Which statement best distinguishes mood from affect in the Mental Status Exam?

• A. Mood is the patient's internal, sustained emotional state; affect is the clinician-observed, moment-to-moment emotional expression.
• B. Mood is outward expression; affect is the long-term internal state.
• C. Mood and affect are the same.
• D. Affect measures cognitive ability.

Answer: (B)

In the Mental Status Exam, the distinction rests on subjective versus objective presentation of emotion. Mood is the patient’s internal, sustained emotional state as they report it—what they feel over time. Affect is what you observe in the moment—the clinician’s impression of emotional expression through facial tone, voice, and body language.

So mood is the enduring feeling the patient describes (for example, depressed, euthymic, or irritable), while affect is the immediate, observable display that accompanies that mood (such as a flat, constricted, or labile expression). They usually align (affect is congruent with reported mood), but they can diverge (a patient may report sadness but present with a relatively flat or incongruent affect).

The option that reverses these roles is not correct because the outward expression is affect, not mood, and mood is the long-standing internal state rather than the long-term internal state being described as affect. Also, affect is about emotional expression, not cognitive ability, which is assessed separately.