Dysthymia

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Kiran Singh, M.D. [2]

Synonyms and keywords: Dysthymic disorder; persistent depressive disorder; double depression

Overview

Dysthymia is a mood disorder that falls on the depression spectrum. It is characterized by the lack of enjoyment or pleasure, clinically referred to as anhedonia, that continues for an extended period. Dysthymia differs from major depression in that it is both longer-lasting and lesser distressing. The symptoms of dysthymia are often underestimated by the patients and misdiagnosed by the clinicians. Dysthymia can have a substantial impact on an individual's life by preventing effective functioning, disrupting sleep patterns, and interfering with activities of daily living (ADLs). It usually presents with mild symptoms on a day-to-day basis. Progressively, the disorder may take a more severe form, resulting in work impairment, social isolation, and high rates of suicide. Due to its chronicity and lesser severity, most of the patients suffering from dysthymia believe that it is a part of their character and do not seek treatment until it gets extremely disabling.

Historical Perspective

• The historical origin of the term 'dysthymia' is basically Greek.
• In 1844, it was used first in psychiatry by C.F. Flemming.
• In 1882, dysthymia was further described by Kahlbaum, and he differentiated it from the fluctuating mood of cyclothymia.
• In Diagnostic and Statistical Manual of Mental Disorders (DSM), dysthymia as a clinical entity has undergone complex evolution from being considered a personality disorder to an affective disorder.

Classification

• Diagnostic and Statistical Manual of Mental Disorders (DSM-II) characterized chronic depression as a personality disorder.
• 'Dysthymic disorder' was the term used in DSM-III to describe depression present for a period of more than two years.
• From the personality disorder of DSM-II, DSM-III-R placed it under the affective category.

• DSM-IV has classified chronic depression into dysthymic disorder and major depressive disorder, chronic type.
• Based on the age of onset, DSM-IV has divided dysthymic disorders into early (before 21 years) and late-onset (after 21 years) subtypes.
• Early-onset dysthymic disorder is related to a higher familial burden of mood disorders and childhood adverse conditions. On the other hand, late-onset has an association with health issues and major losses.
• In DSM-IV, individuals having underlying dysthymic disorder who develop major depressive episode are diagnosed as having both dysthymic disorder and major depressive disorder. So, DSM-IV has categorized dysthymic disorder and major depressive episodes as separate diagnoses instead of phases of a single disorder that fluctuates in severity over time.
• In spite of minor differences in the definitions of Dysthymic Disorder in the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition (DSM-IV) and International Classification of Diseases Tenth Edition (ICD-l0), both the systems have been considered competent to establish the diagnosis.
• Dysthymia and chronic major depression are both included under the new term 'Persistent depressive disorder' in DSM-5.
• Since the introduction in DSM-III, the diagnostic validity of dysthymia has been questioned. It is a heterogeneous diagnosis including various depressive and anxiety conditions. As persistent depressive disorder includes dysthymia as a component, the former is more likely to represent a heterogeneous domain diagnosis, further creating a dilemma regarding the best treatment option to be used.
  

Pathophysiology

• Brain-derived neurotrophic factor (BDNF) has been found to play a major role in the long-term potentiation, functioning of neurons and therefore, affecting neuroplasticity.
• It has been observed that BDNF is significantly lower in individuals with dysthymia, compared to control subjects.
• Interleukin-6 (IL-6) levels are higher in dysthymic patients as compared to controls. Individuals with major depressive disorder also have higher levels of IL-6.
• The expression of cytokines has also been found to have a significant role in the pathophysiology of dysthymia. Macrophage inflammatory protein-1α and Interferon-γ-induced protein10 have a correlation with the clinical response to treatment.
• The elevated Interleukin-1β associated with dysthymia fails to reach the normal range even after symptom resolution. It further suggests that IL-1β can be the trait marker of dysthymia and can help in early detection of the illness.

Clinical Features

• The predominant features of dysthymia are-
  • Low or irritable mood, lack of interest in previously enjoyed activities, and a loss of energy
  • Increased or decreased appetite
  • Weight gain or loss
  • Excessive sleepiness or insomnia
  • Difficulty concentrating
  • Indecisiveness and having pessimistic thoughts
  • Negative self-image
• While comparing dysthymia with major depression, it would be appropriate to state that dysthymia tends to be less intense and persist for a longer duration.
• Other than the variation in magnitude of severity, both these conditions exhibit similar symptomatology.
• To diagnose Major depressive disorder, the symptoms should be present for a minimum duration of 14 days (2 weeks) whereas for dysthymia, the criteria is a minimum of 2 years.

• The symptoms can grow into a full-blown episode of major depression, this conditon is called "double depression" because the intense episode exists with the underlying feelings of low mood.
• People with dysthymia have a greater-than-average chance of developing major depression.
• While major depression often occurs in episodes, dysthymia is more constant, lasting for long periods, sometimes beginning in childhood. As a result, a person with dysthymia tends to believe that depression is a part of his or her character.
• The person with dysthymia may not even think to discuss the symptoms with doctors, family members or friends.
• Dysthymia, like major depression, tends to run in families.
• Some individuals describe dysthymia as being under chronic stress.
• When treating diagnosed cases, it is often difficult to distinguish if they are actually under unusually high environmental stress or if the dysthymia causes them to be more psychologically stressed in a standard environment.

Differential Diagnosis

The differential diagnosis of dysthymia includes the following:

• Mood disorder secondary to General Medical Condition
• Major depressive disorder
• Recurrent depressive disorder
• Personality disorders
• Generalized Anxiety Disorder
• Mixed anxiety and depressive disorder
• Substance induced mood disorder
• Neurasthenia
• Adjustment disorder
• Psychotic disorders

Epidemiology and Demographics

Prevalence

• The 12 month prevalence of dysthymia is 500 per 100,000 (0.5%) of the overall population.

Age

• Individuals of all the age groups may develop dysthymia.
• Based on the age of onset, the etiology of dysthymia varies.
• The individuals with early-onset dysthymia have a history of physical or sexual abuse. They have also been found to have poor relationship with both the parents.
• Compared to adolescents, the children display lesser symptoms of dysthymia. 'Anhedonia' has been observed to be more common in adolescents.
• In younger adults, dysthymia is related to the abnormalities of personality whereas in the elderly, there is a strong association with losses in life and other health related issues.

Gender

• Dysthymia affects both men and women.
• The prevalence of dysthymia is more in women compared to men.
• The symptomatic profile is similar between males and females in adolescent population. While comparing the symptoms of dysthymia in both genders, no specific symptom predominance has been observed.
• Gender differences have been noted for the development of dysthymia in the elderly population.
• In elderly men, dysthymia was more related to lower educational level and in those receiving nursing home/ institutional care. No relation was found based on occupation or marital status.
• As opposed to this, in elderly females dysthymia was predominant in older individuals (70 years +), married and in those with higher education level. It was not found to be related to marital status, occupation or form of health care received.

Race

• Dysthymia has higher lifetime prevalence in individuals of Mexican American and African American background. This can be explained by a number of factors like-
  • Lower education level
  • Poverty
  • Hesitancy in seeking help
  • Lesser utilization of mental health services
  • Non-compliance to the treatment
  • The cultural beliefs

Risk Factors

Common risk factors in the development of Dysthymia are the following:

• Genetic predisposition- First-degree relatives with persistent depressive disorder
• Family history of mood disorders
• Lower social integration
• Co-morbid substance use disorder

• Parental loss or separation
• Physical or sexual abuse
• Lower education level
• Polysomnographic abnormalities

Natural History,Complications, and Prognosis

• Individuals with dysthymia have a greater risk of developing major depressive disorder.
• Similar to adults, the children and adolescents have a higher risk for developing depression.
• These children have poor scholastic performance and deteriorating quality of life.
• Dysthymia has an impact on personal relationships, financial state as well as physical and mental well-being.
• Dysthmia is associated with higher suicide rates and significant disability.

Prognosis

Overall, dysthymia has a worse prognosis than major depressive disorder.

Poor prognostic factors related to dysthymia include:

• Anxiety disorders
• Less education
• Conduct disorder
• Familial loading for chronic depression
• History of poor maternal relationship in childhood
• History of childhood sexual abuse
• Longer duration of symptoms
• Co-morbid personality disorder
• Increased severity of the symptoms
• Higher levels of neuroticism
• Poorer global functioning

Diagnostic Criteria

DSM-5 Diagnostic Criteria for Dysthymia

• Persistent Depressive Disorder (Dysthymia) is diagnosed using DSM-5 Criteria.
• Dysthymia is a combination of dysthymic disorder and chronic major depressive disorder (DSM-IV)

DSM-5 DIAGNOSTIC CRITERIA FOR DYSTHYMIA	SPECIFIERS
The following criteria should be fulfilled- A. For at least 2 years, depressed for most of the day as observed by the individual or others. Irritable mood lasting at least 1 year for adolescents and children. B. With depressed mood, presence of two or more of- 1.Reduced appetite or overeating 2. Fatigue or less energy 3.Low self-esteem 4.Indecisiveness or low concentration 5.Hyper or insomnia 6.Hopelessness C. The person has never been without the symptoms mentioned in Criteria A and B for greater than 2 months at a time. D. Criteria for mthem ajor depressive disorder may be present regularly for two years. E. Criteria have never been met for Cyclothymia and there has never been a hypomanic or manic episode. F. The condition can not be explained by schizophrenia, delusional disorder, schizoaffective disorder, or other schizophrenia spectrum disorder. G. The symptomatology is not secondary to the effects of a substance or other medical condition. H. Presence of clinically significant impairment in occupational, social, and other domains of functioning.	Specify if- With anxious distress With mixed features With atypical features With mood-inconguent psychotic features With mood-congruent psychotic features With melancholic features With peripartum onset
	Specify if- In partial remission In full remission
	Specify if- Early onset (before 21 years) Late onset (at or after 21 years)
	Specify if- With pure dysthymic syndrome With persistent major depressive episode With intermittent major depressive episodes, with current episode With intermittent major depressive episodes,without current episode
	Specify if- Mild Moderate Severe

Treatment

Medications

Selective Serotonin Re-uptake Inhibitors (SSRI)

• The most commonly prescribed anti-depressants for this disorder are the selective serotonin reuptake inhibitors (SSRI), which include fluoxetine (Prozac), sertraline (Zoloft), paroxetine (Paxil), and citalopram (Celexa).
• SSRI have a very high affinity for Serotonin (5-HT) receptors whereas low affinity for noradrenaline uptake receptors. SSRI act by inhibiting the reuptake of 5-HT from the synaptic cleft, increasing its concentration and contributing to the therapeutic effect.
• The different SSRI have variability in efficacy and side-effect profile, which requires a thorough clinical consideration before prescribing them.
• SSRI are easy to take and relatively safe compared with older forms of anti-depressants.

Side Effects of SSRI

• SSRI are associated with some side effects like sleep disturbances, nausea, vomiting, sexual dysfunction, weight gain, cognitive disturbances and SSRI discontinuation syndrome.
• The sleep disturbances are more prominent initially in the treatment course. These are in the form of earlier onset of rapid eye movement (REM) sleep, increased duration of REM sleep and lesser slow-wave sleep.
• The immediate adverse effects of SSRI is due to increased concentration of serotonin at particular receptor subtypes in various parts of the brain. The post-synaptic receptor desensitization in these regions lead to tolerance to these side effects after some time.

Other medications

• Some patients do not respond to SSRI or have to discontinue them due to inability to tolerate the adverse effects.
• Older antidepressants, such as a tricyclic antidepressant (TCA) or an MAOI can be tried in such cases.
• TCA have anticholinergic side-effects like weight gain, dry mouth, urinary retention, constipation, blurry vision, sexual dysfunction, and low blood pressure.
• These medications should be avoided in elderly patients.
• Other anti-depressants that can be used are bupropion (Wellbutrin), venlafaxine (Effexor), mirtazapine (Remeron), and duloxetine (Cymbalta).

Psychotherapy

• Some evidence suggests the combination of medication and psychotherapy may result in the greatest improvement.
• There are different types of psychotherapies. The type of therapy chosen depends upon a number of factors like the nature of any stressful events, the availability of family and other social support, and personal preference.
• Psychotherapy focuses on the education about the disease model.
• Cognitive-behavioral therapy is designed to examine and help correct faulty, self-critical thought patterns and correct the cognitive distortions that persons with mood disorders commonly experience.
• Psychodynamic, insight-oriented, or interpersonal psychotherapy (IPT) can help a person sort out conflicts in important relationships or explore the history behind the symptoms.
• IPT emphasizes on resolving the conflict in current relationships that are exacerbating the depressive symptoms.
• Both CBT and IPT are effective for adolescents. An adapted version for IPT is used because these individuals are in conflict with their parents as well as peers, limiting the outlet options for their emotional burden.

References

Mental and behavioral disorders