What is persistent depressive disorder? Symptoms, causes, and treatment

Like a gray, overcast day, Persistent Depressive Disorder (PDD) is an unrelenting and persistent experience.

The drizzle of rain never quite lifts, enveloping us in a prolonged state of low mood and dimming the vibrant colors of a sunny afternoon.

Understanding PDD is a central aspect of our mental health awareness, as it helps provide more insight into the condition that can subtly erode one’s quality of life over time.

By recognizing its symptoms and causes, we are more capable of seeking support, building resilience, and empowering ourselves to navigate PDD-specific challenges with more compassion and clarity.

What is persistent depressive disorder?

Persistent depressive disorder (PDD), also known as dysthymia or chronic depression, is a mental health condition that presents nuanced challenges.

PDD is defined as a chronic low-level depression characterized as a longer-lasting type of depression, with symptoms less severe yet longer-lasting than major depressive disorder (MDD).

PDD symptoms

According to the Anxiety & Depression Association of America, PDD involves a chronically depressed mood, where individuals often experience a persistent feeling of being in a low, dark, or sad state that lasts nearly all day and on most days. Symptoms persist for two or more years.

While it may be confused for other common mood disorders, such as major depressive disorder, PDD will be more subtle and often last for two or more years.

Cognitive and emotional symptoms

Individuals experiencing PDD are likely to encounter several cognitive and emotional symptoms. These include:

• Difficulty concentrating
• Indecisiveness
• Feelings of guilt and worthlessness
• Persistent sadness or emptiness
• Feelings of hopelessness or pessimism

Harvard Health notes that, unlike major depression, PDD exhibits less intensity of symptoms. So, the emotional toll may be lower yet more enduring, meaning that individuals with PDD may struggle with persistent feelings of sadness and emptiness over an extended period.

Physical symptoms

Similar to most other forms of depression, there are certain physical symptoms to watch out for with PDD. These include:

• Changes in appetite
• Unexplained fluctuations in weight (either gain or loss)
• Sleep disturbances (insomnia or hypersomnia)
• Persistent low energy and fatigue

Observing these physical changes in ourselves and others can provide important clues for diagnosis and treatment planning.

Behavioral symptoms

Some of the common behavioral symptoms that accompany PDD include:

• Social withdrawal and isolation
• Decreased interest in daily activities and hobbies
• Difficulty or disinterest in maintaining relationships
• Reduced productivity at work or school
• Low self-esteem

How we behave, and more importantly, instances where we withdraw from activities, people, and responsibilities are all important features in identifying PDD.

What causes PDD?

Several underlying causes of PDD stem from our upbringing, our brain chemistry, and social environments.

Genetic factors

Studies have consistently indicated that individuals with a family history of depression are at a higher risk of developing the condition themselves. A 2022 study suggests that genetics account for 40-50% of the risk of developing depression in general.

Biological factors

Having such a strong influence on mood, it makes sense that PDD involves a complex interplay of neurotransmitters affecting the brain’s chemistry.

For instance, serotonin, dopamine, and epinephrine (among others) are frequently targeted in interventions for PDD due to their fluctuating levels in the brain.

Hormonal changes and thyroid issues are another area of concern that can give rise to PDD in adults. Though few studies are looking into PDD specifically, a 2020 study on MDD found the following connections:

• The hypothalamic-pituitary-adrenal (HPA) axis becomes dysregulated in depression, leading to elevated cortisol levels and heightened stress sensitivity
• The hypothalamic-pituitary-thyroid (HPT) axis can contribute to depressive symptoms when thyroid hormone levels are imbalanced, affecting mood and energy levels

As a result of these disturbances, individuals with PDD have trouble regulating their mood, energy, and overall emotional well-being.

Psychological factors

Some of the contributing psychological factors involved in PDD include past traumas, chronic stress, and low self-esteem.

While not everyone who is exposed to trauma in their past is going to develop depression later in life, it is a contributing factor.

Similarly, chronic exposure to daily stressors can significantly impact our mental health and contribute to the onset or worsening of depressive symptoms.

Additionally, individuals prone to negative thought patterns may find themselves repeating phrases like “I’m not good enough”, “I could never do that, it’s too difficult”, or “Nothing ever goes right for me.”

These internal dialogues can significantly influence one’s self-perception.

This 2019 NIH study reflects these insights as researchers found that individuals with low self-esteem were less willing and more defensive regarding their self-perceived negative attributes. They also found that negative self-evaluations were linked with depression.

Environmental factors

Our surroundings can have an impact on our mental health and well-being. Some common environmental factors that may cause or worsen depressive symptoms include:

• Being socially isolated and lacking support from friends or family members
• Having a chronic medical condition or disability
• Substance abuse and addiction

Many of these factors stress us out, making it tough to build resilience and foster self-empowerment.

Diagnosing PDD

PDD is far less talked about in both research and everyday life, making it far more difficult to diagnose. According to a study published by the National Institute of Mental Health, 2.5% of U.S. adults experience PDD at some point in their lives.

However, due to the differences in symptom severity among adults, PDD may be under-diagnosed.

For this reason, it is important to recognize these symptoms in yourself or someone you care for as significant and access the resources needed for a formal diagnosis.

Here are some ways of diagnosing PDD:

Clinical assessment

Receiving a formal clinical assessment from a psychiatrist or other licensed healthcare provider is the first step in diagnosing PDD. This involves a thorough examination of:

• Medical history
• Current symptoms
• Psychosocial history and stressors
• Psychometric testing
• Potential risk factors

Taking note of other co-occurring conditions with PDD, such as anxiety disorders or PTSD, is important in this clinical assessment. It is even possible to have both PDD and MDD together, a condition sometimes referred to as “double depression”.

Psychometric testing

Your doctor may also use screening tools, such as questionnaires, scales, or assessments to provide insight into the severity of your symptoms to assist in the diagnosis.

Some common questions and scales include:

• Patient Health Questionnaire (PHQ-9)
• Center for Epidemiologic Studies Depression Scale (CES-D)
• Hamilton Depression Rating Scale (HAM-D)
• Montgomery-Åsberg Depression Rating Scale (MADRS)

Thereafter, the use of standardized diagnostic criteria (DSM-5- TR) is necessary for accurately categorizing and diagnosing mental health conditions.

Differential diagnosis

A differential diagnosis helps rule out other medical causes/conditions such as:

• Major depression disorder
• Bipolar disorder (or other mood disorders)
• Psychotic disorders
• Substance-induced states
• Personality disorders

Some key aspects to differentiate include looking at the duration and persistence of the condition, severity and symptom expression, pattern of symptoms (i.e. chronic low mood with periods of severe symptoms), common co-occurring conditions, and the DSM-5- TR classification.

PDD treatment options

Due to the individuality of this mental health condition, numerous forms of treatment may be effective. From expert-recommended therapy modalities to adopting better sleep hygiene, we will cover all the top treatments for PDD.

Psychotherapy

Therapy is one of the best treatment options for individuals living with PDD as it is tailored to individuals’ needs, helps tackle specific symptoms, and provides long-term benefits to prevent future episodes.

Here are three of the most effective therapeutic modalities.

Cognitive behavioral therapy (CBT)

CBT is a form of talk therapy that helps individuals recognize and modify their ‘automatic’ negative thought patterns, allowing for more adaptive and healthy ones to take their place.

This includes reframing thoughts about themselves, their situations, and their future to help relieve the intensity of symptoms that accompany PDD.

Dialectical behavior therapy (DBT)

DBT works closely with emotional regulation, teaching individuals to focus on present-moment awareness and reduce the instances of negative ruminating thoughts.

This modality incorporates mindfulness to encourage individuals to approach their attitudes or thoughts with less judgment or criticism, allowing for self-acceptance to take its place.

Interpersonal psychotherapy (IPT)

IPT is another helpful strategy that focuses on improving interpersonal relationships and communications, which can help alleviate the intensity of depressive symptoms.

IPT looks at the individuals as a whole, including their biology, psychology, and social environment, and helps identify how certain triggers and relationship problems contribute to depression.

Medication

Medication is another route individuals use as a way to manage their symptoms.

Based on current research, it’s widely accepted that using both therapy and medication together is often more effective than using either treatment alone.

Common forms of antidepressants recommended for depression treatment include:

• Selective serotonin reuptake inhibitors (SSRIs)
• Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)
• Tricyclic Antidepressants (TCAs)

In instances where PPD does not respond to antidepressants alone, there is also the option to augment treatment with other medications. Depending on your symptoms and doctor’s recommendations, medications such as mood stabilizers or antipsychotics can help enhance therapeutic effects.

Lifestyle modifications

Prioritizing a combination of  physical activity and quality dietary intake is instrumental in lowering the risk of depression by facilitating the production of important neurochemicals in the brain that regulate mood and reduce stress.

Of course, stress management can take many other forms, including:

• Mindful exercises (i.e. meditation, tai-chi, or yoga)
• Seeking social support
• Breathing exercises (i.e. deep breathing or square breathing)
• Participating in enjoyable hobbies
• Setting boundaries and committing to time management

Another essential practice that is shown to help reduce the severity of depression symptoms is sleep hygiene.

Research has found that difficulties sleeping and mental health dysfunctions are commonly linked. Focus on catching quality Z’s by getting regular and consistent sleep each night.

Get help for PDD

Persistent Depressive Disorder (PDD) is a long-lasting form of depression characterized by persistent low mood and subtle symptoms that can significantly impact daily life.

Understanding its symptoms, causes, and treatment options is crucial for effective management.

If you or someone you know is struggling with PDD, seeking professional help through therapy can foster resilience and improve quality of life by helping build coping skills, enhance social support, foster positive change, and address the underlying issues contributing to PDD.