Depression is a mood disorder that causes a persistent feeling of Feelings of sadness, tearfulness, emptiness or hopelessness, Angry outbursts, Loss of interest, Sleep disturbances, Tiredness, Reduced appetite and weight loss or increased cravings for food and weight gain, Anxiety, Slowed thinking, Feelings of worthlessness or guilt, Trouble concentrating, suicidal thoughts or even suicide attempts or Unexplained physical problems, such as back pain or headaches.


Depression is a mood disorder that causes a persistent feeling of sadness and loss of interest. Also called major depressive disorder or clinical depression, it affects how you feel, think and behave and can lead to a variety of emotional and physical problems. You may have trouble doing normal day-to-day activities, and sometimes you may feel as if life isn’t worth living.


Although depression may occur only once during your life, people typically have multiple episodes. During these episodes, symptoms occur most of the day, nearly every day and may include:

  • Feelings of sadness, tearfulness, emptiness or hopelessness
  • Angry outbursts, irritability or frustration, even over small matters
  • Loss of interest or pleasure in most or all normal activities, such as sex, hobbies or sports
  • Sleep disturbances, including insomnia or sleeping too much
  • Tiredness and lack of energy, so even small tasks take extra effort
  • Reduced appetite and weight loss or increased cravings for food and weight gain
  • Anxiety, agitation or restlessness
  • Slowed thinking, speaking or body movements
  • Feelings of worthlessness or guilt, fixating on past failures or self-blame
  • Trouble thinking, concentrating, making decisions and remembering things
  • Frequent or recurrent thoughts of death, suicidal thoughts, suicide attempts or suicide
  • Unexplained physical problems, such as back pain or headaches





Clinical depression is a medical condition that goes beyond everyday sadness. It can cause profound, long-lasting symptoms and often interferes with one’s usual daily activities. A person’s vulnerability to developing this disorder is often related to many factors, including changes in brain function, genetics, and life stresses and circumstances.

Depression is the most common psychiatric disorder worldwide. In the United States, nearly 20 percent of the population experiences a bout of clinical depression in their lifetime. Even so, very few people who have the disorder discuss their symptoms with a healthcare provider. Instead, two-thirds of people with depression who see a healthcare provider for routine care come in complaining of physical symptoms, such as headache, back problems, or chronic pain.

People may be reluctant to discuss their depression symptoms for a number of reasons. Often they’re concerned about the stigma of mental illness; sometimes they worry that a primary care provider is not the appropriate health professional to ask; some see their condition as a personal weakness rather than a “real” illness; and some are worried about the implications of having a psychiatric illness entered into their permanent record. But effective treatments do exist, and not treating depression can lead to serious problems.

People with untreated depression have a lower quality of life, a higher risk of suicide, and worse physical prognoses if they have any medical conditions besides depression. In fact, people with depression are almost twice as likely to die as people without depression, mostly due to other medical conditions. What’s more, depression affects not only the person with the disorder but also those around him or her.

This topic reviews the clinical features and diagnosis of depression in adults. The treatment of depression in adults is discussed separately, as are the diagnosis and treatment of depression in children and adolescents.



Depression can take many forms and has varying levels of severity. Part of the variability in the disorder happens because it can co-occur with many other mental disorders (such as anxiety disorders or substance use disorders), which shape the symptoms of depression.

To explore whether you might meet the criteria for depression and how severe it is, see the questionnaire.

Diagnostic criteria — When people talk about so-called “clinical depression,” they’re usually referring to what healthcare providers call unipolar major depression (or major depressive disorder). To be diagnosed with unipolar major depression, a person must have five or more of the following symptoms present most of the day nearly every day for at least two consecutive weeks. For the diagnosis, at least one symptom must be either depressed mood or loss of interest or pleasure.

  • Depressed mood – People with depression tend to feel sad, hopeless, discouraged, “blue,” or “down in the dumps.” Sometimes they do not realize they are down and instead say they feel anxious, “blah,” or have no feelings. Plus, some people with depression feel annoyed, frustrated, irritable, or angry.


  • Loss of interest or pleasure in most or all activities– People with depression are no longer as interested in or feel as much pleasure doing the things they used to enjoy. The medical term for this is anhedonia. Hobbies and activities lose their appeal, and depressed people say “they don’t care anymore.” They may withdraw from or lose interest in friends, and they may even lose interest in sex.


  • Change in appetite or weight– Appetite and weight can either decrease or increase as part of depression. Some people have to force themselves to eat, while others eat more and sometimes crave specific foods (such as junk food and carbohydrates). Some people with severe depression can gain, or lose, so much weight that they have health problems related to their weight change.


  • Insomnia or hypersomnia (sleeping too little or too much)– Depression often disrupts sleep patterns, leading people to either sleep too much or be unable to fall asleep or stay asleep. Even when they do sleep, people with depression often say that they do not feel rested and have a hard time getting out of bed in the morning.


  • Psychomotor agitation or retardation (restlessness or sluggishness)– People with depression can feel agitated and restless, or have the opposite effect and feel slowed down. Agitation can manifest as hand-wringing, pacing, and fidgeting, while retardation can manifest as a slowing of body movements, thinking, or speech.


  • Fatigue or loss of energy– People with depression often feel exhausted and listless. They sometimes need to rest during the day or even feel as though their arms and legs are weighted down. Plus, they have trouble starting or completing tasks.


  • Feelings of worthlessness or excessive guilt – People with depression can feel inadequate, inferior, worthless, or like a failure. They often carry tremendous guilt about things that they may have done or not done. Often this leads them to misinterpret neutral events or minor setbacks as evidence of personal failings.


  • Poor concentration– Some people with depression have trouble thinking clearly, concentrating, or making decisions. They can also be easily distracted or complain of memory problems.


  • Recurrent thoughts of death or suicide– People who are depressed can experience recurrent thoughts of death or suicide, and may attempt suicide. Thoughts of death or suicide, termed “suicidal ideation,” can be passive, meaning the person thinks simply that life is not worth living, but suicidal ideation can also be active, meaning the person actively wants to die or kill themselves. People with active suicidal ideation are severely ill.


Some people have specific plans for suicide or have started making preparations. Preparations can take the form of selecting a time and place for suicide or buying a stockpile of lethal medications or a gun. Some have even made unsuccessful attempts at suicide, and some die by suicide.

Suicidality gets worse when people feel hopeless and see suicide as their only escape from intense and endless emotional pain.

Some people with depression hurt themselves, for example by superficially cutting or burning their skin. Other symptoms of depression can include anxiety, hopelessness, and ruminative thinking.


Subtypes of depression — Aside from unipolar major depression, whose diagnostic criteria are discussed above, there are other subtypes of depression, which are characterized by their most prominent symptoms. Examples include:

  • Depression with mixed features – This is the term for depression that is accompanied by some manic symptoms, but not enough to diagnose a person with bipolar disorder. A person with this type of depression might do things like talk much more than usual, have extra energy, sleep less, or have episodes of seeming unusually happy or excited.


  • Anxious depression – The most prominent symptoms of anxious depression include worrying, pacing, and other manifestations of anxiety.


  • Situation-specific forms of depression – For example, women sometimes develop depression just before or just after giving birth, called “peripartum onset,” or cyclically, just before menstruating, called “premenstrual dysphoric disorder”


  • Seasonal affective disorder (SAD) – This is a form of depression that comes and goes during certain times of the year. The most common form of SAD starts in late fall and goes away in the spring and summer.


Treatment for the subtypes of depression can vary depending on the person’s symptoms and situation.



When a person has two or more medical conditions, the conditions occurring together are called comorbidities. Depression can occur on its own, but it usually occurs along with other psychiatric or medical disorders. In fact, having another psychiatric or medical disorder increases the risk of developing depression.

Psychiatric — Among the psychiatric conditions that can co-occur with depression are anxiety disorders, posttraumatic stress disorder, obsessive-compulsive disorder, attention deficit hyperactivity disorder, substance (alcohol and drug) use disorders, and others. It is also possible to have depression along with a personality disorder, such as avoidant or borderline personality disorder.

Medical — Depression can co-occur with other medical problems, such as diabetes, heart disease, cancer, and many others. The relationship between depression and medical comorbidities is complicated. Depression can worsen in the face of medical problems and, at the same time, cause the medical conditions themselves to worsen. In part that’s because depression makes it hard for a person to manage his or her medical conditions.



If your healthcare provider suspects you could have clinical depression, he or she will ask about your symptoms and state of mind. The most important information will come from your description of your illness.

During the exam, the healthcare provider will:

  • Note and observe which signs of depression you have
  • Determine when your symptoms began and whether they have happened before (and, if so, how they progressed)
  • Figure out how your symptoms are affecting your everyday life and relationships
  • Ask about factors that could be making your symptoms better or worse (such as stressful life events or a loss)
  • Ask whether any of your family members have a history of depression, suicide, bipolar disorder, or other forms of mental illness
  • Address any other psychiatric or general medical conditions you may have (such as an anxiety or substance use disorder, or heart disease), and explore whether any of the medications you take could be contributing to your symptoms
  • Check whether you have ever had symptoms of what healthcare providers call mania, which is when you feel happy, charged, impulsive, frenetic and grandiose (these could be a sign of another psychiatric condition called bipolar disorder).


Suicide risk — As part of your evaluation, your healthcare provider will need to determine whether you are at risk of suicide. He or she will ask if you have thoughts of death or suicide and, if so, whether those thoughts include any specific plans or actions.

Depending on your level of risk, your healthcare provider may decide to simply follow your progress or – if the risk of suicide is high – refer you to a mental health expert or the local hospital’s emergency department.

Suicidal thoughts that are part of depression can improve with treatment, just like other symptoms of depression. This makes it all the more important to see a health care provider because death or injury from suicide attempts in depression can be prevented with proper treatment.

Physical examination — If your symptoms are new or have no apparent precipitant, it’s possible that your healthcare provider will also want to examine you. Some medical conditions can cause symptoms of depression. Accordingly, it’s possible you’ll need lab tests or other types of tests to check for hormonal imbalances or other possible medical conditions that can cause depressive symptoms.


Depression occurs more often in people with certain risk factors or characteristics. These include:

  • A personal or family history of depression
  • Neuroticism (tendency to worry about things in ways that are not healthy or reasonable)
  • Low self-esteem
  • An anxiety disorder that began early in life
  • Substance misuse (such as problem drinking or full on drug addiction)
  • Conduct disorder (a behavioral disorder seen in children or adolescents characterized by aggressive, destructive or deceitful behavior and disregard for rules)
  • Trauma during childhood or adulthood
  • Stressful life events in past year
  • Parental loss or other stressful circumstances during childhood
  • History of divorce or marital problems
  • Low social support
  • Low education



The brains of people with clinical depression show marked differences from those of people without depression in neurotransmitter function, in the number and size of certain types of brain cells, and in the size of certain brain structures. It is not clear, however, whether these differences induce depression or whether being depressed causes these changes to occur.



If you are diagnosed with depression, your healthcare provider will tell you what type of depression you have, and what treatments might work for you. Often treatment involves psychotherapy, antidepressant medication, or a combination of the two. Treatment of depression is discussed separately.