Foreword<br >by Robert N. Butler， M.D.<br > A(;IN(; ltAS ION(; BEEN MISTAKENI，Y EQUATED with disease and an in-<br > evitable &，wnhill pattern in both physical and mental tJnction.ing.<br > Nowhere is this more evident than in the treatment~or rather lack of<br > trratment--{)f mental impairment in the elderly.<br > It is currently estimated that between 500，000 and 1.5 milli~i~n per-<br > sons suffcr tr~m the more serious and irreversible forms of senile<br > dementia. Approxinlately 50 percent of all nursing home residents<br > have some degree of mental impairmeI~t， with Alzheimer s disease be-<br > ing a major reasc~n for admissions to nursing homes. Given that few<br > trends are as evident or predictable as the aging of the American<br > population， th~~se responsible for scientific research and service de-<br > livery are facing a series of challenges. A key element in our prepara-<br > tion tor the thture and ior large numbers of persons surviving into old<br > age must be research aimed at increasing our knowledge of the causes<br > and the biological and behavioral nmchanisms at work in senile<br > dementia. Such research would improve our ability to treat and con-<br > trol these devastati~，，g conditions which take their toll primarily in the<br > elderly populati~n， and perhaps eventually to prevent these diseases<br > altogether.<br > The insidious onset and progressive development of conditions<br >