Dear Sir,

Teixeira da Silva and Daly have both made cogent remarks with regards to nomenclature misrepresentation and “tortured phrases” in Parkinson’s disease [1], as well as language misuse in Alzheimer’s disease (AD) [2] research, which could be confusing and harmful. I would add that any incorrect or imprecise use of certain terms, particularly when taken out of context, can be misconstrued and cause disturbing conceptual confusions and errors in the field.

I shall take the example of the term “infectious” in descriptions and reports related to AD. While there is emerging evidence for an association between microbial brain infections, particularly those by subtypes of Herpes Simplex Virus (HSV) and AD development, we are not yet at the stage of understanding to state unequivocally that HSV infection causes, or otherwise predisposes, an individual to AD. Viral infection of brain tissues and the neuroinflammatory episodes incurred, or reactivation from dormancy, could conceivably trigger amyloid pathogenesis. However, exactly how this might happen is yet unclear and the pathogenic link remained unproven [3]. Importantly, this certainly should not imply that AD is contagious or transmissible, but it can be misconstrued as such, particularly by laypersons under the influence of misinformation.

Unfortunately, the term “infectious” has also been associated with AD in another aspect, namely that of prion diseases. The latter is hallmarked by proteinaceous transmission through pathologically aggregated form of PrPSc [4]. However, the prion concept has been rather elaborately misapplied to other neurodegenerative diseases with a protein aggregation phenotype. For example, a tertiary institution based news article bore the headline “Alzheimer’s disease is a ‘Double-Prion Disorder’, study shows” [5], with reference to amyloid β and tau. While studies have shown that amyloid β and tau could exhibit a “prion-like” seeding or template-driven aggregation, and abnormal forms of these proteins can be transported between neurons in the brain of experimental animal models, these findings do not mean that AD could be infectious in ways resembling those exhibited by transmissible spongiform encephalopathies.

Accurate use of terms in describing and discussing pathological features associated with a debilitating disease like AD is of particularly importance, as patients are critically dependent on the physical proximity and support of family members and caregiver. The latter must not be in any way confused or be left in doubt by misconstrued and untrue information.