In which of the following disease decrease in levels of single neurotransmitter was first identified?
**Core Concept**
The question is testing the knowledge of a specific neurotransmitter disorder that was identified as the first of its kind. This concept revolves around the identification of a single neurotransmitter deficiency as a cause of a neurological disorder. The underlying principle is the role of neurotransmitters in maintaining normal neurological function.
**Why the Correct Answer is Right**
The correct answer refers to Alzheimer's disease. Alzheimer's disease was the first condition where a decrease in levels of a single neurotransmitter, acetylcholine, was identified. This decrease in acetylcholine levels is thought to contribute to the cognitive decline observed in Alzheimer's patients. The enzyme responsible for the synthesis of acetylcholine is choline acetyltransferase. The decrease in acetylcholine levels is believed to lead to a disruption in the normal functioning of the cholinergic system in the brain.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as it does not relate to the identification of a single neurotransmitter deficiency as a cause of a neurological disorder.
* **Option B:** This option is incorrect as it does not specifically refer to Alzheimer's disease or the decrease in levels of a single neurotransmitter.
* **Option D:** This option is incorrect as it is unrelated to the concept of a single neurotransmitter deficiency in Alzheimer's disease.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that Alzheimer's disease is a neurodegenerative disorder characterized by a decline in cognitive function, and the decrease in levels of acetylcholine is a key feature of this condition.
**Correct Answer:** C. Alzheimer's disease is a neurodegenerative disorder characterized by a decline in cognitive function, and the decrease in levels of acetylcholine is a key feature of this condition.