been extensive research to determine whether l-dopa is a better treatment for parkinson's disease rather than other dopamine agonists. some believe that the long-term use of l-dopa will compromise neuroprotection and, thus, eventually lead to dopaminergic cell death. though there has been no proof, in-vivo or in-vitro, some still believe that the long-term use of dopamine agonists is better for the patient. alzheimer's disease while there are a variety of hypotheses that have been proposed for the cause of alzheimer's disease, the knowledge of this disease is far from complete to explain, making it difficult to develop methods for treatment. in the brain of alzheimer's patients, both neuronal nicotinic acetylcholine (nach) receptors and nmda receptors are known to be down-regulated. thus, four anticholinesterases have been developed and approved by the u.s. food and drug administration (fda) for the treatment in the u.s.a. however, these are not ideal drugs, considering their side-effects and limited effectiveness. one promising drug, nefiracetam, is being developed for the treatment of alzheimer's and other patients with dementia, and has unique actions in potentiating the activity of both nach receptors and nmda receptors. future with advances in technology and our understanding of the nervous system, the development of drugs will continue with increasing drug sensitivity and specificity. structure–activity relationships are a major area of research within neuropharmacology; an attempt to modify the effect or the potency (i.e., activity) of bioactive chemical compounds by modifying their chemical structures.