A 32-year-old patient is cycle between periods of extreme happiness and severe sadness. This pattern is indicative of:

The pattern of experiencing extreme happiness followed by severe sadness is characteristic of bipolar disorder. This mental health condition is defined by significant mood changes that include periods of mania or hypomania (where the individual may feel unusually energetic, euphoric, or irritable) and periods of depression (where they may feel hopeless, sad, or severely diminished in capacity). The cycling between these states is a hallmark feature, distinguishing bipolar disorder from other mood disorders.

In contrast, borderline personality disorder generally involves unstable relationships, self-image, and emotions rather than the distinct manic or depressive episodes seen in bipolar disorder. Schizophrenia is marked by symptoms such as hallucinations or delusions, which do not align with the fluctuation of moods described in the scenario. Major depressive disorder is characterized primarily by persistent feelings of sadness and lack of interest, without the manic episodes that define bipolar disorder. Thus, the description of cycling between extreme happiness and severe sadness fits perfectly with bipolar disorder.