Chapter 3: Mood Disorders
Everyone feels down or euphoric from time to time, but this is different from having a mood disorder like major depressive disorder or bipolar disorder. Mood disorders are extended periods of depressed, euphoric, or irritable moods that in combination with other symptoms cause the person distress and interfere with their life.
Mood episodes are shortened periods of mood disruption. A major depressive episode refers to symptoms that last for at least two weeks and cause significant distress or impairment in functioning. Core symptoms include low mood and anhedonia.
Manic and hypomanic episodes are periods of abnormally and persistently euphoric, expansive, or irritable mood and persistently increased goal-directed activity or energy. For mania this must be present for one week or longer, or four days for hypomania.
There are two major types of unipolar mood disorders: major depressive disorder, which is defined by one or more major depressive episodes, and persistent depressive disorder, which is feeling depressed most days for at least two years.
Bipiolar I disorder is characterized by a single or recurrent manic episode whereas Bipolar II is characterized by a single or recurrent hypomanic episode. Cyclothymic disorder is characterized by numerous and alternating periods of hypomania and depression, lasting at least two years.
The lifetime prevalence rate for major depression in Canada is 11.2%. The average age of onset for depression is in the mid-20s, and an earlier age of onset predicts a worse course. About 5-10% of people who experience a major depressive episode will later experience mania.
Women experience 2-3 times higher rates of major depression than men do, although before puberty rates of childhood depression are equal for boys and girls. Major depression is inversely related to socioeconomic status. Unfortunately, sexual minorities experience much higher rates of depression than the general population.
The lifetime prevalence rate for bipolar disorder is 2.6% in Canada. The majority of people with bipolar disorder also meet criteria for another disorder. Adolescence is a significant risk period for bipolar disorder.
Multiple variables are implicated in the development of depressive disorders including genetic factors, stressful life events, early adversity, chronic stress, and attributional styles.
Bipolar disorder is highly heritable and might fundamentally be a biological phenomenon. However, as each person experiences the course of their bipolar disorder differently, environmental variables still impact it including stress and social rhythms.
There are many treatment options for depression including antidepressant medication, electroconvulsive therapy, transcranial magnetic stimulation, deep brain stimulation, cognitive-behavioural therapy, interpersonal therapy, psychodynamic therapy, and mindfulness-based cognitive therapy.
Patients with bipolar disorder are typically treated with lithium, Interpersonal and social rhythm therapy is also effective for bipolar disorder.