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P4‐159: Postmortem neuropathologic assessment of Aβ‐deposition in the precuneus of cognitively normal individuals
Author(s) -
Taylor-Reinwald Lisa,
Carter Deborah,
Felton Angela,
Grant Elizabeth,
Morris John C.,
Cairns Nigel J.
Publication year - 2008
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2008.05.2226
Subject(s) - precuneus , parahippocampal gyrus , pathology , dementia with lewy bodies , posterior cingulate , fusiform gyrus , neuropathology , gyrus , medicine , alzheimer's disease , dementia , clinical dementia rating , psychology , neuroscience , cortex (anatomy) , disease , temporal lobe , cognition , epilepsy
PiB PET imaging. This study tests the hypothesis that synapse loss in the precuneus is an early event in the progression from no cognitive impairment (NCI), to mild cognitive impairment (MCI) and mAD. Methods: Tissue from the ADC at the University of Kentucky and the Religious Orders Study at Rush University Medical Center in Chicago was obtained at autopsy. All individuals from each cohort underwent detailed clinical evaluation within 12 months of death and were categorized as mAD (n 4), MCI (n 6) or NCI (n 5) based upon cognitive tests. Systematic random samples throughout the precuneus were processed for standard transmission electron microscopy. Unbiased stereological techniques employing the physical disector were used to estimate the total number of synapses in lamina 3 of the posterior medial parietal cortex (precuneus). All three groups were matched for both age and post mortem interval. Results: Detailed analysis of total synaptic numbers in lamina 3 failed to reveal any significant change between NCI and either MCI or mAD groups. While there was a decline in the overall cognitive test scores between groups, the global cognitive changes did not correlate with synaptic counts. Conclusions: This is the first study to quantify synaptic numbers in the precuneus in individuals with MCI and mAD. The results imply that while some amyloid based imaging studies suggest that precuneus is affected early in the disease state, change in synaptic numbers are not part of the pathophysiology and may not relate to the accumulation of amyloid.