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The Spectrum of Dementias

We at Hamit-Darwin-Freesh, Inc (HDF) are intensely focused on the prevention of Alzheimer’s disease (AD).  But a thorough discussion of AD should include a narrative that addresses its place amongst other neurodegenerative diseases associated with dementia.  Because AD accounts for 65-75% of all dementias, we will begin with a discussion of its pathological foundation, to the extent our knowledge permits.  

So, what accounts for the balance, the 25-35% of dementia that is not due to AD?  Clinically speaking it is important to consider the balance because AD often coexists with other morbidity, vascular dementia (VaDem) being the most common.  That is to say VaDem and AD commonly coexist.  VaDem is also the second most common dementia, distinct from any comorbid AD pathology.  Finally, the neuropathology of many of the less common dementias might have certain similarities with that found in AD. 


After AD, VaDem and Dementia with Lewy bodies (Lewy Body Disease, LBD) constitute a majority of the balance, followed by Frontotemporal Dementia (FTD), including Pick’s Disease, and the so called Tauopathies.

Tauopathies include Multiple System Atrophy (MSA), Corticobasal Degeneration (CBD), Olivopontocerebellar Atrophy (OPCA), and Progressive Supranuclear Palsy (PSP).  The classification of the tauopathies is more of historical interest, because with the evolution of research we know that one of several forms of the protein tau exist in many of the other degenerative dementias.

Finally, dementias associated with Prion Diseases, and those associated with Infectious Diseases, Autoimmune Disease and Huntington Disease will be mentioned, as will the debated “pseudo-dementias” associated with certain endocrine (e.g., hypothyroid) states and nutritional states (e.g., vitamin B12 deficiency).


You will have noticed this discussion begins with the topic “About Alzheimer’s Disease.”  You also see that all topics are menu driven, so you may choose to read in any order, depending on your interests.  Each topic is written in a manor which we are hopeful will facilitate the introduction of the respective field to the interested neuroscientist or physician who is not already working in the area. 


Not all topics will be immediately available, but will be added as time permits.  It is also hoped that a second edition of this work will in time be written for the lay public.  Finally, each topic will be continuously strengthened and updated as significant advances in therapeutics or scientific knowledge warrant.

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