Clinical picture and diagnostic considerations

Diagnostic criteria for dysthymia in both DSM-IV and ICD-10 stipulate a 2-year duration of low-grade depressive symptoms, exclusive of such indicators of severity as suicidality and psychomotor disturbances. Dysthymia is distinguished from chronic major depressive disorder by the fact that it is not a sequel to well-defined major depressive episodes. Instead, patients often complain that they have always been depressed. ^/j Most are of early onset (less than 20 years). A late-onset subtype(28> first manifesting after the age of 50 is much less prevalent and has not been well characterized clinically, but it has been identified largely through studies in the community.

At their best, dysthymic individuals invest whatever energy they have in work, leaving none for leisure or social activities. According to Tellenbach, (29) such dedication to work represents an overcompensation against depressive disorganization. Kretschmer (3°) had earlier suggested that such persons were the backbone of society, devoting their lives to jobs that require dependability and great attention to detail. These features represent the obsessoid facet of dysthymia. Such individuals may seek outpatient counselling and psychotherapy for what some clinicians might consider 'existential depression': individuals who complain that their life lacks lustre, joy, and meaning. Others present clinically because of an intensification of their gloom to the level of clinical depression; history of lifelong low-grade depressive symptoms would distinguish them from episodic major depressive patients.

The proverbial dysthymic patient will often complain of having been 'depressed since birth'. (21,) In the eloquent words of Kurt Schneider,(29 'they view themselves as belonging to an "aristocracy of suffering"'. These hyperbolic descriptions of suffering in the absence of more objective signs of depression earn such patients the label of 'characterological depression'. (2D The description is further reinforced by the fluctuating depressive picture that merges imperceptibly with the patient's habitual self, leading to the customary clinical uncertainty as to whether dysthymic disorder belongs to the affective or personality disorder domains.

At their worst, patients with low-grade depression having an intermittent course can present such instability in their life, including suicidal crises, that some clinicians would entertain the diagnosis of borderline personality disorder. This is not consistent with the classic picture of dysthymia arising from a temperamental type with more mature ego structure(31) described above. Depressives with unstable (that is to say, 'borderline') personality structure more often belong to the irritable cyclothymic-bipolar II spectrum.

The greatest overlap of dysthymia is with major depressive disorder, but differs from it in that symptoms tend to outnumber signs (more subjective than objective depression). Thus, marked disturbances in appetite and libido are uncharacteristic, and psychomotor agitation or retardation is not observed. Nonetheless, subtle 'endogenous' features are not uncommonly reported: inertia, lethargy, and anhedonia that are characteristically worse in the morning. (2/) Because many patients with dysthymia presenting clinically fluctuate in and out of a major depression, the core DSM-IV criteria for dysthymia tend to emphasize vegetative dysfunction, whereas the alternative criterion B for dysthymia in a DSM-IV appendix lists cognitive symptoms; although the latter appear more characteristic of trait dysthymia, the DSM-IV field trial(32) could not demonstrate their specificity for dysthymia.

A recent Italian investigation(33) of a large sample from community and primary-care medical settings revealed that negative mood (by definition), along with low energy, poor concentration, low self-esteem, sleep and appetite disturbance, and hopelessness (in descending order) were the most common symptoms of dysthymia. These data suggest that the cognitive and somatic symptoms are not easily separable in practice. None the less, this study did raise the possibility that factors could be discerned along two different axes: 'negative affectivity' and 'lassitude with poor concentration'. In our experience, patients loading on the latter factor often complain of hypersomnia and may exhibit subtle bipolar signs; alternatively, they might have some link to the poorly defined constructs of neurasthenia, chronic fatigue syndrome, and fibromyalgia. In terms of differential diagnosis, patients with chronic fatigue syndrome present with disabling fatigue and, typically, deny depressive symptoms; patients with fibromyalgia complain of pain; by contrast, the typical patient with dysthymia cannot stop relating to the physician his or her litany of depressive symptoms. Polysomnography, though not yet definitive, may shed some light on differentiating fibromyalgia from dysthymia proper. (34)

Although dysthymic disorder represents a more restricted concept than does its parent, neurotic depression, it is still quite heterogeneous. Anxiety is not a necessary part of its clinical picture, yet dysthymia is sometimes diagnosed in patients with anxiety and neurotic disorders. That clinical situation is perhaps to be regarded as a secondary or 'anxious dysthymia' or, as some British authors seem to prefer, as part of a 'general neurotic syndrome' (35> (an implicit partial return to the now defunct concept of neurotic depression).

The clinical picture of dysthymic disorder that emerges from the foregoing descriptions is quite varied, with many who fluctuate in and out of major depression, (36) whereas in others the pathology is woven into the habitual self. (2Z> These considerations suggest that a clinically satisfactory operationalization of dysthymia must include both symptoms and trait characteristics (Table, 1). The following vignette illustrates this more prototypical form of dysthymic suffering.

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Table 1 The core characteristics of dysthymia

Case Study This 37-year-old never-married male teacher presented with the complaint that he was 'tired of living' and was considering 'ending it all'. He said that much of his life had been 'wasted', he had never known any joy, that all human existence for him was a 'tragic mistake of God'. He was known to be a dedicated and talented teacher, but he felt all his efforts had been 'useless and in vain'. He said he probably was 'born depressed', because he had not known any happiness and that the only utility he could have for mankind was 'to serve as a specimen to be researched—to shed light on human misery'. Although he conceded that some women found him interesting, even intellectually stimulating, he said he could not enjoy physical intimacy, that even orgasm lacked passion; nonetheless, he masturbated frequently, fantasizing about married female teachers—only to feel guilty. We could not document any major affective episodes. He stated that he had always functioned at a 'mediocre level' (which was at variance with the good feedback students had given him year after year); but did admit he 'appreciated work, because there was nothing else to do'. He denied alcohol and drug habits. There had never been any periods of hypomania, but one of his maternal aunts had been treated for a 'cyclical depression' and was apparently doing well on lithium. The patient's mother was a sombre serious work-oriented woman who had raised three children and had done voluntary work for the church, but had no depressive complaints. His father had died from a coronary attack, but his side of the family was otherwise unremarkable.

Although both DSM-IV and ICD-10 omit suicidal preoccupations in their diagnostic criteria for dysthymia, as testified by the above case, this is what often brings

patients to clinical attention. Course

An insidious onset of depression dating back to late childhood or the teens, preceding any superimposed major depressive episodes by years, even decades, is the most typical developmental background of dysthymic disorder. A return to the low-grade depressive pattern is the rule following recovery from superimposed major depressive episodes, if any—hence the designation 'double depression'. (36)

A long-term prospective study of prepubertal children (37) has revealed an episodic course of dysthymia with remissions and exacerbations, and eventual complication by major depressive episodes, as well as hypomanic, manic, or mixed episodes postpubertally. Persons with dysthymic disorder presenting clinically as adults tend to pursue a chronic 'unipolar' course, which may or may not be complicated by major depression: they rarely develop spontaneous hypomania or mania. However, when treated with antidepressants, some adult patients with dysthymia may experience brief hypomanic switches(38) that typically disappear when the antidepressant dose is decreased. Although ICD-10 and DSM-IV would not 'allow' the occurrence of such switches in dysthymia, systematic clinical observation (39,,40) have verified their occurrence in between 10 and 30 per cent of dysthymic patients. In that special dysthymic subgroup, the family histories are typically positive for bipolar disorder. (38) Such patients, often conforming to the double depressive pattern, represent a clinical bridge between major depressive disorder and bipolar II. (8)

A recent 12-year prospective study(4l) has shown that patients with major depressive disorder spent 44 per cent of their course in low-grade depression (versus 15 per cent of time in major depressive episodes). This suggests that major depression, dysthymia, or otherwise subsyndromal depression constitute somewhat artificial conventions on the threshold and duration of depressive illness, representing alternative manifestations of the same diathesis. In this context, residual intermorbid depressive symptoms have been confirmed as being strongly predictive of a rapid relapse into a new major depressive episode. Various 'major' and 'minor' depressive conditions described in DSM-IV and its appendix must not be viewed as distinct depressive subtypes, but part of a symptomatic continuum. (42) Figure 1 shows a diagram of these putative relationships within a broad depressive spectrum.

Fig. 1 Diagram to show putative relationships within a broad depressive spectrum.

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Responses

  • philipp
    What is meant by diagnostic consideration?
    10 months ago

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