The neurotransmitter and neuropeptide changes in Alzheimer's disease are outlined in Table 1. Many of the changes, such as decreases in CSF ACh and SRIF, are well documented and correlate with the severity of the dementia; however, they are relatively nonspecific. The changes in neurotransmitter availability have offered new insight into both the pathophysiology and possible treatment strategies in Alzheimer's disease. It is evident that the disease is characterized by pathologic involvement of multiple neurotransmitter systems, including those that utilize ACh, SRIF, CRF, and, most probably, monoamines and excitatory amino acids. The role each system has in the signs and symptoms of Alzheimer's disease remains obscure.