depression - causes, symptoms, diagnosis and treatment

Medically Reviewed by Dr Sravya, MBBS, MS 


Depression is a serious mood disorder that generates impressions of sadness, lack of interest and tiredness. It is often termed as clinical depression or major depressive disorder. It influences a person’s thinking, feelings, memory, eating and sleeping patterns leading to numerous physical and emotional problems. As stated by the World Health Organisation, this is the prime cause of disability worldwide.


It is estimates that globally more than 300 million people of all ages suffer from this disorder. Women experience higher rates due to hormonal changes that occur throughout the woman’s life.

Episodes of depression should be supported and treated at the right time, if untreated, lasts about 6 months but sometimes lasts for 2 years or more. Often, episodes may recur several times during their lifetime.

Table of Contents

Causes of depression

Factors that brings about this condition include

1. Genetic factors and family history

If any close family members are affected with this issue, then the chances are more likely to developing this mood disorder. Specific genes responsible for developing this have to be identified. It is estimated that 40% of cases are due to genetics. So genes are one factor, but they are not the only cause.

2. Neurotransmitter imbalances

Neurotransmitters are chemical messengers by which nerve cells of the brain communicate with each other. Especially neurotransmitters like dopamine, serotonin and norepinephrine take part in a key role in building up mood. When these neurotransmitter levels drop, it contributes to developing this situation.

3. Medical conditions

Specific conditions like chronic illness, sleep disorder or thyroid condition, chronic pain, multiple sclerosis, liver disorder and cancer causes this state of illness.

4. Hormonal changes

Women are more likely to suffer from this condition majorly, because of the hormonal changes occurring gradually during their lifetime like menstruation, pregnancy, childbirth and menopause. More often, postpartum depression is noticed in many cases due to hormonal swift after delivery.

5. Lifestyle changes

Many lifestyle factors bring about this situation. By controlling lifestyle factors, this can be reversed.

6. Disruption of Biological rhythm

Interruption of biorhythm clock in the body is also closely associated in causing Depression. Light falling on the eyes shows an impact on this rhythm. People living in cold climatic conditions experience this condition as they spend less time in the sunlight. This declines serotonin and melatonin levels resulting in sleep disturbances and mood alterations. However, this can be overcome by walking or sitting in the sunlight.

7. Poor diet

A 2017 study showed, people with moderate to severe symptoms benefited when they ate a healthy diet for 12 weeks which included mainly a diet containing selenium, vitamin D,B, omega-3-fatty acids, zinc, protein and probiotics.

8. Stress

Many researchers proposed that cortisol released during stressful conditions is capable of altering serotonin and gives rise to this.

9. Grief and loss

Loss of a loved one experiences symptoms like trouble sleeping, poor appetite and loss of pleasure or interest. When these symptoms of grief get worse without subsiding, it turns to this type of mental disorder.

10. Drugs and alcohol

Drugs and alcohol contribute to this mood disorder. Sometimes prescribed drugs are also linked to this. Some of them are anticonvulsants, benzodiazepines, corticosteroids, beta blockers, statins, stimulants, beta blockers.

11. Family and social environment

In a few cases, people with unhappy families or negative, stressful lives with poverty, homelessness, harassment or violence can lead to this disorder. Facing these situations without support can make it easier to depress.

Major types of depression

1.Clinical depression/major depressive disorder

Characterized by key features:

2. Persistent depressive disorder

Symptomsinclude :

3. Disruptive mood dysregulation disorder

It causes:

4. Premenstrual dysphoric disorder

These symptoms include :

5. Bipolar disorder

It shows a range of physical and emotional symptoms :

6. Prenatal and postpartum depression

Significant hormonal shift during pregnancy brings about this. Such symptoms include :

7. Atypical depression

It shows :

Signs and symptoms of depression

The signs and symptoms are different and vary from person to person. They include :

1. Behavioural symptoms

2. Physical symptoms

3. Cognitive symptoms

4. Psychological symptoms

Depression diagnosis

1. Physical exam

The doctor performs a diagnosis by physical examination and asks questions about health.

2. Lab tests

Blood tests help in screening anemia, thyroid, other hormones, calcium and vitamin D levels. By this, they rule out problems causing these symptoms.

3. Psychiatric evaluation

Mental health professional asks about symptoms, thoughts, feelings and behavioural patterns. The doctor asks the patient to fill out the questionnaire by the patient in this screening procedure for better insight of the patient’s mood. By this the doctor diagnoses with more certainty.

4. DSM-5

Mental health practitioners use the criteria for this diagnosis listed in the Diagnostic and Statistical Manual of Mental Disorders {DSM-5} published by the American Psychiatric Association. The patient should experience five or more symptoms for a continuous period of 2 weeks. In that one should be either depressed in mood or lack of interest or pleasure.

Treatment for depression

Medications and psychotherapy are more effective in treating this condition.

1. Medications

Include antidepressants, mood stabilizers and antipsychotic medications. They include Selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, atypical antidepressants, tricyclic antidepressants, monoamine oxidase inhibitors, and other medications.

2. Psychotherapy

It includes cognitive behavioural therapy, family-focused therapy and interpersonal therapy.

3. Exercise

It helps in preventing mild to moderate symptoms.

4. Brain stimulation therapies

This can be tried if psychotherapy and medication are ineffective. These include electroconvulsive therapy for depressive disorder with psychosis or repetitive transcranial magnetic stimulation for treatment of severe depression.

5. Light therapy

A person is exposed to full spectrum light by using a lightbox to regulate the hormone melatonin

6. Alternative approaches

Include acupuncture, meditation, spending time with people you care about, avoiding alcohol, getting quality sleep, faith and nutrition.


Depression is a common disorder that affects millions of people every year. As it is curable, seeking the doctor’s advice at the correct time makes the patient feel better. Currently, effective treatment is available, when it occurs alone or when accompanied with other medical illness.

Frequently Asked Questions
What is treatment-resistant depression? If the patient does not respond to standard treatment then it is described as treatment-resistant depression.
It depends on the person and varies from one to another. In some cases, it is successful within several months. Others may take a longer time to respond. If untreated it may last for many years.
Consulting doctors is essential as these drugs show interaction with other drugs.