What Is Clinical Depression?

Also known as major depressive disorder

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Clinical depression, also called major depression or major depressive disorder (MDD), is often confused with having a sad or low mood. Although feeling sad is one symptom of clinical depression, there must be several other signs and symptoms—in addition to sadness—for someone to be formally diagnosed with clinical depression.

Clinical depression is considered a potentially chronic and severe disorder with medical comorbidities and high mortality. Understanding the signs and symptoms of clinical depression are important to ensure someone can receive an accurate diagnosis and treatment.

clinical depression

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What Is Clinical Depression?

Clinical depression is a serious form of mental illness that impacts more than just a person’s mood. It affects the way a person:

  • Thinks
  • Acts
  • Feels
  • Manages their life

A diagnosis of clinical depression means that a person has symptoms that interfere with the ability to function at work and home, which adversely impacts the way a person is able to enjoy hobbies and leisure activities, socialization, relationships, and more.

Clinical depression involves more than just emotions, it encompasses physical symptoms—such as inability to sleep and loss of appetite—as well. It’s important to note that clinical depression is a set of signs and symptoms that may reflect a chemical imbalance in the brain. 


Some of the most pervasive symptoms of clinical depression are a severe and persistent low mood, profound sadness, or a sense of despair. The characteristics, symptoms, or traits of depression may vary in severity from very mild to severe. Symptoms may include:

  • An ongoing feeling of sadness or depressed mood
  • Loss of interest in hobbies and activities that are usually enjoyable
  • Low energy level or a feeling of fatigue
  • Insomnia (trouble sleeping) or sleeping too much
  • Loss of appetite and subsequent weight loss
  • Eating too much, resulting in weight gain
  • Slowed movement or speech
  • Increase in activity (pacing, nervous gestures such as wringing hands repeatedly)
  • Feelings of guilt or worthlessness
  • Trouble concentrating
  • Difficulty making decisions
  • Thoughts of suicide (or an active plan to commit suicide)
  • Obsession with death

For a formal diagnosis of clinical depression, these symptoms must last at least two weeks and they must represent a change from the former level of functioning experienced before symptoms began and they must cause a person significant impairment or distress in their job, social situations, or other areas of functioning. The symptoms must not be caused by another medical condition, including substance abuse. 

Other physical conditions that can mimic the symptoms of depression include:

  • Thyroid problems
  • A brain tumor
  • A vitamin deficiency


A diagnosis of clinical depression often begins with a physical examination, lab tests, and other diagnostic measures to rule out any physical conditions such as thyroid problems. After which, the primary healthcare provider may refer you to a psychiatrist or other mental health professional (such as a psychologist licensed clinical social worker or LICSW) for an evaluation. An evaluation by a mental health professional may include:  

  • A psychiatric evaluation: This includes a history of current symptoms and an assessment of your thoughts, feelings, and behaviors. You may be asked to answer some questions in written form.
  • A family history: This is used to decipher whether there is any mental illness in your family.
  • A diagnostic evaluation: This evaluates your symptoms as compared to the DSM-5, a diagnostic tool called the Diagnostic and Statistical Manual of Mental Disorders.


The exact cause of clinical depression is unknown, anyone can suffer from major depressive disorder. However, there are some known causes linked with clinical depression, these include:

  • Biochemistry: Specific brain chemicals are thought to play a role in symptoms of depression.
  • Genetics: Depression is known to run in families. If you have a parent or sibling with clinical depression, you have a two to three times higher likeliness of developing depression, compared to someone who does not have this family link.
  • Environmental factors: Such as being exposed to violence, or abuse and neglect, particularly during childhood, can increase a person’s likeliness of depression. Poverty is also known to make a person more vulnerable to clinical depression.

Risk Factors

While no one can predict exactly if a person will become depressed, there are some risk factors that increase the likeliness of being diagnosed with depression, these include:

  • Having had a previous clinical depression episode
  • Having a family history of depression, alcoholism, bipolar disorder, or a family member who has committed suicide
  • Having substance abuse problems
  • Going through significant life changes (such as the loss of a loved one)
  • Having high levels of stress
  • Having experienced a trauma
  • Having certain medical conditions (such as a brain tumor)
  • Taking some types of medications known to cause depression
  • Having certain personality characteristics (such as being extremely pessimistic or having low self-esteem)


There are several different types of depression that a person can have; the primary difference is the features involved. You may or may not have what is called a specifier linked with depression, these specifiers may include:

  • Anxious distress: Depression, along with feelings of restlessness, being worried, keyed up, or tense. 
  • Mixed features: Depression, along with increased energy, excessive talking, inflated sense of self-esteem (also referred to as mania or manic).
  • Melancholic features: Severe depression, linked with early rising, loss of all interest in things that you previously enjoyed, worsened mood in the morning, and guilty feelings.
  • Atypical features: Depression with features that include a mood that can brighten in response to positive events, an increase in appetite, excessive sleep, a heavy feeling in the arms or legs (called leaden paralysis).
  • Psychotic features: Depression accompanied by psychosis, such as hallucinations or delusions.
  • Peripartum onset: Occurs during pregnancy or within four weeks of giving birth.
  • Seasonal Pattern: Also known as seasonal affective disorder, involves depression that is linked with a specific season of the year (usually with lower sunlight exposure, such as fall or winter). Symptoms may include trouble getting up and going to work during the winter months.


Clinical depression is one of the most treatable of all mental health disorders. In fact, between 80 to 90% of people with depression respond favorably to treatment.


When the chemistry in the brain is contributing to a person’s depression, your healthcare provider may prescribe an antidepressant. Antidepressants are not considered habit-forming drugs, they simply help to modify the brain chemistry, thus improving symptoms of depression.

One drawback of antidepressants is that they can take up to several weeks to begin having a therapeutic effect (lowering symptoms of depression). 

If you start taking antidepressants and do not see any improvement in your symptoms after several weeks, your psychiatrist may adjust your dose, or add an additional medication.

Usually, you will be instructed by your healthcare provider to take your antidepressants for at least six months (or longer) after you see improvement in symptoms; you may be advised to take the medication long-term, to reduce the risk of future episodes of depression.


Psychotherapy—sometimes referred to as “talk therapy"—is a common treatment for mild depression. If you have moderate to severe depression, you may be encouraged to engage in talk therapy, along with antidepressant medications. 

A variety of psychotherapy modalities have been found helpful for depression. One of the most effective modes of talk therapy for depression is called cognitive behavioral therapy (CBT), a type of psychological treatment that has been found to be effective for many different issues, such as:

  • Depression
  • Anxiety
  • Alcohol and substance use disorders
  • Eating disorders
  • Other types of mental illness

CBT therapy involves various strategies; some or all of these strategies may be employed during individual or group therapy, they include:

  • Learning to recognize distortions in thinking that lead to problems and reevaluate these distortions
  • Learning to change behavioral patterns (such as facing fears when a person suffers from severe anxiety)
  • Learning problem-solving skills and how to employ them in specific situations
  • Learning how to gain confidence in one’s strengths and abilities
  • Adopting improved insight into the motivation and behavior of others
  • Learning how to calm the mind and relax the body

The time it takes for the treatment of depression can vary, depending on several factors including:

  • The severity of clinical depression
  • The extent of trauma one may have experienced
  • Whether a person has co-occurring conditions, such as substance use disorder
  • The type of depression a person has

ECT Therapy

Electroconvulsive therapy (ECT) is a treatment for depression that is very effective, but is usually reserved for those who do not respond well to other types of treatment, such as medication. ECT is much different today than historically, when a person was awake during the process. This treatment modality began during the 1940s. Today, however, ECT is done under anesthesia. It involves a very brief electrical stimulation to the brain after the person has been put to sleep. ECT is usually comprised of approximately six to 12 sessions.


There are many things you can do to help you cope with clinical depression, some of the most common interventions include lifestyle changes such as:

  • Ensuring that you get enough sleep each night
  • Eating a healthy diet
  • Getting involved in a daily physical workout routine (with the okay from your healthcare provider). Studies have shown exercise can mitigate depression.
  • Avoiding the use of alcohol (which is a depressant) and other drugs
  • Adopting measures to manage stress (such as deep breathing and relaxation techniques, yoga, or mindfulness practice. 

A Word From VeryWell

Keep in mind that clinical depression is a serious illness and treatment is available. With an accurate diagnosis and proper treatment, most people can learn to live with clinical depression, and many get relief from their symptoms. If you have symptoms of clinical depression, be sure to talk to your primary healthcare provider; don’t be afraid to ask for a referral to a mental health professional to get a thorough evaluation/diagnostic assessment. This is the first step to being proactive about your mental health.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Sherry Christiansen
Sherry Christiansen is a medical writer with a healthcare background. She has worked in the hospital setting and collaborated on Alzheimer's research.