Multiprotein deposits in neurodegenerative disorders: our experience in the tissue brain bank of Navarra

The prevalence of neurodegenerative disorders increases dramatically with advancing age. Although in recent decades the study of many neurodegenerative disorders has evolved greatly, the concept of neurodegeneration still remains elusive. Although neurodegenerative disorders are classified according to the major components of protein deposits, coexpression of several abnormal proteins in the brain tissue is more common than that was previously thought. The aim of this report is to describe the type of protein deposits found in brains with neuropathological diagnosis of neurodegenerative disease. The report shows the experience obtained in the Brain Bank of Navarra (Spain). The target population for this retrospective descriptive study comprised 178 brains autopsied in the "Hospital of Navarra" in Pamplona between 1994 and 2004 and 201 brains donated to the Brain Bank of Pamplona between 2004 and 2009. The diagnosis of the 201 brains from the Brain Bank was 62 (30.8%) Alzheimer's disease (AD), 43 (21.3%) multiprotein deposit, 31 (15.4%) α-synucleinopathies, 31 (15.4%) frontotemporal lobar degeneration (FTLD), 17 (8.4%) tauopathies, 9 (4.4%) prion disease, 6 (2.9%) vascular dementia (VD), and 2 (0.9%) Huntington's disease. Among the 43 cases with multiprotein deposits, we found 35 brains with deposits of 3 proteins (tau, β-amyloid, and α-synuclein). In these two series of brains, the high incidence of deposition of multiple proteins in neurodegenerative disorders is shown. Our results are in agreement with previous findings showing that tau, β-amyloid, and α-synuclein are the proteins most frequently deposited together.