Evolving Diagnosis in Psychological Disorders

Maria, a 28-year-old teacher, has recently been feeling overwhelmed by her daily life. She reports persistent feelings of sadness and anxiety, including difficulty concentrating and sleeping. Despite her best efforts, she struggles to engage in activities she once enjoyed, leading to feelings of hopelessness. After consulting with a therapist, Maria is diagnosed with Major Depressive Disorder (MDD). As her treatment progresses, she begins to exhibit episodes of elevated mood, increased energy, and impulsive behavior, leading to significant changes in her social and occupational functioning.

Given the above scenario, which of the following best describes a potential diagnosis that could explain Maria's evolving symptoms?