Delineating psychopathologic clusters within dysthymia: a study of 512 out-patients without major depression

Background: The literature indicates that emotional-cognitive symptoms are much more characteristic of dysthymia than the vegetative and psychomotor s ymptoms of major depression, yet this is insufficiently emphasized in the o fficial criteria listed in the criteria of the American Psychiatric Associa tion. Furthermore, as previous studies have examined these symptoms more in relation to prevalence than to possible symptom aggregation, in the presen t analyses we address both aspects. Methods: In two multicenter collaborati ve trials, 512 out-patients meeting the symptom criteria of DSM-III-R dysth ymia but without major depression were recruited. In this respect they conf ormed to the conceptual framework of ICD-10 which tends to restrict dysthym ia to a subthreshold depression without excursion into severe depressive ep isodes. The Montgomery Asberg Depression Rating Scale (MADRS) and the Hamil ton Anxiety Rating Scale (HAM-A) were used to assess depressive and anxiety symptoms. Results: Symptoms most frequently observed, besides depressed mo od (100% by definition), were 'low energy or fatigue' (96%) and 'poor conce ntration or indecisiveness' (88%), followed by 'low self-esteem' (80%), 'in somnia or hypersomnia' (77%), 'poor appetite or overeating' (69%) and 'feel ing of hopelessness' (42%). Interestingly, in the subjects with fewer than five symptoms, the most frequent were low energy or fatigue (93%), poor con centration or indecisiveness (79%) and low self-esteem (77%), the other sym ptoms being present in no more than half the sample. MADRS factor analysis identified two main factors: the first consisting of apparent and reported sadness, and the second concentration difficulties and lassitude. HAM-A fac tor analysis identified two factors clearly differentiating somatic and psy chic symptoms. Limitations: Because suicidal patients were excluded on the ground of human subject concerns, our sample is representative of the milde r range of symptomatology within the spectrum of dysthymia. This may in par t explain the low prevalence of neurovegetative symptoms. Conclusion: Despi te this, the present study involves the largest sample of pure dysthymia ev er studied. Our results indicate that dysthymic disorder appears to primari ly involve psychologic symptoms. The psychological symptoms themselves seem to cluster into sadness versus mental fatigue; as for anxiety symptoms, th ey appear divisible into somatic and psychic clusters, with the latter prev ailing in dysthymia. Dysthymia proper, dominated by negative affectivity, m ight be distinguishable from a 'neurasthenic' subform dominated by low ener gy or 'deficit' symptoms at mental and physical levels. (C) 1999 Elsevier S cience B.V. All rights reserved.