Persistent Depressive Disorder (PDD)

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) lists criteria for several different depressive disorders, and persistent depressive disorder (PDD) is one of these. Persistent depressive disorder is one type of depression that can last for extended periods—typically more than two years. Understanding this mood disorder and how it may impact your life may be the first step in deciding to seek professional support.

What is persistent depressive disorder?

Persistent depressive disorder, formerly known as dysthymia or dysthymic disorder, is a long-term form of depression. As with other types of depression, PDD is often marked by melancholy, low self-esteem, and loss of interest in activities previously enjoyed. It can also cause significant challenges in functioning that can impact various areas of life, including work, school, relationships, and overall mental health and well-being.

PDD vs. other types

Unlike situational types of depression like seasonal affective disorder and perinatal depression, PDD is a long-term and recurrent form of this illness that involves feeling symptoms on most days for more than two years.

Symptoms

Again, symptoms of PDD are typically similar to symptoms of major depressive disorder, but they’re experienced with lower intensity and for a longer period. According to the DSM-5, key PDD symptoms include:

• Insomnia (trouble sleeping) or hypersomnia (excessive sleeping)

• Significant changes in appetite

• Low self-esteem

• A sense of hopelessness; depressed mood

• Low energy and fatigue

• Difficulty concentrating

If you recognize these signs of chronic depression in yourself, it’s typically recommended that you meet with a mental health professional for evaluation, treatment advice, and possible therapy such as talk therapy or cognitive behavioral therapy (CBT). Living with the effects of PDD over the long term without treatment can also increase a person’s risk of misusing alcohol or recreational drugs and developing a substance use disorder. That’s another reason why it can be important to seek treatment for depression symptoms as soon as possible.

The potential impacts of PDD 

The symptoms of major depressive disorder and persistent depressive disorder can cause many disruptions to daily life. Some of their potential impacts may include the following:  

• Social withdrawal. Depression often causes a person to self-isolate and withdraw from family and friends. As connecting with others may benefit mental health, this symptom of PDD could exacerbate symptoms and make a person feel even more alone in their experience.

• Work or school issues. If you’re living with PDD, you might not be able to be as productive at your job or in class because of the difficulty concentrating it can cause.

• Physical health problems. Depression can cause or contribute to a number of challenges related to physical health and well-being, such as insomnia, a weakened immune system, a lower libido, fatigue, and headaches.

• Decreased self-esteem. Like other forms of depression, PDD can cause a person to be excessively self-critical. These thoughts have the potential to damage self-esteem over time.

• Trouble with daily functioning. PDD can make it challenging to complete daily tasks and self-care activities, such as brushing teeth, cooking a meal, or showering. 

What causes PDD?

As with many mental illnesses—from anxiety disorders to personality disorders—there doesn’t seem to be one, singular cause of mild or moderate depression or persistent depressive disorder. Instead, this type of condition may develop from a combination of factors, including the following.

Biological factors 

The brains of some individuals may have unique structural differences or chemical imbalances that may contribute to an illness like depression or PDD. What causes these differences is not yet understood, but research has suggested that depression may be around 40–50% hereditary. In other words, if you have biological relatives who have experienced depression, you may be at an increased risk of experiencing it as well.

Environmental factors

The experience of traumatic or stressful life events could potentially make a person more vulnerable to several different mental health conditions. It could cause post-traumatic stress disorder or contribute to the development of depression, anxiety, schizophrenia, persistent depressive disorder, and others.

How is PDD diagnosed? 

PDD is likely widely underdiagnosed. Symptoms often occur persistently over long periods, so an individual living with this condition may believe that what they're experiencing is typical. For this reason, those who do seek help and receive a diagnosis are often prompted to do so by a loved one. 

In order to receive a PDD diagnosis, an individual must typically have been experiencing all six of the symptoms listed above consistently for two or more years. The DSM-5 also notes that the symptoms must not have ceased for longer than two months during this period. It also emphasizes that symptoms must not be connected to bipolar disorder or cyclothymic disorder, as these would be separate diagnoses.

Additionally, the moderate depressive symptoms must not be caused by other factors such as substance use or a health condition like a stroke. The symptoms must also significantly impact the person's daily life (e.g., work or school performance, relationships, basic self-care, etc.).

Treatment

Like other forms of depression, PDD is considered treatable. The right type of treatment can vary from individual to individual, so meeting with a qualified mental health professional for personalized support and advice is recommended. Ways to help alleviate some symptoms yourself can include a healthy lifestyle like eating balanced meals, getting enough sleep, and getting daily physical activity if possible. That said, these are some of the most common treatment methods for PDD.

Therapy

Psychotherapy is a practical resource for addressing PDD, and there are multiple modalities that may be effective. One of the most widely used is cognitive behavioral therapy, which aims to help the individual learn to recognize and challenge distorted thoughts that may be contributing to distress. Note that many types of talk therapy can be attended in group, family, or couples’ formats, depending on a given individual's needs. 

Persistent depression that lasts for years can be stressful to cope with alone, but it can also make seeking the help of a mental health professional more challenging. If your symptoms make it difficult to find a therapist or to travel to and from in-person appointments, you might be interested in exploring online therapy. 

With a platform like BetterHelp, you can fill out a brief questionnaire to get matched with a licensed therapist who suits your needs. You can then meet with them remotely from anywhere you have an internet connection. Research indicates that online therapy can be “at least as effective” in treating depression as in-person care in many cases.

Medication 

In some cases, medication such as selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs) will also be prescribed for an individual living with depression—usually in combination with some form of therapy. For many people, finding a medication that works for them may take a few tries. Different medications have different side effects, and some simply work more effectively for some people than others. 

It may take six to eight weeks before you start to feel the effects of many antidepressant medications, so be sure to check in with your doctor as often as they recommend and to track your symptoms and any potential side effects as you go. Remember to always consult a medical professional like a doctor or psychiatrist before starting, changing, or stopping any medication. 

Options for treatment-resistant symptoms

For some people, the commonly prescribed medical or psychotherapeutic treatments for depression don't work for them over an extended period. In these cases, their depression might be labeled as "treatment-resistant." Someone with treatment-resistant depression might be eligible for specific clinical trials or unique treatments such as the following: 

• Transcranial magnetic stimulation therapy (TMS) 

• Electroconvulsive therapy 

• Ketamine IV infusions 

• Vagus nerve stimulation 

• Biofeedback therapy

These treatments are performed in a medical environment under the close supervision of psychiatrists and doctors. If you feel that the treatment you’ve been prescribed by a therapist, psychiatrist, or doctor isn’t helping your depression, you may meet with them to learn about other options or get a second opinion. 

Can you prevent PDD?

Since mental illnesses like PDD are thought to be caused by a complex combination of factors—including genetics—there’s currently no known way to prevent them. That said, there are certain strategies that might put you at a lower risk of developing depression. Some that could help prevent persistent depressive disorder or at least increase mental health resilience in general include:

• Seeking mental health treatment early, when you begin to notice symptoms

• Cultivating a strong social support network (friends, family, neighbors, mentors, etc.)

• Exercising regularly to produce endorphins and contribute to overall health

• Spending time in nature often, which may produce psychological benefits in general

• Meditating regularly, which research suggests could increase gray matter—low levels of which may be associated with recurrent depression