The invention pertains to treating a
cognitive impairment, for example, an aging-associated
cognitive impairment. In certain aspects, a sample obtained from a subject is assayed for the ratio between the levels of any two proteins selected from: DLL1, SMOC1, CD59, TSTD1, STAT3, POLD4, PARP11, LEFTY2, UNC5B, C5, C5.C6, ASH2L, INHBB, RSP3, VAV3, SIRT3 and SERPINB8. A subject may be having or suspected of having a
cognitive impairment. The cognitive impairment can be caused by a neurodegenerative
disease, such as Alzheimer's
disease. A subject may be identified as likely or not likely to respond positively to the
plasma exchange therapy based on the ratio between the levels of measured proteins. In certain aspects, methods for treating a cognitive impairment in the subject comprise administering a
plasma exchange therapy comprising a full and / or
low volume plasma exchange. Also provided are kits suitable for performing such methods.