The term “depressive episode” describes bouts of depression that last for a specific time.  However, there are different forms of clinical depression—some of which can continue for years on end. Understanding the difference between two common types, major depressive disorder (MDD) and dysthymia, may help you understand the condition better. 

What is Major Depressive Disorder?

Also referred to as major depressive disorder (MDD), clinical depression is a common but serious mood disorder. A depressive episode can cause significant impairment in daily life. They can shift the way you act, think, and feel, leading to physical and emotional troubles that impact how you function at home or work. 

How long a depressive episode lasts relies heavily on individual factors, such as lifestyle or whether or not you seek treatment. On average, an episode of MDD can last between 4 and 8 months. With treatment, this window can shrink to 3 to 6 months. 

What is Dysthymia?

Commonly referred to as persistent depressive disorder (PDD), dysthymia is a chronic form of depression. Typically, the effects of PDD are less severe than MDD, but they last for much longer. Dysthymia is a continuous mood disorder which can occur over two years or more.

Due to the prolonged nature of PDD, it can significantly affect your lifestyle, relationships, and physical health. Though, with treatment, individuals with dysthymia can live full, happy lives.

How Common are MDD and Dysthymia?

Currently, 16.2 million American adults, or 6.7 percent of adults in the U.S., have had at least one major depressive episode in a given year. In comparison, just 1.3 percent of American adults experience dysthymia at some point.

What Differentiates MDD from Dysthymia? 

Several factors differentiate major depressive disorder from dysthymia, the most significant being time. MDD often consists of a single episode of major depression, which can last anywhere from a few weeks to several months. Symptoms must last for at least two weeks for a diagnosis of MDD. 

To accurately diagnose dysthymia, symptoms must have been present for at least two years. Likewise, the level of depression associated with dysthymia is usually not severe enough to meet the criteria for MDD, although it is still clinically significant.

Individuals with MDD suffer periods of major depression but have a usual mood baseline when not experiencing an episode. Individuals with PDD, however, experience depression all the time. 

Do MDD and PDD Share Similar Symptoms?

Though MDD and PDD vary in intensity and duration, they share similar symptoms, which include:

  • Memory loss

  • Lack of energy

  • Feelings of guilt

  • Feeling sad or empty

  • Loss of appetite

  • Increasing food cravings

  • Gaining or losing weight

  • Loss of interest in normal daily activities

  • Difficulty concentrating or making decisions

  • Feelings of worthlessness or hopelessness

  • Irregular sleep patterns, such as sleeping too much or too little 

Can You Have Both Major Depressive Disorder and Dysthymia?

Those who struggle with dysthymia can also experience episodes of major depression. However, if you’ve suffered from dysthymia for several years and then experience a major depressive episode, it would be classified as double depression. 

Treatment for either depression is generally different for each individual and involves a combination of medication and psychotherapy.

If you or a loved one believe you have either PDD or MDD, it’s important to speak with a Confidant professional to understand your condition and what steps to take next.