The aim of this study is to investigate the selective epigenetic modifications and their effect on brain's morphology and functionality in the frontotemporal dementia behavioral variant and bipolar disorder. The open-label, multicentric, interventional case-control study involves the analysis of 3 separate cohorts of patients, partly selected over the course of the past 10 years. More specifically, 80 behavioral variant Frontotemporal Dementia (bvFTD) patients (40, of whom 20 carry G4C2 expansion in the C9orf72 gene, are already available, while 40 will be prospectively recruited), 80 Bipolar Disorder (BD) patients (40, including 20 with early onset and 20 with late onset, are already available, while 40 will be prospectively recruited) and 50 healthy control (HC) subjects (20 of whom are already available from other previously approved studies), will be enrolled in this study. For each participant a blood sample will be collected, processed, and studied in order analyze the expression of miRNA. Every participant will also undergo Nuclear Magnetic Resonance Imaging (NMR), Nuclear Magnetic Resonance Spectroscopy (1H-MRS), and Positron Emission Tomography (PET) and, lastly, a battery of behavioral scales to explore different cognitive domains will be administered to all participants by a team of psychologists and physicians. The overall estimated duration of the study is 36 months.