Cognitive dysfunction in fibromyalgia: slow access to the mental lexicon.

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.