Depression: Symptoms, Causes, Diagnosis, Treatment & Prevention

Globally, an estimated 5.7% of adults live with depression, according to the World Health Organization — roughly 280 to 320 million people, with women affected nearly 1.5 times more often than men (6.9% vs 4.6%). In Bangladesh, a 2022 Demographic and Health Survey analysis found moderate-to-severe depression in about 4.9% of married women nationally, rising to 7.6% in Rangpur division, while a separate nationwide study found roughly a quarter of adolescents showed at least mild depressive symptoms. Yet the WHO estimates that more than 75% of people with mental disorders in low- and middle-income countries like Bangladesh receive no treatment at all — often because the condition is mistaken for personal weakness, stress, or simply "bad luck" rather than recognized as a treatable medical illness.

What Is Depression, and What Causes It?

Depression (clinically called Major Depressive Disorder) is a mood disorder that affects how a person feels, thinks, and functions day to day. It is not the same as ordinary sadness — it is a medical condition involving changes in brain chemistry, structure, and function, and it has real, identifiable risk factors:

• Biological factors: Imbalances in neurotransmitters such as serotonin, norepinephrine, and dopamine; family history of depression; hormonal changes (postpartum, thyroid disorders, menopause).
• Psychological factors: Chronic stress, unresolved trauma, childhood adversity, or persistent negative thought patterns.
• Social and environmental factors: Loss of a loved one, job loss or financial hardship, social isolation, relationship conflict, or living with a chronic illness.
• Medical contributors: Certain illnesses (hypothyroidism, chronic pain, stroke, anemia, vitamin B12 or D deficiency) and some medications can trigger or worsen depressive symptoms — which is why doctors usually order blood tests to rule these out before diagnosing depression itself.

In most cases, depression results from a combination of these factors rather than a single cause.

Depression vs. Normal Sadness and Grief

Everyone feels sad, grieves a loss, or has a bad week — this is not depression. The key differences doctors look for:

• Grief usually comes in waves, with moments of relief or even laughter in between, and a person's ability to function gradually returns over days to weeks.
• Depression is more constant and pervasive — it can appear without any clear triggering loss, tends to include persistent feelings of worthlessness or guilt that go beyond the loss itself, and does not lift on its own after a reasonable period.
• Sadness is an emotion; depression is a diagnosable clinical condition with specific criteria (below).

Symptoms of Depression (DSM-5 Criteria)

According to DSM-5 criteria used by clinicians worldwide, a diagnosis of major depressive disorder requires at least 5 of the following 9 symptoms, present nearly every day for at least 2 consecutive weeks, representing a clear change from previous functioning — and at least one of the first two must be present:

• Depressed, sad, or empty mood most of the day
• Markedly reduced interest or pleasure in almost all activities (anhedonia)
• Significant weight loss or gain, or appetite change
• Insomnia or sleeping far more than usual
• Observable restlessness or noticeably slowed movement/speech
• Fatigue or loss of energy nearly every day
• Feelings of worthlessness or excessive, inappropriate guilt
• Difficulty concentrating, thinking, or making decisions
• Recurrent thoughts of death or suicide, or a suicide attempt or plan

These symptoms must also cause clinically significant distress or impairment in work, social, or daily functioning — not simply be explained by another medical condition.

Warning Signs That Need Urgent Attention

Some symptoms should never be ignored and need immediate professional help, the same day if possible:

• Any thoughts of suicide or self-harm, or talking/writing about wanting to die
• Giving away possessions, saying goodbye, or a sudden, unexplained sense of "calm" after a period of severe depression
• Inability to carry out basic daily functions (eating, hygiene, work) for several days
• Psychotic symptoms — hearing voices, delusions, or severe confusion

If you or someone you know is having thoughts of suicide, seek emergency medical care immediately or contact a crisis helpline such as Kaan Pete Roi (09612-119911) — do not wait for a scheduled appointment.

How Is Depression Diagnosed?

There is no blood test or scan that diagnoses depression directly. Diagnosis is clinical, based on a detailed history and symptom assessment by a doctor or mental health professional, often supported by a validated screening tool such as the PHQ-9 (Patient Health Questionnaire):

• 9 questions, each scored 0 ("not at all") to 3 ("nearly every day"), total score 0–27
• 0–4: minimal/none   5–9: mild   10–14: moderate   15–19: moderately severe   20–27: severe
• A score of 10 or higher has about 88% sensitivity and 88% specificity for major depression in validation studies
• Any non-zero answer on the suicidal-thoughts item warrants immediate clinical follow-up regardless of total score

Doctors typically also order blood tests (thyroid function, complete blood count, vitamin B12/D, blood sugar) to rule out medical causes that mimic or worsen depression, since the PHQ-9 is a screening tool, not a diagnosis on its own.

Depression in Special Groups

• Postpartum depression: Different from the common "baby blues," which is mild and resolves within about two weeks after delivery. Postpartum depression is more severe, lasts longer, and can impair a mother's ability to care for herself or her baby — it needs professional evaluation, not just reassurance.
• Elderly adults: Depression is common in older age but is NOT a normal part of aging. It is frequently under-recognized because sadness is dismissed as "just old age," symptoms overlap with other illnesses, or older patients describe physical complaints (aches, fatigue, poor appetite) rather than mood changes.
• Adolescents: A Bangladesh nationwide study found roughly a quarter of adolescents had at least mild depressive symptoms, with girls more affected in most categories — school pressure, social media, and family conflict are common contributing stressors in this age group.
• People with chronic illness: Diabetes, heart disease, kidney disease, and chronic pain significantly raise depression risk, and untreated depression in turn worsens management of the physical illness — so clinicians treating chronic disease should also screen for mood symptoms.

Treatment Options

Depression is treatable, and most people improve significantly with appropriate care. Treatment is usually tailored to severity:

• Psychotherapy — particularly Cognitive Behavioral Therapy (CBT), which helps identify and change negative thought patterns. Research shows CBT and antidepressant medication are similarly effective for many adults with major depression, especially for mild-to-moderate cases.
• Antidepressant medication — SSRIs such as sertraline, fluoxetine, and escitalopram are commonly prescribed first-line options. They typically take about 4 weeks to show their full effect, and should never be stopped abruptly without a doctor's guidance, as this can cause withdrawal symptoms or relapse.
• Combination treatment — therapy plus medication is often recommended for moderate-to-severe depression.
• Lifestyle measures — regular physical activity, consistent sleep schedules, social connection, and reducing alcohol use support recovery alongside formal treatment, though they are not a substitute for professional care in moderate-to-severe cases.
• For treatment-resistant cases — options such as electroconvulsive therapy (ECT) or transcranial magnetic stimulation (TMS) may be considered by a psychiatrist when standard treatments haven't worked.

No single medicine or dose is right for everyone — never start, stop, or adjust an antidepressant without consulting a qualified doctor or psychiatrist.

When to See a Doctor

Seek professional evaluation if low mood, loss of interest, or related symptoms last more than two weeks and interfere with work, relationships, or daily functioning. Start with a general physician, who can rule out medical causes and refer to a psychiatrist or psychologist if needed. In Bangladesh, the National Institute of Mental Health (NIMH) in Dhaka and psychiatry departments at government medical college hospitals offer specialist care, and helplines such as Kaan Pete Roi provide confidential emotional support for anyone in distress.

Depression vs. Anxiety: Not the Same, Often Together

The two conditions are frequently confused because they often occur together. Anxiety centers on excessive worry, fear, or physical arousal (racing heart, restlessness) about future events, while depression centers on persistent low mood and loss of interest or pleasure, often with a sense of hopelessness about the past or present. Many people experience both simultaneously, and treatment approaches — therapy and/or SSRIs — frequently overlap.

Common Myths vs. Facts

• Myth: Depression just means being lazy or weak-willed. Fact: It is a medical condition involving measurable changes in brain chemistry and function, not a character flaw or lack of willpower.
• Myth: Talking about suicidal thoughts will put the idea in someone's head. Fact: Asking directly and calmly about suicidal thoughts does not increase risk — it is one of the most effective ways to identify someone who needs urgent help.
• Myth: Antidepressants change your personality or are addictive like sedatives. Fact: SSRIs are not habit-forming in the way addictive substances are, though they should still be tapered under medical supervision rather than stopped suddenly.
• Myth: If you have a good life, you can't be depressed. Fact: Depression can affect anyone regardless of external circumstances, income, or apparent success, because it involves biological and neurochemical factors, not just life events.

How Family and Friends Can Help

Support from people close to someone with depression meaningfully improves outcomes. Useful approaches include listening without judgment or trying to "fix" the person's feelings, encouraging (not forcing) professional help, helping with practical tasks during difficult periods, checking in consistently rather than only during visible crises, and taking any mention of self-harm or suicide seriously by helping the person reach a doctor or helpline immediately rather than assuming it will pass. Avoid dismissive responses such as "just stay busy" or "others have it worse," which can deepen a person's sense of isolation and guilt.

Prevention and Everyday Protection

• Maintain consistent sleep habits and regular physical activity
• Stay socially connected; isolation is a strong risk factor
• Manage chronic stress early rather than letting it accumulate
• Seek help promptly for grief, major life changes, or chronic illness rather than waiting for symptoms to worsen
• Reduce stigma within families — treat mood changes as a health issue deserving the same attention as a physical illness, not a character flaw

Sources: Guidelines and data from the World Health Organization (WHO), the American Psychiatric Association's DSM-5 criteria, the Bangladesh Demographic and Health Survey (BDHS) 2022, and the National Institute of Mental Health (NIMH), Bangladesh.