Comparative anatomic data suggest that several systems of brain regions underwent selective expansion or differentiation during primate evolution, according to the principle of 'integrated phylogeny'. This involved expansion of the neocortex. Certain human neurodegenerative diseases, including Alzheimer's disease, affect such systems, suggesting that they ar 'phylogenic' diseases and that the genetic changes that promoted integrated phylogeny are related to the genetics of these diseases. Measurements of brain blood flow using positron emission tomography, during cognitive stimulation, suggest that reversible synaptic failure underlies early functional deficits in Alzheimer's disease. A within-subject method to analyze blood flow responses in Alzheimer's patients subjected parametric cognitive stimulation, with and without drugs that modulate synaptic efficacy, has been developed. The critical temperature for maintaining stable lipid monolayers in vitro is reduced from 37oC to less than 30oC, using lipids from temporal association but not cerebellar cortex of Alzheimer's brain. Cell membrane instability in vulnerable brain regions likely contributes to progression of Alzheimer's disease.
