Bipolar Disorder versus Unipolar Depression
Unipolar depression (or Major Deperssion, or Major Depressive Disorderis like bipolar depression without the mania. It consists purely of major depression's depressive episodes without mixed or manic episodes to break things up. In contrast to bipolar mood cycling, a person with major depression does not swing out of the low energy depressive state but rather remains there until the disorder has run its course. Unipolar depression may strike one time, or it may reoccur repeatedly as a series of episodes.
Although there is some debate about whether unipolar depression is a form of bipolar disorder, the evidence currently seems to support the idea that there are two distinct but related mental illnesses at work. Firstly, unipolar depression (lifetime prevalence being approximately 5%) occurs more commonly than bipolar disorder (lifetime prevalence of approximately 1%). Also, more women are affected by unipolar depression than by bipolar disorder. Furthermore, bipolar disorder has an onset at a younger age on average, and shorter intervals between episodes once it is established, thus producing more episodes during a lifetime. In addition, treatment for unipolar depression differs from that of bipolar disorders. Unipolar depression can be treated with antidepressants alone, whereas bipolar disorder treatment requires the use of mood stabilizing drugs (which are different than antidepressant drugs). Antidepressant drugs are used to treat bipolar disorder, but generally in conjunction with mood stabilizers and not alone.
Bipolar Disorder versus Premenstrual Dysphoric Disorder
Another disorder that can be confused with bipolar disorder symptoms is Premenstrual Dysphoric Disorder (PMDD), which in the past was known as Late Luteal Phase Dysphoric Disorder. PMDD is a female-only mental health disorder characterized by serious premenstrual distress, and associated deterioration of social and emotional functioning. Women with PMDD experience a labile (changeable) mood disorder which may manifest in the form of anxiety, depression, irritability or anger, beginning approximately one week before menstruation. The difference between PMDD and regular old premenstrual symptoms (e.g., PMS) is largely a matter of severity rather than kind. PMDD symptoms are severe enough that they interfere with occupational and social functioning. For example, women who routinely must take a few days off from school or work before they get their period may have PMDD. Typically, symptoms subside a few days after the onset of menses.
Although PMDD and bipolar disorder are both associated with labile and rather extreme mood states, the two problems can be differentiated based on the rather tight synchronization of PMDD mood swings with the menstrual cycle. In contrast, the mood swings associated with bipolar disorder are not tightly linked to any regular body cycle.
Because physiological (body) illnesses, substance abuse, and other mental disorders can mimic bipolar mood symptoms, it is important that any clinician attempting to diagnose bipolar affective disorder be careful to rule out alternative causes for observed symptoms. A definitive diagnosis of bipolar disorder can only be made after a patient has been medically screened and cleared for other medical conditions which might contradict bipolar disorder diagnosis, has been sober for a long enough time for any suspected substances that might influence mood to have cleared the body, and is known not to have other mental disorders which would contradict bipolar disorder. This process takes some time to complete. Though a provisional diagnosis may be made rather quickly, so as to facilitate rapid treatment, it is common for doctors to hold off making a final and definitive bipolar disorder diagnosis until they have had time to observe a patient over a period of several months, and conduct a review of any past hospitalizations and treatments which may have occurred