Cognitive impairments in Chronic Fatigue Syndrome Patients: Choice reaction time, encoding of new information, response organisation and selective attention

Background: One of the features of Chronic Fatigue Syndrome (CFS) is the reporting of cognitive impairment. Prior research has confirmed this using cognitive performance test batteries. Psychomotor slowing and episodic memory impairments appear to be robust, but little is known about selective attention or the stages of processing leading to slower reaction times. The present study addressed these gaps in the literature. Methods: CFS patients were recruited from a health service clinic. Sixty-seven patients agreed to carry out cognitive tasks measuring aspects of focused attention and categoric search and the components (encoding and response organisation) of choice reaction time. They were compared with 126 healthy controls. As well as carrying out the performance tasks, the participants also completed symptom checklists and questionnaires measuring fatigue, mental health and cognitive failures. Results: The questionnaires revealed the typical profile of symptoms of CFS patients. With regards to the objective performance tasks, the CFS patients had significantly slower choice reaction times on both tasks. This is likely to be due to slower motor responses as neither of the measures of stimulus encoding or response organisation showed differences between the groups. There was also little evidence for the groups differing in aspects of selective attention. Conclusions: CFS patients report greater fatigue, more somatic symptoms, greater mental health issues and more cognitive difficulties. Objective testing revealed slower choice reaction times which probably reflect motor slowing. These measures can now be used to assess the efficacy of the management of CFS