Depression is a term that can refer to a wide variety of abnormal variations in an individual's mood. If changes in an individual's mood are persistent and cause distress or impairment in functioning, then a mood disorder may be present. Individuals with mood disorders experience extremes of emotions, for example sadness, that are higher in intensity and longer in duration than normal.

Mood disorders are generally classified as either a type of unipolar depression or bipolar depression. Unipolar depression is characterized by periods of depressed mood, profound sadness, or loss of interest in activities. Bipolar depression is characterized by periods of depressed mood that alternate with periods of extremely elevated mood, increased energy, and euphoria. These periods of elevated mood are referred to as mania. Within both unipolar and bipolar categories, specific sets of symptoms are characteristic of particular disorders, each of which has its own diagnostic profile, treatments, and prognosis. The Diagnostic and Statistical Manual of Mental Disorders (DSM), now in its fourth revised edition, describes the diagnostic criteria for each disorder.

Depressive disorders are very common medical conditions. Unipolar depression will affect 20% of individuals at some point during their life span while bipolar depression will affect 4% of individuals. Unipolar depression is twice as common in females than males, but bipolar depression is equally common in both sexes. The etiology of depressive disorders is most likely multifactorial with both complex genetic factors and environmental stressors (for example, emotional stress, substance abuse, psychological, physical, or sexual abuse) likely contributing to the neuronal changes seen in affected individuals. In an individual who has a high genetic predisposition to a depressive disorder, little or even no environmental stress may provoke a depressive illness. In an individual with a low genetic predisposition to depressive disorders, a major stressor may or may not provoke a depressive illness. Individuals with first degree relatives (i.e., parents, siblings, children) with a depressive disorders are more likely to be a risk for experiencing a depressive disorder themselves. Regardless of whether the causal factors for a depressive illness are genetic or environmental, both produce physiologic changes in the neurotransmitter systems within the brain.

Advances in pharmacological and psychotherapeutic treatments have allowed for very high rates of success in treating depressive disorders. However, only about one-quarter of individuals with a depressive disorder seek treatment. Of those who do seek treatment, over 90% can be successfully treated. Psychiatrists, medical doctors who specialize in treating mental illness, and clinical psychologists, who are trained in various modalities of psychotherapy, are experienced in treating depressive disorders. A general practitioner, family doctor, or other primary care physician can also initiate treatment for individuals with depressive disorders.

Unipolar depression

While all individuals occasionally experience sadness, individuals with unipolar depressive disorders may experience extreme and profound painful sadness that persists for a period of weeks or even years. A loss of interest in activities such as work, hobbies, or spending time with family is common, and the individual may not be able to experience enjoyment or pleasure in activities they once enjoyed. The feelings of sadness and loss of interest may cause a depressed individual to have trouble functioning in occupational, social, or academic settings.

The unipolar depressive disorders include major depressive disorder, dysthymia, seasonal affective disorder, and other similar depressive illnesses. These disorders share many of the same symptoms but differ in the severity of the illness, the timing of the onset, and the duration of the symptoms. Separate diagnostic categories exist for depressive illnesses caused by general medical conditions and those due to the direct physiologic effects of a substance. In a minority of individuals, depressive episodes might be accompanied by psychotic symptoms, for example hearing auditory hallucinations or having bizarre delusions.

There is a wide gradient in the severity of symptoms in unipolar depression, and the symptoms can vary dramatically. Mild depression may be characterized by a low-grade but persistent sadness, the inability to feel happy, or a low level of energy and interest. Severe depression can be so incapacitating that an individual is unable to get out of bed for weeks or months at a time or is in such great emotional pain that he or she is driven to commit suicide. While depressive illnesses are under reported to health care providers, they usually respond well once treatment is initiated.

Major depression

A major depressive episode is characterized by either feelings of sadness or a loss of interest that persists for at least two weeks and causes difficulties in an individual's functioning at work, school, home, or in relationships with friends or family. Other common symptoms that might be present include:

  • A low mood for most of the day
  • Feelings of guilt
  • Feelings of worthlessness
  • Feeling nervous or anxious
  • Feeling slow and sluggish
  • Changes in appetite/weight loss or gain
  • Irritability or agitation
  • Trouble sleeping or sleeping too much
  • Decreased libido
  • Having trouble with concentration or memory
  • Loss of energy or feeling fatigued
  • Unexplained physical symptoms
  • Frequently experiencing breakdowns or crying
  • Thoughts of suicide or thoughts or wishes of death

Most individuals with major depression will not have all or even most of these symptoms. Individuals may also have "masked" depression, when they do not realize that they are depressed, but it is noticed by others. Major depressive episodes are classified as being mild, moderate, severe with or without psychotic symptoms (e.g., hearing voices). Subtypes of major depressive episodes include catatonic, melancholic, and atypical. If an individual has had more than one major depressive episode, then the diagnosis of major depressive disorder can be made.

Individuals with a major depressive episode or major depressive disorder are at increased risk for suicide. It is common for depressed individuals to feel that they are somehow responsible and "to blame" for the way they are feeling, and it is easy for them to believe that others are "better off without them". It is vital that professional help and treatment is sought as soon as possible and that treatment follows. Seeking help and treatment from a health professional dramatically reduces the individual's risk for suicide. Research studies have demonstrated that asking if a depressed friend or family member has thought of committing suicide is an effective way of identifying those at risk, and it does not "plant" the idea or increase an individual's risk for suicide in any way.

Both antidepressant medications and psychotherapy are used to treat major depression. Studies have demonstrated that the combination of an antidepressant medication with psychotherapy is more likely to be effective than either treatment alone. The selective serotonin reuptake inhibitors (SSRIs) such as sertraline (Zoloft) and paroxetine (Paxil), serotonin-norepinephrine reuptake inhibitors such as venlafaxine (Effexor), and bupropion (Wellbutrin), a norepinephrine and dopamine reuptake inhibitor, are the most common first-line drugs used to treat major depression. These drugs are typically used first due to their favorable side effect profiles. Other older classes of drugs such as tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs) are sometimes used as well. Studies have demonstrated that most approved antidepressants have comparable efficacies, and so the selection of a particular medication is usually based on its side effect profile. Cognitive behavioral therapy, a type of psychotherapy that focuses on how thoughts and behaviors affect mood, has been shown to be effective in treating major depression. Other types of psychotherapy including psychoanalysis, psychodynamic psychotherapy, and interpersonal psychotherapy are also commonly used and may be effective as well.

Dysthymia

Dysthymia (also referred to as Dysthymic Disorder) is a chronic low grade depression that is less severe than a major depressive episode but that persists for at least two years during which the individual is not without the depressive symptoms for more than two months. Dysthymia is often characterized by a disinterest in activities, an inability to feel enjoyment or pleasure, and/or feelings of chronic sadness. Like with major depression, there is some decrease in functioning at work, school, or home or difficulty in relationships with friends or family members. Individuals with dysthymia can have the same symptoms as those with major depression. So-called "double depression" can exist when an individual with dysthymia develops a major depressive disorder as well. The treatment of dysthymia is largely the same as for major depression, including antidepressant medications and psychotherapy.

Seasonal affective disorder

Seasonal affective disorder (SAD) is a type of unipolar depression that develops annually, usually in the winter when the sun's light is less intense and the length of the day is shorter. People who live at higher latitudes tend to have less sunlight exposure in the winter and therefore experience higher rates of SAD. SAD is also more prevalent in people who are younger and typically affects more females than males

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), the criteria for seasonal affective disorder include:

  • The person experiences a regular pattern of depressive episodes, which begin at a certain time of the year
  • The depressed mood also stops or changes at a regular time each year
  • It has lasted longer than 2 years
  • The person has experienced more seasonal types of depression than other types (major depression for example)

Eventually, with the onset of spring, the affected individual comes out of the depressive episode, and depending on circumstances, the improvement may be almost immediate. The emotional difficulties that occur with major depressive episodes may also occur with SAD; however, compared with individuals with non-seasonal major depressive episodes, individuals with SAD are more likely to report increased sleep, increased appetite, weight gain, and consuming greater amounts of foods high in sugars and carbohydrates.

The treatment of SAD usually involves antidepressant medications, especially the selective serotonin reuptake inhibitors (SSRIs), and bright light therapy. In bright light therapy, an individual sits directly in front of a specially designed bright light that usually delivers 10,000 lumens of light at a distance of 18 inches (46 cm). During the light exposure the lamp must be at the proper distance and directed towards the patients eyes, which must be open so that the light enters the eyes and hits the retina. The bright light exposure is typically prescribed for 30 to 45 minutes shortly after awakening in the morning.

A very small minority of individuals with seasonal affective disorder have recurrent depressive episode during summer and starting to feel better towards winter. This is known as summer SAD and is quite rare.

Bipolar depression

Bipolar disorders (previously known as manic depression) are characterized by alternating periods of depressed mood and extremely elevated mood. A manic episode is a period of elevated mood that is often characterized by feelings of elation, increased energy, and racing thoughts. Some manic episodes are also accompanied by psychotic symptoms such as hallucinations or delusions, particularly delusions of grandeur.

Individuals with bipolar disorders people experience both poles of mood—the extreme highs and the extreme lows. The bipolar disorders include bipolar I disorder, bipolar II disorder, and cyclothymia ("cycling mood" in Latin).

Bipolar I disorder

People with bipolar I disorder have periods where they meet the classification for major depression, then eventually their mood alters and they begin to experience the extreme opposite - increased energy and feelings of wellbeing.

Possible major depression phase symptoms
  • Loss of interest and enjoyment
  • Reduced energy
  • Fatigue
  • Lethargy
  • Apathy
  • Depressed mood
  • Lowered concentration and attention
  • Reduced self-esteem and self-confidence
  • Guilt
  • Unworthiness
  • Becoming pessimistic
  • Diminished sleep and appetite
  • Ideas or acts of self-harm or suicide
Possible manic phase symptoms
  • A distinct increase in energy and activity
  • Impaired judgement
  • Lack of insight
  • Distractability
  • Hostile behaviour
  • Disjointed thinking
  • Feelings of wellbeing
  • Physical efficiency
  • Mental efficiency

While a person experiencing mania may appear more sociable and talkative, they may feel like they are losing control with all these extreme feelings. With bipolar I, the person may also experience paranoia and hallucinations which modify their perceptions of the world around them.

 Bipolar II disorder

A person with bipolar II disorder will experience both ups and downs such as those with Bipolar I, and feel the same sense of depression. However, the important difference between Bipolar I and II is that the person experiences hypomania, not mania. Hypomanic symptoms include becoming more sociable, feeling the constant need to talk, being extremely friendly, experiencing a decrease in the amount of sleep needed.

A person with bipolar II disorder will not have hallucinations or paranoid ideas. The manic feelings are less extreme in this type of Bipolar Disorder, however the impact on the person can be similar. The depression phase of both conditions is what causes the most impairment to life. This phase lasts longer than the manic or hypomanic phases and is considered to be the most distressing feature of Bipolar Disorder.

Cyclothymia

Cyclothymia is a related condition to bipolar disorder; however, bipolar disorder can improve within a number of years, while cyclothymia is a chronic condition that can last for a longer time. The symptoms of bipolar II disorderdo not necessarily lead to a disruption in social or occupational environments, although they have the potential to negatively impact the life of those affected.

Postpartum depression

Postpartum depression does not differ diagnostically from other forms of unipolar or bipolar depression except that its onset is within the first four weeks after giving birth. It is thought to be brought about by the hormonal and social changes that follow birth including the constant time demands and interruption of sleep that occur with a newborn, a changing relationship with a partner, the loss of independence, losing contact with friends, adjusting to a different lifestyle, and increased financial pressures from new expenses and reduce income. Earlier life events may contribute to the susceptibility for postpartum depression. Women who have experienced poor parenting when they were young may be more at risk. A history of abuse is also a risk factor that can predispose a woman to postpartum depression. The severity of the depression can range from mild to very severe, and the length can vary from two weeks to months or even greater than a year.

It is quite common for women to experience the "baby blues", a short term feeling of tiredness and sadness in the first few weeks after giving birth. However, postpartum depression is different because it can cause significant hardship and impaired functioning at home, work, or school as well as possibly difficulty in relationships with family members, spouses, friends, or even problems bonding with the newborn.

Treatment of postpartum depression can be complicated by the fact that many women wish to avoid taking medications in order to continue breastfeeding. It is important to evaluate the possible benefits of pharmacological treatments versus the possible benefits of breastfeeding and the possible risks of breastfeeding if a medication will be prescribed. Not all medications are transmitted via breast milk, and of those that are transmitted via breast milk, some are transmitted at only trace concentrations and some might pose little or no risk to the infant. In the treatment of postpartum major depressive disorders and other unipolar depressions in women who are breastfeeding, nortriptyline, paroxetine (Paxil), and sertraline (Zoloft) are generally considered to be the preferred medications.

Other mood disorders

Other depressive disorders include mood disorders due to a general medical condition and substance-induced mood disorders. Both of these types of mood disorders can have episodes that are manic, depressive, or mixed. Mood disorders due to a general medical condition can not be due to delirium, the direct physiological effects of a substance or medication, or be more easily explained by the diagnosis of other mental disorder. There must be evidence of the general medical condition provided by the history, physical exam, or laboratory test findings. Substance-induced mood disorders must be due to the direct physiological effects of a medication or other substance, including intoxication or withdrawal, and the onset must occur within one month of the use of the medication or other substance. There also must be evidence from the patient's history, physical exam, or laboratory test findings that the medication of substance is etiologically related to the development of the mood disorder.

A depressed mood can also be classified as adjustment disorder with depressed mood when the depressed mood can be linked to a particular stressful life event. For mood disorders not described by any of the diagnostic criteria, a separate diagnostic category exists for mood disorders not otherwise specified (NOS).

Schizoaffective disorder, which is actually classified as a psychotic disorder, is diagnosed when an individual with schizophrenia develops a manic episode, depressed episode, or mixed episode that fits the diagnostic criteria.

Co-occurring disorders

Individuals with a variety of other mental disorders are at higher risk for a co-occurring mood disorders. These other mental disorders include: generalized anxiety disorder, obsessive-compulsive disorder, panic disorder, agoraphobia, posttraumatic stress disorder, dementia, Alzheimer's disease, attention-deficit hyperactivity disorder (ADHD), substance abuse disorders, body dysmorphic disorder, conversion disorder, hypochondriasis, pain disorder, somatization disorder, gender identity disorder, anorexia nervosa, bulimia nervosa, and some personality disorders including avoidant personality disorder, dependent personality disorder, and obsessive-compulsive personality disorder.

Conversely, individuals with a mood disorder are also at higher risk for other co-occurring mental disorders. These include: substance abuse disorders, generalized anxiety disorder, panic disorder, agoraphobia, body dysmorphic disorder, hypochondriasis, pain disorder, somatization disorder, anorexia nervosa, and bulimia nervosa.

References

  1. ^ The ICD-10 Classification of Mental and Behavioural Disorders. World Health Organisation. 1993.
  2. ^ The ICD-10 Classification of Mental and Behavioural Disorders World Health Organisation 1993
  3. ^ Lam, Raymond W. and Robert D. Levitan. "Pathophysiology of seasonal affective disorder: A review". Journal of Psychiatry and Neuroscience, 25, 469-480. 2000.
  4. ^ National Institute of Health (USA)
  5. ^ O'Hara, Michael W. "Postpartum Depression: Causes and consequences." 1995.
  6. ^ Weissman, A.M., et al. "Pooled Analysis of Antidepressant Levels in Lactating Mothers, Breast Milk, and Nursing Infants." American Journal of Psychiatry, 161:1066-1078, June 2004.