Overexpression of drebrin in hippocampal neurons leads to the formation of abnormally large spines (Mizui et al., 2005), conversely loss of drebrin results in sparse, thin spines (Takahashi et al., 2006) and reduced drebrin levels in humans are associated with Alzheimer Disease (Calon et al., 2004; Shim and Lubec, 2002). This evidence concerns the gene DBN1 and early-onset autosomal dominant Alzheimer disease.