Linking hippocampal structure and function to memory performance in an aging population.

Archives of neurology

PubMedID: 19901171

Reitz C, Brickman AM, Brown TR, Manly J, DeCarli C, Small SA, Mayeux R. Linking hippocampal structure and function to memory performance in an aging population. Arch Neurol. 2009;66(11):1385-92.
BACKGROUND
Hippocampal atrophy and reductions in basal cerebral blood volume (CBV), a hemodynamic correlate of brain function, occur with cognitive impairment in Alzheimer disease, but whether these are early or late changes remains unclear. Magnetic resonance imaging is used to assess structure and function in the hippocampal formation.

OBJECTIVE
To estimate differences in the associations of hippocampal and entorhinal cortex volumes and CBV with memory function in the early and late stages of cognitive impairment by relating these measures to memory function in persons with and without dementia who underwent detailed brain imaging and neuropsychological assessment.

DESIGN
Multivariate regression analyses were used to relate entorhinal cortex volume, entorhinal cortex CBV, hippocampal volume, and hippocampal CBV to measurements of memory performance. The same measures were related to language function as a reference cognitive domain.

SETTING
Community-based cohort.

PARTICIPANTS
Two hundred thirty-one elderly Medicare recipients (aged > or =65 years) residing in northern Manhattan, New York.

MAIN OUTCOME MEASURES
Values for entorhinal cortex volume, hippocampal volume, entorhinal cortex CBV, and hippocampal CBV and their relation to memory performance.

RESULTS
No association was noted between entorhinal cortex volume or hippocampal CBV and memory. Decreased hippocampal volume was strongly associated with worse performance in total recall, and lower entorhinal cortex CBV was associated with lower performance in delayed recall. Excluding persons with Alzheimer disease, the association of entorhinal cortex CBV with memory measures was stronger, whereas the association between hippocampal volume and total recall became nonsignificant.

CONCLUSIONS
In the early stages of Alzheimer disease or in persons without dementia with worse memory ability, functional and metabolic hippocampal hypofunction contributes to memory impairment, whereas in the later stages, functional and structural changes play a role.