer's disease., Objective: To determine if deficits in episodic memory and progressive cognitive decline, hallmarks of Alzheimer's disease, are prominent in the cognitive makeup of fibromyalgia patients., Methods: In a cross-sectional study, performance on 15 neurocognitive (NC) measures was evaluated in 2 cohorts of fibromyalgia subjects. The first cohort contained 94 subjects with a short duration of cognitive problems (≤12 months). The second cohort contained 55 subjects with a long duration of cognitive problems (≥84 months)., Results: The 2 groups were similar in education (14.9 ± 2.3 vs 14.9 ± 2.4), vocabulary scale score (11.2 ± 2.3 vs 11.6 ± 2.7), and depression (17.9 ± 9.8 vs 17.7 ± 9.4). The mean durations of cognitive problems in the short- and long-term group were 7.3 ± 3.9 months and 13.3 ± 7.1 years, respectively. There was no evidence of decline on 14 of 15 measures in the fibromyalgia group with an additional 12.6 years of cognitive dysfunction. Normality of function was in evidence on 4 measures of episodic memory in both cohorts., Conclusions: Fibromyalgia patients' fear of developing Alzheimer's disease was not borne out by the data. The cognitive pattern of fibromyalgia appears distinct from that of Alzheimer's disease. Fibrofog is not associated with either episodic memory loss on standard tests of episodic memory or progressive cognitive decline. Patients with fibrofog remember personally experienced events termed episodic memory at a normal rate in quiet, distraction-free conditions. Patients with Alzheimer's disease do not. They forget the essential elements of short stories just read to them in environments free of distractions. In Alzheimer's disease, the brain mechanisms responsible for encoding personally experienced events into memory are irreversibly impaired. In fibrofog, the encoding mechanisms are intact. At the heart of memory loss in fibromyalgia is the inability to appropriately filter out relevant distractions. Encoding mechanisms that otherwise operate normally in forming episodic memories for everyday events in fibromyalgia appear to malfunction when 2 streams of information operate concurrently (relevant information and a source of distraction overlap). The findings should allay the worries of many with fibromyalgia who fear that fibrofog is the start of a dementing process.

Lexical access speed, the time needed for the brain to access the catalogue of words in long-term memory, is assumed to provide a foundation for a broad array of cognitive operations. It was hypothesized that deficits in lexical speed are likely to play a central role in deficiencies in cognitive performance of patients with fibromyalgia, who as a group show deficits in lexical speed. This was tested in a sample of 209 patients with fibromyalgia and in 72 control patients with memory deficits. Participants completed the Stroop word-naming measure of lexical access speed and 12 neurocognitive measures. Deficit in lexical access speed occurred at approximately twice the frequency (48.3% vs 25.0%) in fibromyalgia. The average delay in speed of lexical access was 171 msec. in fibromyalgia and 163 msec. in controls. Those with deficits in lexical access speed displayed deficiencies on 10 of 12 cognitive measures in the fibromyalgia group, and on 8 of 12 cognitive measures in the control group. The premise that lexical access speed is disproportionately present in fibromyalgia and serves as a foundation for a wide array of cognitive operations is supported.

Objective: To examine the impact of distraction on the retention of rehearsed information in patients with fibromyalgia syndrome (FMS)., Methods: Data refer to the neurocognitive examination of 134 patients (91 with FMS and 43 control subjects) presenting with memory loss. Four neurocognitive measures free of distraction, along with 2 measures with added distraction, were completed. Differences in the retention of rehearsed and unrehearsed information with a source of distraction present were calculated., Results: Patients with FMS showed normal cognitive functioning on verbal memory tests free of distraction. Adding a source of distraction caused unrefreshed information to be lost at a disproportionate rate in patients with FMS. Over 87% of patients with FMS scored in the impaired range on a task of unrehearsed verbal memory. Adding a source of distraction to well-rehearsed information produced a normal rate of recall in FMS., Conclusion: Rehearsal mechanisms are intact in patients with FMS and play beneficial roles in managing interference from a source of distraction. In the absence of rehearsal, a source of distraction added to unrefreshed information signals a remarkable level of cognitive deficit in FMS that goes undetected by conventionally relied-upon neurocognitive measures. We present a theory to promote understanding of the cognitive deficit of people with FMS based on reduced speed of lexical activation and poor recall after distraction.

Objective: Abnormal processing of information in fibromyalgia may hold clues to brain abnormalities in this illness. The purpose of this study is to examine the speed of mental operations in people with the fibromyalgia syndrome (FMS) under the pressure of time. The central question addresses whether FMS is associated with processing speed deficits across a spectrum of speeded tasks., Methods: Sixty-seven patients with fibromyalgia with a history of memory complaints and 51 controls presenting with complaints of memory loss completed 10 timed cognitive measures of processing speed. Controls were patients with memory complaints who did not have FMS., Results: The majority of FMS patients (>70%) performed within 1 standard deviation of the norm on 7 or more of 10 speeded measures. However, more than 49% of FMS patients tested as impaired (>1.67 SD below normative mean) on 2 specific validated speed tasks (reading words and naming colors). Compared with controls, the number of FMS patients showing impairment was 2.0 times greater for reading speed, and 1.6 times greater for color naming speed. A mean time delay of 203 milliseconds was recorded for reading words and 285 milliseconds for naming colors in the FMS impaired sample. A 203 milliseconds delay in reading words represents a 48% (203/417) time increase over the normal time for reading the same stimulus word., Conclusion: Abnormalities in naming speed are an unappreciated feature of FMS. Selective deficits in naming speed in association with otherwise well preserved global processing speed set patients with FMS apart from controls with memory complaints. Clinicians would be wise to specifically request adding a rapid naming test such as the Stroop Test to the cognitive battery; to document cognitive dysfunction in FMS patients who otherwise appear to test normally, despite often intense complaints of memory and concentration difficulties that can affect job performance and increase disability.

Objective: Patients with fibromyalgia (FM) frequently complain of poor memory, severe enough to affect job performance and to lead to disability. Yet common practices in neurocognitive examinations often fail to document cognitive abnormalities that match the severity of their memory complaints. Often, neuropsychologists gauge memory competence with measures free of distraction and produce high rates of normality on neurocognitive examination. We hypothesized that neurocognitive tests encoded with a source of stimulus competition that interferes with the processing and/or absorption of information would be better than others in gauging FM memory competence., Methods: Thirty-five patients with FM and 35 controls, matched for age and sex, and presenting with complaints of memory loss, completed cognitive measures with and without stimulus competition., Results: Eleven (31.4%) patients with FM showed impairment on at least one measure of memory encoded free of stimulus competition. By comparison, 30 (85.7%) showed impairment on at least one measure encoded with a source of stimulus competition. The Auditory Consonant Trigram detected impairment in 29 (82.6%) cases, and was by far the most sensitive measure. FM patients lost information at a 58% rate following a 9 second distraction. This loss was disproportionate to the loss shown by both age matched controls with memory problems (40%) and to normative values (20%) based on individuals free of memory problems., Conclusion: The findings validate the perception of failing memory in patients with FM and are the first psychometric based evidence to our knowledge of short-term memory problems in FM linked to interference from a source of distraction. Adding a source of distraction caused the majority of FM patients to retain new information poorly, and may be integral to an understanding of FM memory problems. Much needs to be learned about why new information is disproportionately lost by FM populations when a source of distraction enters the experiential field.