Final answer:
The best response by the nurse is to ask, "Help me understand what you mean when you say 'feeling down'." This facilitates a deeper understanding of the individual's experience with depression, which is essential for assessing their affective symptoms.
Step-by-step explanation:
To provide the best assessment of a patient with major depressive disorder who expresses concern about their prolonged feelings of sadness, the nurse's response should be aimed at getting a deeper understanding of the patient's affective symptoms. The most suitable reply among the options provided would be, "Help me understand what you mean when you say 'feeling down'." This open-ended question invites the patient to describe their experience in more detail, which can help the nurse in evaluating the severity and impact of the depressive symptoms on the patient's life.
Understanding the patient's specific feelings and experiences is crucial, as depression symptoms can manifest differently among individuals and entail aspects such as changes in mood, withdrawal, loss of interest in activities, difficulty concentrating, and feelings of worthlessness, among others.
It is also important to differentiate between major depressive disorder and other mood disorders or conditions that may affect mood, such as seasonal affective disorder (SAD), where factors like melatonin levels play a role during specific seasons.