The nurse is working in a clinic and sees a resident of a long-term-care facility, age 82 years, who has come in to be checked by her physician.The caregiver accompanying her reports that the client has been displaying the following: drowsiness, excessive sleeping, decreased attention span, irritability, and signs of depression.The client's daughter and family, who usually visit her, moved away from the area 6 weeks ago due to the husband's job.The nurse suspects which problem?