Comprehending the distinction between major depressive disorder and persistent depressive disorder: Insights into dysthymia

Persistent Depressive Disorder (PDD) and Major Depressive Disorder (MDD) are two distinct types of depression, although they share some symptoms and diagnostic methods. PDD, previously known as dysthymic disorder, influences a higher number of adult women than men in the United States. On the other hand, MDD is a frequently encountered mental health condition in the U.S., affecting a greater number of adult females than males.

The primary difference between the two disorders lies in the duration of symptoms. For an adult to be diagnosed with PDD, depressive symptoms must persist for at least two years, while adults with MDD experience major depressive episodes at least two months apart.

Below you can find information regarding the distinctions between major depressive and persistent depressive disorders, including their symptoms, causes, treatment, and more.

Symptoms

PDD and MDD share numerous similar symptoms. It's possible for a person to exhibit symptoms of both disorders simultaneously.

PDD Symptoms

For an individual to receive a PDD diagnosis, they do not need to present every symptom concurrently. PDD symptoms include:

persistently feeling down or irritable
experiencing a lack of appetite or overeating
struggling with insomnia or excessive sleep
feeling tired or having low energy levels
experiencing self-doubt or low self-esteem
facing difficulties concentrating or making decisions
feeling hopeless

Children and adolescents with PDD may display irritability rather than depression as a symptom. In this case, the symptom must be present for a shorter period, only one year.

Individuals with PDD may struggle with fulfilling responsibilities at work, school or home. The disorder can also make social interactions difficult and heighten feelings of overwhelm during stressful situations.

MDD Symptoms

Similar to PDD, people with MDD do not need to exhibit all symptoms simultaneously for a diagnosis.

The symptoms of MDD include:

experiencing a depressed mood for most of the day
losing interest or pleasure in most activities
feeling fatigued
feeling worthless or guilty
facing challenges with concentration and decision-making
unintentionally losing or gaining significant weight
suffering from insomnia or sleeping excessively
experiencing restlessness called psychomotor agitation or struggling with thinking, speaking, and doing everyday tasks (psychomotor impairment)
having frequent thoughts of death

Individuals with MDD may also have panic disorders, social anxiety disorder, and obsessive-compulsive disorder, as well as other mental health issues. Many people with MDD also have substance abuse disorders.

Social functioning can become difficult with MDD, impacting work, school, and family responsibilities. The person may withdraw from friends and activities they once enjoyed.

Causes

While some causes of MDD and PDD may be similar, there are crucial differences.

MDD Causes

Mood disorders like MDD may have genetic and external causes. In the case of MDD, scientists believe that these factors interact, and each symptom of MDD may have a separate cause.

Some researchers argue that the hippocampus, a part of the brain, plays a significant role in MDD. In individuals with MDD, the hippocampus is smaller compared to those without the disorder. The hippocampus plays a crucial role in forming memories, adapting to stressful situations, and processing emotions. A decrease in hippocampus size can affect its functioning.

MDD is also associated with a decrease in gray matter in the brain. Gray matter is involved in numerous processes, including speech, decision-making, and self-control.

The neurotransmitters serotonin, dopamine, and norepinephrine travel through gray matter. A reduction in gray matter can result in less production of these neurotransmitters, contributing to the disorder's symptoms.

Factors that increase the likelihood of developing MDD include:

having a history of depressive episodes
experiencing a stressful life event
having a family history of MDD
living with chronic medical conditions
having dementia
experiencing anxiety
engaging in substance misuse

PDD Causes

Research on the causes of PDD is ongoing, and it is believed that disruptions in the neurotransmitters serotonin, epinephrine, norepinephrine, and glutamate play an essential role.

Studies have also shown that certain parts of the brain, such as the orbitofrontal cortex and the hippocampus, are smaller in people with PDD than in those without the disorder.

Other factors contributing to PDD include genetic, environmental, and psychological causes, such as:

serious medical conditions, including diabetes and cancer
a personal or family history of depression
trauma or chronic stress
exposure to certain medications that can cause depression as a side effect

Diagnosis

The diagnostic methods for PDD and MDD are similar.

MDD Diagnosis

Doctors, including psychiatrists, diagnose MDD based on its symptoms. For a doctor to recognize MDD, a person must exhibit at least five symptoms, one of which must be feeling depressed frequently or experiencing a loss of interest or pleasure in life. The symptoms must negatively affect the person's social well-being, job, or other important aspects of their life.

The symptoms doctors use to diagnose MDD are symptoms of major depressive episodes. For a diagnosis, a person must have experienced at least two depressive episodes, separated by at least two months.

PDD Diagnosis

Doctors diagnose PDD based on its symptoms as well. For an individual to receive a PDD diagnosis, they must display persistent symptoms of depression for a minimum of two years.

To be diagnosed with a Persistent Depressive Disorder (PDD), an individual must display PDD symptoms coupled with prolonged periods of depression or irritability. In adults, this prolonged period spans over 2 years, while in children and teenagers, it lasts for a year or more.

These symptoms significantly impact an individual's social life, job, or other crucial domains. It's essential to note that during a 2-year stretch, in adults, or a 12-month period, in the younger population, these symptoms cannot go unnoticed.

Treatment

The treatment strategies for PDD closely resemble those employed for Major Depressive Disorder (MDD).

MDD Treatment

MDD treatment options vary based on the severity and type of symptoms. For moderate MDD, a combination of psychotherapy and medication is often recommended.

Psychotherapy includes approaches such as:

Cognitive Behavioral Therapy (CBT)
Behavioral Activation
Interpersonal Psychotherapy

Medications for MDD may include:

Selective Serotonin Reuptake Inhibitors (SSRIs), like sertraline (Zoloft) and citalopram (Celexa)
Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs), including venlafaxine (Effexor) and duloxetine (Cymbalta)
Other medications, such as bupropion (Wellbutrin) and mirtazapine (Remeron)

Medication dosages typically begin at a low level, which can be gradually increased if necessary. Symptom improvement may be observed within a few weeks, but complete relief may not occur before the 8th to 12th week.

Combining medication and psychotherapy often yields better results than medication alone.

PDD Treatment

PDD treatment closely mirrors MDD treatment, primarily focusing on psychotherapy methods, such as CBT, and medications, including SSRIs or SNRIs. A psychotherapist may typically start with an SSRI as this type tends to have fewer side effects.

However, treatment decisions are based on a multitude of factors, including the individual's unique needs and response to different medications.

FAQs

Below are some frequently asked questions about Major Depressive Disorder and Persistent Depressive Disorder:

Is PPD the same as MDD?

PPD is a type of depression that endures for at least 2 years. MDD, on the other hand, is characterized by major depressive episodes that are separated by at least 2 months. While similar and sometimes diagnosed together, PPD and MDD are two distinct conditions.

Can a person have both MDD and PPD?

Individuals may suffer from both MDD and PDD, provided they meet the diagnostic criteria for each disorder.

Can depression be inherited?

Research suggests that genetics may contribute to the development of depressive disorders, but the exact role is yet to be fully understood. Depressive disorders may run in families, increasing the risk for children of individuals with depressive disorders. However, inheritance does not guarantee the development of these disorders.

Summary

PDD and MDD share common symptoms and treatment methods, but the key difference lies in the duration of symptoms. PDD lasts for at least 2 years (in adults) or 1 year (in children and teenagers), while individuals with MDD experience depressive episodes that are separated by at least 2 months.

Genetic, social, and physical factors contribute to the development of both PDD and MDD, with various parts of the brain playing essential roles. Treatment may involve psychotherapy methods, such as CBT, and medications, including SSRIs and SNRIs, which have shown to be particularly effective when used in combination.

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