In humans, the picture is also far from being clear: some research groups showed elevated levels of DCX and neuron-specific markers (Jin et al. 2004), while others reported a decrease in DCX-positive cell number via bone morphogenetic protein 6 (BMP6) signaling (Crews et al. 2010) in the hippocampus of AD patients compared to non-demented controls. Here, BMP6 is linked to Alzheimer disease.