Definition and Diagnosis
Persistent Depressive Disorder (formerly dysthymia) involves a depressed mood present for most of the day, more days than not, for at least two years in adults, along with additional depressive symptoms that do not reach full remission for extended periods.
Epidemiology
Lifetime prevalence is estimated at around 2-3%, and the disorder often begins earlier in life than MDD, sometimes in childhood or adolescence. Because symptoms are chronic rather than acute, the condition is frequently under-recognized.
Risk Factors
Risk factors overlap with those for MDD and include family history, early childhood adversity, and chronic stress. Co-occurring anxiety disorders and personality factors can also contribute to persistence of symptoms.
Symptoms and Subtypes
Symptoms include low energy, poor appetite or overeating, sleep disturbance, low self-esteem, poor concentration, and feelings of hopelessness, at a milder but more chronic level than MDD. Some individuals experience superimposed major depressive episodes, known as "double depression."
Diagnosis
DSM-5-TR criteria require a two-year duration in adults (one year in children/adolescents) with no symptom-free period longer than two months. Clinicians distinguish this from MDD largely on the basis of chronicity rather than symptom severity.
Treatment
Psychotherapy, particularly CBT and long-term supportive approaches, along with antidepressant medication, are the mainstays of treatment. Because of the chronic nature of the disorder, treatment often continues over an extended period to prevent relapse.
Prognosis
The chronic course means many individuals experience symptoms for years, but a substantial proportion achieve meaningful improvement with sustained treatment. Early treatment is associated with better functional recovery.
Reference
American Psychiatric Association. (2022). Diagnostic and Statistical Manual of Mental Disorders (5th ed., text rev.).