Abstract: The invention generally relates to methods for assessing a neurological disorder by characterizing circulating nucleic acids in a blood sample. According to certain embodiments, methods tor assessing a neurological disorder include obtaining RNA present in a blood sample of a patient suspected of having a neurological disorder, determining a level of RNA present in the sample that is specific to brain tissue, comparing the sample level of RNA to a reference level of RNA specific to brain tissue, determining whether a difference exists between the sample level and the reference level, and indicating a neurological disorder if a difference is determined.