Unipolar & Bipolar Disorders

Conceptual View of Mood Disorders

As indicated in the concluding section of the preceding literature Opens in new window, a good way to understand mood disorders Opens in new window is to view them in three clusters:

  1. unipolar, in which mood roots itself in a depressive state,
  2. bipolar, in which mood fluctuates between the lows of depression and the highs of mania, and
  3. other, in which mood is affected by other disorders or conditions.

These varying mood disorders are listed in Table X-1.

Table X-1. Mood Disorders
Major Depressive DisorderBipolar Disorder IMood Disoder Due to Medical Condition
  1. Seasonal Onset
Bipolar Disorder IISubstance-Induced Mood Disorder
  1. Postpartum Onset
Cyclothymic DisorderMood Disorder Not Otherwise Specified
Dysthymic DisorderBipolar Disorder NOSAdjustment Disorder with Depressed Mood (ADDM)

In order to fully understand these disorders, it’s important to explain the definition of unipolar and bipolar. The term “polar” implies that the range of human emotions has at one end despair, while the other endpoint is mania Opens in new window.

Psychiatrists have noted that healthy well-being involves a variety of feelings—good, bad, and in-between. If a child or adult was in the midst of a unipolar experience, the ebb and flow of emotions would linger in the margins of depression and despair.

Unmoored and adrift, these feeling states and cognitive levels never sustain the upbeat ranges. The course of illness would range from “despair”, “well-being”, and “mania”.

The bipolar experience involves the polar extremes of despair and mania—and pitches the individual from one pole to the other. The intensity and length of time for each mood swing is uniquely specific to each person.

Mood swings can be rapid or slow in their cycling. In fact, the intensity, timing, and frequency of a mood swing helps to determine which type of bipolar disorder is operating.

Now that you have a working understanding of these disorders, let’s summarize each one in more detail.


There are three unipolar disorders that comprise the depressive experience.

Those who have a unipolar disorder experience varying degrees of deep, unshakable sadness, loss of interest, slow thinking, poor judgment, and in some cases, suicidal thinking.

Major Depressive Disorder (MDD)

Major depressive disorder is the most serious of the unipolar disorders. Patients suffering from major depressive disorder (MDD) must first be determined to be experiencing a major depressive episode. The two key symptoms of a major depressive episode are depressed mood or sadness, and greatly lessened pleasure in most activities.

MDD can be diagnosed after a single depressive episode that has lasted for a period of two weeks. Some of the hallmark symptoms of MDD include depressed mood, fatigue, slowness of thinking, changes in appetie and sleep, and a debilitating sense of hopelessness— which can lead to despair and suicide. MDD can occur in children as well as adults, and symptoms must not come from bereavement, a medical condition, or substance abuse.

MDD can have various types on onset. For example, depression that hits at various seasonal changes will meet the criteria for “seasonal onset.” Depressive symptoms that occur after pregnancy will be diagnosed as “postpartum onset.” Diagnostic specificity for major depressive disorder can include assigning the depressive episode as mild, moderate, severe, or profound, as well as having an early or late onset.

Dysthymic Disorder (DD)

Dysthymic disorder is characterized by depressed or irritable mood for at least one year for children and two years for adults. The depressive experience takes on a less severe form than MDD but is more chronic than major depressive disorder.

Though dysthymic disorder is often described as low-grade depression, the depressive impairment is quite significant. With major depressive disorder, the significant change in mood is more readily noticeable.

Dysthymic symptoms can be harder to detect. Fatigue, irritability, negative thinking, and melancholy can cast an imperceptible shadow—one that may not be seen so clearly. Because of the slow and subtly harmful trajectory of dysthymia, individuals who experience dysthymic disorder can also fall into a major depressive disorder. Double depression is the clinical term used to describe individuals who endure both a major depressive disorder and dysthymic disorder.

Depressive Disorder Not Otherwise Specified (D-NOS)

When depressive symptoms do not meet the criteria for MDD or DD, a diagnosis of “depressive disorder not otherwise specified” can be given. This diagnosis is generally offered when the reason for the presenting depressive characteristics is unclear, but is of significant enough concern to warrant treatment.

The most well known in this category is premenstrual dysphoric disorder (PMDD). The symptoms of PMDD are remarkably similar to those of major depressive disorder (MDD). PMDD is diagnosed when severe depressive symptoms arise before a menstruation cycle. Once menstruation occurs, symptoms improve and eventually resolve.


There are four bipolar disorders that comprise this depressive and elevated mood experience. Those who have a bipolar disorder have a fluctuation of moods, some ranging to the extremes of human experience, from despair to mania—while other symptoms are less intense in their arc.

The experience of bipolar disorders involves a greater fluctuation of moods than do unipolar disorders. Because of this variability, bipolar disorders possess a slightly greater level of pathological risk.

Bipolar Disorder I (BD-I)

Bipolar I disorder is the most serious of the bipolar disorders and is diagnosed after at least one episode of mania. Mania is defined as an elevated mood where euphoria, impulsivity, irritability, racing thoughts, and decreased need for sleep significantly impair judgment and daily functioning. Children or adults with bipolar I disorder typically also have a major depressive episode in the course of their lives, but this is not needed for initial diagnosis.

Bipolar Disorder II (BD-II)

Bipolar II disorder is characterized by at least one major depressive episode and an observable hypomanic episode. Hypomania is a milder form of elevated mood than is mania and does not necessarily impact daily functioning. Sometimes called “soft bipolar disorder,” the symptoms are less intense than bipolar I, but more chronic.

Cyclothymic Disorder (CD)

In cyclothymic disorder, there are numerous hypomanic periods, usually of a relatively short duration, that alternate with clusters of depressive symptoms.

The sequence and experience of these symptoms do not meet the criteria of major depressive disorder or bipolar I or II.

The mood fluctuations are chronic and have to be present at least two years before a diagnosis of cyclothymic can be made. Many individuals with cyclothymic disorder eventually develop bipolar disorder I or II.

Bipolar Disorder Not Otherwise Specified (BD-NOS)

For symptoms that don’t align with the above-mentioned disorders or follow a different pattern of euphoric and dysphoric symptoms, “bipolar disorder not otherwise specified” may be used as a diagnosis.

Researchers and professionals believe that bipolar disorders has a spectrum of experience and expression—and that current diagnostic manuals may change as research better defines bipolar disorders.


There are times when specific situations and/or medical conditions can alter mood. In those cases, symptoms fall into the category of “other mood disorder.” The categories in this section include.

Adjustment Disorder with Depressed Mood (ADDM)

When a child or an adult moves through identifiable traumas or stressors, and reports depressive symptoms, “adjustment disorder with depressed mood” is diagnosed. Criteria for ADDM is met if symptoms occur within three months of the identified trauma and do not persist longer than six months.

Mood Disorder Due to Medical Condition

Mood disturbances often accompany medical conditions. For example, hypoglycemia (low blood sugar) can spike irritability. Anemia (iron-poor blood) can fatigue and make a person feel listless. Hypothyroidism (hormone imbalance) can flatten or even agitate mood.

Mood changes may also occur from the psychological stress of coping with a medical condition or may be caused by the illness itself or by the medications used to treat it. This is why it’s so important to obtain a differential diagnosis—a diagnosis that evaluates all possibilities for symptoms.

Substance-Induced Mood Disorder

Substance-induced mood disorder is the diagnosis if mood changes are the direct result of substances such as drugs, alcohol, medications, or exposure to toxins.

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    The research data for this work heavily relied on:
  1. Living with Depression: Why Biology and Biography Matter along the Path to ... By Deborah Serani
  2. Oxford Handbook of Psychiatry By David Semple, Roger Smyth