Individuals who have bipolar disorder go through different periods of moods that are dictated by time. At one point, they may seem to be in a deep depression and exhibit most or all of the symptoms of depressive disorder. Then, at another point, the same individual may exhibit none of these depressive symptoms, and seem to be overly elevated in their mood and behaviors, seeming overly euphoric or like they have an excess of energy that is quite a contrast to the low energy levels observed during the depressive episode.
Because of this, there are also some links between bipolar disorder and schizophrenia, but the two disorders should not be confused. “In bipolar disorder, episodes of minor to severe depression and episodes of hypomania or mania occur over a course of time. Rarely, patients have recurrent episodes of mania without ever having a depressive episode” (Dilsaver, 1989). Schizophrenia has been observed to have signs of gradual deterioration in the individual as they exhibit symptoms that get worse and worse, while bipolar disorder has been observed to go into remission and then recur while the individual goes back to baseline behavior.
Bipolar individuals are classified as type I bipolar and type II bipolar. In type I cases, the depressive episodes are severe and are considered to be major, and the manic episodes are also considered to be major. In type II cases, the depressive episodes are still major, while the manic episodes are not. It is also possible for individuals to suffer both minor depressive and minor manic episodes, but less is known about this sort of bipolar condition. Generally, bipolar disorder is seen to be a major disorder that shows
itself in symptoms of exaggerated moods and behaviors that change. It is the changing of the moods and behaviors that makes the disorder bipolar. These changes occur between what are considered to be episodes. Bipolar individuals go through depressive and manic episodes over time, and also return to baseline behavior. Bipolar disorder is less prevalent than depressive disorder but is more prevalent than schizophrenia. One reason for this could be problems in the epidemiology due to misdiagnosis.
As mentioned above, psychiatrists who deal with patients on a cross- sectional level only may not pick up on the signs of bipolar disorder because it must also be looked at longitudinally. Therefore, many individuals currently diagnosed with severe depression may actually be bipolar, if they exhibit mood swings that bring them to the manic end of the scale.
These mood swings may not be observed unless the patient is looked at longitudinally. In fact, many individuals with bipolar disorder have been diagnosed earlier with depression, and this is even one of the preconditions of diagnosis. So this may affect the epidemiology of bipolar disorder because it is particularly difficult to diagnose properly without looking at the patient over a span of at least two episodes, between which they may baseline for an indeterminate amount of time and exhibit no mood swings at all. Therefore there may be more individuals in the population with bipolar disorder than current epidemiological studies account for, due to the trickiness of the diagnosis.