Overview
Depression is a serious mood disorder causing persistent feelings of sadness, hopelessness, and loss of interest in activities once enjoyed. It is not simply 'feeling sad' — it is a genuine medical condition affecting how a person thinks, feels, and functions. Depression can affect anyone at any age and is one of the leading causes of disability worldwide. With appropriate treatment, the vast majority of people with depression improve significantly.
Causes and risk factors
The following factors are associated with the development of Depression:
- Brain chemistry and neurotransmitter imbalances
- Genetic predisposition
- Stressful life events: bereavement, job loss, relationship breakdown
- Chronic illness or pain
- Certain medications
- Substance misuse
- Social isolation
- Childhood trauma or adverse experiences
- Hormonal changes
- Other mental health conditions
Signs and symptoms
Common signs and symptoms of Depression include:
- Persistent low mood lasting over two weeks
- Loss of interest or pleasure in activities (anhedonia)
- Feelings of worthlessness, hopelessness, or guilt
- Fatigue and loss of energy
- Difficulty concentrating or making decisions
- Changes in appetite
- Sleep disturbances
- Psychomotor slowing
- Recurrent thoughts of death or suicide
- Physical symptoms: headaches, digestive problems
Diagnosis
Depression is typically diagnosed through a combination of medical history, physical examination, and appropriate investigations such as blood tests, imaging, or specialist review, depending on the specific condition and presentation. Your doctor will consider all relevant symptoms and risk factors before making a diagnosis.
Treatment options
Treatment approaches for Depression may include:
- Cognitive behavioural therapy (CBT) — first-line treatment
- SSRIs (fluoxetine, sertraline) — most commonly prescribed antidepressants
- SNRIs (venlafaxine, duloxetine)
- Interpersonal therapy (IPT)
- Mindfulness-based cognitive therapy (MBCT)
- Regular physical exercise
- Behavioural activation
- Social support
- Electroconvulsive therapy (ECT) for severe cases
Prevention
Strong social connections, regular sleep and exercise, limiting alcohol, stress management, early professional help when needed.
Complications
If left untreated or poorly managed, Depression can lead to complications including:
Social isolation, relationship problems, job loss, substance misuse, physical decline, self-harm, and suicide risk.
Sources and references: This article is written in accordance with NHS UK, WHO, and Mayo Clinic clinical guidelines. It is reviewed for accuracy by the SymptomSense content team. ICD-10 code: F32. Last reviewed June 2026.