Dysthymia ( ), known as persistent depressive disorder (PDD) in the DSM-5-TR and dysthymic disorder in ICD-11, is a psychiatric condition marked by symptoms that are similar to those of major depressive disorder, but which persist for at least two years in adults and one year among children. The term was introduced by Robert Spitzer in the late 1970s as a replacement for the concept of "depressive personality".
With the DSM-5 publication in 2013, the condition assumed its current name (i.e., PDD), having been called dysthymic disorder in the DSM previous edition (DSM-IV), and remaining so in ICD-11. PDD is defined by a two-year history of symptoms of major depression not better explained by another health condition, as well as significant distress or functional impairment.
Individuals with PDD, defined in part by its chronicity, may experience symptoms for years before receiving a diagnosis, if one is received at all. Consequently, they might perceive their dysphoria as a character or personality trait rather than a distinct medical condition and never discuss their symptoms with healthcare providers. PDD subsumed prior DSM editions' diagnoses of chronic major depressive disorder and dysthymic disorder. The change arose from a continuing lack of evidence of a clinically meaningful distinction between chronic major depression and dysthymic disorder.
Signs and symptoms Dysthymia is characterized by a two-year history of depressed mood, as well as at least two of the following symptoms: poor appetite or overeating, hypersomnia or insomnia, fatigue or low energy, low self-esteem, poor concentration or difficulty making decisions, and hopelessness. Irritability, rather than sadness, may predominate in the pediatric setting.
Mild degrees of dysthymia may result in withdrawal from stress-inducing activities and avoidance of opportunities for failure. In more severe cases of dysthymia, the patient may withdraw from daily activities. They will usually find little pleasure in usual activities and pastimes, a symptom of depression known as anhedonia.
Diagnosis of dysthymia can be difficult because of the subtle nature of the symptoms and patients can often hide them in social situations, making it challenging for others to detect symptoms. Additionally, dysthymia is often comorbid with other psychological conditions, adding complexity to dysthymia recognition due to overlapping symptoms. Dysthymia is frequently comorbid with anxiety disorders, substance use disorders, and personality disorders, and suicidal ideation is common.
Causes There are no known biological causes that apply consistently to all cases of dysthymia, which suggests diverse origin of the disorder. However, there are some indications that there is a genetic predisposition to dysthymia: "The rate of depression in the families of people with dysthymia is as high as fifty percent for the early-onset form of the disorder". More recent studies have indicated that the frequency of dysthymia is likely influenced more heavily by "family environmental and non-shared environmental factors," rather than genetic or neurobiological factors. Part of the reason for the uncertainty with regard to understanding the biological basis of dysthymia is due to the lack of genetic and neurobiological research, genome wide studies, and "grossly underpowered sample sizes". Other factors linked with dysthymia include stress, social isolation, and lack of social support.
In a 1998 study using identical and fraternal twins, results indicated that there was not a stronger likelihood of identical twins both having dysthymia than fraternal twins. This provides support for the idea that dysthymia does not have a consistent genetic basis.
Co-occurring conditions Dysthymia often co-occurs with other mental disorders. A "double depression" is the occurrence of episodes of major depression in addition to dysthymia. Switching between periods of dysthymic moods and periods of hypomanic moods is indicative of cyclothymia, which is a mild variant of bipolar disorder.
"At least three-quarters of patients with dysthymia also have a chronic physical illness or another psychiatric disorder such as one of the anxiety disorders, cyclothymia, drug addiction, or alcoholism". Common co-occurring conditions include major depression (up to 75%), anxiety disorders (up to 50%), personality disorders (up to 40%), somatoform disorders (up to 45%) and substance use disorders (up to 50%). People with dysthymia have a higher-than-average chance of developing major depression. A 10-year follow-up study found that 95% of dysthymia patients had an episode of major depression. When an intense episode of depression occurs on top of dysthymia, the state is called "double depression".
Double depression
Double depression occurs when a person experiences a major depressive episode on top of the already-existing condition of dysthymia. It is difficult to treat, as patients accept these major depressive symptoms as a natural part of their personality or as a part of their life that is outside of their control. The fact that people with dysthymia may accept these worsening symptoms as inevitable can delay treatment. When and if such people seek out treatment, the treatment may not be very effective if only the symptoms of the major depression are addressed, but not the dysthymic symptoms.Double Depression: Definition, Symptoms, Treatment, and More. Webmd.com (7 January 2012). Retrieved on 2012-07-01.
Patients with double depression tend to report significantly higher levels of hopelessness than is normal, while patients diagnosed with only dysthymia or major depression displayed more temperate levels of hopelessness. This provides mental health service providers a baseline of reference when considering double depression diagnoses in comparison to others. Additionally, it can be a useful symptom for providers to focus on when working with patients to treat the condition.Joiner, Thomas E., et al. “Double Depression in Older Adult Psychiatric Outpatients: Hopelessness as a Defining Feature.” Journal of Affective Disorders, vol. 101, no. 1-3, Aug. 2007, pp. 235–238, https://doi.org/10.1016/j.jad.2005.03.019. Accessed 24 May 2022. Cognitive therapies can be effective for working with people with double depression in order to help change negative thinking patterns and give individuals a new way of seeing themselves and the environment.Double Depression: Definition, Symptoms, Treatment, and More. Webmd.com (7 January 2012). Retrieved on 2012-07-01.
It has been suggested that the best way to prevent double depression is by treating the dysthymia. A combination of antidepressants and cognitive therapies can be helpful in preventing major depressive symptoms from occurring. Additionally, exercise and good sleep hygiene (e.g., improving sleep patterns) are thought to have an additive effect on treating dysthymic symptoms and preventing them from worsening.
Pathophysiology There is evidence that there may be neurological indicators of early onset dysthymia. There are several brain structures (corpus callosum and frontal lobe) that are different in women with dysthymia than in those without dysthymia. This may indicate that there is a developmental difference between these two groups.
Another study, which used fMRI techniques to assess the differences between individuals with dysthymia and other people, found additional support for neurological indicators of the disorder. This study found several areas of the brain that function differently. The amygdala (associated with processing emotions such as fear) was more activated in dysthymia patients. The study also observed increased activity in the insula (which is associated with sad emotions). Finally, there was increased activity in the cingulate gyrus (which serves as the bridge between attention and emotion).
A study comparing healthy individuals to people with dysthymia indicates there are other biological indicators of the disorder. An anticipated result appeared as healthy individuals expected fewer negative adjectives to apply to them, whereas people with dysthymia expected fewer positive adjectives to apply to them in the future. Biologically these groups are also differentiated in that healthy individuals showed greater neurological anticipation for all types of events (positive, neutral, or negative) than those with dysthymia. This provides neurological evidence of the dulling of emotion that individuals with dysthymia have learned to use to protect themselves from overly strong negative feelings, compared to healthy people.
There is some evidence of a genetic basis for all types of depression, including dysthymia. A study using identical and fraternal twins indicated that there is a stronger likelihood of identical twins both having depression than fraternal twins. This provides support for the idea that dysthymia is caused in part by heredity.
A new model has recently surfaced in the literature regarding the HPA axis (structures in the brain that get activated in response to stress) and its involvement with dysthymia (e.g., phenotypic variations of corticotropin releasing hormone (CRH) and arginine vasopressin (AVP), and down-regulation of adrenal functioning) as well as forebrain serotonergic mechanisms. Since this model is highly provisional, further research is still needed.
Diagnosis The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), published by the American Psychiatric Association, characterizes dysthymic disorder. The essential symptom involves the individual feeling depressed for the majority of days, and parts of the day, for at least two years. Low energy, disturbances in sleep or in appetite, and low self-esteem typically contribute to the clinical picture as well. Those with the condition have often experienced dysthymia for many years before it is diagnosed. People around them often describe them in words similar to "just a moody person". The following are the diagnostic criteria:, ICD9, Retrieved 2 May 2009
During a majority of days for two years or more, the adult patient reports depressed mood, or appears depressed to others for most of the day. When depressed, the patient has two or more of: decreased or increased appetite; decreased or increased sleep (insomnia or hypersomnia); fatigue or low energy; reduced self-esteem; decreased concentration or problems making decisions; feelings of hopelessness or pessimism. During this two-year period, the above symptoms are never absent longer than two consecutive months. During the duration of the two-year period, the patient may have had a perpetual major depressive episode. The patient has not had any manic, hypomanic, or mixed episodes. The patient has never fulfilled criteria for cyclothymic disorder. The depression does not exist only as part of a chronic psychosis (such as schizophrenia or delusional disorder). The symptoms are often not directly caused by a medical illness or by substances, including substance use or other medications. The symptoms may cause significant problems or distress in social, work, academic, or other major areas of life functioning.
In children and adolescents, mood can be irritable, and duration must be at least one year, in contrast to two years needed for diagnosis in adults.
Early onset (diagnosis before age 21) is associated with more frequent relapses, psychiatric hospitalizations, and more co-occurring conditions. Personality disorders co-occur in 20 to 40 per cent or more of those with early-onset dysthymia. However, in older adults with dysthymia, the psychological symptoms are associated with medical conditions and/or stressful life events and losses.