1. A 27-year-old male is brought into the emergency room by the police, who found him walking aimlessly, shouting the names of former Presidents. Urine toxicology is negative, and the man appears to be oriented with respect to person, place, and time. He has had five similar admissions over the past year. Attempts to interview the patient are fruitless, as he seems easily derailed from his train of thought. A phone call to a friend listed in the chart provides the additional information that the man is homeless, and unable to care for himself. This patient is exhibiting the signs and symptoms of