The purpose of this study is to learn more about the medical problems and the genetic factors involved in a recently defined form of inherited dementia called "familial dementia with neuroserpin inclusion bodies (FDNIB)." Abnormal substances in nerve cells of patients with this disease affect brain and nervous system function, causing confusion, memory decline and impaired cognition (thinking ability). Patients also develop movement disorders and, possibly, seizures. Symptoms begin in midlife, between 45 and 55 years of age.