Dual Photonics Probing of Structural Abnormalities in Cells/Tissues and DNA Molecular Mass Spatial Densities in the Human Brain with the Progression of Alzheimer's disease*

Alzheimer’s disease (AD) is the most common form of dementia, characterized pathologically by amyloid plaques and neurofibrillary tangles. One of the earliest overt signs of AD is a loss of cognitive function.  It has been reported that AD affects the nanoscale structure of the brain cells which begins long before the cognitive symptoms appear. However, these alterations are undetectable in the initial stages with currently used bulk diagnostic techniques such as MRI and OCT. Thus, the elucidation of a neuroimaging method that can uniquely characterize these structural disorders at the nanoscale is imperative for clinical diagnosis. Recently developed finer-focused partial wave spectroscopy (PWS) is a sensitive technique for probing nanoscale structural alterations in cells /tissues in terms of the average structural disorder strength. Results of PWS technique measurements of brain tissues from the human subjects show a significant increase in the disorder strength with the progression of AD relative to their controls. To enhance our study, the IPR approach was utilized to further analyze the spatial structure of changes in the molecular mass density of nuclear DNA components using confocal imaging. In addition, IPR studies conducted on DNA nuclei indicate that spatial structural disorder is significantly increased in DNA nuclei.