What Is Major Depressive Disorder? Types

Depression causes sadness and/or a loss of interest in activities once enjoyed. It can also decrease a person’s ability to function at work and home.

The American Psychiatric Association defines major depressive disorder (depression) as a common, but serious, medical illness that negatively affects how one feels, thinks and acts.

Depression causes sadness and/or a loss of interest in activities once enjoyed. It can lead to a variety of emotional and physical problems and decrease a person’s ability to function at work and home.

A nervous or mental breakdown is a common term used to describe a period of intense mental distress during which one is unable to function in everyday life. This term is used to refer to a wide variety of mental illnesses, including depression, anxiety and acute stress disorder.

Genetic causes of depression

First-degree relatives of depressed individuals are about three times as likely to develop depression

External stressors causing depression

Stressors can be personal, familial, social and environmental, such as:

• Chronic pain
• Medical illness
• Psychosocial stress
• Lack of sleep
• Impaired social supports
• Caregiver burden
• Loneliness
• Bereavement
• Negative life events
• Loss of a loved one
• Harassment
• Bullying
• Alcohol and drug abuse
• Certain medications
• Domestic abuse
• Poor parent-child relationship
• Traumatic life events
• Major life changes – divorce, loss of employment, etc.

Risk-factor interactions that cause depression

The relationship between genetic vulnerability, environmental stressors and brain structural abnormalities are risk factor interactions in the development of depression.

Neuroendocrine abnormalities and neurodegenerative diseases

Abnormalities of the neurotransmitter systems may cause depression.
Neurodegenerative diseases (especially Alzheimer and Parkinson), stroke, multiple sclerosis, seizure disorders, cancer and chronic pain have been associated with higher rates of depression

Vascular depression

Medical problems that affect blood flow to the brain may also trigger depression:

• Patients experience a higher incidence of depression following a stroke
• Higher prevalence of ischemic (loss of oxygenation) brain changes exist in older adults with depression
• A strong association exists between depression and heart disease as well as depression and diabetes
• Higher rates of depression exist among patients with vascular dementia 

At least five of the following symptoms must have been present during the same two-week period (and at least one of the symptoms must be diminished interest/pleasure or depressed mood):

• Depressed mood: For children and adolescents, this can also be irritability.
• Diminished interest or loss of pleasure in almost all activities (anhedonia)
• Significant weight change or appetite disturbance: In children, this can be a failure to gain weight and weight gain in adults
• Sleep disturbance (insomnia or hypersomnia)
• Fatigue
• Feelings of worthlessness
• Diminished ability to think or concentrate and indecisiveness
• Recurrent thoughts of death, recurrent suicidal ideation or a suicide attempt

Anxious distress may be added to a depression diagnosis if at least two of the following symptoms are present:

• Feeling tense
• Unusually restless
• Difficulty concentrating
• Fear that something awful may happen
• Feeling of potential loss of control

Severity is further specified as:

• Mild: two symptoms
• Moderate: three symptoms
• Moderate-severe: four or five symptoms
• Severe: four or five symptoms with shaking or other movement symptoms  (motor agitation)

At least three of the following are required for this specific diagnosis:

• A depressed mood that is distinctly different from the kind that is felt when a loved one is lost
• Depression that is worse in the morning
• Waking up 2 hours earlier than usual
• Observable psychomotor retardation or agitation
• Significant weight loss or anorexia
• Excessive or inappropriate guilt

• Stupor (near state of unconsciousness)
• Catalepsy (trance/seizure with unconsciousness, rigidity, loss of sensation)
• “Waxy flexibility” of skeletal muscles, meaning limbs stay in a position the doctor puts them in with only mild initial resistance, like bending soft wax
• Mutism
• Negativism
• Stereotypy (purposeless persistent repetition of an act)
• Agitation without provocation
• Grimacing
• Echolalia (meaningless repetition of another person’s words)
• Echopraxia (meaningless repetition of movements of others)

Depression in the postpartum period is common and potentially serious. Up to 85% of women can develop mood disturbances during the period after childbirth. Postpartum depression is characterized by fluctuating mood, tearfulness, irritability and anxiety.

Depression symptoms worsen during the winter and improve during the summer.

Major Depressive Disorder with Psychotic Features

This type of depression with psychotic features like:

• Delusions
• Hallucination 
• Mood instability

Individuals with depression who have metabolic syndrome may be more likely to have persistent or recurrent depression.

Depression may cause one to act on suicidal thoughts or promote substance abuse, disrupt interpersonal relationships and make it difficult to work.

• Major depression
• Older age
• Male sex
• Previous history of suicide attempts
• Burden of medical disease and presence of a current serious medical condition
• Recent stressful life events
• Lack of social support
• Family discord, being widowed or divorced
• Presence of a gun in the home
• Unexplained weight loss
• Severe anxiety
• Real or perceived lack of meaningful life pursuits
• Presence of a specific suicide plan and its rehearsal

Major depressive disorder causes significant distress and makes it difficult for people to form relationships, enjoy leisure or be functional at work. With appropriate medical treatment, therapy and emotional support, 70-80% of patients may be cured or at least drastically reduce their symptoms.