_ Two distinct patterns in of brain damage predicted by studies one studying how brain circuits wire up structurally in their natural manner and the other their functional connections, converged on a remarkably similar model which predicted the sites of degeneration in each forms of dementia .These studies have been proved significant since the models to predict and study the human neural degeneration has remained elusive.  Neurodegenerative process is thought to involve the accumulation of abnormal toxic proteins and the spread of these toxic proteins between neurons, which may be contagious through their synaptic connections.

http://www.todaysseniorsnetwork.com/diabetes_impact_dementia_brain_patterns.htm

http://www.ncbi.nlm.nih.gov/pubmed/17267521