About 12 years ago when I was a psychiatric resident, I was taught that there were two kinds of mood disturbance. The most common pattern of mood disturbance consisted of periods of depression lasting at least a couple weeks, alternating with periods of normal mood. This was called major depressive illness, or unipolar (only one pole, down) affective (which means mood in psychiatric jargon) disorder. A second, less common pattern, was marked by not only periods of depression with intervening normal mood, but also periods of elevated mood lasting at least a week. The periods of elevated mood were called manic episodes and the disorder manic depressive illness or Bipolar (two poles, up and down) Affective Disorder. A third pattern which you might expect, manic and normal mood without depression, was very seldom observed, and it was thought that anyone who had a manic episode would eventually have a depressive episode.
Over the last decade it has become increasingly clear that the picture is much more complex. More importantly, some mood patterns, such as mixed or rapid cycling mood disturbance (see below) may respond better to certain medications. This has led to increased interest in describing mood disturbances, and, perhaps not co-incidentally, these "atypical" mood patterns are being diagnosed more and more frequently.
The identifying diagnostic feature of Bipolar Disorder is the occurrence of one or more Manic Episode. Most, but not all, people with this disorder will also experience one or more Major Depressive Episodes at some point in time. Manic Episodes are periods of abnormally euphoric, expansive, grandiose, or irritable mood, which is distinctly different from the person's normal non-depressed mood. However, mood does not have to be elevated; it can be predominately irritable, usually a "get-out-of-my-way" sort of irritability. In either case, central nervous system activity is increased, marked by increased mental and physical activity, decreased need for sleep, increased talkativeness, racing thoughts, distractibility, and often increased sexual drive. Characteristically, individuals take on too much, and engage in pleasurable activities without regard for their painful consequences. Thinking and judgement can be severely effected, and sometimes delusions and/or hallucinations appear. Diagnosis requires that the manic episode must be of at least a week duration, although shorter episodes are of clinical significance as described below. A manic episode must cause significant distress or impairment in functioning to meet diagnostic criteria.
Bipolar mood disturbance is a recurrent illness, and over 90 percent of people who have a manic episode will have future episodes of mania or depression. Although this is not true for all patients, there is a tendency for episodes to become increasingly severe and more often to occur spontaneously rather than in response to loss or stressful event. Some recent research suggests that preventing manic episodes may improve the long term course of the illness, making early diagnosis and treatment especially important
See DSM-IV Criteria for detailed diagnostic criteria for a Manic Episode and for Bipolar I Disorder.
Some individuals have distinct periods of elevated mood which are clinically significant but which do not meet the criteria for true Manic Episodes, either because of shorter duration, or because they do not interfere as severely with their ability to function. Such episodes are called Hypomanic Episodes. "Hypo" means "a little" so hypomanic really means "a little manic." Individuals with hypomania may not complain, or may even like their elevated mood. However, their impulsive behavior can be troubling to others, and they may eventually begin to complain that their unstable mood in interfering with their lives in various ways.
A mood pattern marked by Hypomanic Episodes as well as Major Depressive Episodes in the absence of any true Manic Episodes is called Bipolar II Disorder. Although less severe, Bipolar II Disorder appears to be more similar to Bipolar I Disorder than to Major Depressive Illness with regard to its response to treatment, clinical course, and risk of being exacerbated by antidepressants (see below).
See DSM-IV Criteria for a Hypomanic Episode and for Bipolar II Disorder.
Rapid-Cycling and Mixed Bipolar Illness
Recently, there has been increasing interest in several other abnormal mood patters. Some individuals may experience rapid shifts between depressed and elevated mood, Such swings can occur monthly, weekly, daily, or even several times per day. These Rapid Cycling mood disturbance can occur spontaneously, or can be triggered by antidepressant treatment (see below). Rapid cycling mood disturbance can be very disabling and is often difficult to treat. It may respond better to anticonvulsant medications such as Depakote or Neurontin than to lithium. DSM-IV does not currently have a category for many types of rapid-cycling mood disturbance, and they are classified as Mood Disorders Not Otherwise Specified if the individual does not also meet criteria for Bipolar I or Bipolar II disorder (although if they do, there is a "Rapid Cycling Specifier"). In my opinion, our understanding of these more complex mood pictures is poor, and more research is clearly needed to clarify their relationship to classic bipolar illness and their treatment implications.
Some individuals may develop symptoms of depression and mania at the same time. This is called a Mixed Episode in DSM-IV if all of the criteria for both a Depressive Episode and a Mixed Episode are met. By this definition, mixed episodes are rather rare. However, it is more common to see a combination of depression with agitation or some symptoms of mania, or hypomania with some depressive features. Many clinicians are coming to believe that these conditions are part of a "bipolar spectrum" and are best treated with mood stabilizing agents.
Many individuals who have a history of severe childhood trauma suffer from a number of psychological symptoms, including unstable mood which may appear to fit a mixed or rapid-cycling pattern. This has been called Complex Post-Traumatic Stress Disorder by some experts in the field who believe there is a causal relationship between the childhood trauma and adult symptomatology. No one really knows whether this is really a form of bipolar illness or a form of PTSD. In my experience, mood stabilizers such as Depakote or Neurontin are often helpful, but these individuals may also find that SSRI antidepressants make their mood more stable rather than less stable, as would be expected for variants of Bipolar Disorder.
There is increasing concern among psychopharmacologists that antidepressant medications may make mood less stable in individuals with a bipolar type of mood disturbance. For example, a person with bipolar illness who presented as depressed might be started on antidepressants, Initially, the depression would improve as desired, However, the improvement in mood caused by the antidepressant would keep "right on going" until a full-blown manic episode emerged. Or, the person might cycle out of depression, but cycle back in again, with increasing rapidity, and develop a rapid-cycling mood pattern. Or, mixed features of depression and mania might be observed..
In addition, it has been observed that when this occurs, and the antidepressants are stopped, the mood pattern continues to cycle or remains mixed. This has raised the disturbing possibility that antidepressants might permanently "convert" a typical bipolar disorder to one of these more complex mood pictures. Since these are harder to treat, there is concern that antidepressants could actually harm rather than help such individuals. As a result, evidence for a bipolar mood pattern is a relative contraindication to the use of antidepressants, unless a mood stabilizer is prescribed at the same time. Mood stabilizers appear to usually (but not always) protect against this effect.
In my opinion, it is important not to become too alarmed by these observations. Most people who are treated for depression improve and remain stable for many years on antidepressants. In fact, there is a growing body of evidence that individuals with recurrent major depression do better with long-term antidepressant treatment. Also, some individuals with an atypical mood pattern find that their mood becomes more stable on antidepressants. So, the final word on this issue is not yet in. However, these observations need to be taken very seriously, and I would certainly recommend that anyone starting antidepressants have a careful diagnostic evaluation by a qualified psychiatrist or mental health professional if there is any past history or family history suggestive of a bipolar mood disorder.