PSEN1 and familial Alzheimer disease: The major findings were that APP and PS1 gene mutations affected the structure and function of the frontostriatal pathway in a different manner in presymptomatic stage, where APP primarily impaired the structural connectivity; disease progression especially affected the structure of hippocampus-PCC pathway; and structural connectivity of both frontostriatal and hippocampus-PCC circuits were associated with general cognitive function in FAD.