Bipolar disorder is primarily characterized by:

Bipolar disorder is primarily characterized by rapid shifts between manic and depressive episodes. This condition involves significant mood swings that can include periods of intense euphoria, energy, and irritability covered under mania, as well as episodes of deep sadness, hopelessness, and lethargy associated with depression. The fluctuation between these two extremes is a defining feature of the disorder, which distinguishes it from other mood disorders.

In this context, focusing on the nature of bipolar disorder encompasses not just the occurrence of these episodes, but also their impact on daily functioning and relationships. The presence of both manic and depressive phases is crucial; thus, the description of rapid shifts accurately portrays the core aspect of bipolar disorder.

The other options do not capture the full scope of bipolar disorder. For instance, stating that it is characterized solely by intense episodes of depression overlooks the manic episodes that are equally significant. Describing it as a chronic state of hypomania misses the critical element of depressive episodes that contrasts so dramatically with hypomania. Finally, the idea of consistent mood stability is fundamentally inaccurate, as the hallmark of bipolar disorder is indeed the variability in mood states.