The ability to accurately identify patients with MCI who will progress to AD would be a great asset to clinical trials of drugs designed to reduce rates of progression of the disease. There is already evidence that phosphorylated tau appears in the CSF of MCI patients and may be used as a marker for who will progress to AD. There are two papers to this effect (Buerger et al., 2002a and de Leon et al., 2002), which were not cited by these authors. It would appear that phosphorylated tau is a superior marker to total tau in CSF, as it does not show elevations in concentration in the absence of AD pathology (Buerger et al., 2002b;).

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