The interesting phenomenon of dysthymia disorder

K Y Mak 麥基恩

HK Pract 2003;25:224-230

Summary

In the past, the concept of dysthymia has been broadly used to include persons with depressive personality and to those in various stages of depression. In recent years, it has been narrowed down to mean those with a characteristic mild, chronic depression, as part of an affective disorder. As prompt diagnosis and management may abort its chronic morbidity, recognition of the disorder in the primary care setting is important. Antidepressants especially the newer types are useful though maintenance therapy may be necessary, and various psychological therapies, especially interpersonal psychotherapy, may be adjunctive to improve the psychosocial functioning of the patients.

摘要

從前，情緒失調這個概念被廣泛地用來包括抑鬱性格以至不同程度的抑鬱症患者。近年， 此概念被限制為表示輕度慢性的抑鬱症，是情緒病的一種。因為盡早診治可以中止其慢性病程， 所以基層醫生識別此病非常重要。維持治療方面，可能需要採用新的抗抑鬱藥物。各種心理治療， 尤其是人際關係的心理治療，可以輔助病人改善其心理社交功能。

Introduction

The term "dysthymia" has its origin in Greek meaning "ill-humoured", and refers to melancholy which was a depressive personality spoken of by Hippocrates. This term was used clinically by Kahbaum in 1863 as a chronic form of melancholia, while "cyclothymia" was used for a fluctuating mood disorder.¹ Kreapelin likewise equated dysthymia with a "depressive temperament" (a form of neurotic "character")² with affective episodes arising from unstable temperamental disturbances, and lacking the psychotic symptoms of hospital cases of manic-depression.

In the DSM-II classification of the American Psychiatric Association, chronic depression was initially called "depressive neurosis" under the section of personality disorders and neuroses. Dysthymic disorder appeared in the DSM-III as a chronic depression lasting more than two years, but not meeting the full severity or duration of a major depressive disorder.

Clinical diagnosis

As chronic depression is increasingly being noted by primary care physicians rather than by psychiatrists,³ the recognition of "dysthymic disorder" or "dysthymia" is important. Though less severe than major depressive disorder, this psychiatric disorder can cause quite a lot of functional impairment to the patients due to its protracted course.⁴

According to the DSM-IV, dysthymic disorder is defined as "depressed mood" for most of the day, for more days than not, as indicated either by subjective account or observation by others, for at least two years (one year for children or adolescents). While depressed, the patient has two or more of the following symptoms:

1. poor appetite or overeating;
2. insomnia or hypersomnia;
3. low energy or fatigue;
4. low self-esteem;
5. poor concentration or difficulty making decisions; and
6. feelings of hopelessness.

Dysthmia is divided into an early onset and a late onset type (cut-off age at 21 years). Akiskal further divided it into a secondary "character spectrum disorder" and a primary "subaffective dysthymia".⁵ For the former, there is often a personal or family history of substance abuse superimposed on an unstable personality. For the subaffective dysthymia, the personality trait is often of the depressive type, and there is more likely a family history of mood disorder. When the mood brightens in response to positive events (be it actual or potential) and when there is either increase in weight, appetite or sleep, the disorder may be called "atypical dysthymic disorder".

For both typical and atypical conditions, there is clinically significant distress or impairment in functioning, and the disorder is not caused by any other psychiatric disorder (including major depressive disorder) or a general medical condition (including the effects of a drug or medication). For children and adolescents, the mood can be irritable. Within the two-year period, the person has never been without the above symptoms for more than two months at a time, nor has there been any major depressive episode. This means that major depressive disorder can be present prior to or after the two year period. Furthermore, there has never been any hypomanic episode, and the criteria have never been met for cyclothymic disorder that contains numerous periods of elated mood.

In the ICD-10 of the W.H.O., there is no strict operational definition for dysthymia. It states that "dysthymia has much in common with the concepts of long-standing depressive neurosis and neurotic depression", and the depressive episodes must not be severe enough to meet the diagnostic criteria for a recurrent depressive disorder.

Differential diagnosis

1. Chronic major depressive disorder

Major depressive disorder sometimes runs a chronic continuous course and can be labeled as chronic major depressive disorder. Its main difference from a dysthymic disorder is the lesser symptoms in the latter, which can sometimes be called "subsyndromal depression" or "minor depression". Dysthymic disorder also differs by having an insidious onset, but such distinction is not of any clinical difference. In the DSM-IV classification the stress is on the cognitive symptoms of pessimism and low self- esteem rather than the neuro-vegetative symptoms of a major depressive disorder. There is indeed a close relation between dysthymic disorder and major depressive disorder, and they often breed in the same family,⁶ and the former can turn into the latter when followed prospectively. However, partially responsive or refractory patients should not be diagnosed as "dysthymic disorder".

2. Double depression

This is a major depressive disorder superimposed on a dysthymic disorder. Pure dysthymia is relatively uncommon in clinical practice. Patients with dysthymia often develop major depressive episodes with symptom exacerbation (with additional symptoms lasting for 2 weeks or more). The DSM-IV field trial⁷ found that 79% of the subjects also had a life-time history of major depression. However, this term "double depression" may erroneously indicate that the patient is having two distinct mood disorders, but that is not real.

3. Depressive personality disorder

In the past, dysthymia has been regarded as a character problem. The DSM-II considered depressive personality disorder as a distinct entity that can exist concurrently. In the DSM-IV, this personality disorder is only included in the appendix. Klein & Miller⁸ provided evidence that although depressive personality and dysthymia are overlapping constructs, the former is not completely subsumed by mood disorders categories. However, some would consider the two conditions as "trait" and "state" differences only, and that depressive personality disorder should only be considered when the patient has not responded to antidepressive therapies.

4. Adjustment disorder

When a depression occurs amidst a specific aversive life-event e.g. bereavement, and it continues as long as the event is present, it is best considered an adjustment disorder. But if such condition becomes chronic, the diagnosis can be replaced by "dysthymic disorder" as it reflects a more basic affective dysregulation.⁹ If the patient subsequently develops an anxiety disorder or a major depressive disorder, there should be reclassification again.

5. Mixed anxiety and depression

This is a heterogenous group¹⁰ not well differentiated, and is not included in the DSM-IV. In the ICD-10, it is a term to be used when "symptoms of both anxiety and depression are present but neither, considered separately, is sufficiently severe to justify a diagnosis". It can be considered part of a major depressive disorder with autonomic hyperactivity, including panic attacks.

6. Neurasthenia

Beard in 1881¹¹ coined the term to mean a chronic stage of anxiety-depression, characterised by chronic irritability and mental fatigue and exhaustion. It has been used quite popularly in China to denote a variety of non-psychotic disorders¹² especially anxiety and mood disorders. But in Western psychiatric classification, it is associated with the chronic fatigue syndrome,¹³ and should be distinguishable from dysthymic disorder.

Prevalence

Dysthymic disorder usually begins early in adult life. If it occurs later in life, it is often the aftermath of a depressive episode, and is associated with some obvious stress such as bereavement. Kessler et al¹ in the National Comorbidity Study suggested that up to 3% of the American adults in their life-time have dysthymic disorder, including 4% of women; while the point prevalence was 1.6%. The prevalence rate at psychiatric clinics can be as high as 36%.¹⁴ According to the Epidemiological Catchment Area (ECA) study in the US,¹⁵ those 18 to 64 years of age were at greater risk than those over 65. Diagnosis was greatest among women aged between 45 and 64 years old. Those between the 18 and 44 age range who reported low income were also at risk. Race, education and employment status did not affect likelihood of having the disorder. However, the rate is much lower in European countries, perhaps due to the existence of the "recurrent brief depression" entity in the ICD-10. For example, Angst reported the life-time prevalence in Zurich as only 0.9%.¹⁶

Comorbidity

Dysthymic patients are likely to seek medical and mental health care, but are often under-recognised. Spitzer et al¹⁷ found that dysthymic subjects frequently suffer from another psychiatric disorder: mainly other types of mood disorders, anxiety disorders and avoidant personality disorders. There is also an increased risk of substance abuse including alcoholism. On the other hand, Akiskal stated that many borderline personality disordered patients also suffered from dysthymia and cyclothymia, with transient shifts into affective episodes.¹⁸ Besides medical morbidity, the patients also suffer chronic work and social disabilities, with a high utilisation of psychiatric and general health care services.¹⁹ They have a low self-esteem, despite their loyalty to work and hard labour. They frequently feel miserable in life, and have difficulty in enjoying leisure time. They regard inter-personal relationships as hopeless, their "badness" will eventually lead to rejection by others.

Treatment

The development of empathy or rapport is not easy as the patients tend to irritate and alienate their doctors. In the past, dysthymia was regarded as a chronic personality disorder and had been managed mainly by psychotherapy especially the analytical type. But it is now considered a mood disorder and the most important point is early recognition, even in the primary care setting.

1. Pharmacotherapy

Dysthymia is notable for its low placebo response rate, but Akiskal²⁰ first demonstrated successful treatment with antidepressants, especially for his primary subaffective dysthymic patients. Kocsis et al²¹ also found that the tricyclics such as imipramine are more effective than placebo. The clinical improvement can affect the social and vocational functioning as well. Other types of antidepressants e.g. the MAOIs²² and its newer reversible form such as Moclobemide,²³ the second generation antidepressants SSRIs,^24,25 and the third generation antidepressants such as Venlafaxine²⁶ and Mirtazapine,²⁷ are all effective. The therapeutic dosage of these antidepressants is similar to that for major depression, but dysthymic patients oftentolerate the tricyclic antidepressants less well than genuine depressive patients.²³ In contrast to major depressive episodes, long-term maintenance treatment is often necessary to prevent relapse and recurrence, and cessation of medication may carry the risk of relapse. For those with a family history of bipolar disorder, and those with "soft bipolarity", lithium or valproate therapy or augmentation can be used.

2. Psychotherapy

The use of time-limited manualised therapies as for major depression seems helpful. The use of psychoanalysis is not convincing, but cognitive-behavioural therapies showed a response rate of around 40%.²⁸ Specific anti-dysthymic psychotherapy is indicated when medication response is not satisfactory. The use of "interpersonal psycho-therapy" (ITP) that focuses on social adjustment rather than past or intrapsychic experience is particularly useful.²⁹ The technique is described in detail by Markowitz.¹⁴

Combining medication and psychotherapy is often useful. Psycho-educational approaches for both patient and spouse are needed to combat the demoralising nature of the disorder, and may address the personality difficulties. Sometimes marital and family therapies are beneficial, while social skills training and group support are also realistic.³⁰

Prognosis

Historically, dysthymics are difficult to treat, as they are "self-defeating" patients especially in psychotherapy. The disorder usually lasts for at least several years and sometimes for life, and the patients view themselves as long-term sufferers with continuous symptoms and psychosocial morbidity.³¹ Without a superimposed major depression, hospitalisation is not necessary, and most patients function adequately at work and socially, albeit with difficulty. Despite the recent advances in the treatment of mood disorders especially depression, the overall outcome for dysthymia is still relatively poor with high relapse rate. However, it sometimes responds quite well to pharmacotherapy (about 60%) and/or focused psychotherapy. A few patients develop hypomanic spells with antidepressants, and as happens in major depression some patients do end up in suicide.³²

Conclusion

"Dysthymic disorder" is a modern term that cuts across disorders of anxiety, mood and even personality. The recent concept points to a subsyndromal but persistent form of an affective disorder, but without psychotic features. Nevertheless, dysthymia can cause significant morbidity. However, it can be quite responsive to psychological and pharmacological treatments. The newer types of antidepressants are relatively safe, and can be of particular use even in the primary care setting.

Key messages

1. Primary care doctors often encounter patients with a mixture of fluctuating anxiety and depressive symptoms that persist for a long time.
2. These patients are often diagnosed as suffering from anxiety depression or neurotic depression, and even "personality disorder".
3. As a result, they are treated mainly with anxiolytics (especially benzodiazepines) with or without a subtherapeutic dosage of anti-depressant.
4. Nowadays, these patients can be re-diagnosed as "dysthymics" and they belong more to the mood disorder category; they could also be called chronic "minor depression" or "subsyndromal depression".
5. Dysthymia has a more insidious onset, with less neuro-vegetative symptoms than a major depressive disorder, and runs a chronic course with significant morbidities.
6. The mainstay of treatment is an antidepressant rather than an anxiolytic, and this should be given in an adequate dosage for an adequate time, sometimes for a long duration. It can be supplemented with a limited period of benzodiazepine when coexisting anxiety symptoms are marked.
7. Rapport is important to engage the patient for long-term care, and skills in cognitive-behavioural or interpersonal psychotherapies can, in addition, improve the psychosocial functioning.