Today, the clinical notion of 'memory disorder' is largely synonymous with 'Alzheimer's disease.' Only 50% of all dementias are of the Alzheimer's type though, and dementias represent only the more severe of all learning/memory disorders that derive from heredity, disease, injury or age. Perhaps as many as 30 million Americans suffer some type of clinically recognized memory disorder. To date, therapeutic drugs of only one class have been approved for the treatment of Alzheimer's disease. Fortunately, basic research during the past 25 years has begun to define a 'chemistry of brain plasticity,' which is suggesting new gene targets for the discovery of memory enhancers.