Abstract: The present inventors have identified a panel of biomarkers present in a biological sample of an individual (e.g. blood, including serum or plasma) whose concentrations or levels are altered in individuals with a neurological disorder. Accordingly, changes in the level of any one or more of these biomarkers can be used to assess cognitive function, to diagnose or aid in the diagnosis of a neurological disorder and/or to monitor a neurological disorder in a patient (e.g., tracking disease progression in a patient and/or tracking the effect of medical or surgical therapy in the patient). Changes in the level of any one or more of these biomarkers can also be used to stratify a patient (i.e., sorting an individual with a probable diagnosis of a neurological disorder or diagnosed with a neurological disorder into different classes of the disorder) and diagnosing or aiding in the diagnosis of mild cognitive impairment (MCI) as well as diagnosing or aiding in the diagnosis of cognitive impairment.