Alzheimer's disease (AD) is a progressive degenerative disease of the nervous system characterized neuropathologically by the presence of senile plaques and neurofibrillary tangles in amygdala, hippocampus and neocortex (Katzman, 1986). AD is now known to be the most common cause of dementia in the elderly and accounts for approximately 50-60% of all cases of dementia. It is believed to affect about 10% of the population over the age of 65 years, although a recent epidemiological study conducted in an East Boston community (Evans et al, 1989) suggests that the prevalence of AD in those 85 years or older may be as high as 47%. These data, as well as the continuing growth of the older population groups in developed countries, emphasizes the need to define potentially modifiable causal factors for AD (Evans et al, 1989). The constellation of clinical and pathological markers in AD is also associated with selective abnormalities of specific neurotransmitter and neuropeptide systems. Identification of these abnormalities has opened new avenues for assessing the preand postsynaptic integrity of these neuronal systems in AD, and offered hope for potential drug therapy. This chapter reviews neuropeptide and neurotransmitter chemistry in AD, focusing in particular on the role of corticotrophin releasing factor (CRF) in the pathophysiology of AD.