**Question:** A 19 year-old woman is brought to psychiatry outpatient by her boyfriend for depression and suicidal thoughts. Boyfriend reports that patient yesterday expressed extreme sadness and desire to die. The boyfriend reports that they, along with a couple of friends, had been partying for the last three days as exams had ended and, on further prodding, revealed that they used alcohol and 'other things' too. He further reports that the patient was in great spirits and was enjoying till yesterday, however subsequently she slept for 20 hours, missed the college and was looking very tired. The patient herself reports that she is feeling very low, and feeling hungry and that she saw very vivid and upsetting dreams during the sleep? Which of the following is the most likely diagnosis in this patient?

A. Major Depressive Episode
B. Postpartum Depression
C. Substance-Induced Mental Disorder
D. Acute Psychotic Disorder

**Correct Answer:** C. Substance-Induced Mental Disorder

**Core Concept:**

In this scenario, the patient presents with symptoms such as mood disturbance, suicidal ideation, sleep disturbance, and vivid dreams, which are indicative of a mental health issue. These symptoms are likely caused by the use of substances, specifically alcohol and "other things," which were consumed during a period of intense partying lasting three days, following exam stress relief.

**Why the Correct Answer is C:**

The most appropriate diagnosis in this case is Substance-Induced Mental Disorder (option C). This diagnosis considers the patient's symptoms to be a result of the consumption of substances (alcohol and other substances) during the intense partying following stress relief from exams. The symptoms experienced by the patient, including mood disturbance, suicidal ideation, sleep disturbance, and vivid dreams, align with the clinical manifestations of a mental disorder induced by substances.

**Why Other Options are Incorrect:**

A) Major Depressive Episode (option A) might be considered initially, but the sudden onset and resolution of symptoms along with the influence of substances would make this diagnosis less likely.

B) Postpartum Depression (option B) is less likely as the patient is not pregnant and the symptoms started after the intense partying.

D) Acute Psychotic Disorder (option D) may be considered, but the influence of the consumed substances and the sudden onset and resolution of symptoms make this diagnosis less probable.

A thorough assessment and further evaluation are essential to confirm the diagnosis and address the substance abuse issues, as well as any existing psychiatric condition if present. It is crucial to determine the type of substance(s) consumed to develop an appropriate treatment plan.