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What is Depression?
Depression, clinically referred to as Major Depressive Disorder (MDD), is a common but serious mental health condition characterized by persistent feelings of sadness, hopelessness, and a lack of interest in daily activities. According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), depression significantly impairs social, occupational, or other critical areas of functioning and differs from typical mood fluctuations (American Psychiatric Association, 2013). The International Classification of Diseases, 11th Revision (ICD-11) similarly defines depression as a mood disorder marked by low mood, energy, and self-esteem, lasting at least two weeks (World Health Organization, 2022).
What Are the Symptoms of Depression?
Per DSM-5 criteria, a depression diagnosis requires at least five of the following symptoms, present nearly daily for two weeks, with at least one being either (1) depressed mood or (2) loss of interest or pleasure (anhedonia):
- Persistent sadness, emptiness, or irritability
- Markedly diminished interest in activities once enjoyed
- Significant weight loss/gain or appetite changes
- Insomnia or hypersomnia
- Psychomotor agitation or retardation
- Fatigue or loss of energy
- Feelings of worthlessness or excessive guilt
- Impaired concentration or indecisiveness
- Recurrent thoughts of death or suicide
Symptoms must cause clinically significant distress and cannot be attributed to substance use or medical conditions (e.g., hypothyroidism) (DSM-5; ICD-11).
Types of Depression
The DSM-5 and ICD-11 recognize several depressive disorders:
- Major Depressive Disorder (MDD): Episodes lasting ≥2 weeks with severe symptoms.
- Persistent Depressive Disorder (Dysthymia): Chronic low mood lasting ≥2 years (DSM-5).
- Seasonal Affective Disorder (SAD): Depression recurring seasonally, often in winter.
- Peripartum (Postpartum) Depression: Occurs during pregnancy or within four weeks postpartum.
- Premenstrual Dysphoric Disorder (PMDD): Severe mood swings before menstruation.
- Atypical Depression: Mood reactivity with increased appetite/sleep and leaden paralysis.
- Psychotic Depression: MDD with delusions or hallucinations (Kaplan & Sadock’s Synopsis of Psychiatry, 2015).
Causes of Depression
Depression arises from a complex interplay of factors:
- Biological: Neurotransmitter imbalances (serotonin, norepinephrine), genetic predisposition (family history increases risk 2-3x), and structural brain changes (e.g., reduced hippocampal volume) (Oxford Textbook of Psychiatry).
- Psychological: Negative cognitive patterns (Beck’s Cognitive Triad), trauma, or chronic stress.
- Social: Adverse childhood experiences, socioeconomic hardship, or isolation (Maudsley Guidelines, 2021).
How to Diagnose Depression
Diagnosis follows structured criteria:
- Clinical Interview: Assess symptom duration, severity, and functional impairment (DSM-5).
- Rule-Out Tests: Exclude medical causes (e.g., thyroid dysfunction) via blood tests.
- Standardized Tools: Patient Health Questionnaire-9 (PHQ-9) or Hamilton Depression Rating Scale (HAM-D).
- Differential Diagnosis: Distinguish from bipolar disorder, anxiety, or adjustment disorders (ICD-11).
Treatment for Depression
Evidence-based treatments include:
- Pharmacotherapy:
- SSRIs/SNRIs: First-line options (e.g., sertraline, venlafaxine) (Maudsley Prescribing Guidelines).
- Atypical Antidepressants: Bupropion or mirtazapine for refractory cases.
- TCAs/MAOIs: Reserved for treatment-resistant depression.
- Psychotherapy:
- Cognitive Behavioral Therapy (CBT): Targets negative thought patterns.
- Interpersonal Therapy (IPT): Addresses relationship conflicts.
- Mindfulness-Based Cognitive Therapy (MBCT): Prevents relapse (NICE Guidelines).
- Neuromodulation: Electroconvulsive Therapy (ECT) or Transcranial Magnetic Stimulation (TMS) for severe cases.
- Lifestyle Adjustments: Regular exercise, balanced nutrition, and sleep hygiene enhance outcomes (Kaplan & Sadock, 2015).
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