What is Persistent Depressive Disorder?
In 2013, a new condition called Persistent Depressive Disorder (PDD) was introduced in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). This condition condensed two previous categories: dysthymia and chronic major depressive disorder. The way we categorize and understand depression symptoms has a long and complex history, going back as far as ancient Greek physician Hippocrates’ writings on a state of constant sadness, called melancholic temperament.
According to the DSM-5, PDD is marked by a mood of depression that lasts most of the day, occurs more days than not, and continues for at least 2 years, or at least 1 year in the case of children and teenagers. It is possible to experience major depression before developing PDD. Additionally, major depression episodes can also happen while a person is dealing with PDD, which is referred to as double depression. PDD can start early in life and its symptoms may increase and decrease in intensity but never fully disappear.
What Causes Persistent Depressive Disorder?
Depression is a complicated health condition that can be caused by many factors. Scientists believe that it could develop from a mix of biological influences, social surroundings, personal thoughts and feelings, and even spiritual beliefs. It could be influenced by things like your genes, prior mental illness, high anxiety levels, self-esteem, mental health, traumatic events, daily life stress, and wider social issues that affect health. However, depression symptoms can vary from person to person and there isn’t much research on people who develop depression when they were healthy previously. Similarly, there’s limited research on why depression can come back.
Long-lasting depression can be traced back to negative experiences in childhood such as severe hardship, neglect, or loss of a parent. It’s also common among people whose relatives suffer from chronic depression, or who had depression early in life. It often goes hand-in-hand with borderline personality disorder, meaning the two conditions might share similar root causes – perhaps genetics, vulnerability to mood changes, interpersonal stress, or childhood neglect. People with long-term depression experience more traumatic events in their lifetime.
A study on long-lasting depression found that people with depression don’t necessarily struggle with understanding other people’s emotions, but they might find it difficult to handle when someone else is upset. People with this type of depression might be too sensitive, get overwhelmed by emotional situations, and experience a high degree of empathy for others’ distress, which could make their own depression worse. They reported a significantly higher number of personal relationship problems and more childhood mistreatment (including physical and emotional abuse, and neglect) compared to people without depression. Problems in their relationships may result in feeling less supported, weaker social connections, and long-term loneliness.
Risk Factors and Frequency for Persistent Depressive Disorder
Persistent Depressive Disorder (PDD) was newly defined in 2013 in the DSM-5 as a combination of dysthymia and chronic major depressive disorder. As a recently established diagnosis, PDD hasn’t been extensively researched yet. It’s estimated, however, that in a year, about 0.5% deal with dysthymia, and 1.5% struggle with chronic major depressive disorder according to the DSM-5 Text Revision.
In a study of 3720 individuals in Zurich, it’s found that 15.2% had PDD with consistent major depressive episodes, 3.3% had PDD with only dysthymia, and 28.2% had major depressive disorder. In the United States, around 7% experience major depressive disorder in a year, which is more common among women and young people. Globally, the prevalence of major depressive disorder can vary significantly. It’s important to notes that these figures may underestimate the actual number of older adults dealing with depression, as their symptoms can sometimes be mistakenly attributed to physical health issues that get more common as people age.
Signs and Symptoms of Persistent Depressive Disorder
Persistent Depressive Disorder (PDD) often goes undetected. In trying to diagnose it, a history is necessary, as well as a mental status examination. The important thing is to assess any risks of self-harm or harm to others and consider the influence of substance use. People with PDD have an increased suicide risk. Getting information from family or close contacts can be beneficial. The main goal is to rule out other medical or mental conditions and verify the diagnosis using DSM-5-TR criteria.
There are key elements of history that must be obtained:
- Current symptoms: Get the timeline of symptoms, including mood, sleep, appetite, energy, self-esteem, decision-making ability, and feelings of hopelessness. It’s also necessary to review other psychiatric symptoms and comorbid diagnoses. Specific screening tools could be useful in detecting PDD.
- Past psychiatric history: Understand previous episodes of mania or depression, hospitalizations, treatments, adherence to treatments, and medication effects. Any history of suicidality or self-injury should be explicit.
- Substance use history: Find out if the patient uses tobacco, alcohol, cannabis or other substances.
- Medical history: Note medical illnesses, allergies, treatments, surgeries, and other relevant health information. Look out for specific diagnoses like Parkinson’s disease, multiple sclerosis.
- Medications: Ask about all medications being used and what they treat.
- Family history: Understand the family history of psychiatric illness and how treatments have responded.
- Personal and social history: Discuss language preferences, life circumstances, relationships, employment history, cultural views on mental illness, stressors, trauma history, access to weapons, and legal concerns.
- Developmental history: Ask about complications during childbirth, early development, trauma and abuse history, and education.
Apart from history, a physical examination and a mental status examination are critical. The former will help to identify any underlying health issues such as neurological, cardiovascular, and respiratory system issues. While the latter will help evaluate patients’ mental status.
- Appearance and behavior: People may present with untidy attire, indicative of a lack of personal care. Assess for psychomotor retardation. Patient’s responses will vary.
- Speech: Evaluate the rate and tone of their speech.
- Mood and affect: Individuals may express feeling depressed or “down in the dumps”.
- Thought content: Check for hallucinations and delusions.
- Thought process: The patient’s speech suggests their thought process. Is it clear and coherent?
- Risk: Check for current suicidality, self-injury, and aggressive thoughts or behaviors.
- Cognition: Evaluate if the person is oriented to person, place, and date.
- Insight and judgment: Some patients may have partial awareness of their condition, while others may lack it. Their judgment may be impaired, affecting their decision-making ability.
No tests can diagnose PDD in the laboratory or through radiology.
According to DSM-5-TR, PDD diagnosis depends on several clinical features. These include depressed mood most days for at least two years, at least two symptoms such as poor appetite or overeating, insomnia or hypersomnia, low energy, low self-esteem, poor concentration, difficulties in decision-making, or feelings of hopelessness. The symptoms cannot be attributable to any substance or other medical condition.
- Depressed mood most days for at least two years
- At least two symptoms including poor appetite, insomnia or hypersomnia, low energy or fatigue, low self-esteem, poor concentration or decision-making difficulties, feelings of hopelessness
- Never been without these symptoms for more than two months at a time for 2 years
- Never had a manic or hypomanic episode
- Symptoms not due to the physiological effects of a substance or another medical condition
- Significant distress or impairment in social, occupational, or other essential areas of functioning caused by the symptoms
It’s possible for a patient to have concurrent PDD and major depressive disorder, necessitating a separate diagnosis for the latter. The severity and nature of PDD may vary, leading to different presentations of the condition.
Testing for Persistent Depressive Disorder
If you visit the doctor with symptoms related to mental health, the doctor might need to perform a range of tests to make sure your symptoms aren’t caused by a physical health issue. Testing is especially important if other things in your medical history, or symptoms you’re experiencing, suggest that further investigations might be needed.
Sometimes, depression symptoms might be caused by physical health problems, but routine lab tests for depression in generally healthy patients are not always beneficial. Despite this, there are several lab tests your doctor might order to help them make decisions about your health. These include: a complete blood count (which measures different types of cells in your blood), a comprehensive metabolic panel (a group of tests that show how well your organs are working), a urine pregnancy test, a urine test to check for drugs, tests for HIV, rapid plasma reagin (a test for syphilis), vitamin B12 and folate tests (which measure certain nutrients in your blood), and a thyroid panel (tests that measure thyroid function). Your doctor will decide which tests could be useful based on your symptoms and medical history.
Treatment Options for Persistent Depressive Disorder
Treatment for Persistent Depressive Disorder (PDD), a type of depression that lasts for at least two years, is often less successful due to delays in diagnosing the condition, the patient’s feelings of hopelessness, and not giving the treatment sufficient time to work. Some individuals with PDD may have experienced traumatic events during childhood, which increases their risk of developing chronic depression from an early age. Therapies specifically targeting these traumas, like the cognitive behavioral analysis system of psychotherapy, may be more successful in treating these patients.
Similar to other treatments, the effectiveness of psychological therapy for dysthymia (a mild but long-term form of depression) appears to increase with the number of therapy sessions provided.
Unfortunately, there is limited research on how effective medication or psychotherapy is in treating PDD. A study in 2014 found that several medications and a dietary supplement were more effective than a placebo for patients with different forms of mild, severe, and chronic depression. These treatments included fluoxetine, paroxetine, sertraline, moclobemide, imipramine, and ritanserin (some of these are not approved for use in the U.S.), amisulpride and acetyl-l-carnitine.
When it comes to psychological therapies, Interpersonal psychotherapy (a type of therapy that focuses on your relationships with other people and the problems you’re having in your life) was less effective by itself than when it was given with medication. The studies on the cognitive behavioral analysis system of psychotherapy when given with medication were inconsistent. There was not enough evidence to suggest that several other treatments, like mirtazapine, venlafaxine, and psychodynamic psychotherapies (psychological therapies that explore unconscious thoughts and past experiences), are effective against PDD.
Although no clear benefit has been identified for combination therapy- that is, using medication and psychotherapy together – this approach has led to more improved outcomes and better function in patients.
In response to these challenges, new models of treatment for PDD are being considered. These treatments aim to not only address the symptoms of depression, but also enhance the patient’s understanding of their own mental state, develop empathy, increase motivation, overcome avoidance and improve social skills. They also focus on healing trauma, dealing with feelings of hopelessness and helplessness, and addressing any other mental health conditions that may be present. One case study showed that the mood stabilizer lamotrigine led to remission of symptoms for over 2 years.
When it comes to children and adolescents, the American Association of Child and Adolescent Psychiatrists recommends cognitive behavioral therapy or interpersonal psychotherapy for PDD treatment. However, there is not enough evidence about the effectiveness or possible side effects of selective serotonin reuptake inhibitors, a type of antidepressant, in children and adolescents with PDD.
What else can Persistent Depressive Disorder be?
According to the DSM-5-TR, a handbook used by healthcare professionals to diagnose mental conditions, the conditions that have similar symptoms to Persistent Depressive Disorder (PDD) and can be considered for diagnosis are:
- Major depressive disorder (MDD): If the person meets the criteria for MDD during the time they’ve been diagnosed with PDD, they can be diagnosed with both disorders.
- Other specified depressive disorder: This refers to individuals who don’t meet the criteria for either PDD or MDD but have signs of depression for over 2 years.
- Bipolar I and Bipolar II disorders: If a person has a history of a manic or hypomanic episode, they can’t be diagnosed with PDD. Instead, they should be evaluated for either Bipolar I or II disorder.
- Cyclothymia: This is diagnosed when a person has hypomanic symptoms that don’t meet the criteria for a hypomanic episode and has been in a depressed mood for at least 2 years.
- Psychotic disorders: If depressive symptoms only occur during a psychotic disorder, a PDD diagnosis wouldn’t be warranted.
- Depressive or bipolar and related disorder due to another medical condition: If the depressive symptoms are due to another medical condition, like multiple sclerosis, this would be the appropriate diagnosis.
- Substance/medication-induced depressive or bipolar and related disorder: This would be diagnosed if the depressive symptoms are caused by substance abuse, medication, or a toxin.
- Personality disorders: These disorders cause enduring patterns of inner experience and behavior and often occur alongside PDD. In such cases, both can be diagnosed.
What to expect with Persistent Depressive Disorder
Even before the COVID-19 pandemic, depression and anxiety were among the top health issues people faced around the world. This is despite the fact that there were methods available that could help reduce their impact.
Persistent Depressive Disorder (PDD), also known as chronic depression, has a prognosis that is just as challenging, if not more so, than Major Depressive Disorder (which is a severe form of depression). A 10-year study has indicated that PDD is linked to greater severity of depression, anxiety, and physical symptoms among individuals who are already suffering from Major Depressive Disorder. This points out that people with PDD experience more severe symptoms than those with Major Depressive Disorder alone.
Possible Complications When Diagnosed with Persistent Depressive Disorder
Persistent depressive disorder (PDD) can severely affect a person’s social and work life. It can bring about challenges that are as burdensome, or even more burdensome, than those caused by major depressive disorder. PDD also raises the risk of suicide. The symptoms of PDD are less likely to disappear completely over time.
People with PDD are more prone to develop personality or substance use disorders. Certain studies have found that inpatients with PDD who were emotionally abused as children were more likely to engage in suicidal activities, including attempted suicide.
According to a specific study, the risk of suicide in people suffering from sleep disorders was approximately 1.4 times higher than in those who didn’t have sleep disorders. In comparison, people with PDD had about 7.2 times higher suicide risk. Additionally, those with both sleep disorders and PDD had a roughly 1.2 times higher risk of suicide compared to those without sleep disorders.
Potential Risks of PDD:
- Negative impact on social and work life
- Increased risk of suicidal outcomes
- Higher likelihood of developing personality or substance use disorders
- Increased suicidal activities in patients who suffered childhood emotional abuse
- Raised suicide risk in individuals with sleep disorders
- Higher suicide risk in patients with PDD than those without
- Increased suicide risk in patients with both sleep disorders and PDD
Preventing Persistent Depressive Disorder
Teaching patients about their health condition is especially important for those with PDD. If patients understand their illness and the treatment, they are more likely to follow the advice of the doctor. This understanding can lead to a better outcome and a stronger likelihood of recovery. PDD refers to a condition that significantly affects mental functions like memory or learning ability.
