Depression is a psychiatric disorder and is classified as a mood disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which is the standard classification system used by mental health professionals.
The official term for clinical depression is major depressive disorder (MDD).
Why is depression a psychiatric disorder?
- Affects brain function
-
- Depression is associated with imbalances in brain chemicals (neurotransmitters) like serotonin, dopamine, and norepinephrine, which regulate mood, motivation, and emotions.
- Defined symptoms
-
- Depression meets clear diagnostic criteria, including persistent sadness, loss of interest, fatigue, sleep disturbances, and suicidal thoughts, lasting at least two weeks or longer.
- Impairment in daily life
-
- It considerably disrupts normal functioning in areas such as work, relationships, and personal well-being.
- Biological and psychological causes
- Effective medical treatment
-
- Since it has biological underpinnings, depression is often treated with antidepressant medications (SSRIs, SNRIs, etc.), psychotherapy (CBT, interpersonal therapy), or both.
- Heritability and genetic links
-
- Studies show that depression runs in families, with 40-50% heritability in cases of severe depression.
- Specific genes related to serotonin regulation (such as SLC6A4) have been linked to increased depression risk.
- Structural and functional brain changes
-
- Brain imaging studies reveal reduced activity in the prefrontal cortex, which is responsible for decision-making and emotional regulation.
- The amygdala is involved in processing emotions and frequently shows increased activity, leading to heightened negative emotions.
- The hippocampus (linked to memory and stress regulation) tends to be smaller in people with depression.
- Chronic stress and HPA axis dysfunction
-
- The hypothalamic-pituitary-adrenal (HPA) axis controls stress responses and is regularly overactive in many depressed individuals.
- This leads to higher cortisol levels, contributing to symptoms like anxiety, fatigue, and sleep issues.
- Comorbidity with other psychiatric disorders
-
- Depression frequently coexists with other psychiatric conditions, such as anxiety disorders, bipolar disorder, PTSD, and schizophrenia.
- This suggests a common neurological or genetic basis for these conditions.
- Global recognition by health authorities
-
- Organizations like the World Health Organization (WHO) and the American Psychiatric Association (APA) classify depression as a mental disorder based on scientific research and clinical evidence.
- The WHO ranks it as one of the leading causes of disability worldwide.
- Response to psychiatric treatment
-
- Unlike temporary sadness, clinical depression typically requires medical or therapeutic intervention.
- Antidepressants (SSRIs, SNRIs, MAOIs), psychotherapy (CBT, DBT, IPT), and even electroconvulsive therapy (ECT) are helpful for many patients.
- These treatments wouldn’t work if it were merely an emotional state.
- Evolutionary and developmental aspects
-
- Some theories suggest that depression evolved as a biological response to stress, loss, or trauma, helping individuals to withdraw and conserve energy.
- Childhood trauma and early life adversity are known risk factors that can impact brain development and emotional regulation.
Final note
Depression is classified as a psychiatric disorder because it involves biological, neurological, genetic, and psychological factors that disrupt normal brain function and emotional regulation.
It is not just temporary sadness but a clinically recognized condition with defined symptoms, clear diagnostic criteria, and a major impact on daily life.
