Clinical depression is a medical condition that goes beyond everyday sadness. It causes profound, long-lasting symptoms and often disrupts a person’s ability to perform routine tasks. 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, 17 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 are 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 enlist; 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. The problem is, effective treatments do exist, and not treating depression can cause 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 the condition. 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 (See "Patient information: Depression treatment options for adults (Beyond the Basics)" and "Patient information: Depression in adolescents (Beyond the Basics)" and "Patient information: Depression treatment options for adolescents (Beyond the Basics)".)
More detailed information about depression is available by subscription. (See "Unipolar depression in adults: Assessment and diagnosis" and "Diagnosis and management of late-life depression" and "Unipolar major depression in adults: Choosing initial treatment" and "Unipolar depression in adults: Treatment of resistant depression" and "Unipolar depression in adults and initial treatment: General principles and prognosis" and "Unipolar depression in adults: Management of highly resistant (refractory) depression".)
SYMPTOMS OF DEPRESSION
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 manifestation of depression.
To explore whether you might meet the criteria for depression and how severe it is, see the questionnaire (calculator 1) (table 1).
Diagnostic criteria — When people talk about 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, angry, or hostile.
●Loss of interest or pleasure in most or all activities – People with depression lose interest in or no longer feel 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).
●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 this. 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 they can also be active, meaning the person actively wants to die or commit suicide. 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.
Suicidality gets worse when people feel hopeless and see suicide is their only escape from intense and endless emotional pain.
Some people with depression hurt themselves, for example by superficially cutting or burning their skin. They say they do it to relieve pain and that they expected the injury to be minor, but this behavior (nonsuicidal self-injury) indicates the person is severely depressed.
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 prevalent symptoms (see 'Diagnostic criteria' above). For example, there is a subtype of depression called anxious depression, whose most prevalent symptoms include worrying, pacing, and other manifestations of anxiety. There are also forms of depression that are situation-specific. 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” (see "Patient information: Premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD) (Beyond the Basics)"). There is also a form of depression that happens during certain times of the year, seasonal affective disorder.
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 a 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 general 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 symptoms 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). (See "Patient information: Bipolar disorder (manic depression) (Beyond the Basics)".)
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.
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.
RISK FACTORS FOR DEPRESSION
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)
●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
●Low parental warmth
●History of divorce or marital problems
●Low social support
BIOLOGICAL BASIS OF DEPRESSION
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 a combination of psychotherapy and antidepressant medications. Treatment of depression is discussed separately. (See "Patient information: Depression treatment options for adults (Beyond the Basics)".)
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Depression (The Basics)
Patient information: Premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD) (The Basics)
Patient information: Medicines for depression (The Basics)
Patient information: Electroconvulsive therapy (ECT) (The Basics)
Patient information: Post-traumatic stress disorder (The Basics)
Patient information: Postpartum depression (The Basics)
Patient information: Seasonal affective disorder (The Basics)
Patient information: When you have depression and another health problem (The Basics)
Patient information: Serotonin syndrome (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Depression treatment options for adults (Beyond the Basics)
Patient information: Depression in adolescents (Beyond the Basics)
Patient information: Depression treatment options for adolescents (Beyond the Basics)
Patient information: Bipolar disorder (manic depression) (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
The following organizations also provide reliable health information.
●National Library of Medicine
●National Institute of Mental Health
●American Psychiatric Association
●American Psychological Association
●American Academy of Child and Adolescent Psychiatry
●Depression and Bipolar Support Alliance (DBSA)
●Mental Health America
●National Alliance for the Mentally Ill