Final answer:
The experimental medication that Ed is taking for Alzheimer's disease is likely designed to increase the neurotransmitter acetylcholine.
Step-by-step explanation:
Ed has been diagnosed with Alzheimer's disease and is taking an experimental medication designed to increase the level of a neurotransmitter. In the context of Alzheimer's disease, the decreased activity of cholinergic neurons (which use acetylcholine) is common, and drugs to treat the disease often aim to increase acetylcholine levels. These medications work by inhibiting the enzyme that breaks down acetylcholine in the synaptic cleft, thus enhancing acetylcholine neurotransmission. Therefore, the medication Ed is taking is likely designed to increase his levels of acetylcholine (C).