Fibromyalgia, chronic fatigue syndrome, and functional neurological disorders share common cognitive symptoms, including forgetfulness, distractibility (inability to pay attention to one topic), and word-finding difficulties, according to a new analysis.
The study, “A unifying theory for cognitive abnormalities in functional neurological disorders, fibromyalgia and chronic fatigue syndrome: systematic review,” was published in the Journal of Neurology, Neurosurgery, and Psychiatry.
Researchers in the U.K. performed a systematic review of studies reporting cognition-related outcomes in functional neurological disorders, fibromyalgia, and chronic fatigue syndrome.
Functional neurological disorders is a term for symptoms linked to problems in the nervous system for which there isn’t a physical neurological disease.
“Our hypothesis was that the cognitive profiles associated with functional motor, fatigue, and pain syndromes would be similar to each other,” researchers wrote.
“This would support the existence of a shared causal mechanism contributing to cognitive symptoms in these conditions with important implications for diagnosis and treatment,” they added.
After a search in the Pubmeb public database, they identified studies reporting cognition-related outcomes in each disease — 52 studies on fibromyalgia, 95 on chronic fatigue syndrome, and 39 on functional neurological disorders.
The studies’ outcomes included self-reported cognition difficulties on neuropsychological tests.
Researchers analyzed and compared results linked to: “cognitive symptoms; objective neuropsychological abnormalities (memory, attention and executive functions, information processing, language and social cognition); consistency on repeat assessment; performance validity testing (PVT);” and a correlation between self-reported symptoms and objective deficits in cognition.
From 50-90 percent of patients with fibromyalgia reported cognition problems, including forgetfulness, distractibility, speech difficulties, and lack of organized thinking.
The prevalence for these symptoms was higher than in healthy people (controls) or in patients with rheumatic disorders. Contributing factors included pain, fatigue, depressed mood, and poor sleep.
These cognitive symptoms were also common in patients with chronic fatigue syndrome and functional neurological disorders, including functional movement disorders (FMDs) — characterized by jerky motions or spasms — and non-epileptic attacks (NEAs).
The analysis also revealed several specific abnormalities for each disorder, mainly in fibromyalgia and chronic fatigue syndrome. For example, only in fibromyalgia was an impairment in cognitive inhibition reported, described as an “inability to filter distracting information, underpinning the vulnerability to distraction.”
“We hypothesize that pain, fatigue, and excessive interoceptive monitoring produce a decrease in externally directed attention. This increases susceptibility to distraction and slows information processing, interfering with cognitive function, in particular multitasking,” researchers concluded.