Depression: mood, thinking, body and daily life

Depression involves more than sadness

In everyday language, depression may mean feeling low. A depressive disorder requires assessment of a continuing pattern of changes. Central features include low mood or reduced interest and enjoyment in previously valued activities. Fatigue, altered sleep or appetite, concentration difficulties, excessive guilt and hopelessness may also occur. People show different combinations; irritability, emotional numbness or physical discomfort can be prominent. Constant crying is not a requirement for taking someone’s difficulties seriously. NIMH: Depression

In our teaching example, Zhou continues going to work but no longer anticipates weekend football, struggles to eat and repeatedly rereads simple emails. Asking only whether Zhou smiled today could miss changes in interest, energy and thinking. Conversely, one tired day or one disappointment does not establish a depressive disorder. Compare these observations with the person’s previous life: which changes are new, whether they occur together and how they alter ordinary activities. The pattern is more informative than a single outward expression.

Consider duration and functioning together

A depressive episode generally involves relevant symptoms for at least two weeks, nearly every day and for much of the day. Two weeks is neither the only consideration nor a barrier to seeking help earlier. Severity also depends on the combination and intensity of symptoms and effects on functioning. Grief after a loss deserves understanding and support. An adverse event does not prove that a reaction is only ordinary sadness, just as bereavement should not automatically be labelled a disorder. WHO: Depressive disorder

Suppose Zhou’s sleep difficulties began after a death in the family. Further questions concern whether comfort remains possible at times, whether basic self-care has become difficult, whether worthlessness is persistent and whether there are safety concerns. “There is an obvious reason, so this cannot be illness” closes the discussion too soon. The learner’s task is to identify useful questions rather than diagnose from a few sentences. Severe deterioration, inability to maintain basic food or fluid intake, or immediate danger also calls for help without waiting for a two-week threshold. NICE NG222: Depression in adults, via NCBI Bookshelf

What contributes to depression and keeps it going?

Depression involves interacting biological, psychological and social factors. Genetic susceptibility, adversity, physical illness and psychological processes may contribute, but no single cause explains every person. Unemployment or chronic pain can increase risk, while withdrawal and work difficulties associated with depression can create additional stress. This reciprocal relationship means that care can address symptoms and living conditions. It does not place the entire responsibility on an individual’s attitude. WHO: Depressive disorder

One possible maintaining process is that low energy reduces activity, removing opportunities for connection or accomplishment and leaving fewer positive experiences. Behavioural activation examines links between activity and mood and supports a gradual return to meaningful actions. This is not a promise that keeping busy cures depression or proof that reduced activity originally caused it. If Zhou cannot yet return to a full football match, a care plan might begin with one manageable daily action and adjust from feedback. Past performance should not become a demand that exceeds present capacity. NHS: Treatment for depression in adults

Why assessment asks about health, medicines and past mood

Assessment includes previous episodes, course, functioning, support and life stress rather than merely counting symptoms. Physical conditions and medication effects can resemble depression. Investigations help assess relevant alternatives; a single blood result does not directly establish depression. Questionnaires can identify concerns and follow changes, but identical totals can arise from different symptom combinations. Decisions therefore require the person’s history and circumstances as well as a score. NICE NG222: Depression in adults, via NCBI Bookshelf NIMH: Depression

Assessment also asks about past periods of unusually elevated or markedly irritable mood, increased energy, much less need for sleep and increased risky behaviour. These may suggest bipolar disorder and change assessment and treatment considerations. Ordinary happiness or an occasional late night is not mania. If Zhou describes current low mood but omits a previous sustained period of unusual excitement, the clinician receives an incomplete picture. Reporting earlier changes accurately is more useful than selecting a familiar diagnosis in advance. NIMH: Bipolar disorder

Treatment choice and review form one process

Effective treatments exist, and selection considers severity, previous response, preferences and available services. Psychotherapy is more than reassurance. Cognitive behavioural therapy examines unhelpful patterns of thought and action; interpersonal therapy addresses relationships and life events; behavioural activation focuses on activity and mood. Some people receive psychotherapy, others medication or combined treatment. Treatment for children and adolescents requires age-appropriate assessment and should not simply copy an adult plan. NHS: Treatment for depression in adults

Antidepressant benefits usually require time to evaluate, with continuing review of symptoms, functioning and adverse effects. Marked agitation or thoughts of self-harm, especially after starting or changing a dose, warrant prompt professional contact. Improvement is not a reason to stop abruptly. A stopping plan should be agreed with the prescriber because withdrawal effects and recurrence require distinction. An unsuccessful initial approach does not mean no help remains. Review whether treatment was adequately implemented, whether other problems coexist and which adjustments might be appropriate. NIMH: Mental health medications NICE NG222: Depression in adults, via NCBI Bookshelf

Support includes everyday help and urgent responses

Friends and relatives can listen, acknowledge that the difficulty is real and assist with appointments, meals or essential tasks. Inviting manageable participation is more constructive than interpreting unfinished work as laziness. Recovery may be uneven: sleep can improve while interest and working capacity still need time. Observe gains and remaining difficulties so that both can be discussed at review. Support should not become a promise that someone will recover quickly or a demand that their progress follow a uniform schedule. NHS: Depression in adults overview NIMH: Depression

When someone mentions not wanting to live or thoughts of self-harm, listen seriously, ask directly about suicidal thoughts and help connect them with professional support. Asking directly does not implant the idea. Immediate danger requires local emergency help; when safe for the supporter, stay with the person and help reduce access to dangerous items. Do not promise secrecy about danger. If Zhou says that everyone would be better off without them, the priority shifts from productivity to understanding safety, maintaining contact and obtaining timely assistance. NIMH: Helping someone having thoughts of suicide

Bilingual terms

兴趣或愉悦减退 · Loss of interest or pleasure

Reduced interest or enjoyment in previously valued activities.

抑郁发作 · Depressive episode

A period assessed through persistent depressive symptoms and effects on functioning.

行为激活 · Behavioural activation

Treatment examining activity–mood links and rebuilding meaningful actions.

双相障碍 · Bipolar disorder

A group of disorders involving mood changes such as mania, hypomania, and depression. Diagnostic patterns differ; bipolar I disorder does not require a previous depressive episode.

停药反应 · Withdrawal effects

Symptoms after dose reduction or stopping that require distinction from recurrence.

功能恢复 · Functional recovery

Regaining capacity for self-care and important life activities.

Sources and further reading

• WHO: Depressive disorder
• NIMH: Depression
• NICE NG222: Depression in adults, via NCBI Bookshelf
• NHS: Treatment for depression in adults
• NIMH: Mental health medications
• NIMH: Bipolar disorder
• NIMH: Helping someone having thoughts of suicide
• NHS: Depression in adults overview

Original course source-check record: 9 September 2026. Full Chinese and English sentence-by-sentence language review: 14 September 2026. AI editing and language review are not human clinical review. Linked institutions have not participated in or endorsed this course.