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What is Depression? Causes, Symptoms, Types

  • Author: Dr. Shiva K. Lam
  • Category: Depression
  • Last Update: 10/12/2023 at 7:25 AM
What is Depression? Causes, Symptoms, Types

Table of content

1. What is depression?

Depression is a severe condition that negatively affects how a person thinks/ feels/acts/ behaves. Depression invites feelings of sadness/ sorrow/ hopelessness/ loss of interest in activities (engaged earlier)

Conclusively, depression is different from the fluctuations in mood (that people experience as a part of a healthy life). For instance, temporary emotional responses (to the challenges in everyday life) do not constitute depression. Likewise, even the feeling of grief resulting from the death of near and dear ones cannot be termed ‘depression as it is in general, not persistent.

2. Causes of depression

The causes of depression are not fully understood. It occurs due to a complex combination of factors. The causative factor behind recession is changes in brain chemistry (Clinical depression is thought to be caused by a chemical imbalance in the brain. In many cases among depressed patients, there is a reduction in the number of certain neurotransmitters—such as serotonin).

Issues like Depression and mental Anxiety can result from a host of factors, as stated below.

  • Genetic factors: Having near relatives with a higher income level and a better standard of living, Is found common. This is an essential risk factor for causing a feeling of depression and disappointment.
  • Biological factors: They bring changes in the neurotransmitter levels.
  • Environmental factors: They affect stress/ anxiety leading to depressive disorder. The environmental factors include air/ water/ food pollution.

Other non-chemical environmental sources include: Noise pollution, Electrical pollution, Natural disaster

  • Psychological and psycho-social factors: Psychological factors causing depressive disorder include: the loss of parents at an early age/ loss or separation from a loved one. Psycho-social factors contributing to Depression are job dissatisfaction and hostility with friends/ office colleagues/business partners.
  • Personal: Those having less competence and coping strategies are more susceptible to depressive disorder.
  • Life events: Bereavement on account of financial loss and problems/ loss of family member/ divorce/ medical concerns can trigger mental stress and Depression
  • Childhood trauma: Many adverse childhood experiences can overwhelm a child. These are negligence/ violence/sexual abuses.
  • Prescription drugs: Some drugs prescribed by the doctor can cause or aggravate depression. These include Corticosteroids/ Beta-blockers/ Interferon.
  • Non-prescription drugs: Abuse of alcohol and drugs like Amphetamines are strongly linked to Depression.
  • Past head injury: Having experienced head injuries in the past may increase the risk of subsequent Depression.
  • Chronic pain syndrome: Chronic pain syndrome and other chronic conditions (that make Depression more likely) include diabetes/ cardiovascular disease/ COPD (Chronic Obstructive Pulmonary Disease. It is a type of obstructive lung disease characterized by long-term breathing problems and poor airflow. The damaged lungs can burn ten times more calories as compared to normal/ healthy lungs even if one has a good appetite. This leads to weight loss).


  • The cause may also include: taking a longer time for recovery (from illness/ injury)/ longer time in surgery (than expected).
  • Additionally, many other conditions trigger the symptoms of Depression. These are reactions (on account of taking anesthesia/ antibiotics/ pain killers) / pain and discomfort during recovery/ physical, mental, the emotional stress caused by inadvertent medical disorder/ risking high probability of death caused by a severe prolonged illness.
  • Various research studies reveal the fact that the postoperative depression rate is higher in the case of some surgeries as listed below.
    • Heart surgery
    • Gastric bypass surgery (it is a surgical procedure in which the stomach is divided into a small upper pouch, and a much larger lower bag. After that the small intestine is rearranged to connect the both).
    • Brain surgery
    • Hip replacement (It is a surgical procedure in which a prosthetic implant replaces the hip joint)
    • Hysterectomy (it is the surgical removal of the uterus. It may also involve removal of the cervix, ovaries, fallopian tubes, and other surrounding structures )
    • Cancer resection (The surgical procedure removes all or part of the tumor.)
    • Mastectomy (Removing one or both the breasts by surgical procedure)
    • Plastic surgery (It is a surgical procedure involving the restoration, alteration, and reconstruction of the human body)

3. Symptoms of depression

The following symptoms are observed in the case of the patients having Depression.

  • Depressed mood: It is a normal temporary reaction to life events (such as prevention or interference in love affairs). Depressed mood is also a symptom of some physical diseases and side effects of some drugs and medical treatments.
  • Reduced interest and pleasure (in activities previously enjoyed): It is known as  Anhedonia—one of the significant symptoms of depressive disorder. It is the loss of interest in prior experienced activities (such as loss of interest in hobbies/friend relationships and even food and sex.)
  • Unintentional weight loss (without dieting): It may be an inevitable outcome of Depression. This can lead to reduced appetite and weight loss.
  • Insomnia (difficulty in sleeping): It is a condition with sleep deprivation or lack of adequate sleep. The underlying causes are: anxiety/ stress/ depression and various emotional and psychological factors (such as anger/ worrying/grief/trauma)
  • Hypersomnia (Excessive sleeping): It is a condition in which the person, stays awake during the daytime, but can fall asleep at any time.
  • Restlessness (pacing up and down)
  • Impaired psychomotor skills: Psychomotor skills occur when the activities of thinking and physical movement are combined. However psychomotor skills are known to be negatively affected by depressive disorder. More significant impairment relating to psychomotor skills is observed in older people, particularly those having severe Depression.
  • Fatigue and loss of energy: Extreme tiredness and feeling less energetic are the outcome of mental as well as physical exertion.
  • Feeling of guilt: Feeling guilty (for something wrong done) is quite reasonable. But the problem occurs when one ruminates over the sin
  • Impaired ability (to think/ concentrate/ decide): It may involve a noticeable and conspicuous decline in cognitive skills (such as memory and thinking skills)
  • Recurrent thoughts on death and suicide: Many suicidal thoughts are one of the significant symptoms of Depression. In such a case, the patients with depressive disorder spend most of their time wishing death.

4. Depression Diagnosis & Tests

Diagnosis is the procedure to identify the root cause of the disease by applying various tests (to ascertain the signs) /observing the symptoms/ interrogating the patient (about his feelings/ family history/ personal history including lifestyle)

Diagnostic tests are essential for providing safe/ secure/ effective treatment. Diagnostic tests start only after freely consulting with the doctor/ mental health specialists and other specialists.

To attain and assess the diagnostic test results correctly, medical experts have designed some questionnaires to assess the severity of Depression.

The HDRS (Hamilton Depression Rating Scale) is one of the most widely used assessment instruments in the world. The HDRS contains 21 questions.

The scores indicate the severity of the depressive condition of the patient.

HDRS (Hamilton Depression Rating Scale)

(Patient’s name, address with the date of assessment)

(The score ranges from 0- 4 under varying conditions)

Depressing Symptoms & Score


Depressing Symptoms


1 Depression Mood (gloomy attitude/pessimism/sadness/tendency to weep)
  • Absent (0)
  • Sadness (1)
  • Occasional weeping (2)
  • Frequent weeping (3)
  • Extreme weeping (4)
2 Feeling of guilt
  • Absent (0)
  • Repentance (1)
  • Feeling guilty (2)
  • Feeling that frequent illness is a punishment for misconduct (3)
  • Hallucination for sin (4)
3 Suicide
  • Absent (0)
  • Feeling that life is not worth living (1)
  • Wishing death (2)
  • Suicidal ideas/ gestures (3)
  • Attempt for suicide  (4)
4 Insomnia (difficulty in falling asleep)
  • Absent (0)
  • Occasional (1)
  • Frequent (2)
5 Insomnia (Feeling disturbed and restless during the night)
  • Absent (0)
  • Occasional (1)
  • Frequent (2)
6 Insomnia (waking up during sleep and unable to fall asleep again)
  • Absent (0)
  • Occasional (1)
  • Frequent (2)
7 Interests in work
  • No difficulty (0)
  • Feeling of incapacity/listlessness to work (1)
  • Loss of interest in hobbies and work activities (2)
  • Productivity decreased (3)
  • Unable to work even after treatment (4)
8 Retardation (Slowness in thought/ speech/activity)
  • Absent (0)
  • Slight retardation observed in an interview (1)
  • Apparent impediment observed in the discussion (2)
  • His interview is challenging (3)
  • Complete stupor (4)
9 Agitation (restlessness associated with anxiety)
  • Absent (0)
  • Occasional (1)
  • Frequent (2)
10 Anxiety (psychic)
  • Absent (0)
  • Tension and irritability (1)
  • Worrying about minor matters (2)
  • Apprehensive attitude (3)
  • Fears (4) 
11 Anxiety (somatic: urinary, respiratory, and gastrointestinal problems/indigestion)
  • Absent(0)
  • Mild (1)
  • Moderate (2)
  • Severe (3)
  • Incapacitating (4)
12 Gastrointestinal symptom (loss of appetite/heavy abdominal discomfort)
  • Absent (0)
  • Mild (1)
  • Severe (2)
13 Somatic symptoms (General: fatigue/headache/backache/loss of energy)
  • Absent (0)
  • Mild (1)
  • Severe (2)
14 Genital symptoms (Menstrual disturbance)
  • Absent (0)
  • Mild (1)
  • Severe (2)
15 Hypochondriasis (fear of prolonged serious illnesses despite medical assurances)
  • Absent(0)   
  • Self-absorption bodily (1)    
  • Preoccupation with health (2)  
  • Querulous attitude (3)
  • Hypochondriasis delusion (4)
16 Weight loss
  • Absent (0)
  • Slight (1)
  • Severe (2)
17 Insight
  • No loss (0)
  • Partial loss (1)
  • Loss of insight (2)
18 Diurnal variation (Symptoms get worse in the morning or evening time)
  • No modification (0)
  • Mild variation (1)
  • Severe difference (2)
19 Depersonalization and de-regularization (feeling of nihilistic ideas)
  • Absent (0)
  • Mild (1)
  • Moderate (2)
  • Severe (3)
  • Incapacitating (4)
20 Paranoid symptoms (intense and irrational mistrust/suspicion/fear)
  • None (0)
  • Suspicious (1)
  • Ideas of reference (2)
  • The delusion of reference and persecution(3)
  • Hallucinations are persecuting (4)
21 Obsessive thoughts and compulsions (against which the patient struggles)
  • Absent (0)
  • Mild (1)
  • Severe (2)

5. Health Complications

5.1) Depression affects the whole body. An even milder form of depression and mood disorder can affect the quality of life. Serious health complications may arrive in the form of heart disease/ stroke/ diabetes/ cancer.

Additionally, Depression dampens the urge to eat / sexual desire/ job performance/ quality of sleep.

5.2) The brain stores memories and regulates the production of hormones called cortisol. The body releases cortisol during the time of physical and mental stress, including Depression. This can lead to a memory problem (such as forgetfulness/ concentration).

Over and above, Depression makes it difficult to concentrate and focus on tasks/ make correct decisions/ think clearly/ behave rationally

5.3) Depression can cause significant mental suffering significantly and uncontrollably. At its worst, depression can lead to suicide.

6. Types of depression

Identifying the type is quite remarkable. Because treatment procedure largely depends on the nature of the disease. Various types of depressive disorders are stated below

6.1) Unipolar depression

Unipolar Depression can involve Anxiety and other symptoms, but no manic episodes. In the case of unipolar Depression, the dominant feature is a depressed mood (it is a normal temporary reaction to life events, such as prevention in romance and love affairs. Depressed mood is also a symptom of some physical diseases as well as side effects of some drugs and medical treatments).

6.2) Bipolar depression

It is a mental health condition that involves changes in moods and other mental conditions.

There may be different types of bipolar Depression, depending on the patterns of mood swings. The condition is characterized by both manic as well as depressive episodes  (a manic episode includes clinical Depression as part of the diagnosis. On the other hand depressive episode is characterized by feeling sad and unhappy at least for two weeks continuously ). Bipolar Depression is separated by periods of normal moods.

Conclusively, It is important to seek timely treatment as the impact of bipolar Depression on health and quality of life can be severe.

6.3) Major depressive disorder with psychotic features

The condition is characterized by depression accompanied by psychosis  (it is a severe mental disorder in which emotions are so impaired that contact is lost with external reality).

Psychosis can involve false belief /detachment from reality/ sensing things that do not exist/ delusion and hallucination (Delusion is a symptom of mental disorder with impression maintained despite being contradicted by rational argument. And the illusion is an experience involving the apparent perception of something not present).

6.4) Postpartum depression

It is also known as postnatal depression, which may be severe. Women had this condition experience baby blues with newborn babies.

The postpartum or postnatal period begins immediately after the birth of a child.

‘Baby blues’ refers to the babies that are born with blue eyes. The condition occurs due to the lack  of ‘melanin pigment.’

6.5) Major depressive disorder with seasonal pattern

The condition is related to the reduced daylight of winter. Depression occurs during the season and is responsive to light therapy (it is also known as photo-therapy. It is a method to treat the seasonally affected disorder by exposure to artificial light).

Conclusively,  the patients in countries with prolonged or severe winter, are affected more.

6.6) Agitated Depression

It is characterized by a low mood involving uneasiness and anxiety.

6.7) Mild depression

It is a condition with frequent changes in attitudes and behavior. The fluctuating emotions occur displaying regularity.

6.8) Post Surgery depression

After surgery, it is quite common to lose hope and feel mentally depressed.

The surgery may also be invasive (It is a surgical procedure that is carried out by entering the body through the skin or anatomical opening, allowing the smallest possible damage to the structures. Most of the surgical procedures administered are minimally invasive).

The cost of surgery ( in terms of worries caused by not having good health) may aggravate the feelings of depression and despair.

7. Depression Treatment

Depression is a treatable mental illness. There are three main components of the treatment plan. Also, other treatments are applied, as stated below.

7.1) Support

The treatment procedure ranges from discussing the problems with the solution to educating the family members

7.2) Psychotherapy (or talking therapy)

The treatment procedure includes interpersonal therapy and  CBT (Cognitive Behavioral Therapy is a form of psychotherapy that treats the problem affecting mental stability. The treatment is done by modifying dysfunctional emotions, behaviors, etc.).

In mild cases, psychotherapies are the 1st option for treatment. CBT may be effectively delivered to the patient in several ways, as stated below :

  • Face to face
  • In a group
  • Over the telephone
  • Through computer

Interpersonal therapy is used to identify the problems that affect relationships and communication.

7.3) Drug treatment (antidepressant medications)

Antidepressants are drugs used for the treatment of major depressive disorder. The doctor prescribes these only for the adolescent (and not for the children).

Several medications are used for the treatment, which are stated below.

  • SSRI  (Selective Serotonin Reuptake Inhibitors)
  • MAOI (Monoamine Oxidase Inhibitors)
  • Tri-cyclic antidepressants
  • Atypical antidepressants
  • SSNRI (Selective Serotonin-Norepinephrine Reuptake Inhibitors)

Conclusively, each class of antidepressants acts as a different neurotransmitter. The drugs prescribed should be continued even after the symptoms have improved.

7.4) Other treatments (Exercise and therapies)

7.4.1) Aerobic exercise:

Aerobic exercise helps against mild depression. Because it stimulates the neurotransmitters which are related to mood. Aerobic exercise is also known as the cardio exercise of low to high intensity. The practice primarily depends on the aerobic energy-generating process.

In contrast, anaerobic, i.e. ‘without oxygen’ exercise is a physical activity that causes one to be quickly out of breath, such as lifting a heavyweight.

Examples of aerobic exercises include

  • Running
  • Swimming
  • Walking
  • Hiking
  • Climbing
  • Dancing
  • Skating

Neurotransmitters are endogenous chemicals that enable neurotransmissions. It is a type of chemical messenger that transmits signals across a chemical synapse ( such as neuromuscular junctions-- from one neuron to another).

7.4.2) Brain stimulation therapy:

It can play a crucial role in treating specific mental disorders. The treatment procedure involves activating or inhibiting the brain directly with the use of electricity. The electricity can be given directly by an electrode implanted in the brain.

7.4.3) RTMS  (Repetitive Transcranial Magnetic Stimulation):

To date, several randomized controlled trials have shown the efficacy of RTMS in the treatment of major depression. The treatment procedure has been proven effective in patients with resistant unipolar Depression.

7.4.4) Electro-cardiovascular therapy:

It is one of the safest, cheapest, and yet effective treatments in psychiatry. It is the most consistently effective treatment for severe depression.

7.4.5) Sticking to a sleep schedule:

Sleep is essential for every living being (including man and animal) to stay healthy and energetic. For an adult, daily 7- 9 hours of sleep is necessary to remain active and energetic. However, it does not mean that one should sleep longer than needed. Neither underrest nor oversleeping is good for health.

It is essential to set a sleep schedule and adhere to it. Maintaining a regular schedule (for bedtime and waking up) may help the patient feel better and free of stress and anxiety. More importantly, it is recommended to follow a healthy lifestyle by consuming healthy foods and drinks (in addition to avoiding unhealthy foods as well as expensive bad habits like smoking and alcohol).

8. Key global information

  • Globally, 350 million people are affected by Depression.
  • Depression is twice as common among women (as compared to men)
  • About 20% of women will experience at least one episode of Depression across their lifetime.
  • Suicidal thoughts result mostly from Depression. Suicide is the  2nd leading cause of death among the youths (15- 29 years)
  • Depression is the most common illness worldwide. It is the leading cause of disability (according to the report of the World Health Organization).

9. Popular questions and answers on Depression (Q =  A = Answer)

Q. I) What is the most prominent symptom of Depression?

Ans (A patient is diagnosed with Depression if at least five symptoms are experienced for two consecutive weeks. Of the five signs, one must be either a depressed mood or loss of interest and pleasure )

Q. II) Why is Depression more prevalent in women than men?

Ans (After attaining puberty, girls become more likely to experience depression than boys. Biological/psychological/hormonal factors operate uniquely in girls during puberty. This leads to an increased rate of Depression in women )

Q. III) What happens concerning Depression during menopause?

Ans. (Menopause is the time in most women’s lives when the menstrual period stops permanently. Women with menopause are no longer able to bear children. Menopause occurs at 49- 52 years of age. Such women experience increased risks of Depression)

Q. IV) What is about Depression in older people?

Ans. (Older people suffer from restricted blood flow called ischemia. At this stage, the changes in brain/ body may occur. Over time blood vessels become less flexible. This may harden and prevent blood from flowing normally to the body's organs, including the brain. The condition may result in vascular Depression in older people).

Q. V) Can brain condition guide treatment for Depression?

Ans. (Brain imaging has confirmed the biological nature of many psychiatric illnesses over the past 30 years. In the mid-1990s, Functional Magnetic Resonance Imaging was used to identify structural brain changes in depressed people).

10. Concluding remarks

  • To be called ‘depression,’ the symptoms must be persistent (lasting 6-8 months)
  • Depression can’t be dealt with overnight. In addition to applying all treatment procedures, the family members need to play a vital role to understand and help the patient to stay motivated and mentally active until the full recovery.
  • Though Depression mostly affects the mind, it can also lead to physical illness. Again physical health is an essential foundation of mental health. People lacking in physical fitness are at increased risk of developing Depression.
  • It is also crucial for the patients to keep a record of all questions coming to mind and regularly consult the doctor. This can significantly reduce stress.

11. TIPS

  • D = DEPRESSION (is more common in women than men)
  • E = ENVIRONMENTAL (factors like air/water/food pollution cause depressive disorder)
  • P = PSYCHOTHERAPY (is the 1st option for treatment of mild Depression)
  • R = RISK (of developing Depression is high in people lacking in physical fitness)
  • E = EVENTS (like financial loss/divorce/lack of adjustment with family may cause Depression)
  • S = SLEEP (for 7-9 hours daily is essential to stay away from depressive effects)
  • S = SUICIDAL (thoughts result mostly from Depression)
  • I = INTERPERSONAL (therapy is used to identify and treat problems affecting relationships)
  • O = OBSTRUCTIVE (lung disease with diseased lungs trigger depression/cause weight loss)
  • N = NEGATIVE (impact on feelings /thoughts/ behavior patterns result from depression)

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Author: Dr. Shiva K. Lam


Dr. Shiva Lam, a psychiatrist in Austin, TX, specializes in mental health care, diagnosing and treating conditions like depression, anxiety, and OCD. Utilizing methods such as medications and psychotherapy, Dr. Lam provides personalized and comprehensive treatment for various mental health disorders.


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