Which symptom could help diagnose bipolar disorder over borderline personality disorder?

The correct choice involves the lack of interest in activities, which is known as anhedonia. This symptom is more closely associated with the depressive episodes that occur in bipolar disorder, particularly during the depressive phase. Individuals with bipolar disorder can experience significant mood fluctuations, alternating between manic and depressive episodes. During the depressive phases, they often show a marked lack of interest or pleasure in almost all activities, which is a key characteristic that can differentiate bipolar disorder from borderline personality disorder.

Borderline personality disorder, on the other hand, is primarily defined by patterns of unstable relationships, self-image, and emotions, where individuals may experience intense emotional responses but do not typically present with the same type of profound anhedonia. While both disorders can have overlapping symptoms such as mood instability and impulsive behaviors, the presence of anhedonia during depressive episodes is more indicative of bipolar disorder. Thus, recognizing this symptom can be crucial for accurate diagnosis and treatment planning.