The fourth element targeting hypothesis of Alzheimer's disease pathogenesis and pathophysiology.

"Conflict of Interest Statement The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest."

"The author is grateful to Harvey J. Karten, M.D., both for criticism of an early version of the manuscript, as well as for an earlier, seminal discussion in which he forced the author to reassess the fact that the primary cellular target(s) of Alzheimer's disease is (are) unknown. It was this basic insight that led to this hypothesis, as part of the quest to determine the array of possible primary targets in neurodegenerative disorders, and their correlates at different levels of both conceptual and empirical analysis. The authors’ work on the topics discussed herein was supported by the Brain-Mind Project, the United Through Knowledge Fund's Research Cooperability Program, the Croatian Ministry of Science, Education and Sport (MZOS 108-1080003-0020, M. Šalković-Petrišić, Principal Investigator) and received prior support from the Public Health Service (grant NS 29856, Rodrigo O. Kuljiš) and United States Department of Veterans Affairs (grant 5065.01 and Special Emphasis Program grant, Rodrigo O. Kuljiš)."