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[IC‐P‐092]: THE INDEPENDENT EFFECT OF CEREBRAL MICROBLEEDS ON COGNITION
Author(s) -
Deocariza Guevarra Anne Cristine,
Ruan Xu Cong,
Kandiah Nagaendran
Publication year - 2017
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.2017.06.2365
Subject(s) - cognition , hyperintensity , montreal cognitive assessment , audiology , medicine , cognitive decline , cohort , memory clinic , cognitive test , memory span , effects of sleep deprivation on cognitive performance , cardiology , fluid attenuated inversion recovery , psychology , cognitive impairment , magnetic resonance imaging , dementia , disease , working memory , radiology , psychiatry
Background:Episodic Memory processes are supported by different subregions of the medial temporal lobe (MTL). In contrast to a unitary model of memory recognition supported solely by the hippocampus, a current model suggests that item encoding engages perirhinal cortex while relational encoding engages parahippocampal cortex and the hippocampus. However, this model has not been examined in the context of aging, neurodegeneration, and MTL morphometrics. Methods:Forty-four healthy subjects (HS) and 18 cognitively impaired subjects (9 MCI and 9 AD patients) were assessed with the relational and item-specific encoding task (RISE) and underwent 3T MRI. The RISE assessed the differential contribution of relational and item-specific memory. Freesurfer was used to obtain measures of cortical thickness of MTL regions and hippocampus volume. Results:Memory accuracies for both item and relational memory were significantly better in the HS group than the MCI/AD group. In MCI/AD group relational memory was disproportionately impaired. In HS, hierarchical regressions demonstrated that memory was predicted by perirhinal thickness after item encoding and by hippocampus volume after relational encoding (both at trend level), and significantly by parahippocampal thickness at associative recognition. The same brain morphometry profiles predicted memory accuracy in MCI/AD although more robustly: perirhinal thickness for item encoding (R21⁄4 0.31), and hippocampal volume and parahippocampal thickness for relational encoding (R21⁄4 0.31). Conclusions:Our results supported a model of episodic memory in which item-specific encoding was associated with greater perirhinal cortical thickness, while relational encoding was associated with parahippocampal and hippocampal morphometrics. We identified these relationships not only in HS, but also in individuals with MCI and AD. In the subjects with cognitive impairment, reductions in hippocampal volume and impairments in relational memory were especially prominent.