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Abstract:
Low episodic memory performance characterizes elderly subjects at increased risk for Alzheimer's disease (AD) and may reflect neuronal dysfunction within the posterior cingulate cortex and precuneus region (PCP). To investigate a potential association between cerebral neuro-metabolism and low episodic memory in the absence of cognitive impairment, tissue specific magnetic resonance spectroscopic imaging (MRSI) at ultra-high field strength of 7 Tesla was used to investigate the PCP-region in a healthy elderly study population (n=30, age 70±5.7 years, Mini Mental State Examination 29.4±4.1). The Verbal Learning and Memory Test (VLMT) was administered as part of a neuropsychological battery for assessment of episodic memory performance. Significant differences between PCP-gray and white matter could be observed for glutamate-glutamine (p=0.001), choline (p=0.01) and myo-inositol (p=0.02). Low VLMT performance was associated with high N-acetylaspartate in PCP-gray matter (p=0.01), but not in PCP-white matter. Our data suggest that subtle decreases in episodic memory performance in the elderly may be associated with increased levels of NAA as a reflection of increased mitochondrial energy capacity in PCP-gray matter.