and disentangle their relationships. We profiled over six hundred postmortem samples assembled in the Harvard Brain Tissue Resource Center (HBTRC, McLean Hospital, Belmont, MA). We used metagene (factor) analysis [21], [22], [23], [24], [25] to distinguish several major gene expression patterns involved in brain aging and disease and to quantitatively define the corresponding biomarker scores. The correlation analysis of the biomarker scores between three profiled brain regions revealed systemic effects of the same disease processes on different brain regions. We also propose a model of Alzheimer's disease progression that specifies the complex sequence of molecular pathological events associated with the disease that are driven by aging, which appears as the main factor in the disease initiation and progression [1], [8].
