OBJECTIVETo recognize relationship of protein related neurodegeneration abnormal aggregation in the aged brains with their cognitive and motor functions.

METHODSBrain tissues from the consecutive autopsy cases of the aged from January 2005 to December 2006 in PLA General Hospital were carried out for immunohistochemical staining with beta amyloid, tau, α-synuclein and ubiquitin antibodies. The consortium to establish a registry for Alzheimer's disease (CERAD) was used to semi-quantitatively analyze Aβ positive core plaques density and Braak staging for tau positive neurofibrillary tangles (NFTs) and α-synuclein positive Lewy bodies. In addition, Aβ positive cerebral amyloid angiopathy (CAA), neuritic plaques and various ubiquitin positive structures were also observed. The relationship of these protein abnormal depositions in the aged brains with cognitive and motor functions were analyzed.

RESULTSIn brain tissues of 16 consecutive autopsy cases of the aged from 78 to 95 years, there were 13 cases with Aβ positive core plaques, their density was 2 cases with sparse, 2 cases with moderate and 9 cases with frequent, respectively, according to CREAD.Eight cases with Aβ positive CAA were found, including 6 cases of mild CAA and 2 cases of severe CAA. There were 12 cases with tau positive NFTs, including 6 cases with Braak stageI-II, 4 cases with stage III-IV and 2 cases with stage V-VI. There were 5 cases with frequent Aβ core plaques, meanwhile existing numerous tau/ubiquitin positive neuritic plaques and Braak stage IV-VI of tau positive NFTs, all of them presented cognitive dysfunction. Among 4 other cases with frequent Aβ core plaques, only one case coexisted α-synuclein positive Lewy bodies showed moderate cognitive impairment, remaining 3 cases did not present cognitive dysfunction. There were 4 cases with α-synuclein positive Lewy bodies in the brainstem, and all of these cases presented parkinsonian motor dysfunction. 13 cases with ubiquitin positive structures were found.

CONCLUSIONSBeta amyloid protein positive deposit in the aged brain is an important marker of normal brain aging and cognitive impairment; frequent Aβ core plaques in the neocortex plus Braak IV and above tau positive NFTs are closely related to cognitive dysfunction of Alzheimer's disease; α-synuclein positive Lewy bodies in the brainstem is one of the important pathological markers of parkinsonian motor disorders; ubiquitin deposition involves the development of some characteristic structures of several neurodegenerative diseases.