Differential Diagnosis

The patient's symptoms include a significant change in behavior, weight loss, altered sleep patterns, deteriorated school performance, defiance, and mood swings. Considering these symptoms, the differential diagnosis can be categorized as follows:

• Single Most Likely Diagnosis

  • B) Major Depressive Disorder: This is the most likely diagnosis due to the patient's persistent feelings of sadness, tearfulness, and loss of interest in activities (e.g., school). The weight loss, changes in sleep patterns (initially oversleeping and then experiencing insomnia), and decreased school performance are also consistent with major depressive disorder.

• Other Likely Diagnoses

  • C) Marijuana Use Disorder: The patient's behavioral changes, such as defiance, stealing, and loss of interest in activities, could be indicative of substance use. Marijuana use can lead to mood swings, altered sleep patterns, and changes in appetite, which might explain the weight loss.
  • E) Stimulant Use Disorder: The recent increase in energy levels and inability to sleep could suggest stimulant use. However, this would not fully explain the initial oversleeping and the overall pattern of behavior.

• Do Not Miss Diagnoses

  • Bipolar Disorder: Although not listed, bipolar disorder is a critical diagnosis to consider due to the patient's significant mood swings, from sadness to increased energy and decreased need for sleep. Missing this diagnosis could lead to inappropriate treatment and worsening of symptoms.
  • Substance-Induced Psychotic Disorder or Other Psychotic Disorders: If the patient's behavior and mood swings are accompanied by psychotic symptoms (not explicitly mentioned but possible), these diagnoses must be considered to provide appropriate treatment and prevent harm.

• Rare Diagnoses

  • Schizophrenia: Although rare in adolescents, schizophrenia could present with mood swings, social withdrawal, and behavioral changes. However, the classic symptoms of schizophrenia, such as hallucinations and delusions, are not mentioned in the scenario.
  • Neurodegenerative or Medical Conditions: Certain medical conditions (e.g., hypothyroidism, autoimmune disorders) can present with mood changes, weight loss, and altered sleep patterns. While rare, these conditions should be considered if the patient does not respond to psychiatric treatment or if other systemic symptoms are present.