Although not in routine clinical use, there are also PET ligands that bind to phosphorylated-tau (FDDNP molecule (Small et al., 2006) and 18F AV1451) that have recently been shown to track progressive tau accumulation in aging and Alzheimer's disease Schöll et al. The expense of these tests is prohibitive in most centers. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.