Major Depressive Disorder
Major Depressive Disorder is not simply sadness or a difficult week. It involves at least 5 of 9 symptoms during the same 2-week period, representing a clear change from previous functioning. At least one symptom must be depressed mood or markedly diminished interest or pleasure.
The symptoms substantially affect daily life and are not better explained by a substance, medication, medical condition, bipolar episode, or psychotic disorder. Depression is treatable, but the appropriate plan depends on severity, risk, history, and preferences.
What Is Major Depressive Disorder?
A major depressive episode affects feeling, thinking, body and functioning most hours of the day, almost every day. In children and adolescents the mood may seem more irritable than sad. A diagnosis of the disorder requires at least one such episode and no history of mania or hypomania. Severity is judged not only by number of symptoms, but also by intensity, impairment, psychosis, catatonia and suicidal risk.
Key Features and Signs
The nine symptoms assessed in the full episode are:
- Depressed or, in some young people, highly irritable mood most of the day.
- Significant loss of interest or pleasure in most activities.
- Significant weight or appetite change without deliberate dieting.
- Insomnia or hypersomnia almost every day.
- Notable psychomotor agitation or slowing.
- Fatigue or loss of energy.
- Feelings of worthlessness or excessive and inappropriate guilt.
- Impaired concentration, thinking or decision making.
- Recurrent thoughts of death, suicidal ideation, plan or attempt.
How It Is Diagnosed
Diagnosis is made by clinical interview and assessment of functioning, risk, previous periods of mood elevation, substances, medications, and physical health.
- There are at least 5 of the 9 symptoms during the same 2-week period, with a change from previous functioning.
- At least one of the symptoms is depressed mood or a significant loss of interest or pleasure.
- Symptoms cause significant distress or impairment and are not attributable to a substance, drug, or other medical condition.
- There has never been a manic or hypomanic episode unless it was fully attributable to a substance or the physiological effects of another medical condition, and the presentation is not better explained by Schizoaffective Disorder, schizophrenia, or another psychotic disorder.
How It Can Affect Daily Life
Some people appear to keep functioning despite substantial internal distress, so severity is not always visible.
Causes and Risk Factors
Major depression is multifactorial. Genetic and temperamental vulnerability, stress, loss, trauma, social isolation, poverty, discrimination, chronic physical illness, sleep, and other factors may interact. There is no one test or "chemical imbalance" that explains every case. Substances, medications, and medical conditions may cause or worsen symptoms and need evaluation.
Similar or Co-occurring Conditions
Mood history and context of loss or exposure are important:
- Bipolar I or II is carefully considered for prior mania or hypomania because this changes diagnosis and treatment.
- Bereavement and major depression can co-occur. A loss does not rule out depression when the criteria are met.
- Prolonged Grief Disorder focuses on persistent longing or preoccupation with the deceased and may co-occur with depression.
- Persistent Depressive Disorder has a chronic course and may include full-blown major episodes.
- Thyroid disease, anaemia, neurological conditions, substances, medications and sleep problems can have overlapping symptoms.
Treatment and Support
Treatment is matched to severity and risk and decided together with the individual.
- For less severe depression, options such as guided self-help, behavioural activation, and other evidence-based psychotherapies are discussed.
- For more severe depression, psychotherapy, antidepressants, or a combination may be offered, based on needs, preferences, and past response.
- Efficacy, side effects, and suicidal ideation are monitored especially in the first weeks and after changes.
- When discontinuation is appropriate, medication is tapered gradually in collaboration with the prescriber to reduce withdrawal symptoms.
- In psychotic, catatonic or very severe depression, specialist pharmacological or other somatic treatments and hospitalisation may be needed.
- Sleep, health-adjusted physical activity, practical help and social support complement but do not replace treatment.
When to Seek Help
Seek evaluation when low mood or loss of interest persists for about two weeks, affects functioning, or is accompanied by guilt, significant change in sleep or appetite, and thoughts of death. You do not need to wait two weeks if the symptoms are severe or there is a risk. Assessment is especially urgent for suicidal ideation, psychosis, catatonia or inability to take food and fluids.
Frequently Asked Questions
Are all 9 symptoms needed for diagnosis?
No. It takes at least five during the same two-week period, and one of them must be low mood or a significant loss of interest or pleasure.
Can depression be diagnosed after bereavement?
Yes. Normal mourning, Prolonged Grief Disorder and a major depressive episode can occur separately or together. The assessment examines the full diagnostic presentation.
Is a high score on a questionnaire enough?
No. Questionnaires are useful for screening and follow-up, but diagnosis requires clinical assessment, exclusions, and assessment for current or past mania, psychotic symptoms, and suicide or self-harm risk.