ElderWeb

In 1845, Congress enacted a law giving public land to each of the states "for the benefit of indigent insane persons", and the states started to build insane asylums and hospitals for the insane. Many of the mentally-ill poorhouse inmates transferred to these new facilities were elderly. (Vladek, 1980) 

That group probably included some victims of dementia. The words "dotage" and "dementia" had been used by physicians and researchers as far back as Roman times, but the distinctions between dementia, other types of mental illness, and normal aging were not well understood in the 1800's. The term "senile dementia"  was first used in 1838 by Dr. Jean Étienne Esquirol. Dr. Alois Alzheimer would not discover that "Alzheimers Disease" resulted from plaques and tangles in the brain until 1906. (David Shenk, The Forgetting, 2001)