Final answer:
The nurse should plan to interview the older adult client in a private setting, which is crucial for ensuring privacy and accurate mental health assessment.
Step-by-step explanation:
When a nurse is obtaining a mental health history from an older adult client, the appropriate action to take is to interview the client in a private setting. This setting ensures privacy and confidentiality, helping the client feel safe and comfortable to share personal information. It also reduces distractions and helps the nurse to accurately observe and assess the client's mental status.
Additionally, starting the interview by explaining the plan of care can help set clear expectations and establish rapport. Raising the pitch of the voice when speaking to the client is unnecessary and could even be perceived as patronizing. Instead, the nurse should speak clearly and respectfully. Lastly, while detailed questionnaires can be helpful, they may be overwhelming for some older adults, especially those with cognitive impairments, and should be used with caution and adapted to each client's needs.