Objective: This study aimed to explore the relationship between self-reported cognitive difficulties, objective neuropsychological test performances, and subjective health complaints in chronic fatigue syndrome (CFS) and to examine the degree of impaired cognitive functions. Method:A total of 236 consecutively recruited outpatients, aged between 18 and 62 years, completed the tests. Self-administered questionnaires were used for assessing fatigue, pain, depression, anxiety and subjective cognitive complaints (Everyday Memory Questionnaire, EMQ). Also, neuropsychological tests, i.e., Stroop I-IV, CVLT-II learning/delay, WAIS-III L-N Sequencing, and PASAT were performed to examine whether these objective measures correlated with subjective complaints and were compared with normative data. Results: There was a trend of association (p<0.05) between unadjusted EMQ with Stroop IV (inhibition and shifting attention), CVLT-II learning/delay (verbal learning and memory) and WAIS-III L-N Sequencing (working memory), but none were statistically significant at the 0.001 level. EMQ was positively associated with fatigue, pain, and depression (p<0.001). PASAT (working memory) was negatively associated with pain (p<0.001). Between 21% and 38% of the patients performed below the 1.5 SD cut-off for clinically significant impairment on the Stroop tests. Conclusion:The self-reported cognitive performance was not strongly associated with the objective cognitive performances on any domains in patients with CFS. Patients with higher fatigue, pain and depression levels reported greater subjective cognitive difficulties, also higher pain related to lower objective working memory function. The CFS patients had problems mainly in domains of psychomotor speed and attention measured by the objective neuropsychological tests. Public Significance Statements:In patients with chronic fatigue syndrome, their self-reported cognitive performance reflects, to some extent, the objective cognitive performances on certain domains. They report a high level of cognitive difficulties, which are positively correlated with fatigue, pain, and depression; however, the relationships with objective tests are weak. They display problems mainly in domains of psychomotor speed and attentional control measured by objective neuropsychological performance tests.

Objective: To study whether standard cognitive behavioral therapy (CBT) and a shorter, interpersonal oriented cognitive behavioral therapy (I-CBT) can improve physical function and fatigue in patients diagnosed with mild to moderate chronic fatigue syndrome (CFS) in a multidisciplinary fatigue clinic.Design: Consecutively 236 participants 18–62 years old meeting the Centre of Decease Control, CDC 1994 criteria, with a subsample also fulfilling the Canadian criteria for CFS, were randomly allocated to one of three groups. Two intervention groups received either 16 weeks of standard CBT or 8 weeks of I-CBT vs. a waiting-list control group (WLC). Primary outcome was the subscale Physical Function (PF) from SF-36 (0–100). Secondary outcome was amongst others fatigue measured by Chalder Fatigue Questionnaire (CFQ) (0–33). Outcomes were repeatedly measured up to 52 weeks from baseline.Results: The additional effect relative to baseline at post-intervention for SF-36 physical function was 14.2 (95% CI 7.9–20.4 p &lt; 0.001) points higher for standard CBT and 6.8 (0.5–13.2 p = 0.036) points higher for I-CBT compared with the control group. The additional effect relative to baseline at post-intervention for fatigue was 5.9 (95% CI 0.5–10.5 p = 0.03) points lower for standard CBT compared with the control group but did not differ substantially for I-CBT 4.8 (95% CI −0.4 to 9.9 p = 0.07). The positive change in physical function persisted at 1-year follow-up for both treatment groups, and for standard CBT also in fatigue. The two intervention groups did not differ significantly in self-reported physical function and fatigue at the 1-year follow-up. No serious adverse reactions were recorded in any of the groups during the trial period.Interpretation: A 16-week standard, individual CBT intervention improves physical function and fatigue in CFS outpatients with mild to moderate disease. A shorter 8-week I-CBT program improves physical function. Both treatments are safe, and the effect persist 1 year after baseline.Clinical Trial registration:ClinicalTrials.gov, Identifier: NCT00920777, registered June 15, 2009.REK-project number: 4.2008.2586, registered April 2, 2008. Funding: The Liaison Committee for Education, Research and Innovation in Central Norway.

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