Hippocampal neurochemistry, neuromorphometry, and verbal memory in nondemented older adults.
BACKGROUND
Characterization of the behavioral correlates of neuromorphometry and neurochemistry in older adults has important implications for an improved understanding of the aging process. The objective of this study was to test the hypothesis that a measure of hippocampal neuronal metabolism was associated with verbal memory in nondemented older adults after controlling for hippocampal volume.


METHODS
4-T MRI, proton magnetic resonance spectroscopy ((1)H MRS), and neuropsychological assessment were conducted in 48 older adults (23 women; mean age 81 years). Average hippocampal N-acetyl aspartate/creatine ratios (NAA/Cr) and hippocampal volumes were obtained. Neuropsychological evaluation included tests of verbal memory (Buschke and Grober Free and Cued Selective Reminding Test-Immediate Recall [FCSRT-IR], Wechsler Memory Scale-Revised Logical Memory subtest) and attention and executive function (Trail Making Test Parts A and B).


RESULTS
Linear regression analysis indicated that after adjusting for age, hippocampal NAA/Cr was a significant predictor of FCSRT-IR performance (beta = 0.38, p = 0.01, R (2) = 0.21). Hippocampal volume was also a significant predictor of FCSRT-IR performance after adjusting for age and midsagittal area (beta = 0.47, p = 0.01, R (2) = 0.24). In a combined model, hippocampal NAA/Cr (beta = 0.33, p = 0.03) and volume (beta = 0.35, p = 0.03) were independent predictors of FCSRT-IR performance, accounting for 30% of the variance in memory.


CONCLUSIONS
These findings indicate that nondemented older adults with smaller hippocampal volumes and lower levels of hippocampal N-acetyl aspartate/creatine ratio metabolites perform more poorly on a test of verbal memory. The integrity of both the structure and metabolism of the hippocampus may underlie verbal memory function in nondemented elderly.
Zimmerman
M E
ME
Albert Einstein College of Medicine, Saul R. Korey Department of Neurology, 1165 Morris Park Ave., Room 343, Bronx, NY 10461, USA. mzimmerm@aecom.yu.edu
Pan
J W
JW
Hetherington
H P
HP
Katz
M J
MJ
Verghese
J
J
Buschke
H
H
Derby
C A
CA
Lipton
R B
RB
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology* / Q000523:psychology*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000032:analysis; D003401:Creatine / Q000032:analysis; D005260:Female; D006624:Hippocampus / Q000033:anatomy & histology / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008568:Memory; D008569:Memory Disorders / Q000453:epidemiology / Q000473:pathology; D009483:Neuropsychological Tests; D009929:Organ Size; D012494:Sampling Studies; D014705:Verbal Behavior
D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine