Major Depression: Symptoms, Causes, Treatments

The major depressive disorder, also called major depressive disorder or clinical depression, is a mental illness characterized by a depressed mood and decreased extremely interested to experience any pleasure in life.

In addition, it includes:

  • Cognitive symptoms: indecision, feelings of low worth.
  • Altered physical functions: changes in appetite, changes in weight, altered sleep, loss of energy.

Although all symptoms are important, the physical changes are remarkable in this disorder and indicate their appearance.

Major Depression Treatment

It is also said that people who suffer from this disorder have “unipolar depression”, because the mood is maintained in a pole.

It is now known that it is strange to have a single episode of major depressive disorder (MDD).

If two or more separate episodes occur for at least two months without depression, it is called “recurrent major depressive disorder.”

The diagnosis of MDD is based on the experiences reported by the person, on the behavior reported by friends or relatives, and on the assessment of mental state.

There is no laboratory test for major depression, although tests are usually done to rule out the possibility that the symptoms are caused by physical illness.

The most common time of appearance is between the 20 and 40 years, with a peak between the 30 and 40 years.

Patients are usually treated with antidepressants, supplemented with cognitive-behavioral therapy.

The more severe depression is, the greater the effect of antidepressants. On the other hand, hospitalization may be necessary in the most serious cases or at risk of suicide or damage to others.

The proposed causes are psychological, psychosocial, hereditary, evolutionary and biological.

Symptoms of Major Depression

Although depression can occur only once during life, several depressive episodes usually occur.

During those episodes, the symptoms occur most of the day and can be:

  • Feelings of sadness, emptiness or unhappiness.
  • Explosions of anger, irritability, or frustration.
  • Loss of pleasure in normal activities.
  • Sleep problems, including insomnia or hypersonic.
  • Tiredness or lack of energy, to the point that any task requires effort.
  • Changes in appetite: reduced appetite (resulting in weight loss) or increased appetite (weight gain).
  • Anxiety, agitation or restlessness.
  • Thought, speech or slow movements.
  • Feelings of little value or guilt.
  • Focus on past failures or events.
  • Problems concentrating, making decisions or remembering things.
  • Frequent thoughts of death, suicidal thoughts or attempted suicide.
  • Unexplained physical problems, such as headaches or backaches.

Depressive symptoms in children and adolescents

The symptoms of MDD in children and adolescents are common to those of adults, although there may be some differences:

  • In young children, symptoms may include sadness, irritability, worry, pain, refusal to go to school or being underweight.
  • In adolescents, symptoms may include sadness, irritability, negative feelings, low self-esteem , hatred, school absence, alcohol or drug use, self-harm, loss of interest in normal activities, avoidance of social interactions.

Depressive symptoms in elderly people

MDD is not a normal part of older people and should be treated.

Depression in older people is often diagnosed and treated little, and may refuse to seek help.

Symptoms of depression in older people may be different or less obvious and may include:

  • Difficulties to remember or changes of personality.
  • Fatigue, loss of appetite, sleep problems, pains not caused by medical or physical conditions.
  • Do not want to leave the home.
  • Suicidal thoughts.

Causes of Major Depression

The biopsychosocial model proposes that the factors involved in depression are biological, psychological and social.

Biological factors

Monoaminergic hypothesis

Most antidepressants have an influence on the balance of three neurotransmitters: dopamine, noreprinefrin and serotonin.

Most antidepressant medications increase levels of one or more monoamines (neurotransmitters serotonin , noreprinefrin and dopamine ) in the synaptic space between brain neurons. Some medications directly affect monoaminergic receptors.

It is hypothesized that serotonin regulates other neurotransmitter systems; the reduction of serotonergic activity could allow these systems to act erroneously.

According to this hypothesis, depression arises when low levels of serotonin promote low levels of noreprinefrin (a monoaminergic neurotransmitter). Some antidepressants directly improve noreprinephrine levels, while others increase levels of dopamine, another monoaminergic neurotransmitter. At present, the monomaminergic hypothesis states that the deficiency of certain neurotransmitters is responsible for the symptoms of depression.

  • Noreprinephrine is related to energy, alertness, attention and interest in life.
  • The lack of serotonin is related to anxiety, compulsions and obsessions.
  • Dopamine is related to attention, motivation, pleasure, interest in life and reward.

Other hypotheses

1- MRI images of patients with depression have shown some differences in brain structure.

People with depression have a greater volume of lateral ventricles and adrenal gland, and a smaller volume of basal ganglia, thalamus, hypothalamus and frontal lobe.

On the other hand, there could be a relationship between depression and hippocampal neurogenesis.

2-Loss of neurons in the hippocampus (involved in memory and mood) occurs in some people with depression and correlates with less memory and dysthymic mood.

Certain drugs can stimulate the level of serotonin in the brain, stimulating neurogenesis and increasing hippocampus mass.

3-A similar relationship have been observed between depression and the anterior cingulated cortex (involved in the modulation of emotional behavior).

4-There is some evidence that major depression may be caused in part by over activation of the hypothalamic-pituitary-adrenal axis, resulting in a similar effect to the stress response.

5-Estrogen has been related to depressive disorders due to their increase after puberty, prenatal period and post menopause.

6-The responsibility for a molecule called cytokines has also been studied.

Psychological Factors

There are several aspects of personality and development that appear to be integral to the occurrence and persistence of MDD, with the tendency to negative emotions being the primary precursor.

Depressive episodes are correlated with negative events in life, although their coping characteristics influence indirectly.

On the other hand, low self-esteem or the tendency to have irrational thoughts is also related to depression.

Psychologist Aaron T. Beck developed a known model of depression in the early 1960s. This model proposes that there are three concepts that create depression:

  • The triad of negative thoughts: irrational or negative thoughts about oneself, irrational or negative thoughts about the world, and irrational or negative thoughts about the future.
  • Recurrent patterns of depressive thoughts (schemas).
  • Distorted information.

From these principles, Beck developed cognitive-behavioral therapy.

Another psychologist, Martin Seligman, proposed that depression is similar to learned helplessness; learn that you have no control over situations.

In the 1960s, John Bowl by developed another theory; the theory of attachment, which proposes a relationship between depression in adulthood and the type of relationship between the child and the parent or caregiver in childhood.

It is believed that experiences of loss of family members, rejection or separation may cause the person to be considered of low value and insecure.

There is another personality trait that depressive people often have; they often blame themselves for the occurrence of negative events and accept that they are the ones who create the positive results. This is the so-called pessimistic explanatory style.

Albert Bandera proposes that depression is associated with a negative self-concept and lack of self-efficacy (they believe that they cannot achieve personal goals or influence what they do).

In women there are a number of factors that make depression more likely: loss of the mother, being responsible for several children, lack of reliable relationships, unemployment.

Older people also have some risk factors: going from “giving care” to “needing care”, death of someone close to them, changing personal relationships with spouses or other family members, changes in health.

Finally, existential therapists relate depression to a lack of meaning in the present and a lack of vision for the future.

Social factors

Poverty and social isolation are associated with an increased risk of developing mental disorders.

Sexual, physical or emotional abuse in childhood is also related to developing depressive disorders in adulthood.

Other risk factors in family functioning are: parent depression, parent conflict, death or divorce.

In adulthood, stressful events related to social rejection are related to depression.

Lack of social support and adverse conditions at work-poor decision-making capacity, poor working environment, and poor general conditions-are also related to depression.

Finally, prejudices can lead to depression. For example, if a child develops the belief that working in a certain profession is immoral and adulthood is working in that profession, the adult can blame himself and direct prejudice.

Evolutionary factors

The evolutionary psychology suggests that depression may have been incorporated into human genes, due to the high heritability and prevalence has.

Current behaviors would be adaptations to regulate personal relationships or resources, although in the modern environment are maladaptaciones.

From another point of view, one might see depression as an emotional program of the species activated by the perception of personal futility, which may be related to guilt, perceived rejection and shame.

This tendency could have appeared in the hunters of thousands of years who were marginalized by the descent of their abilities, something that could continue to appear today.

Drug and alcohol abuse

In the psychiatric population there is a high level of substance use, especially sedatives, alcohol and cannabis.

According to DSM-IV, a diagnosis of mood disorder cannot be made if the direct effect is the effect produced by substance use.

Excessive alcohol consumption significantly increases the risk of developing depression, as do benzodiazepines (central nervous system depressants).


Diagnostic Criteria for Major Depressive Disorder, Single Episode (DSM-IV)

  1. A) Presence of a single major depressive episode.
  2. B) Major depressive episode is not better accounted for by a schizoaffective disorder and are not superimposed on schizophrenia, a schizophreniform disorder, a delusional disorder or psychotic disorder not otherwise specified.
  3. C) There has never been a manic episode, a mixed episode or a hippomanic episode.


  • Chronic.
  • With catatonic symptoms.
  • With melancholic symptoms.
  • With atypical symptoms.
  • Start in the postpartum.

Diagnostic Criteria for Major Depressive Episode (DSM-IV)

  1. A) Presence of five or more of the following symptoms over a 2-week period, representing a change from previous activity; one of the symptoms should be 1. Depressed mood, or 2. Loss of interest or ability for pleasure:
  2. Depressed mood most of the day, almost every day as indicated by the subject (sad or empty) or the observation made by others (crying). In children or adolescents mood can be irritable.
  3. A marked decrease in interest or ability for pleasure in all or almost all activities, most of the day.
  4. Significant weight loss without regimen, or weight gain, or loss or increase in appetite almost every day. In children, the failure to achieve the expected weight gain should be assessed.
  5. Insomnia or hypersonic every day.
  6. Excessive or inappropriate feelings of worthlessness or guilt almost every day.
  7. Decreased ability to think or concentrate, or indecision, almost every day.
  8. Recurrent thoughts of death, recurrent suicidal ideation without a specific plan or suicide attempt, or a specific suicide plan.
  9. B) Symptoms do not meet the criteria for a mixed episode.
  10. C) Symptoms cause clinically significant discomfort or social, occupational, or other significant areas of activity.
  11. D) The symptoms are not due to the direct physiological effects of a substance or a medical illness.
  12. E) The symptoms are not explained better by the presence of mourning, the symptoms persist for more than two months or are characterized by a marked functional incapacity, morbid preoccupations of uselessness, suicidal ideation, psychotic symptoms or psych0m0tor retardation.


The DSM IV recognizes 5 TDM subtypes:

  • Melancholic depression: loss of pleasure in most activities. A depressed mood, more than a duel or loss. Worsening of morning symptoms, psych0m0tor retardation, excessive weight loss or excessive guilt.
  • Atypical depression: characterized by excessive gain of weight, excessive sleep, sensation of heaviness in the limbs, hypersensitivity to social rejection and deterioration of social relations.
  • Catatonic depression: disturbances in motor behavior and other symptoms. The person remains mute and almost in stupor, or remains motionless and shows strange movements.
  • Postpartum depression: it has an incidence of 10-15% in new mothers and can last up to three months.
  • Seasonal affective disorder: depressive episodes that arrive in autumn or winter and that cease in the spring. At least two episodes have had to occur in cold months without occurring in other months, over a period of 2 years or more.

Co morbidity

Major depressive disorder usually co-occurs with other mental disorders and physical illnesses:

  • About 50% also suffer from anxiety.
  • Alcohol or drug addiction.
  • Post-traumatic stress disorder.
  • Attention deficit and hyperactivity.
  • Cardiovascular diseases.
  • Depression.
  • Obesity.
  • Pain.

Differential diagnosis

When diagnosing MDD, other mental disorders that share some characteristics should be considered:

  • Dysthymic disorder: this is a persistently depressed mood. Symptoms are not as severe as in depression, although a person with dysthymia is vulnerable to developing a major depressive episode.
  • Bipolar disorder: this is a mental disorder in which it alternates between a depressed state and a manic.
  • Adaptive disorder with depressive mood: this is a psychological response to a stressful event.
  • Depressions due to physical illness, substance abuse or medication use.

Treatments for Major Depressive Disorder

The three main treatments for depression are cognitive-behavioral therapy, medication and electroconvulsive therapy.

The American Psychiatric Association recommends that initial treatment be tailored to the severity of symptoms, co-occurring disorders, patient preferences, and response to previous treatments. Antidepressants are recommended as initial treatment in people with severe or moderate symptoms.

Cognitive Behavioral Therapy

At the moment it is the therapy that more evidence of its effectiveness in children, adolescents, adults and elderly people.

In people with moderate or severe depression, they can work as well or better than antidepressants.

It is about teaching people to challenge irrational thoughts and to change negative behaviors.

Variants that have been used in depression are rational behavioral emotional therapy and mindfulness.

Specifically, mindfulness seems to be a promising technique for adults and adolescents.


The sertraline  (SSRI) compound has been the most prescribed in the world, with more than 29 million prescriptions in 2007.

Although more results are needed in people with moderate or acute depression, there is evidence of its utility in people with dysthymia.

 Research from the  National Institute for Health and Care Excellence  found strong evidence that selective serotonin reuptake inhibitors (SSRIs) are more effective than placebo by reducing moderate and severe depression by 50%.

To find the proper pharmacological treatment, the doses can be readjusted and even combining different classes of antidepressants.

It usually takes 6-8 weeks to begin to see results and is usually continued for 16-20 weeks after remission to minimize the possibility of recurrence. In some cases it is recommended to keep the medication for one year and people with recurrent depression may need to take it indefinitely.

SSRIs are the most effective compound or drug today. They are less toxic than other antidepressants and have fewer side effects.

The monoamine oxidase inhibitor (MAOI) are another class of antidepressants, but found that can interact with food and drugs. Currently little is used.

Other medications

There is some evidence that selective COX-2 inhibitors have positive effects for major depression.

Lithium appears effective in reducing the risk of suicide in people with bipolar disorder and depression.

Electroconvulsive Therapy

Electroconvulsive therapy is a treatment by which electric convulsions are induced in patients to reduce psychiatric illness.

It is used as a last option and always with the consent of the patient.

One session is effective for approximately 50% of people resistant to other treatments and half of respondents fall within 12 months.

The most common adverse effects are confusion and memory loss.

It is given under anesthesia with a muscle relaxant and is usually given two to three times a week.


Bright or light therapy reduces the symptoms of depression and seasonal affective disorder, with effects similar to those of conventional antidepressants.

For non-seasonal depressions, adding light therapy to normal antidepressants is not effective.

Physical exercise is recommended for mild and moderate depression. According to some research is equivalent to the use of antidepressants or psychological therapies.


The average duration of a depressive episode is 23 weeks, being the third month in which more recoveries occur.

Research has found that 80% of people who suffer their first episode of major depression will suffer at least one more during their life, with an average of 4 episodes in life.

Recurrence is more likely if symptoms have not been fully resolved with treatment. To avoid it, current indications recommend continuing with the medication for 4-6 months after remission.

People suffering from recurrent depressions require ongoing treatment to prevent long-term depressions and in some cases it is required to continue the medication indefinitely.

People with depression are more likely to suffer from heart attacks and suicide . Up to 60% of people who commit suicide suffer from mood disorders.


Once an episode of major depression arises one is at risk of suffering another.

The best way to prevent is to be aware of what triggers the episode and the causes of major depression.

It is important to know what the symptoms of major depression are for early action or treatment.

Here are some tips for prevention:

  • Avoid alcohol or drug use .
  • Do sport or physical activity for at least 30 minutes 3-5 times per week.
  • Maintain good sleep habits.
  • Do social activities.
  • Doing fun or exciting activities.
  • Volunteering or group activities.
  • Try to seek positive social supports.
  • If medical treatment is followed: keep medication as prescribed and continue with therapy sessions.

Risk factors

More women are diagnosed than men, although this trend may be due to the fact that women are more willing to seek treatment.

There are several risk factors that seem to increase the odds of developing major depression:

  • Depression has begun in childhood or adolescence.
  • History of anxiety disorders, borderline personality disorder or post-traumatic stress disorder.
  • Personality traits such as being pessimistic, emotionally dependent or having low self-esteem.
  • Alcohol or drug abuse.
  • Have had serious illnesses such as cancer, diabetes or heart disease.
  • Having suffered traumatic events, such as sexual or physical abuse, couple difficulties, financial problems or loss of family members.
  • Family members with depression, bipolar disorder, suicidal behavior or alcoholism.


According to the World Health Organization, depression affects more than 350 million worldwide, being the leading cause of disability and contributing significantly to morbidity.

It is more likely that the first depressive episode develops between 30 and 40 and there is a second peak of incidence between 50 and 60.

It is most common after cardiovascular disease, Parkinson’s, stroke, multiple sclerosis and after the first child.


Untreated depression can lead to health, emotional, and behavioral problems that affect all areas of life.

  • Complications can be:
  • Alcohol and drug abuse.
  • Excess weight or obesity.
  • Anxiety, social phobia or panic disorder.
  • Family problems, couple conflicts or problems in school.
  • Social isolation.
  • Attempts of suicide or suicide.
  • Autolysins.

How to help if you are a family member or friend

If you have a family member or friend who is affected by depression, the most important thing is to help diagnose the disease and start treatment.

You could set up an appointment and accompany your family member, encourage follow-up treatment or seek a different treatment if there is no improvement after 6-8 weeks.

You can follow these tips:

  • Talk to your family member and listen carefully.
  • It offers emotional support, patience, encouragement and understanding.
  • Do not dismiss feelings but offer hope.
  • Do not ignore comments about suicide and communicate them to the therapist.
  • Invite to participate in play activities.
  • Accompany the therapeutic appointments if the family member asks for it.

Help yourself if you have depression

If you have depression you may feel hopeless, lacking energy and not wanting to do anything.

It may be very difficult for you to act to help yourself, although it is necessary to recognize the need for help and treatment.

Some advices:

  • Try to visit a professional as soon as possible. The more you expect the more complicated the recovery can be.
  • Exercise frequently, 30 minutes at least for 3-5 days per week.
  • Participate in activities such as sports, going to the movies, taking a walk, attending events…
  • Divide large tasks into small ones and set priorities.
  • Set realistic goals that motivate you. Divide big goals into small goals.
  • Do not isolate yourself socially; spend time with friends, family and new friends.
  • He hopes that the depression will be overcome little by little, not suddenly.
  • If you have to make important decisions, wait until you are in a stable mood.
  • Continue to inform yourself about depression (without obsessing) and acting to overcome it.