Depression can be considered both a symptom and a disease, depending on the context.
Nevertheless, depression is more frequently a symptom rather than a disorder.
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Depression as a disease (major depressive disorder – MDD)
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- Depression is diagnosed as major depressive disorder (MDD) or another depressive disorder when it is persistent and meets clinical criteria. (DSM-5, American Psychiatric Association).
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- MDD is a mental illness with distinct biological, psychological, and social causes, including genetics, brain chemistry imbalances, trauma, and chronic stress.
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- It requires medical intervention, such as therapy, medication, or lifestyle changes.
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Depression as a symptom
Depression can also appear as a symptom of another medical condition rather than a standalone disease.
Examples consist of:
Parkinson’s disease, Alzheimer’s disease, and stroke.
Hypothyroidism, Cushing’s syndrome.
Cancer, diabetes, and heart disease.
Low vitamin D, B12, or iron.
Alcohol or drug withdrawal.
Treating the underlying cause can help alleviate the depressive symptoms in these cases.
Why is depression more commonly a symptom?
- Reaction to life events
Many people experience depressive symptoms due to stress, grief, trauma, or significant life changes, such as job loss, divorce, or the death of a loved one.
This type of depression is often situational and temporary, resolving once the stressor is managed.
- Medical conditions and hormonal changes
Depression is frequently a symptom of other illnesses, such as:
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- Thyroid disorders (hypothyroidism).
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- Chronic pain conditions (fibromyalgia, arthritis).
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- Neurological diseases (Parkinson’s, Alzheimer’s).
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- Autoimmune diseases (lupus, multiple sclerosis).
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- Hormonal shifts (postpartum depression, menopause, PMS).
Curing the underlying condition often improves the depressive symptoms.
- Substance use and medications
Alcohol and drug withdrawal can cause fleeting depressive symptoms.
Some medications (corticosteroids, beta-blockers, hormonal birth control) list depression as a possible side effect.
When is depression a disease?

- If depressive symptoms persist for weeks or months without an obvious cause, it may be major depressive disorder (MDD) or another clinical depressive disorder.
- MDD is a chronic condition that requires treatment (therapy, medication, or both).
- Unlike situational or secondary depression, MDD doesn’t always have a clear external trigger and is often linked to brain chemistry, genetics, and long-term stress.
Conclusion
- If depression is persistent and meets clinical diagnostic criteria, it is a disease (MDD or another depressive disorder).
- If depression is a temporary response to another condition (like hypothyroidism, grief, or chronic pain), it is a symptom.
- Depression as a symptom is more common and often linked to external factors or medical conditions.
- Depression as a disease (MDD) is less widespread but more serious and persistent.
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