Major Depressive Disorder

Causes, symptoms and treatment

Major depressive disorder (MDD) is the most common depressive illness, and the most insidious. For most people, symptoms start in the late teens or twenties. In the early stages, symptoms are usually mild although periodic bouts of more severe depressive episodes occur that may last days, weeks or months.

Over time, the symptoms increase in severity and frequency. Many people have no idea they are slowly sliding into depression until the symptoms are so severe they can barely function. By then, the mental confusion, cognitive deterioration, exhaustion, and emotional pain deter many from getting help.

Prior to starting treatment for severe MDD, my doctor asked, “How long have you been experiencing these symptoms?” I replied, “About three years.” (My response was based on the length of time extreme symptoms occured every day).

But after successful treatment with medication, I realized it had been over 30 years since I felt so healthy. I had no idea that the initially mild but chronic physical, emotional and mental problems were symptoms of a slowly developing brain disease. It was an indescribable joy to get back my mind and personality, motivation and emotions, and energy and physical health. I will be forever grateful.
Read Judy's story

What causes major depressive disorder?

Major depressive disorder is not caused by disappointing events in a person life (unless he or she already has a mild form of the disease, in which case trauma can accelerate its progression). Following are the main causes of MDD:

Just as people may inherit a genetic vulnerability to heart disease or cancer, others inherit a vulnerability to brain malfunction. Neuroscientists say that most cases of major depressive disorder are inherited, which is why it tends to run in families. However, the genetic link can manifest in different depressive disorders. For example, the descendants of a person with major depressive disorder may develop bi-polar disorder or an anxiety disorder such as OCD.

Brain trauma
Head trauma can damage the part of the brain that controlls thought and mood, triggering depression or other mental illnesses. The head trauma can be as simple as falling and hitting your head on a sidewalk. This is one reason why more attention needs to be paid to sports injuries.

Stroke and Parkinson's disease
More than 50% of stroke victims develop clinical depression within one year, and up to 60% of Parkinson's disease patients experience mild to moderate depression.

Immune and inflammatory responses
Depression can be caused or worsened by problems in other parts of the body, such as inflammation and immune problems triggered by environmental and nutritional toxins and allergens, nutritional deficiencies and digestive imbalances caused by the overuse of antibiotics and autoimmune diseases.

Childhood trauma, abuse and neglect
A child’s developing brain is extremely vulnerable. A major trauma, such as losing a parent, can affect brain development. Neurobiological studies show that severe neglect and abuse in childhood (especially sexual abuse) can also alter both the chemistry and structure of the developing brain. Without early intervention, many of these children later develop depressive illness.

Drug and alcohol addiction
Hallucinogenic drugs and excessive alcohol use can damage brain cells. Some drugs increase the damage with each use.

What about severe stress or trauma?
Severe stress or emotional trauma does not cause major depressive disorder (except during early childhood when the brain is still developing). But it can worsen the symptoms, in the same manner that severe stress worsens the symptoms of almost every other physical illness. Although major depressive disorder typically develops slowly, serious physical illness or severe emotional trauma can trigger the worsening of symptoms in someone who already has the condition in a milder form.

What are the symptoms of major depressive disorder?

Major depressive disorder is diagnosed if at least five of the following symptoms persist for at least two months or longer and are not related to a major loss such as bereavement, or other life circumstance or stress. (note: the DSM diagnoses MDD after two weeks of these symptoms). The symptoms are characterized by marked functional impairment

  • Depressed mood most of the day, nearly every day (in children this often manifests as irritability rather than sadness)

  • Markedly diminished interest in all or most activities most of the day, including an inability to experience pleasure in activities once enjoyed

  • Diminished ability to think or concentrate and make decisions, nearly every day

  • Persistent uncontrollable cluttering of sad, negative thoughts. Racing thoughts are common.

  • Progressive mental deterioration. To understand information you are reading or listening to, specific circuits in your brain must be working right. With depression, malfunctions in those circuits make reading and information processing difficult and at times impossible.

  • Overwhelming fatigue often combined with either feeling slowed down (psychomotor retardation) or excessive agitation and restlessness that can't be controlled (psychomotor agitation)

  • Significant weight loss when not dieting, or unusual weight gain

  • Inappropriate or excessive guilt or feelings of worthlessness nearly every day

  • Sleep problems, usually insomnia. The typical pattern is waking up early and not being able to get back to sleep. Some people oversleep.

  • Chronic physical pain or other physical symptoms that don't respond to treatment

  • Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide.

Suicide is the greatest risk of depression. More than 90% of people who commit suicide suffered from depression. Most people hide their symptoms, and family members of suicidal victims are usually stunned to learn about their loved one's depression. If you are having thoughts of suicide, or thoughts of death, see your doctor immediately or go to the nearest emergency ward.

Medical training is required to diagnose major depressive disorder. If you think you may be suffering from a clinical depression, see a medical doctor. The information on this website is intended for informational purposes only and is not intended to replace the advice of a mental health professional.


Back to clinical depression introduction
Judy's story
Non-clinical depression



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