What Is Persistent Depressive Disorder?

Overview

In a world with an increasing incidence of mental health disorders, increasing awareness and research on mental health has become essential. 

Depression, a mood disorder, is one of the most common mental health disorders and the leading cause of disability¹ and suicide deaths worldwide.² Persistent depressive disorder (PDD), sometimes referred to as dysthymia, is a form of depression characterised by its long duration. With a prevalence of around 12%, PPD has a huge impact on our society.³ Increasing awareness of this disorder is essential so that sufferers can understand what they are going through, get the help they need and know that they’re not alone. Even though there are both psychological and pharmacological treatments available, further research is needed, mainly because antidepressants canhave many side effects and are not very effective in many cases. 

This article will explore what persistent depressive disorder is by talking about aspects such as its causes, symptoms, treatment and diagnosis.

Causes of persistent depressive disorder

The exact cause of persistent depressive disorder (PDD) remains unknown. However, its development seems to usually be linked to one or more of physiological, genetic, environmental, or psychological factors:

Biological differences

The development of PDD is often associated with physical changes that affect the brain such as:

• Brain anatomy - wasting of the prefrontal cortex (part of the brain that regulates are thoughts, actions and emotions)
• Brain chemistry - Decrease in the concentration of serotonin - chemical that carries messages between brain and rest of body andplatelet monoamine oxidase - enzyme that breaks down amines in the brain
• Dysregulation of the immune system
• euroendocrine abnormalities - Changes to hormones in brain such as the increase in cortisol concentration.⁴ This hormone, which is also referred to as the stress hormone, can lead to other changes such as neuronal death in the hippocampus⁵

Genetic factors

Those with a family history of PDD are more likely to suffer from the disorder. 

Psychological and environmental factors

 Traumatic events (e.g. sexual or emotional abuse) and chronic stress can lead to PDD⁶

Signs and symptoms of persistent depressive disorder

PDD is associated with different signs and symptoms and knowing these can facilitate people suffering from this disorder to get the help they need. Depressive symptoms include:⁷

• Depressed mood
• Reduced or increased appetite
• Difficulty falling asleep (insomnia) or sleeping too much (hypersomnia)
• Lack of energy or fatigue
• Low self-esteem 
• Indecisiveness and poor concentration
• Pessimism and feeling of hopelessness

Management and treatment for persistent depressive disorder

The primary treatment strategy for PDD consists of using antidepressants and psychotherapies alone or in combination. These treatments have been shown to be less effective in chronic forms of depression (dysthymic disorder) than in non-chronic ones. T Symptoms of around 40% of patients suffering from PDD are considered to be treatment resistant.⁴

Psychotherapy

One of the most effective current treatments used is Cognitive Behavioural Therapy (CBT). This talk therapy is based on improving the patient’s knowledge and awareness of PDD, so that they can understand what they are going through, and on helping patients to identify and deal with what is making them feel depressed.⁸

Drug-based depression treatments

Fortunately, some PDD patients do respond satisfactorily to their pharmacological treatments. Specifically, antidepressant medications such as selective serotonin reuptake inhibitors (SSRIs) and the antipsychotic amisulpride have shown to be relatively efficacious for treating PDD. The SSRI fluoxetine may be less effective than other drugs.⁴

Diagnosis

If a doctor suspects that a patient might be suffering from dysthymia, they may carry some tests out such as lab tests and physical exams in order to ensure that the symptoms are not being caused by an underlying physical health condition (e.g. hypothyroidism). 

Patients may be referred to mental health professionals for  a full evaluation where they may be askedabout their thoughts, feelings, and behaviour to determine whether they are suffering from PDD.

In the USmental health professionals use the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) from the American Psychiatric Association. This manual establishes that, to be diagnosed with PDD, the patient must have a depressed mood for at least 2 years. Children and adolescents may present with a irritable mood and 1 year is enough to be diagnosed. Symptoms cannot be absent for more than 2 months and at least two of the symptoms characteristic of PDD must be present.³

Risk factors

Risk factors that can contribute to the development of a persistent depression include:⁹

• Family history: Although no specific genes have been linked yet to the development of PDD, it is known that genetic factors are involved. Having a family history of PDD puts aperson more at risk for developing the condition. Having a family history of other mental health conditions can also be a risk factor for developing PDD
• Trauma or stress: Traumatic life events and excessive stress can also increase the likelihood of developing PDD
• Depressive personality: Personality traits such as negativity, low self-esteem, high self-criticism and being too dependent are associated with developing PDD
• Low social support: Having a low social support together with interpersonal difficulties can increase the risk of developing a mental health disorder such as PDD
• Substance abuse disorder: Substance misuse increases the risk of suffering from PDD. In fact, approximately 21% of people with a substance abuse disorder also suffer from depression.¹⁰ However, substance misuse can both make people more likely to suffer from PDD and be a complication linked to PDD 
• Physical illness: People suffering from health conditions such as cardiovascular disease, cancer, and diabetes are more likely to suffer from depression as they might have difficulties linked to the management of their condition. For instance, people with diabetes are twice as likely to suffer from depression, and may thus lead to a person developing PDD¹¹
• Gender: Females are twice likely to suffer from PDD than males

Complications

The complications that can derive from untreated PDD are similar to those of other mental health disorders. These include:

• Suicidal ideation and behaviour: The main complication that can derive from PDD is suicidal thought and self-harm
• Personal problems: PDD can lead to relationship difficulties, family conflicts and school or work problems due to the difficulty that patients have to get things done and their poor concentration
• Substance misuse: Substance abuse disorder can be considered to be a complication of PDD aswell as a risk factor
• Health problems: PDD itself can lead to the development of other mental health disorders (e.g. personality disorders and bipolar disorder) and can also affect physical health (e.g. heart disease due to the increased heart rate, blood pressure, and cortisol levels characteristic of depression)¹²
• FAQs

How can I prevent persistent depressive disorder?

There is no clear way of preventing PDD. However, there are some strategies that might help to prevent its symptoms. These include, being physically active, having a healthy diet,¹³ controlling stress, trying to boost your self-esteem and being close to your family and friends. To prevent a relapse of symptoms once you have suffered from PDD, consider getting a long-term treatment plan.

How common is persistent depressive disorder?

In the UK, the prevalence of mild depression is 11.3% whilst severe depressive symptoms is 3.3%.¹⁴ For PDD specifically, it has been suggested that the prevalence for PDD with chronic major depressive disorder is 15.2% and the prevalence for PDD with pure dysthymia is 3.3%.³

When should I see a doctor?

If you have some of the characteristics of PDD, you should make an appointment with either your doctor or a mental health professional, as having an early diagnosis can be crucial. If you are having a depressive episode and either feel you might hurt yourself or are having suicidal thoughts, call your local emergency number as soon as possible.

Summary

PDD is a form of depression characterised by the long duration of its symptoms, which in adults must last longer than 2 years in order to be diagnosed. The development of PDD might be linked to biological, psychological, environmental and genetic factors. Its symptoms can be really challenging, which is one of the reasons why PDD, as well as other forms of depression, is associated with a high risk of self-harm and suicidal ideation. Symptoms include depressed mood, changes in appetite and sleep, fatigue, low self-esteem and feeling of hopelessness. Treatment of PDD is based on the use of pharmacotherapy and/or psychotherapy. However, further research is needed due to the low effectiveness, side effects and resistance to treatments that occurs in some cases. At the same time, it is also importantto increase awareness of PDD so that both people suffering from it and the people around them understand how to act.