This disclosure relates to methods of diagnosing neurodegenerative disease by analyzing proteins or protein expression profiles in a subject, or RNA or RNA expression profiles in a subject. In certain embodiments, the disclosure contemplates the diagnosis of preclinical or symptomatic stages of Alzheimer's disease, mild cognitive impairment, or chronic traumatic encephalopathy by identification of components of U1 small nuclear ribonucleoproteins or fragments thereof which are capable of forming cytoplasmic tangle-like structures.