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Persistent depressive disorder: long term depression

felix gussonerob roy britt

Reviewed by Felix Gussone, MD, written by Robert Roy Britt

Last updated: Apr 26, 2021
5 min read


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

We all feel depressed now and then. But clinical depression, which can be diagnosed by a psychiatrist and can often benefit from treatment, goes beyond brief flashes of sadness. It’s chronic and can be debilitating, getting in the way of work, relationships, and the enjoyment of life. 

There are several different terms used to define and discuss varying types of depression. One distinction psychiatrists will make in a diagnosis involves the duration of symptoms: persistent depressive disorder and major depressive disorder.

If you’re really feeling down, and the feeling won’t go away, and you also feel unable to deal with it, you may have one of these types of clinical depression.


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Major depressive disorder vs. persistent depressive disorder 

There is no single type of depression nor one simple definition or cause (Institute of Medicine (US) Committee on Depression, 2009). Depression can be bipolar (meaning it is matched with a manic phase) or unipolar. 

It can be seasonal or long-lasting, and the underlying causes or triggers can vary greatly. Depending on how it’s defined, depression affects about 10% of US adults in a given year and some 21% during their lives (Hasin, 2018).

Psychiatrists define major depressive disorder as “a serious medical illness that negatively affects how you feel, the way you think and how you act” (American Psychiatric Association, 2013). 

Major depressive disorder, also sometimes called “unipolar major depression,” involves one or more episodes of serious, clinically diagnosed depression, including five or more of the symptoms noted below for at least two straight weeks (Lyness, 2021).

Persistent depressive disorder is similar, but rather than being episodic, it lasts for two years or more. People with persistent depressive disorder (also called dysthymia) often say they’ve been depressed for a long time (Patel, 2020). 

Symptoms of depression

The core symptoms for persistent or major depression are the same, and a diagnosis can be made when a person’s usual level of functioning is hampered by at least some of the following symptoms (American Psychiatric Association, DSM-5, 2013):

  • Sadness or depressed mood most of the day
  • Loss of interest or pleasure in usual activities
  • Weight gain or loss
  • Poor sleep or oversleeping
  • Fatigue or loss of energy
  • Pacing, fidgeting, or other purposeless activity
  • Slowed movement or speech
  • Guilt or a sense of worthlessness
  • Difficulty thinking, concentrating, or making decisions
  • Recurring thoughts of death or suicide

Grief and sadness may come and go based on events or transient experiences and feelings, but clinical depression—whether episodic or constant—is marked by the inability to cope amid feelings of self-loathing or worthlessness.

What causes depression

Depression has many causes. Genetics is thought to be about 40 to 50% responsible for cases of depression (Lohoff, 2010), and heredity—the genes you inherit from your parents—seems to play a greater role in the most severe cases (Sullivan, 2000).

Environment and experience can certainly factor in, however. Traumatic events from childhood or adult life, poverty, alcohol use, even diseases, and other medical conditions can contribute to the disease (Institute of Medicine Committee on Depression, 2009).

Depression can set at any point in life, and it can come and go over time or become a fixture. While children go through many mood phases and naturally have mood swings that can look like depression, about 3% of them actually meet the definition of clinical depression (Ghandour, 2019).

Seeking diagnosis and treatments

If you feel depressed for more than two weeks—based on any of the symptoms above—there is, of course, no need to wait years to learn whether you might experience the episodic nature of major depressive disorder or if your condition might become persistent. It’s time to talk to a medical professional. 

And it’s wise to go in armed with the above information. Most people with depression visit a primary care healthcare provider rather than a psychiatrist. While a family doctor should be able to help with an initial evaluation, studies have shown that the diagnosis of depression is missed in at least 50 percent of depressed primary care patients (Mitchell, 2009). Oftentimes, a referral to a psychiatrist is necessary to properly diagnose and treat depression. 

The persistent depressive disorder isn’t very different from the management of a major depressive disorder and the general principles of pharmacotherapy and psychotherapy remain the same.

Antidepressants and talk therapy are among the most commonly prescribed treatments, regardless of the type of depression. This combination has been shown to be more effective than either treatment independently (Cuijpers, 2009).

When it comes to antidepressants, SSRIs (selective serotonin reuptake inhibitors) such as fluoxetine (brand name Prozac; see Important Safety Information) are often the first-line treatment (Patel, 2020).

People suffering from depression need to be informed of all the treatment options and possible outcomes, especially considering these facts. Therapies for depression have been scientifically proven to be effective for many people with depression.

However, some people—especially children and adolescents—can recover from depression on their own. This so-called spontaneous improvement is still understudied but has become a focus of recent research.

At the same time, many others don’t respond positively to the treatments (Cuijpers, 2020). Talk to your healthcare provider about what treatment option is right for you.

The label of depression can deter people from seeking a professional evaluation of their unending sadness or grief. But depression is common, and in today’s world, it’s certainly understandable.

If your lousy mood becomes persistent and you just don’t know how to deal with it, heed those signs and seek help.


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Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.