Differential Diagnosis

The patient's symptoms and history suggest a range of possible diagnoses. Here is a categorized differential diagnosis:

• Single Most Likely Diagnosis
  • Major Depressive Disorder (MDD): The patient's symptoms of daily lack of interest or pleasure in activities, feelings of sadness and hopelessness, fatigue, poor appetite, feelings of failure, and difficulty concentrating are classic for MDD. The patient's history of depression, partial response to antidepressants, and current stressor of divorce also support this diagnosis.
• Other Likely Diagnoses
  • Adjustment Disorder with Mixed Anxiety and Depressed Mood: The patient's symptoms could be triggered by the stress of divorce, and the fact that they have not been on any antidepressant for the past five months suggests that this could be an adjustment disorder.
  • Anxiety Disorder (e.g., Generalized Anxiety Disorder): The patient's symptoms of anxiety, feeling on edge, irritability, and excessive worry could indicate an anxiety disorder.
  • Dysthymia (Persistent Depressive Disorder): The patient's long history of depressive symptoms, despite some response to treatment, could suggest dysthymia.
• Do Not Miss Diagnoses
  • Bipolar Disorder: Although there is no reported history of elevated mood, inflated self-esteem, racing thoughts, increased energy, or decreased need for sleep, it is essential to consider bipolar disorder, as it can be deadly if missed, particularly if the patient is started on an antidepressant without a mood stabilizer.
  • Suicidal Ideation or Behavior: Although the patient has no history of suicidal ideation or attempts, it is crucial to assess for suicidal thoughts, as depression and anxiety can increase the risk of suicide.
  • Substance Use Disorder: The patient's history of taking multiple medications and recent discontinuation of Prozac could suggest substance use or dependence, which would require separate evaluation and treatment.
• Rare Diagnoses
  • Attention Deficit Hyperactivity Disorder (ADHD): Although the patient suspects ADHD, the overlap between MDD and ADHD symptoms, and the lack of specific ADHD symptoms (e.g., hyperactivity, impulsivity), make this a less likely diagnosis.
  • Other Psychotic or Neurodevelopmental Disorders: These diagnoses are unlikely given the patient's presentation and history, but should be considered if the patient's symptoms worsen or if new symptoms emerge.