However, since these transgenic mice overexpress hTau throughout most of the brain, it is difficult to know whether the resulting cognitive deficits are due specifically to tau-induced dysfunction of AD-vulnerable brain regions (e.g. entorhinal-hippocampal areas), as opposed to brain regions vulnerable to other tauopathies with cognitive symptoms (e.g. frontal cortex). This evidence concerns the gene MAPT and Alzheimer disease.