Depression

Depression, also known as depressive disorder, is a mental health condition involving a prolonged period of low mood or a loss of interest or pleasure in activities. Major depressive disorder, the most recognised form of depression, is marked by distinct episodes lasting at least two weeks and often longer. These episodes involve significant changes in mood, sleep, appetite, interest, physical activity, cognition, and functioning, with periods of remission between them.

References

1. WHO. Depressive disorder (depression). Accessed January 16, 2026. https://www.who.int/news-room/fact-sheets/detail/depression
2. Diagnostic and Statistical Manual of Mental Disorders | Psychiatry Online. DSM Library. Accessed January 16, 2026. https://www.psychiatryonline.org/doi/book/10.1176/appi.books.9780890425596

Depression is a complex condition with no single cause. It often results from a combination of genetic, biological, environmental, and psychological factors. For some individuals, a family history of depression may increase their risk. Imbalances in brain chemicals, such as neurotransmitters like serotonin and dopamine, can underlie symptoms of depression. Stressful life events, such as trauma or significant life changes, can trigger depression, especially in people who are already predisposed or vulnerable.

References

1. Diagnostic and Statistical Manual of Mental Disorders | Psychiatry Online. DSM Library. Accessed January 16, 2026. https://www.psychiatryonline.org/doi/book/10.1176/appi.books.9780890425596

Depression is common, affecting around 5% of adults worldwide, or about 280 million people. By the age of 75, the chances of developing depression at some point in life are estimated to be 20% for men and 34% for women.

References

1. WHO. Depressive disorder (depression). Accessed January 16, 2026. https://www.who.int/news-room/fact-sheets/detail/depression
2. McGrath JJ, Al-Hamzawi A, Alonso J, et al. Age of onset and cumulative risk of mental disorders: a cross-national analysis of population surveys from 29 countries. Lancet Psychiatry. 2023;10(9):668-681. doi:10.1016/S2215-0366(23)00193-1

Common symptoms of depression include persistent feelings of sadness, emptiness, or irritability, often accompanied by physical and cognitive changes that significantly impair an individual’s ability to function. These symptoms are more intense and longer-lasting than everyday mood changes and can seriously disrupt daily life. People with severe depression may experience suicidal thoughts and may make attempts to harm themselves. The functional impact of major depressive disorder often stems directly from its individual symptoms. For example, feeling constantly exhausted can make it difficult to get out of bed or go to work, while feelings of hopelessness might cause a person to withdraw from family and friends. In some cases, the impairment may be mild enough that those around the affected person may not notice the depressive symptoms. However, the degree of impairment can vary significantly. In severe cases, individuals may be completely unable to perform basic self-care tasks or may become mute or catatonic. People with major depressive disorder who seek treatment in general medical settings often experience higher levels of physical pain, illness, and significant reductions in their ability to function physically, socially, and in daily responsibilities.

References

1. Diagnostic and Statistical Manual of Mental Disorders | Psychiatry Online. DSM Library. Accessed January 16, 2026. https://www.psychiatryonline.org/doi/book/10.1176/appi.books.9780890425596
2. Depression – National Institute of Mental Health (NIMH). Accessed November 25, 2024. https://www.nimh.nih.gov/health/publications/depression

Depression is diagnosed by a healthcare professional, such as a general practitioner or a psychiatrist, based on a thorough clinical evaluation. This evaluation often includes a discussion of symptoms, medical history, and sometimes a physical examination to rule out other conditions. The diagnosis is typically guided by the criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) or the International Classification of Diseases (ICD-11), which outlines specific symptoms and the necessary duration for diagnosing major depressive disorder.

References

1. Diagnostic and Statistical Manual of Mental Disorders | Psychiatry Online. DSM Library. Accessed January 16, 2026. https://www.psychiatryonline.org/doi/book/10.1176/appi.books.9780890425596
2. Depression – National Institute of Mental Health (NIMH). Accessed November 25, 2024. https://www.nimh.nih.gov/health/publications/depression

Effective care for depression often includes psychotherapy, medication, or a combination of both. If these approaches do not significantly alleviate symptoms, neurostimulation therapies may be considered as alternative treatment options.

Medications:
Antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) and serotonin–norepinephrine reuptake inhibitors (SNRIs), help treat depression by influencing brain chemicals involved in mood regulation, including serotonin and norepinephrine. These medications may take several weeks to show effects and can cause side effects such as nausea, headaches, and sleep disturbances, which often improve over time. In some cases, antidepressants may increase the risk of suicidal thoughts in the short term, particularly in young people, making close monitoring important during the early stages of treatment.

Psychotherapy:
Psychological treatments, including cognitive-behavioural therapy (CBT) and other therapeutic approaches, can help individuals identify and change unhelpful thought patterns and behaviours that contribute to depressive symptoms.

Other treatments:
In cases of severe or treatment-resistant depression, medication combinations with or without psychotherapy and brain stimulation therapies are options that might be helpful. Brain stimulation therapies include electroconvulsive therapy (ECT), a highly effective option typically used when conventional treatments have proven ineffective, and transcranial magnetic stimulation (TMS), a less invasive approach. Vagus Nerve stimulation is also useful in some patients with chronic treatment resistant depression.

Depression is highly treatable, and many people make a full recovery. However, for some individuals, depression may be recurrent or chronic and require long-term management. The overall goal of treatment is to reduce symptoms and support people in leading fulfilling lives, even if occasional episodes occur.

References

1. WHO. Depressive disorder (depression). Accessed January 16, 2026. https://www.who.int/news-room/fact-sheets/detail/depression
2. Diagnostic and Statistical Manual of Mental Disorders | Psychiatry Online. DSM Library. Accessed January 16, 2026. https://www.psychiatryonline.org/doi/book/10.1176/appi.books.9780890425596
3. Depression – National Institute of Mental Health (NIMH). Accessed November 25, 2024. https://www.nimh.nih.gov/health/publications/depression
4. IQWiG. Depression: Learn More – How effective are antidepressants? In: InformedHealth.Org [Internet]. Institute for Quality and Efficiency in Health Care (IQWiG); 2024. Accessed January 16, 2026. https://www.ncbi.nlm.nih.gov/books/NBK361016/

Positive lifestyle changes can be crucial for managing depression. Staying connected with friends and family, keeping up with enjoyable activities, exercising regularly, and maintaining healthy eating and sleeping habits can all promote wellbeing. Alcohol and drugs can worsen symptoms and should be avoided. Speaking with a trusted person and seeking support from a healthcare professional are essential.

References

1. WHO. Depressive disorder (depression). Accessed January 16, 2026. https://www.who.int/news-room/fact-sheets/detail/depression

• Antidepressants: Medications used to treat depression by balancing chemicals in the brain that affect mood and emotions.
• CBT (Cognitive Behavioural Therapy): Therapy that targets unhelpful thoughts and behaviours to reduce distress and improve functioning.
• Dopamine: A neurotransmitter in the brain that plays a key role in how we feel pleasure and motivation.
• Diagnostic and Statistical Manual of Mental Disorders (DSM-5): A manual used by healthcare professionals to diagnose mental health conditions, including depression.
• ECT (Electroconvulsive Therapy): A treatment for severe depression that involves sending small electric currents through the brain to trigger a brief seizure, often helping to improve symptoms.
• ICD-11 (International Classification of Diseases, Eleventh Revision): A global standard for diagnosing health conditions and diseases, maintained by the World Health Organization.
• Neurotransmitters: Chemicals in the brain that transmit signals between nerve cells, affecting mood, emotions, and behaviour.
• Norepinephrine: A neurotransmitter that helps regulate mood, alertness, and stress response.
• Psychotherapy: Talk therapy that helps people understand and manage their mental health issues by talking with a therapist.
• Serotonin: A neurotransmitter that affects mood, sleep, and appetite. Low levels of serotonin are linked to depression.
• SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors): A type of antidepressant that increases levels of both serotonin and norepinephrine in the brain.
• SSRIs (Selective Serotonin Reuptake Inhibitors): A type of antidepressant that increases serotonin levels in the brain, commonly used to treat depression.
• TMS (Transcranial Magnetic Stimulation): A non-invasive treatment for depression that uses magnetic fields to stimulate nerve cells in the brain.

References

1. WHO. Depressive disorder (depression). Accessed January 16, 2026. https://www.who.int/news-room/fact-sheets/detail/depression
2. Diagnostic and Statistical Manual of Mental Disorders | Psychiatry Online. DSM Library. Accessed January 16, 2026. https://www.psychiatryonline.org/doi/book/10.1176/appi.books.9780890425596
3. Depression – National Institute of Mental Health (NIMH). Accessed November 25, 2024. https://www.nimh.nih.gov/health/publications/depression
4. APA Dictionary of Psychology. Accessed January 16, 2026. https://dictionary.apa.org/