PSYCHIATRIC COMORBIDITY IN CHRONIC FATIGUE SYNDROME

Introduction: fatigue is a common symptom in the community, with up to half of the general population reporting fatigue in large surveys. It also is reported by at least 20% of patients seeking medical care. Typically the fatigue is transient, self-limiting, and explained by prevailing circumstances. However, a minority of persons experience persistent and debilitating fatigue. When the fatigue cannot be explained by a medical condition such as anemia or hypothyroidism, it may represent chronic fatigue syndrome. A 1994 revision of the CDC case definition constitutes the current criteria for CFS and the most widely used definition internationally. This definition requires at least 6 months of persistent fatigue that substantially reduces the person’s level of activity. In addition, four or more of the following symptoms must occur with fatigue in the 6-month period: impaired memory or concentration, sore throat, tender glands, aching or stiff muscles, multijoint pain, new headaches, unrefreshing sleep, and postexertional fatigue. Medical conditions that may explain the prolonged fatigue as well as a number of psychiatric diagnoses (i.e., eating disorders, psychotic disorders, bipolar disorder, melancholic depression, and substance abuse within 2 years of the onset of fatigue) exclude a patient from the diagnosis of CFS. The symptoms of chronic fatigue, as well as chronic fatigue syndrome itself, often co-occur with other so-called functional illnesses such as fibromyalgia (FM), which is a chronic, non-articular rheumatic condition characterized by diffuse aching, pain or stiffness in the muscles or joints, and the presence of tenderness on examination at specific, predictable anatomic sites known as tender points (TPs). Since a consistent physiological marker or physical finding for chronic fatigue syndrome has not been identified, some researchers have postulated that chronic fatigue syndrome is primarily a psychiatric disorder. Several researchers believe that CFS and related disorders are manifestations of a psychiatric condition such as somatisation disorder, hypochondriasis, major depression, or atypical depression. Indeed, persons with chronic fatigue syndrome have an increased prevalence of current and lifetime mood disorders, primarily major depression, compared to other chronically ill subjects or healthy comparison subjects; 25% and 50%–75% of patients have a current or a lifetime history of major depression, respectively. Generalized anxiety disorder and somatoform disorder also occur at a higher rate in these subjects than in the general population. In most, but not all cases, the mood or anxiety disorder precedes the onset of chronic fatigue syndrome. Methods: a consecutive sample of 51 patients with a diagnosis of CFS was consecutively recruited at the Rheumatology outpatient Unit of the University of Pisa between June 2010 and January 2011. Eligible subjects included new and continuing patients, of at least 18 years of age, according to the classification criteria of Fukuda of 1994. We also recruited a consecutive sample of 27 patients with a diagnosis of FM in the same Unit, who met the 1990 American College of Rheumatology criteria for diagnosis of FM. Psychiatric diagnoses were made through the Structured Clinical Interview for the DSM-IV Axis I disorders (SCID-I/P), administered by psychiatrists trained and certified in its use. The following questionnaires were also administered: the MOODS-SR lifetime version, the PAS-SR lifetime version, the Fibromyalgia Impact Questionnaire (FIQ) and the Software CNS Vital Signs, tests for the assessment of neurocognitive tasks. Results: according to the DSM-IV-TR criteria, current Axis I mental disorders were diagnosed in 5 (9.8%) CFS patients, moreover, in CFS group a lifetime Axis I mental disorder was diagnosed in 24 subjects. Even in the FM sample, a current Axis I mental disorder was diagnosed in 5 patients (18.5%) and in FM group a lifetime Axis I mental disorder was diagnosed in 18 subjects (66.7%). A psychiatric family history was recorded in 24 patients of CFS group (47.1%) and in 18 patients of FM group (66.7%). Neurocognitive aspects were evaluated in both groups: in the CFS group 57% had a “average” or “above” score, in FM sample was only 26%, which is the only significant difference (p= .020). We also evaluated the presence of mood and panic-agoraphobic symptoms with MOOD-SR in FM subjects were higher Sociability/extraversion, Irritability and psychotic symptoms. PAS-SR was more present in FM group, especially Agoraphobia and Claustrophobia. Conclusion: findings emerged from the comparison between CFS and FM groups using the MOOD-SR and PAS-SR shown a higher burden of psychopathology in the second one. More specifically, FM patients seem to have mood factors that indicate higher instability, such as Sociability/Extroversion and Irritability. Results of analysis of PAS-SR show us a higher presence of panic-agoraphobic spectrum in FM sample (up to 6/10 positive domains). We showed the importance of those questionnaires, often administered in psychiatric studies, because they represent a useful support to identify subthreshold symptoms of mood and panic-agoraphobic spectrum. We also evaluated the cognitive performance with a computerized test (CNS Vital Signs) to measure objectively the complaints of the patients, but this data suggest that there is a difference between the subjective feeling of the patient and the result of the computerized test, probably linked to mood or anxiety symptoms