Differential Diagnosis

• Single most likely diagnosis
  • Major depressive disorder: The patient's symptoms, including headaches, insomnia, feelings of sadness, loss of energy, forgetfulness, difficulty making decisions, and loss of interest in daily activities, have been present for 18 months. Although the symptoms started after the death of his wife, the duration and severity of the symptoms suggest a more complex condition than normal bereavement. Major depressive disorder is a common condition in older adults, especially after significant life events like the loss of a spouse.
• Other Likely diagnoses
  • Bereavement: The patient's symptoms started after the death of his wife, which could suggest a normal grief reaction. However, the duration and severity of the symptoms are beyond what is typically expected for normal bereavement.
  • Adjustment disorder with depressed mood: This diagnosis could be considered if the patient's symptoms were less severe and more directly related to the stress of losing his wife. However, the presence of significant depressive symptoms like loss of interest in daily activities and difficulty making decisions suggests a more severe condition.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Dementia: Although the patient's symptoms could be suggestive of depression, it is essential to rule out dementia, especially given his age and symptoms like forgetfulness and difficulty making decisions. Dementia can present with depressive symptoms, and missing this diagnosis could lead to delayed treatment and poor outcomes.
• Rare diagnoses
  • Persistent depressive disorder (dysthymia): This diagnosis is less likely given the patient's age and the fact that his symptoms started after a significant life event. Persistent depressive disorder typically has an earlier onset and a more chronic course.