A 28-year-old female presents with low mood, decreased energy, and loss of interest for several weeks. She reports that at times her mood suddenly shifts to periods of increased energy, reduced need for sleep, and elevated mood. What is the most likely diagnosis?

Appeared in: NORCET 10 Prelims-2026

Explanation

The patient's report of distinct periods of low mood/energy (depression) and periods of high energy/elevated mood with reduced sleep (mania/hypomania) is the classic presentation of bipolar disorder.
The diagnosis hinges on identifying these two opposite mood poles, which distinguishes it from unipolar depression.
Bipolar disorder is characterized by these cyclical shifts in mood, energy, and activity levels, as described in the patient's history.

Option A: Major Depressive Disorder (MDD) does not include manic or hypomanic episodes. The patient's history of high-energy periods with elevated mood and reduced need for sleep explicitly rules out a diagnosis of MDD alone.
Option C: Generalized Anxiety Disorder (GAD) is primarily characterized by persistent, excessive, and uncontrollable worry, not the distinct, episodic mood swings between depression and mania described in the scenario.
Option D: While Borderline Personality Disorder (BPD) involves mood instability, the shifts are typically more rapid (lasting hours to days), often triggered by interpersonal stressors, and part of a larger pattern of unstable relationships and self-image. The patient's symptoms suggest more sustained, distinct episodes.

Visual 1: Chart: A comparative chart showing the mood fluctuations over time in Major Depression, Bipolar I, Bipolar II, and Cyclothymia to visually represent the different patterns.
Visual 2: Infographic: Key diagnostic criteria for a manic episode vs. a depressive episode according to DSM-5.

Clinical Relevance

Nursing practice connection: Use the key finding related to Differential diagnosis of mood disorders based on clinical presentation to guide bedside assessment, documentation, and the next nursing action.
Accurate diagnosis is critical because prescribing antidepressants alone to a patient with undiagnosed bipolar disorder can trigger a manic episode, worsening their condition. Mood stabilizers are the cornerstone of treatment.
Nurses must prioritize patient safety, which involves suicide risk assessment during depressive phases and managing impulsivity and potential for self-harm during manic phases.
What if the patient's high-energy periods only lasted 4 days and didn't cause significant functional impairment? The diagnosis would more likely be Bipolar II Disorder, which involves hypomania rather than full mania.

How to Approach the Question

First, analyze the patient's symptoms presented in the clinical vignette.
Identify the key features: there are two distinct sets of symptoms—one cluster for depression (low mood, low energy) and another for mania (high mood, high energy, less sleep).
Evaluate the options based on these clusters. The diagnosis must account for both sets of symptoms.
Rule out disorders that only account for one part of the clinical picture (like Depression) or have different characteristic patterns (like GAD or BPD).
Select the diagnosis that encompasses the full range of the patient's episodic mood swings.

Concept Tested & Keywords

Concept Tested: Differential diagnosis of mood disorders based on clinical presentation.
Stem keywords: low mood, decreased energy, loss of interest, increased energy, reduced need for sleep, elevated mood
Lead-in keywords: most likely diagnosis
Clinical cues: The presence of distinct, alternating periods of depressive and manic symptoms is the key clinical cue.
Negative lead-in flag: false

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Attempt every question from this paper in a timed mock, then review the full solution for each one.