Another emerging feature from these GM studies is that the normal developmental trajectory is essentially the opposite of the neurodegenerative pattern seen in Alzheimer's disease (AD). In AD, cortical degeneration spreads from the medial temporal lobe entorhinal cortex in a forward wave through the limbic system (P. M. Thompson et al., 2004), consistent with the spread of neurofibrillary tangles and amyloid pathology seen post mortem. The same trajectory has also been revealed in PET scans with new amyloid-sensitive ligands, and it correlates with variations in cognitive function years before any overt symptoms of AD are detectable (Braak & Braak, 1991; Braskie et al., 2008).
