Systematic appraisal using immunohistochemistry of brain pathology in aged and demented subjects

Abstract

Background/aims: Abnormal processing of hyperphosphorylated tau (HPtau), amyloid-beta (Abeta) and alpha-synuclein (alphaS) proteins is considered as causative with regard to the clinical symptoms in age-related neurodegenerative diseases.

Methods: In this retrospective, postmortem study applying immunohistochemical methodology, we assessed Alzheimer's-disease (AD)-related HPtau and Abeta pathology in 178 subjects with alphaS pathology.

Results: These pathologies were frequently seen concomitantly, i.e. HPtau in 83% and Abeta in 62% of the alphaS-positive cases. Furthermore, the striatum was frequently involved, particularly in subjects with cognitive impairment (65%). The predictive value of widespread HPtau pathology, i.e. stages V-VI, with respect to cognitive impairment was high, since all 18 subjects presenting with this stage were demented. In contrast, the predictive value of widespread alphaS pathology, i.e. stages 5-6 according to Braak's Parkinson disease staging, was debatable. Fifty-three percent of the subjects with widespread alphaS pathology and no or mild AD-related HPtau pathology were cognitively unimpaired. It is noteworthy that striatal Abeta pathology was more often seen in demented subjects independently of HPtau and/or alphaS status.

Conclusion: The causative pathology in subjects with clinically diagnosed dementia with Lewy bodies needs to be clarified in future studies.