Depressive Disorders

Major Depressive Disorder (MDD)

Commonly called Depression, MDD is a mood disorder that causes persistent sadness and a loss of interest. MDD affects how you think, feel, and behave, leading to various emotional and physical issues. People with MDD may struggle to do normal daily activities and think life isn’t worth living. Depression is more than just sadness, and it’s not something that someone can “snap themselves out of”. It’s not a short-term thing; it’s a long-term psychiatric disorder. That’s not meant to be discouraging but rather the opposite. If you struggle with depression, it’s not just you being sad, moody, or lazy; it’s a psychiatric disorder that needs treatment. That means there are plans and paths you can take to treat this and make progress.


    • Feelings of sadness, emptiness, or hopelessness

    • Angry outbursts, irritability, or frustration, sometimes over seemingly small things

    • Loss of interest in things you used to care about, such as hobbies, activities, sex, etc

    • Sleep issues, insomnia, or sleeping too much

    • Over-tiredness and lack of energy – small tasks taking large amounts of effort

    • Reduced appetite and weight loss or increased cravings and weight gain

    • Anxiety or restlessness

    • Slowed thinking, speaking, or body movements

    • Feelings of worthlessness, guilt, or fixating on past failures, embarrassments, or self-blame

    • Trouble thinking or concentrating, making decisions, or remembering things

    • Frequent or recurring thoughts of death or suicide

    • Unexplained physical problems such as back pain or headaches

Symptoms are often severe enough to be noticeable in daily activities and relationships with others. Some people may feel generally miserable without necessarily knowing why.


Researchers don’t know the exact cause(s) of depression, but they think several factors can contribute to its development. These may include:

    • Brain chemistry (Imbalances of neurotransmitters, including serotonin and dopamine, can contribute to the development of depression)

    • Genetics (Having a biological parent or sibling with depression makes you three times as likely to develop the condition as the general population, so researchers know there is a genetic component. However, you can develop depression without a family history.)

    • Stressful life events (Experiencing trauma, death of loved ones, divorce, isolation, lack of support, etc., can cause or contribute to depression)

    • Medical conditions (Chronic pain and chronic conditions like diabetes can cause depression)

    • Medication (Some medications can cause depression as a side effect. Additionally, substance use or abuse can cause depression or worsen it.)


If you are dealing with MDD, be reassured that it is one of the most treatable mental health conditions. Approximately 80-90% of people with MDD who seek treatment eventually respond well to it and see improvement. These treatment options include:

    • Psychotherapy (talk therapy)

    • Cognitive Behavioral Therapy (CBT)

    • Dialectical Behavior Therapy (DBT)

    • Behavioral Activation (BA)

    • Medication

    • Complementary Medicine (acupuncture, hypnosis, biofeedback, etc.)

Persistent Depressive Disorder (PDD)

PDD is a mild to moderate chronic depression. It constitutes a dark, dull, or sad mood for the majority of the day on most days for two years or more. PDD is common and can happen to anyone at any age.

What is the difference between MDD and PDD?

PDD is another type of depression. It’s less severe than MDD, but is significantly long-lasting. It’s defined as lasting at least two years in adults and at least one year in children and teens. During this time, symptoms can’t be absent for more than two consecutive months without ruling out criteria for PDD.

How common is PDD?

PDD is very common. 3% or more of the U.S. population will experience it. PDD is more common in women and those with a genetic component (family members with the same condition).


    • Sad, low, or dark mood

    • Fatigue

    • Feelings of hopelessness, worthlessness, or isolation

    • Lack of appetite or overeating

    • Lack of concentration

    • Low self-esteem

    • Trouble at work or school

    • Trouble sleeping or sleeping too much

    • Most people with PDD will also have an episode of MDD at some point.


Researchers don’t know exactly what causes PDD, but they suspect it may be related to low levels of serotonin. PDD also may be triggered by a traumatic life experience or event.


    • Psychotherapy (talk therapy)

    • Cognitive Behavioral Therapy (CBT)

Disruptive Mood Dysregulation Disorder (DMDD)

DMDD is a childhood condition that causes chronic and intense irritability and frequent temper tantrums disproportionate to the situation. Symptoms must begin before the age of 10 to meet the diagnostic criteria.

What is the difference between DMDD, Oppositional Defiant Disorder (ODD), and Bipolar Disorder?

ODD is a behavioral condition in which a child shows a consistent pattern of defiant and sometimes hostile behavior, specifically towards those in authority. While some symptoms overlap with ODD, DMDD is considered a more severe condition with a significant mood component. Therefore, children who meet the criteria for ODD and DMDD are only diagnosed with DMDD.

Bipolar Disorder is a lifelong mood disorder that causes extreme mood changes, energy levels, thought patterns, and behavior. These shifts can last for varying amounts of time, from days to months, sometimes interrupting someone’s ability to carry out daily tasks. While similar behaviors may overlap between Bipolar Disorder and DMDD, symptoms of BD are contained within episodes, while symptoms of DMDD are ongoing. Additionally, BD is less common in children and adolescents and is usually a lifelong condition. In contrast, DMDD is a childhood condition more likely to ‘change’ into MDD or generalized anxiety disorder later in life.

Who Does DMDD Affect?

DMDD symptoms often begin before age 10. DMDD doesn’t get diagnosed in children under six or those over 18.

How Common is DMDD?

DMDD is a somewhat new diagnosis, so research is still needed to determine its prevalence. However, current research shows it may affect around 2-5% of children in the U.S.


    • Irritable or angry mood most of the day, almost every day

    • Severe temper tantrums that are disproportionate to the situation (generally 3+ times per week)

    • Issues with daily functioning due to irritability in more than just one environment.


Since DMDD is a newly understood condition, little research has been done on its treatment. As a result, the current treatment path is based on other childhood conditions like anxiety and ADHD. Luckily, studies have shown that those treatments work well for those with DMDD.

    • Psychotherapy (talk therapy)

    • Cognitive Behavioral Therapy (CBT)

    • Dialectical Behavior Therapy (DBT)

    • Parental Training

    • Medication

Substance/Medication-Induced Depressive Disorder

A Substance-Induced Depressive Disorder is a persistent, significant emotional disorder or disturbance that stems directly from the physiological effects of:

    • Substances (including legal substances such as alcohol) or illegal substances


This disorder is challenging due to its wide variety of causes, symptoms and the fact that each case is very individual. For example, it could be due to the person abusing an illegal substance or improperly using a prescribed medication. In addition, the symptoms can widely vary due to the different potential causes, mixed drugs that might be at play, and different comorbidities that the patient might be dealing with.


Much of this page was inspired by Mayo Clinic and Cleveland Clinic articles.

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Last updated on November 14, 2023
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