Validation of a neuropsychological battery in a sample of patients with chronic fatigue syndrome

Aims: Some cognitive deficits have been identified, although the findings are inconsistent and hindered by methodological heterogeneities. One of these limitations is the neuropsychological battery used. Some studies show that cognitive measures that share variance in healthy people can dissociate and contribute to unique variance in people with some cognitive impairment. They suggest that the validity in neuropsychological measures should be tested in homoge- neous samples. The aim of this study was to test the validity of a neuropsychological battery in a sample of patients with CFS. Methods: Sixty-eight women, aged between 29 and 67 years-old and diagnosed with CFS according to the criteria of Fukuda were enrolled. We excluded patients with mental disorders (except depression reactive to illness) and organic diseases that can course with cognitive impairment. Patients were assessed with the following neuropsycholog- ical test: Mental Control, Paced Auditory Serial Addition Test, Digit Span, Symbol Digit Modalities Test, Stroop Test, Trail-Making Test, verbal fluency test, Tower of London test, Rey Auditory Verbal Learning test, Rey-Osterreith Complex Figure and Grooved pegboard. Twenty-five cognitive measures were obtained. Because the multi- dimensionality of the cognitive functions studied, principal components analyses including all the measures were carried in order to assure that each one was comprised of only one cognitive dimension. Results: The neuropsychological measures were categorized into 7 specific cognitive domains: Attention/concentration, divided attention, verbal memory, visual memory, executive functioning, problem solving and motor functioning. The Cronbach's alpha for all analyses was upper than .05. Conclusion: This study proposes a validation of a neuropsychological battery in a homogeneous sample of CFS. This proposition could reduce one of the main limitations in the studies about CFS and cognitive function- ing, such as the inconsistent findings associated to the different neuropsychological test used.