Which diagnosis is characterized by persistent low mood and fatigue?

• A. Depression
• B. Anxiety
• C. Oppositional Defiant Disorder
• D. Autism Spectrum Disorder

Answer: (A)

Persistent low mood with ongoing fatigue points directly to a mood disorder where the core issue is a sustained change in emotional state and energy. Depression in children and adolescents presents as a mood that is persistently down or irritable most of the day, nearly every day, and is often accompanied by low energy and fatigue that make it hard to engage in usual activities. This combination reflects a disruption in mood and energy levels that impairs functioning at home, school, or with friends.

The other conditions focus on different domains. Anxiety centers on excessive worry, fear, or physiological arousal rather than a prolonged low mood. Oppositional Defiant Disorder involves persistent defiant or oppositional behavior toward authority figures, not a primary mood disturbance. Autism Spectrum Disorder features social communication difficulties and restricted, repetitive behaviors, not a primary issue with mood and energy.

In youth, depression can show as irritability rather than sadness, with fatigue contributing to withdrawal from activities and reduced functioning. That combination of persistent low mood and fatigue best fits depression.