Psychiatric morbidity in the chronic fatigue syndrome: are patients with personality disorder more physically impaired?

OBJECTIVE: The long-term consequences of chronic fatigue syndrome (CFS) include substantial impairment in physical functioning and high levels of work disability. In the absence of a medical explanation for this impairment, some have speculated that it may be due to comorbid psychiatric illness or personality disorder. We addressed this possibility by comparing the functional status of three CFS groups: no psychiatric diagnosis, psychiatric illness only, psychiatric illness and personality disorder. A second aim of the study was to determine whether a continuous measure of psychological distress could provide a better account of impairment than psychiatric diagnosis.
METHOD: The study sample consisted of 84 consecutive female referrals with CFS. All participants satisfied the case definition and completed an assessment protocol consisting of: physical examination, psychiatric interview and self-report questionnaires.
RESULTS: Psychiatric illness, either alone or in combination with a comorbid personality disorder, was not associated with physical impairment or disability in female participants. A regression model of physical functioning found that psychological distress accounted for 6% and symptom severity for 41% of the variance (P=.06 and <.01, respectively). In the case of disability, the corresponding percentages were 2% and 18% (NS and P<.01, respectively). The modest effects of psychological distress could not be attributed to symptom severity.
CONCLUSIONS: Although psychiatric illness and personality disorder was prevalent, neither could explain the effects of CFS on physical functioning and disability. As yet, there is no psychological or medical explanation for the behavioral consequences of CFS.