Persistent depressive disorder

Persistent depressive disorder (PDD) is a category including various types of chronic depression lasting 2 or more years. Identification of people with persistent depressive disorder should be part of the differential diagnosis of patients who have mood disorders. Patients presenting with a current major depressive episode should be evaluated for chronic course (>2 years). Persistent depressive disorder is largely under-diagnosed or misdiagnosed because the correct criteria to evaluate the chronicity of this condition are not used. Recognition of mood disorders in practice settings are likely to be enhanced by using depression rating scales on a routine basis. Some rating scales in the public domain that could be used include the Patient Health Questionnaire,[34]Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001 Sep;16(9):606-13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1495268 http://www.ncbi.nlm.nih.gov/pubmed/11556941?tool=bestpractice.com the Beck Depression Inventory,[35]Beck AT, Ward CH, Mendelson M, et al. An inventory for measuring depression. Arch Gen Psychiatry. 1961 Jun;4:561-71. http://www.ncbi.nlm.nih.gov/pubmed/13688369?tool=bestpractice.com and the Quick Inventory of Depressive Symptoms.[36]Trivedi MH, Rush AJ, Ibrahim HM, et al. The Inventory of Depressive Symptomatology, Clinician Rating (IDS-C) and Self-Report (IDS-SR), and the Quick Inventory of Depressive Symptomatology, Clinician Rating (QIDS-C) and Self-Report (QIDS-SR) in public sector patients with mood disorders: a psychometric evaluation. Psychol Med. 2004 Jan;34(1):73-82. http://www.ncbi.nlm.nih.gov/pubmed/14971628?tool=bestpractice.com

Patients with single episodes (or recurrent episodes) of major depression who have complete resolution of mood symptoms can look forward to complete recovery. In contrast, patients who return to a dysthymic baseline essentially never feel well. They have been demonstrated to have impaired work functioning, impaired social functioning, increased use of medical services, higher rates of recurrence of major depression, and increased risk of suicide. Consequently, it is important for clinicians to identify individuals with persistent depression, and to attempt to develop adequate treatment strategies in order to improve outcomes.

History

Persistent depressive disorder is diagnosed by using the DSM-5-TR criteria.[1]American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 5th ed., text revision (DSM-5-TR). Washington, DC: American Psychiatric Publishing; 2022. It is a form of depression characterized by a chronic course. That is, the disorder has been persistent for 2 years or longer (1 year or longer in children/adolescents).

Symptoms of persistent depressive disorder include 2 or more of the following and should be present for most of the day, most days:

• Poor appetite or overeating

• Insomnia or hypersomnia

• Low energy or fatigue

• Low self-esteem

• Poor concentration or difficulty making decisions

• Feelings of hopelessness.

There should be no medical condition, medication, excessive use of alcohol, or drug abuse that could cause the mood disorder.

Clinicians should also assess whether patients present with anxious distress (feeling keyed up or unusually restless) or with atypical features (mood reactivity, weight gain, increased sleep, leaden paralysis, interpersonal rejection sensitivity).

Dysthymia is often complicated by major depressive episodes. In the DSM-5-TR, subtypes of PDD include: 1) pure dysthymia (low-grade chronic depression), without full criteria for major depression during the preceding 2 years; 2) persistent major depressive episode; 3) intermittent major depressive episodes with current major depression; 4) intermittent major depressive episodes without current major depressive disorder (MDD) episode.[1]American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 5th ed., text revision (DSM-5-TR). Washington, DC: American Psychiatric Publishing; 2022.

Current severity should be assessed as mild, moderate, or severe.

Excluding other depressive disorders

A major depressive episode is defined as having 5 out of 9 of the following symptoms present nearly every day for 2 weeks or longer (by DSM-5-TR):[1]American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 5th ed., text revision (DSM-5-TR). Washington, DC: American Psychiatric Publishing; 2022.

• Depressed mood most of the day, nearly every day

• Markedly diminished interest or pleasure in usual activities

• Insomnia or hypersomnia

• Change in appetite/weight (over- or under-eating)

• Psychomotor slowing or agitation

• Fatigue/loss of energy

• Feelings of worthlessness or excessive guilt

• Difficulty concentrating or indecisiveness

• Recurrent thoughts of death, recurrent suicidal ideation without a specific plan, a specific suicide plan, or a suicide attempt.

Individuals with persistent depressive disorder may currently meet criteria for a major depressive episode or may present with a milder dysthymic episode that does not meet the criteria for major depression. To meet criteria for an episode of major depression (but not persistent depressive disorder), duration must be less than 2 years.

Patients with dysthymia may have the same depressive symptoms as a major depressive episode, but are less likely to report sleep and appetite changes than patients with a chronic major depressive disorder.

In dysthymia, the depressive symptoms are present more than 50% of the time. If the depressive symptoms are present 100% of the time, then in order to differentiate dysthymia from a chronic major depressive disorder, insufficient symptoms need to be present, to diagnose a major depressive episode (i.e., <5 of the symptoms defined in the DSM-5-TR).

If depressive symptoms are present <50% of the time and all other criteria for dysthymia are met, the diagnosis is "Depressive disorder, other specified type".

The diagnostic criteria for persistent depressive disorder require that periods of euthymia last no longer than 2 months. If a patient has all the other criteria for persistent depressive disorder but has euthymia for more than 2 months, the diagnosis would be "Depressive disorder, other specified type".

Persistent depressive disorder is a "unipolar" mood disorder. The presence of periods of elevated mood would result in a diagnosis of a bipolar mood disorder.

Using depression rating scales

Recognition of mood disorders in practice settings is enhanced by using depression rating scales on a routine basis. Some rating scales in the public domain that could be used include:

• Patient Health Questionnaire[34]Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001 Sep;16(9):606-13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1495268 http://www.ncbi.nlm.nih.gov/pubmed/11556941?tool=bestpractice.com Patient Health Questionnaire (PHQ-9) Opens in new window

• Beck Depression Inventory[35]Beck AT, Ward CH, Mendelson M, et al. An inventory for measuring depression. Arch Gen Psychiatry. 1961 Jun;4:561-71. http://www.ncbi.nlm.nih.gov/pubmed/13688369?tool=bestpractice.com Beck Depression Inventory (BDI) Opens in new window

• Quick Inventory of Depressive Symptoms.[36]Trivedi MH, Rush AJ, Ibrahim HM, et al. The Inventory of Depressive Symptomatology, Clinician Rating (IDS-C) and Self-Report (IDS-SR), and the Quick Inventory of Depressive Symptomatology, Clinician Rating (QIDS-C) and Self-Report (QIDS-SR) in public sector patients with mood disorders: a psychometric evaluation. Psychol Med. 2004 Jan;34(1):73-82. http://www.ncbi.nlm.nih.gov/pubmed/14971628?tool=bestpractice.com Quick Inventory of Depressive Symptoms (QIDS) Opens in new window

The rating scales measure depression severity for the past week. Although they are not diagnostic instruments and are not specific to persistent depressive disorder, they can help with the screening of patients with mood disorders. If all patients were screened with a depression rating scale, it is likely that depression would be detected in more patients. Once a depressed patient is diagnosed, measurement of ongoing severity by using a rating scale is useful.

Investigations

Persistent depressive disorder is a clinical diagnosis. Investigations for underlying medical conditions should be performed if suggested by clinical findings. Patients presenting with chronic depression should be evaluated for possible medical conditions that may cause or contribute to their psychiatric presentation. A physical examination including vital signs and ECG can determine whether there are signs of medical illness. Medical tests should include serum metabolic profile, complete blood count, thyroid screen, vitamin D level, and urinalysis as well as possibly urine toxicology. Generally these evaluations are done by the patient’s primary care physician. Abnormalities in thyroid function, hematologic indices, metabolic profile and other measures of physical health may provide evidence for primary nonpsychiatric etiology, or medical factors that may contribute to or maintain depression.