Underlying alzheimer's disease is a deterioration in neurons that produce:

Dopamine

Alzheimer's Disease is characterized by an impediment in the dopamine regulation function in the brain. Dopamine is a neurotransmitter that is involved in many functions including: memory, mood, cognition and behavior. In Alzheimer's Disease a lack of dopamine production in the brain causes symptoms such as: memory loss and impaired cognitive functioning.

Deterioration in neurons that produce acetylcholine is an underlying Alzheimer's disease. Acetylcholine is an organic chemical that functions as a neurotransmitter at neuromuscular junctions, at synapses, in the ganglia of the visceral motor system, and at a variety of sites within the central nervous system in the brain and body of many types of animals, including humans. A neurotransmitter is a substance released by synaptic terminals for the purpose of transmitting information from one nerve cell to another.