Studies in Ageing of the Brain.

It appears that some local factor is associated with the discrete increase of silicon in the Alzheimer plaque, and total silicon showed no consistent corresponding increase in the cerebrum as a whole, in various systemic organs, or in various body fluids.

Abstract

The purpose of this chapter is 2-fold: (1) to determine whether human tissues and body fluids remote from the plaque itself had an increase in Si, and (2) to determine the relationship between age and Si in normal human controls. A focal increase in silicon is noted in the core and rim of the senile plaques in Alzheimer's disease. Thus, it appears that some local factor is associated with the discrete increase of silicon in the Alzheimer plaque. Two types of local affinity come to mind. One type would be an enhanced affinity between Si and another molecule, such as a protein. To explore this as a possibility for some excessive binding of Si, plasma was divided into bound and unbound fractions. Following this interpretation, the neurofibrillary change and microtubular disorder could be viewed as the primary event, and the pile-up of Si might be secondary to impaired removal. In the present chapter, total silicon showed no consistent corresponding increase in the cerebrum as a whole, in various systemic organs, or in various body fluids. More silicon and phosphorus exists in the bound form in plasma with advancing age.