Efforts continue toward the goal of uncovering a dominant pathogenetic and therapeutic model for Alzheimer type dementia. This article critically reviews the evolution and current status of unitary transmitter concepts, the prototype of which is the cholinergic model proposed by Deutsch and others, from early animal studies to ongoing drug trials. We conclude that evidence is sufficient to dismiss such models as a means of directing treatment and further resources. A survey of novel approaches to Alzheimer type dementia, many of which transcend unitary thought, reveals a more promising direction for further research.