Is Alzheimer's Disease Infectious?<br><i>Relative to the CJD Bacterial Infection Model of Neurodegeneration</i>

Alzheimer's disease (AD) has been recently considered as a possible brain infection related to the Creutzfeldt-Jakob disease (CJD) transmissible dementia model. As with CJD, there is controversy whether the infectious agent is an amyloid protein (prion theory) or a bacterium. In this review, we show that the prion theory lacks credibility because spiroplasma, a tiny wall-less bacterium, is clearly involved in the pathogenesis of CJD and the prion amyloid can be separated from infectivity. In addition to prion amyloid deposits, the transmissible agent of CJD is associated with amyloids (A-β, Tau, and α-synuclein) characteristic of other neurodegenerative diseases including AD and Parkinsonism. Reports of spiroplasma inducing formation of α-synuclein in tissue culture and <i>Borrelia</i> spirochetes inducing formation of A-β and Tau in tissue culture suggests that bacteria may have a role in the pathogenesis of the neurodegenerative diseases