Presentation: Clinical and Biochemical features of Atypical and Melancholic Depression Subtypes in Fibromyalgia Patients (2007)

1541 Clinical and Biochemical features of Atypical and Melancholic Depression Subtypes in Fibromyalgia Patients

PURPOSE: Major depressive disorder (MDD) is a common co-morbidity in fibromyalgia (FM) patients, with a lifetime prevalence of about 60%. Two common DSM-IV-TR MDD subtypes are atypical depressive episodes (ADE) and melancholic depressive episodes (MDE). Approximately 60% of depressed patients have one of these 2 subtypes. Previous work has reported that depressed patients with ADE have reduced hypothalamic-pituitary-adrenal (HPA) axis activity compared to the MDE subtype. The aim of this study was to describe the demographic and clinical characteristics of FM subjects with ADE, MDE and no MDD in relation to HPA axis activity.
METHODS: Subjects were randomly selected and interviewed from a mailing to 1582 FM patients. The diagnosis of MDD and subtypes were determined by a semi-structured clinical interview using the DSM-IV-TR diagnostic criteria for MDD with ADE and MDE subtype specifiers. Clinical features of FM and MDD (pain and depression severity; sleep quality; quality of life; impact of FM on ability to function) were measured using standard instruments. HPA function was assessed using the dexamethasone suppression test (DST) in 65 subjects and a combined DEX suppression/CRH stimulation test in 19 subjects. Descriptive statistics were used to characterize demographics (age, gender, race, ethnicity, education, disability and marital status). Chi square tests and analysis of variance (ANOVA) were used to explore differences between the diagnostic groups on demographic and clinical characteristics in relation to HPA activity.
RESULTS: A total of 76 FM subjects were studied; 9 had no MDD (12%), 40 had ADE (56%) and 27 had MDE (32%). Subjects with MDD had significantly higher scores on pain intensity, quality of life, quality of sleep and FM impact compared to subjects with no MDD. The MDE group had the most severe symptoms. Several diagnostic criteria of ADE were also seen in MDE, namely: leaden paralysis (100% v 96%), mood reactivity (100% v 74%) and interpersonal rejection sensitivity (71% v 48%). Following DST testing (n=65), peak plasma cortisol levels were <5 ng/dl in 100% of ADE subjects and >5 ng/dl in 55% of MDE subjects. There was a moderate correlation between peak plasma cortisol levels and MDD subtypes (r= 0.39, p< .002). The DEX/CRH test appeared to be more discriminatory for depression subtypes with a peak value in ADE of 1.25 (±2.14) ng/dl and 9.88 (±5.15) in MDE (n=19, p = 0.002).
CONCLUSIONS: This study provides 4 novel findings: 1) DSM-IV-TR subtypes of MDD exist in FM and exhibit similar characteristics to those found in non-FM depressed patients; 2) atypical depressive episodes are more common than melancholic depressive episodes; 3) HPA axis dysfunction is reflective of MDD subtypes; and 4) the ADE diagnostic criterion of “leaden paralysis” is found in the majority of FM patients, regardless of depression subtype. This last finding requires further investigation to see if it is a unique FM symptom, or is another description for “morning stiffness”.

 R. Ross, None; K. Jones, None; D. Eldredge, None; R. Bennett, None.