What Is Depression?

Depressive disorder—also known as depression—is a mental health condition that occurs when a person has long-lasting sadness or no longer has an interest in activities that they used to enjoy. Other than affecting your mood, depression can alter your thoughts and behaviors and limit your ability to function.

The condition affects 17 million adults in the United States and people of any age can experience symptoms. There is more than one type of depression—and while symptoms of each depressive disorder are similar, they have their own distinct features.

There is no singular cause of depression, but a variety of genetic, environmental, and lifestyle factors can increase your risk of developing symptoms. While depression can be hard to endure, the good news is that you don't have to go through the condition all alone.

In fact, depression is one of the more treatable mental health conditions, and options such as medications and therapy can significantly improve symptoms and your overall quality of life.

Types of Depression

There are a few major classifications of depression, which include:

  • Disruptive mood dysregulation disorder (DMDD): This is a condition that affects children and adolescents from ages 6 to 18. It features chronic irritability that frequently results in verbal or behavioral temper tantrums, which occur three or more times a week.
  • Major depressive disorder (MDD): Major depressive disorder causes symptoms of depression that last for at least two weeks. Symptoms may include extreme sadness, inability to carry out daily tasks, hopelessness, and a loss of interest in activities you used to enjoy doing.
  • Persistent depressive disorder (PDD): This type of depression lasts for at least two years for adults. To receive a diagnosis for PDD, you must experience depressive moods and thoughts on most days.
  • Premenstrual dysphoric disorder (PMDD): PMDD is a condition that occurs when you experience depressive or other mood-related symptoms that interfere with your life before your menstrual period begins.
  • Depressive disorder due to another medical condition: In this instance, depression occurs as a secondary condition to other medical issues (e.g., cancer or chronic pain).
  • Postpartum depression: Depression that occurs in people who give birth after the baby is born.
  • Seasonal affective disorder: A type of depressive disorder that you can experience when the seasons change, which most often occurs during winter or colder months.


A person may have a depressive disorder if they experience any of the following symptoms, on more days than not, for at least two weeks:

  • A depressed mood or constant sadness
  • Lack of interest or pleasure in previously-enjoyed activities
  • Appetite changes leading to unintentional weight loss or gain
  • Sleep issues, including being unable to sleep or sleeping too much
  • Feeling extremely tired or not having energy
  • Changes in movement, such as restlessness or slow speech and movement
  • Feelings of worthlessness or guilt
  • Lower sex drive or libido
  • Difficulty concentrating, thinking, or making decisions
  • Thinking about suicide or self-harm

Looking for Support?

If you or someone you know is thinking about suicide, call the toll-free National Suicide Prevention Lifeline at 1-800-273-TALK (8255) or dial or text 988.


In order to receive an official diagnosis of depression, you must experience five of the nine symptoms—in which one of the symptoms has to be sadness or loss of interest in enjoyable activities.

Keep in mind: how long symptoms last, how frequently you experience depressive episodes, and how severe your symptoms are will vary from person to person. Regardless of if your symptoms or mild, severe, or somewhere in between, you can still have depression even if you don't experience all nine symptoms.


A combination of genetic, environmental, and lifestyle factors can increase your risk of developing symptoms of a depressive disorder.

Depression is associated with neurotransmitters, which are chemical messengers in the body that can affect the way people feel and behave. These messengers include serotonin, dopamine, and epinephrine. When these neurotransmitters are out of balance, you may experience one or more mood disorders.

However, a chemical imbalance plays just one role in your risk of depression. Environmental factors and stressful life events can also trigger symptoms.

Risk Factors

Depression comes with a number of risk factors. You may be at an increased risk of developing symptoms if you:

  • Were assigned female at birth
  • Recently gave birth
  • Live with chronic health conditions such as cancer or lupus
  • Received a diagnosis for other Parkinson's disease or a traumatic brain injury (TBI)
  • Drink alcohol, use drugs, or have a pre-existing diagnosis of substance use disorder
  • Have a family history of depression or other mental health conditions
  • Are dealing with stressful life events (e.g., death of a loved one or divorce), trauma (e.g., abuse or being in a car accident), or difficult societal issues (e.g., war or natural disaster)


There are no lab tests that can diagnose depression. Instead, healthcare providers and mental health professionals (e.g., psychologists, psychiatrists, and licensed counselors) might use the following to give you an accurate diagnosis for depression:

  • Learning about your personal and family medical history
  • Getting to know your social history, such as your lifestyle habits and stressors
  • Performing a physical exam to screen for other conditions that may be causing symptoms that mimic depression
  • Giving you depression questionnaires (e.g., Beck's Depression Inventory) to screen you for depression and gain a better understanding of your symptoms
  • In rare cases, ordering blood or imaging tests to rule out any other conditions that may be causing depressive moods


The primary goals of depression treatment are to reduce your symptoms and improve your quality of life. Generally, the earlier you start treatments, the more effective they can be for relieving symptoms. 

There are three primary types of treatment for depression: medication, psychotherapy, and brain stimulation therapies. Medications and psychotherapy are typically the first lines of treatment, while brain stimulation therapies become an option only if you aren't responding well to other treatment options.


Your healthcare provider can prescribe you medication to improve symptoms. The most common medications used for depression are called antidepressants, which work to increase serotonin (the "feel-good" hormone) in your brain.

Depending on your symptoms and treatment plan, your provider may prescribe you one of the following medications: they may include:

  • Selective serotonin reuptake inhibitors (SSRIs)
  • Serotonin/norepinephrine reuptake inhibitors (SNRIs)
  • Atypical antidepressants (e.g., norepinephrine-dopamine reuptake inhibitors, or NDRIs)


Psychotherapy—or talk therapy—is a form of treatment that allows you to meet with a licensed mental health professional (e.g., psychologist, counselor, or social worker) to talk about your feelings, thoughts, and stressors.

Based on your needs, your therapist can use a combination of therapy techniques that help you meet your treatment goals and reduce symptoms. Common types of psychotherapy include:

  • Behavioral therapy
  • Cognitive therapy
  • Cognitive-behavioral therapy (CBT)
  • Interpersonal psychotherapy (IPT)
  • Mindfulness-based cognitive therapy (MBCT)
  • Psychodynamic therapy
  • Supportive therapy

Brain Stimulation Therapy

In situations where a person does not respond well to other treatment options, a provider may recommend brain stimulation therapies. Brain stimulation is a treatment that uses electrodes that send electric impulses to your brain.

The purpose of this treatment is to target certain areas of the brain and change the way the brain functions. While more research on brain stimulation therapy is needed, the most commonly used therapy currently is electroconvulsive therapy (ECT).


Depression can't always be prevented—especially because mental health can fluctuate throughout your lifetime. Certain factors like genetics, childhood trauma, and major stressful life events—which are things you have little to no control over—can all increase your risk of depressive disorder.

However, you can reduce how often you're experiencing depressive episodes by prioritizing self-care and treating your condition. Some ways to prevent depressive episodes include:

  • Taking your medications on time
  • Going to therapy and learning about healthy stress management techniques
  • Keeping your body moving through exercise or physical activities
  • Being outside in nature and getting sunlight
  • Getting enough sleep throughout the night
  • Making time for hobbies you enjoy
  • Spending time with your loved ones and getting social support
  • Limiting time on social media
  • Eating nutritious foods
  • Reducing your alcohol or tobacco use

Related Conditions

It is common for other health conditions to mimic symptoms of depression (similar conditions) or occur at the same time depression does (co-occurring conditions). That's why your healthcare provider will ask you about your medical and social history, so they are able to make an accurate diagnosis of depression and rule out the possibility of other conditions.

Conditions that may also produce depressive symptoms include anxiety, grief, hypothyroidism, chronic fatigue syndrome, and schizophrenia, among others.

Depression can often co-occur alongside other health conditions, meaning that you can have depressive disorder and another health condition at the same time. Conditions that can co-occur with depression include (but are not limited to) heart disease, cancer, diabetes, HIV, sleep disorders, and chronic pain.

Living with Depression

While there is no surefire cure for depression, there are several treatment options that are effective in treating depression. Depression, however, can come and go throughout the lifespan—especially because your moods and mental health can change. Unfortunately, depression is also a leading cause of nearly 40,000 deaths by suicide each year.

Getting treatment for depression early can significantly reduce symptoms. Along with standard treatments for depression, practicing stress management techniques and making time to take care of yourself can help improve your quality of life and provide mental health relief.

To further improve your condition, you may also consider:

  • Establishing a support system of people who are close to you and keeping them updated about your condition
  • Finding peer support groups for people with depression or those who are experiencing other stressors
  • Staying in touch with your provider and playing an active role in decisions about your treatment plan

These actions might make it less difficult to open up about how you're feeling and provide opportunities for you to get the help and healing you need. Keep in mind: even though depression affects you individually, you don't have to go through it all alone.

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  1. National Institute of Mental Health. Depression.

  2. Chand SP, Arif H. Depression. In: StatPearls. StatPearls Publishing; 2022. 

  3. American Psychiatric Association. What is depression?

  4. Loula R, Monteiro LHA. Monoamine neurotransmitters and mood swings: a dynamical systems approach. MBE. 2022;19(4):4075-4083. doi:10.3934/mbe.2022187

  5. UpToDate. Patient education: depression in adults (beyond the basics).

  6. American Psychological Association. Depression assessment instruments.

  7. American Psychological Association. Depression treatments for adults.

  8. MedlinePlus. Antidepressants.

  9. National Institute of Mental Health. Brain stimulation therapies.

  10. Krijnen-de Bruin E, Scholten W, Muntingh A, et al. Psychological interventions to prevent relapse in anxiety and depression: A systematic review and meta-analysis. Vousden G, ed. PLoS ONE. 2022;17(8):e0272200. doi:10.1371/journal.pone.0272200

  11. Choi KW, Stein MB, Nishimi KM, et al. An exposure-wide and Mendelian randomization approach to identifying modifiable factors for the prevention of depressionAJP. 2020;177(10):944-954. doi:10.1176/appi.ajp.2020.19111158

  12. MentalHealth.gov. For people with mental health problems. U.S. Department of Health & Human Services.

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