Review Question - QID 212408

A 77-year-old man presents to the emergency department with a change in his mental status. The patient’s daughter states that he can cook and clean up after himself and only needs help paying bills. Yesterday the patient seemed fine; however, this morning she noticed that he struggled to perform simple tasks and was forgetful while cooking, leaving the stove on. They recently returned from a trip to Mexico and admit to drinking unfiltered water and eating local cuisines while abroad. The patient has a past medical history of hypertension and diabetes. His temperature is 97.5°F (36.4°C), blood pressure is 187/118 mmHg, pulse is 90/min, respirations are 16/min, and oxygen saturation is 100% on room air. Which of the following is the most likely diagnosis?