A man, aged 84 years, was stopped for going through a red light in a small town where he lives. He told the officer, 'It wasn't there yesterday.' He was unable to tell the officer his address and demonstrated labile mood, seeming pleasant one minute and angry the next. The officer took the man home to discuss his condition with the family and found that he has been wandering around the neighborhood, sometimes taking tools from people's garages, saying they belong to him. The family reluctantly agreed that he should go to the emergency department. What cardinal sign of Alzheimer's disease does this patient demonstrate?
Correct Answer: A
Rationale: The correct answer is A: Agnosia. Agnosia is the inability to recognize or interpret sensory information, such as objects, people, sounds, or shapes. In this case, the patient's inability to recognize the red light, his own address, and the ownership of tools indicates a problem with perception and recognition. This aligns with the symptoms of agnosia commonly seen in Alzheimer's disease.
Choices B and C are incorrect. Apraxia is the inability to perform purposeful movements, and aphasia is the loss of ability to understand or express speech. These symptoms are not the primary cardinal sign demonstrated by the patient in the scenario. Choice D, "None of the above," is also incorrect as the patient's symptoms align with the characteristics of agnosia.