The prevalence for the development of dementia is about 10% and 20% in people over the age of 65 and 80, respectively. Underlying causes for its development are various. With the progress of modem medicine, the mean survival age is dramatically increased and for the consequence, greater number of people suffer from dementia. According to the postmortem studies, 70% of the dementia patients were of the Alzheimer's type. In recent times, active research on the relationship between the Alzheimer's disease and the neurochemical changes is being conducted and much progress has been made. In addition to the consistant deficiency of cholinergic system, abnormal ities in noradrenergic and GABAergic systems and reductions of somatostatin have been reported. In the same areas of brain of patients who suffered from Alxheimer's disease where these changes of neurotransmitters were found, there were massive accumulation of aluminium. Therefore, this review discusses the specific changes of various neurotransmitters in the brain and the potential therapeutic agents in Alzheimer's disease.