Let’s know about Persistent Depressive Disorder (PDD)

Let’s know about Persistent Depressive Disorder (PDD)

We all have come across the term depression. Clinical depression or commonly known as depression is a set of symptoms that results in persistent lowering of mood and loss of interest in things which you may have previously. We all might have encountered depression at some point in life. 

As data suggest depression affects individuals globally with no limits compared to other disorders. Depression is currently one of the leading causes of world disability. According to World Health Organization (WHO), depression is 1 in 3 individuals in India which constitutes around 59% of the Indian population and this trend is just increasing.

On looking into the Diagnostic and Statistical Manual of Mental Disorders, depressive disorders include persistent depressive disorder (PDD), disruptive mood dysregulation disorder, premenstrual dysphoric disorder, substance/medication-induced depressive disorder, depressive disorder due to another medical condition and unspecified depressive disorder.

People often misunderstand persistent depressive disorder or previously known as dysthymia. These misunderstandings may arise due to a lack of clarity about the condition, its constant evolution and overlapping symptoms. 

Fun Fact: Previously PDD due to its permanent and pervasive nature was a depressive personality disorder in DSM-II. Researchers suggest considering PDD as a temporary state subject to change. 

Risk Factors

The word “dysthymia” (though no longer used today) was formulated by CF Fleming around 1844 referring to psychiatry. A 10-year study reports PDD, in comparison to major depressive disorder, is associated with increased severity of depression, anxiety and somatic symptoms. Determining the risk factors of PDD will involve looking into numerous articles and a range of theories surrounding depression.

You may do your research into this topic as no evidence of solid risk factors for PDD is present but label a few specific factors:

  • Genetics and Epigenetics
  • History of mental illness in medical records
  • Neuroticism
  • High anxiety states
  • Sense of self-worth
  • Psychological health and trauma
  • Life stressors
  •  Social Determinants of Health

The prevalence rate of PDD in comparison to major depressive disorder is relatively low. This may suggest that the condition of depression is naturally relapse and remit and not chronic over an extended period. An urban population study of 3720 patients suggests that the prevalence rate of PDD with major depressive episodes is 15.2% and for PDD with pure dysthymia symptoms is 3.3% further proving that depression may be episodic. Looking into the comparison between gender, PDD is two times higher in females than males. According to studies, PDD tends to decline with age across age groups, especially in people 65 and older. 

Diagnostic Criteria

According to DSM-V diagnostic criteria, PDD should include an increased duration of low moods for most of the days than not for at least 2 years. In children and adolescents, this mood can be irritability with at least a 1-year duration. The individual should have experienced two or more of the following symptoms for at least more than two months:

  • Lack of appetite or overeating
  • Insomnia or hypersomnia
  • Low levels of energy to perform activities or fatigue
  • Low self-esteem
  • Poor concentration or trouble in making decisions
  • Feelings of hopelessness

In addition, the individual had never experienced a manic episode or hypomanic episode. The presence of substance uses or consumption within a short period before diagnosis and preexisting mental conditions may impact the diagnosis of PDD. The most important criteria for PDD are that it should cause clinically significant impairment in various areas of functioning in life. DSM-V also notes down a list of specifiers for this condition which characterizes additional features, its remission, onset, duration of symptoms and severity.

  • PDD can link with various casual factors, a few of which include:
  • Neurotransmitters functioning that impacts brain chemistry such as serotonin and GABA are majorly focused.
  • Brain volume reduction such as frontal areas of the brain and hippocampus show large to moderate reductions.

  • Genetics and inheritance of traits increasing vulnerability to PDD
  • Past traumas paired with life stressors contributing to the diathesis-stress model are said to affect PDD
Treatment Procedure and Strategies

A thorough assessment of PDD involves a set of procedures. If you or someone you know is going for treatment for PDD or depressive disorders you can expect the following process to occur. 

The first step involves ruling out biological and medical causes. This can occur by collecting the patient’s current and past medical history and the medications the patients use. In addition, case history and symptoms are also obtained. Secondly, laboratory screening may take place to support the medical decision. These tests include complete blood count, urine tests chemistry panels and TSH. Thirdly, a psychological assessment for depression takes place. Assessments such as patient health questionnaires, Beck depression inventory, etc. may be used to identify and screen the patients. Finally, the patients may recieve medications and appropriate treatment plans.

In these steps, it is also essential to rule out other possible diagnoses for PDD. Other conditions often confused with PDD or differential diagnosis is as follows:

  • Medical/Organic causes
  • Major depressive disorder
  • Bipolar disorder
  • Psychotic disorders
  • Substance-induced states
  • Personality disorders

In the case of treatment plans the two most used hand-in-hand are pharmacotherapy and psychotherapy. Selective serotonin reuptake inhibitor (SSRI) is the first medication used to treat PDD. Other effective alternatives include serotonin-norepinephrine reuptake inhibitors (SNRI) and atypical depressants. In psychotherapy, the main idea is to form therapeutic rapport. Cognitive-behavioural therapy and interpersonal therapy are commonly studied psychotherapies for PDD. A more specifically focused therapy for PDD is called the cognitive-behavioral analysis system of psychotherapy (CBASP). 

To conclude, in case you have doubts about whether you or someone you know has PDD or depression in general it is essential to seek help from professionals. This is because untreated depression can be detrimental to health, increase healthcare costs and become further difficult to treat. 

Many studies have illustrated that depression may act as an additive functional impairment and worse the symptoms of existing chronic medical conditions. There also exists evidence that depression may increase mortality. Above all depression can adversely impact the individual’s life as it prolongs. Hence, it can even lead to slow and painful progression to death.  Persistent depressive disorder (PDD), otherwise known as chronic depression, is a prolonged state of low mood and loss of energy. PDD can lead to numerous negative outcomes in life. The following article provides an in-depth yet brief look into PDD. It briefly points out the risk factors of PDD, the prevalence of the condition, diagnostic criteria, causes, treatment procedure and management. 

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