Clinical Depression (Major Depressive Disorder)


What is clinical depression (major depressive disorder)?

Clinical depression, also known as major depressive disorder (MDD), is a mental health condition that causes a persistently low or depressed mood and a loss of interest in activities that once brought joy. Clinical depression can also affect how you sleep, your appetite and your ability to think clearly. These symptoms must be present for at least two weeks for a diagnosis.

Clinical depression is a chronic condition, but it usually occurs in episodes, which can last several weeks or months. You’ll likely have more than one episode in your lifetime. This is different from persistent depressive disorder, which is mild or moderate depression that lasts for at least two years.

There are several subtypes of major depressive disorder. Some of the most common subtypes include: 

People with clinical depression often have other mental health conditions, such as:

What is the difference between clinical depression and depression?

It’s normal to feel sad when you’re faced with difficult life situations, such as losing your job or a relationship. Some people may say they feel depressed during these situations. Clinical depression (major depressive disorder) is different in that it persists practically every day for at least two weeks and involves other symptoms than just sadness alone.

It can be confusing because many people call clinical depression or major depressive disorder just “depression.” But there are several different types of depressive disorders, such as persistent depressive disorder and premenstrual dysphoric disorder. Clinical depression is the most severe type of depression.

Who does clinical depression affect? 

Clinical depression can affect anyone, including children and adults. Most cases tend to begin in your 20s, but it can develop at any age. 

Clinical depression is more likely to affect women and people assigned female at birth than men and people assigned male at birth. It’s also more common in people without close interpersonal relationships and people who are divorced, separated or widowed.

How common is clinical depression?

Clinical depression (major depressive disorder) is common. It’s one of the most common mental health conditions. It affects 5% to 17% of people at some point in their lives.

Symptoms and Causes

What are the symptoms of clinical depression (major depressive disorder)?

Symptoms of clinical depression can range from mild to severe, but they typically last most of the day, nearly every day, for at least two weeks.

Signs and symptoms include:

  • Feeling very sad, empty or hopeless (low mood). Children and adolescents may be irritable rather than sad.
  • Loss of interest in things and activities that used to bring joy.
  • Increase or decrease in appetite, which may result in weight gain or weight loss.
  • Slowed speech, decreased movement and impaired cognitive function (psychomotor agitation).
  • Trouble sleeping (insomnia) or sleeping too much (hypersomnia).
  • Low energy or fatigue.
  • Feeling worthless or excessively guilty.
  • Decreased concentration.
  • Thoughts of death or suicide.

If you or a loved one are thinking about suicide, dial 988 on your phone to reach the Suicide and Crisis Lifeline. Someone is available to help you 24/7.

What causes clinical depression?

Researchers don’t know the exact cause of clinical depression (major depressive disorder). They think that several factors contribute to its development, including:

  • Brain chemistry: An imbalance of neurotransmitters, including serotonin, norepinephrine and dopamine, contributes to the development of depression. Researchers used to think these imbalances were a primary issue. However, recent theories suggest that disturbances in more complex neural circuits cause secondary imbalances of neurotransmitters.
  • Genetics: If you have a first-degree relative (biological parent or sibling) with clinical depression, you’re about three times as likely to develop the condition as someone without a family history of the condition. However, you can have clinical depression without a family history of it.
  • Childhood development: Multiple adverse childhood experiences (ACEs) such as abuse and trauma are associated with the development of clinical depression later in life.
  • Stressful life events: Difficult experiences, such as the death of a loved one, trauma, divorce, isolation and lack of support, can trigger clinical depression in people who are susceptible to it.

Diagnosis and Tests

How is clinical depression (major depressive disorder) diagnosed?

Healthcare providers diagnose clinical depression (major depressive disorder) based on a thorough understanding of your symptoms, medical history and mental health history. They may diagnose you with a specific subtype of clinical depression, such as seasonal affective disorder (SAD) or atypical depression, based on the context of your symptoms.

To receive a diagnosis of clinical depression, you must have five or more of the symptoms listed in the symptoms section of this article that last every day, nearly all day, for at least two weeks. Two of the five symptoms must include low mood and loss of interest in previously enjoyed things and activities.

Your provider has to rule out other causes of your symptoms, such as medical conditions or substance use. They may order medical tests, such as blood tests, to do this.

They also have to make sure you haven’t experienced an episode of hypomania or mania, which could suggest bipolar disorder. About 5% to 10% of people with clinical depression develop bipolar disorder.

Management and Treatment

How is clinical depression treated?

Treatment of clinical depression (major depressive disorder) often involves medications and/or psychotherapy (talk therapy). Studies show that the combination of these treatments is more effective than either of them alone.

Psychotherapy involves talking with a mental health professional, such as a psychologist. Your therapist helps you identify and change unhealthy emotions, thoughts and behaviors. There are many types of psychotherapy — cognitive behavioral therapy (CBT) and interpersonal therapy (IPT) are the most common types for treating clinical depression. You may see your therapist once a week or once every other week.

Prescription depression medications called antidepressants can help change the brain chemistry that causes depression. There are several different types of antidepressants. It may take time and trying more than one medication to figure out the one that works best for you. Antidepressants have side effects, which often improve with time.

For severe clinical depression that hasn’t responded to other treatments, electroconvulsive therapy (ECT) is very effective. It involves passing a mild electric current through your brain, causing a short seizure. ECT is safe. It involves general anesthesia and doesn’t hurt.

Other types of stimulation therapy for medication-resistant depression include:

How long does depression treatment take to start working?

You may notice some improvements in your symptoms within the first week or two of starting antidepressants. But you may not see the full benefits until you’ve been on the medication for two to three months.

If the antidepressant isn’t working after this time, talk to your healthcare provider. They may adjust the dose or suggest a different antidepressant.

Depending on the severity of the clinical depression, psychotherapy can take a few weeks or much longer before you start to feel better. In many cases, 10 to 15 sessions result in significant improvement of your symptoms.


Can I prevent clinical depression (major depressive disorder)?

You can’t always prevent clinical depression, but you can help reduce your risk by:

  • Getting quality sleep and having a healthy sleep routine.
  • Managing stress with healthy coping mechanisms.
  • Practicing regular self-care activities such as exercise, meditation and yoga.
  • Managing any underlying medical or mental health conditions you have.
  • Avoiding misuse of alcohol and other substances.

If you’ve had an episode of clinical depression before, you may be more likely to experience it again. If you have depression symptoms, get help as soon as possible.

Outlook / Prognosis

What is the prognosis of clinical depression (major depressive disorder)?

The prognosis (outlook) for clinical depression depends on a few factors, including:

  • Its severity.
  • If it’s treated or untreated.
  • If you have other mental health or medical conditions.

The prognosis is better in people who have mild episodes, seek treatment and have strong support systems. The prognosis is worse in people who have other psychiatric or personality disorders and who are 60 years or older when they’re diagnosed.

Untreated episodes of clinical depression (major depressive disorder) can last six to 12 months.

About two-thirds of people with clinical depression think about suicide. About 10% to 15% of people with the condition die by suicide.

The good news is that clinical depression is one of the most treatable mental health conditions. Approximately 80% to 90% of people with the condition who seek treatment eventually respond well to treatment.

What are the possible complications of clinical depression?

Clinical depression (major depressive disorder) can greatly interfere with your daily functioning and quality of life if it’s not treated.

People with clinical depression are at a high risk of developing anxiety disorders and substance use disorders, which further increase their risk of suicide.

Depression can make underlying medical conditions worse or more difficult to manage, such as:

People with clinical depression are also at high risk of developing self-destructive behavior as a coping mechanism for their symptoms.

Living With

What can I do if I have clinical depression?

Aside from seeking professional, medical help for clinical depression, there are also things you can do at home to help improve your symptoms, including:

  • Getting regular exercise.
  • Getting quality sleep (not too little or too much).
  • Eating a healthy diet.
  • Avoiding alcohol, which is a depressant.
  • Spending time with people you care about.

When should I see my healthcare provider about clinical depression?

If you have symptoms of clinical depression, see a healthcare provider or mental health professional. They can give you an accurate diagnosis and suggest treatment options.

If you’ve started treatment for clinical depression and it isn’t working or you’re having unpleasant side effects, talk to your provider. They can recommend a different treatment plan.

A note from Cleveland Clinic

Clinical depression (major depressive disorder) is one of the most common mental health conditions. Anyone can experience clinical depression — even if there doesn’t seem to be a reason for it. The good news is that clinical depression is highly treatable. If you’re experiencing symptoms, talk to your healthcare provider. The sooner you get help, the sooner you can feel better.

Last reviewed by a Cleveland Clinic medical professional on 11/30/2022.


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  • Bains N, Abdijadid S. Major Depressive Disorder. ( [Updated 2022 Jun 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Accessed 11/30/2022.
  • Merck Manual: Consumer Version. Depression. ( Accessed 11/30/2022.
  • National Institute of Mental Health. Major Depression. ( Accessed 11/30/2022.

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