Background: N-acetylaspartate (NAA) in the medial temporal lobe (MTL) and par ietal lobe gray matter (GM) is diminished in Alzheimer disease (AD). Because NAA is considered a marker of neuronal integrity, reduced medi...Background: N-acetylaspartate (NAA) in the medial temporal lobe (MTL) and par ietal lobe gray matter (GM) is diminished in Alzheimer disease (AD). Because NAA is considered a marker of neuronal integrity, reduced medial temporal and parie tal lobe NAA could be an early indication of dementia-related pathology in elde rly individuals. Objectives: 1) To determine whether cognitively impaired but no ndemented (CIND) elderly individuals exhibit a similar pattern of reduced medial temporal and parietal lobe NAA as AD patients. 2) To compare regional NAA patte rns, hippocampal and neocortical gray matter (GM)-volumes in CIND patients who remained cognitively stable and those who became demented over 3 .6 years of foll ow-up. 3) To examine the relationship between memory performance, medial tempor al lobe NAA, and hippocampal volume. Methods:Seventeen CIND, 24 AD, and 24 cogni tively normal subjects were studied using MRSI and MRI. Results: Relative to con trols,CIND patients had reduced MTL NAA (19 to 21%, p =0.005), hippocampal (11 to 14%, p ≤0.04), and neocortical GM (5%, p = 0.05) volumes. CIND patients wh o later became demented had less MTL NAA (26%, p = 0.01), hippocampal(17 to 23 %, p ≤0.05), and neocortical GM (13%, p = 0.02)volumes than controls, but the re were no significant differences between stable CIND patients and controls. MT L NAA in combination with hippocampal volume improved discrimination of CIND and controls over hippocampal volume alone.In AD and CIND patients, decreased MTL N AA correlated significantly with impaired memory performance. Conclusion:Reduced medial temporal lobe N-acetylaspartate, together with reduced hippocampal and neocortical gray matter volumes,may be early indications of dementia-related pa thology in subjects at high risk for developing dementia.展开更多
文摘Background: N-acetylaspartate (NAA) in the medial temporal lobe (MTL) and par ietal lobe gray matter (GM) is diminished in Alzheimer disease (AD). Because NAA is considered a marker of neuronal integrity, reduced medial temporal and parie tal lobe NAA could be an early indication of dementia-related pathology in elde rly individuals. Objectives: 1) To determine whether cognitively impaired but no ndemented (CIND) elderly individuals exhibit a similar pattern of reduced medial temporal and parietal lobe NAA as AD patients. 2) To compare regional NAA patte rns, hippocampal and neocortical gray matter (GM)-volumes in CIND patients who remained cognitively stable and those who became demented over 3 .6 years of foll ow-up. 3) To examine the relationship between memory performance, medial tempor al lobe NAA, and hippocampal volume. Methods:Seventeen CIND, 24 AD, and 24 cogni tively normal subjects were studied using MRSI and MRI. Results: Relative to con trols,CIND patients had reduced MTL NAA (19 to 21%, p =0.005), hippocampal (11 to 14%, p ≤0.04), and neocortical GM (5%, p = 0.05) volumes. CIND patients wh o later became demented had less MTL NAA (26%, p = 0.01), hippocampal(17 to 23 %, p ≤0.05), and neocortical GM (13%, p = 0.02)volumes than controls, but the re were no significant differences between stable CIND patients and controls. MT L NAA in combination with hippocampal volume improved discrimination of CIND and controls over hippocampal volume alone.In AD and CIND patients, decreased MTL N AA correlated significantly with impaired memory performance. Conclusion:Reduced medial temporal lobe N-acetylaspartate, together with reduced hippocampal and neocortical gray matter volumes,may be early indications of dementia-related pa thology in subjects at high risk for developing dementia.
