Dysthymia is the last diagnostic label introduced after a series of precursors to describe a disorder whose nosological status has long been dubious. The results of published epidemiological, as well as clinical studies about its presentation, course and outcome partly support the validity of this construct — although their interpretation is limited by methodological difficulties: same prevalence in many locations in the world, always lower than that of major depression, somewhat specific clinical pattern, course and outcome.

If some recent studies seem to reveal a more specific familial relationship for dysthymia in addition to a previously known familial relationship to mood disorders, and if results concerning the relationship between dysthymia and depressive personality as well as the search for possible biological and psychological correlates support the nosological validity of dysthymia, comorbidity studies raise difficult questions. Both comorbidity studies with Axis I and Axis II disorders challenge the validity of dysthymia, but as well they question the categorical model presently in use more than the validity of a definite category.

However, there are now enough data confirming some of the hypotheses implied by the nosological construct of dysthymia inside this model for this category not to be discarded. For instance, dysthymia is definitely not a personality disorder, and appears also distinct from major depression. The problem of the complex nature of the relationship between dysthymia and major depression still remains unsolved.

Data on dysthymia and personality presented here are derived from the Zurich cohort study, which followed 591 subjects from the ages of 20 to 35. From childhood on, dysthymics experienced themselves as far more anxious and less self-confident than did major depressives or controls. They manifested more behavioural problems and high neuroticism and introversion scores. Dysthymics scored low in terms of quality of life, self-esteem and mastery, whereas they scored high in avoiding/denying behaviours. The hypothesis is advanced that behavioural problems, anxiety, high levels of neuroticism and personality disorders constitute risk factors for chronic depression. Evidence is presented of the existence of bipolar dysthymia.

As part of the WHO-PPGHC study aimed to better understand the form, frequency and burden of psychiatric conditions in primary care throughout the world, the clinical characteristics of dysthymic patients consulting in primary care were examined. A total of 25,916 general health care attenders at 15 sites in 14 countries were screened using the 12-item General Health Questionaire (GHQ-12). Of those screened, 5,438 were assessed in detail using a Primary Health Care version of the Composite International Diagnostic Interview (CIDI-PHC) in conjunction with among others the Brief Disability Questionnaire (BDQ) and the 28-item General Health Questionnaire (GHQ-28). General practitioners (GPs) gave their opinion on the existence of a psychological problem and indicated what therapeutic intervention was proposed to patients they recognised as psychological cases. The estimated current prevalence of dysthymia as defined by the ICD-10 was 2.1%. The social disability was found to be substantial in patients with dysthymia (52.2% of patients moderately or severely disabled) similar to that observed in patients with Depressive Episode (DE) (57.4%). When both conditions were present, the level of disability was even higher (63.6%). The symptoms presented by dysthymic patients without DE were mostly those specific for the diagnosis of dysthymia (ie, tearful, hopeless, inability to cope, pessimism) while these symptoms were less frequent when dysthymia was complicated by a DE. On the contrary, fatigue and loss of interest were more rarely observed in “pure” dysthymics. In spite of a lower symptomatic severity about half of the patients with dysthymia were recognised as cases by their GPs, a proportion similar to those with DE. However, dysthymics without DE were not, in contrast to patients with DE or with dysthymia and DE, more treated with drugs than non-depressed patients.

Open trials with tricyclics, classical monoamine oxidase inhibitors (MAOIs) or lithium in dysthymia yielded a response rate in 45% of subjects. A long-term treatment of dysthymia with 276 patients treated during 4 years with either moclobemide, tranylcypromine or a combination of amitryptiline plus chlordiazepoxide is described. After discontinuation there was a relapse rate of 89.1%. The controlled studies with tricyclics, MAOIs, reversible inhibitors of monoamine oxidase (RIMAs), specific serotonin reuptake inhibitor (SSRIs) or benzamides showed that drugs well-tolerated work better in dysthymia, due to the fact that the treatment must be long-term. Sertraline was studied vs placebo or imipramine in primary dysthymia. Moclobemide, imipramine and placebo were also studied in 315 patients. Mean doses were 650 mg/d of moclobemide and 203.2 mg/d of imipramine. Moclobemide and sertraline were both efficacious and well tolerated. In a long term treatment the clinician should assess the risk-benefit ratio. Dysthymic patients are very sensitive to unwanted effects and compliance is a serious issue.

In 1987, DSM-III introduced the term delusional disorder. In so doing they gave new life to a concept that had predated but was delineated in its modern form by Kraepelin and developed most notably in France in the second and third decades of this century. While the current concept of delusional disorder is defined in a manner that distinguishes it from schizophrenia, a consideration of the evolution of thinking about delusional syndromes in France suggests that current distinctions are based on descriptive convenience rather than any understanding of the mechanisms that might produce phenotypic variations. If the purpose of accurate descriptions is to assist research, this state of affairs would seem unsatisfactory.