Various mice and human studies have demonstrated that progranulin insufficiency is associated with familial frontotemporal dementia (FTD), where structural changes such as decreased brain volumes and dendritic density as well as reduced functional connectivity were observed prior to the onset of FTD symptoms (Borroni et al., 2008; Pievani et al., 2014; Dopper et al., 2014; Rohrer et al., 2015). This evidence concerns the gene GRN and frontotemporal dementia.