Background and Purpose - MRI segmentation and mapping techniques were used to assess evidence in support of categorical distinctions between periventricular white matter hyperintensities (PVWMH) and deep WMH (DWMH). Q...Background and Purpose - MRI segmentation and mapping techniques were used to assess evidence in support of categorical distinctions between periventricular white matter hyperintensities (PVWMH) and deep WMH (DWMH). Qualitative MRI studies generally identify 2 categories of WMH on the basis of anatomical localization. Separate pathophysiologies and behavioral consequences are often attributed to these 2 classes of WMH. However, evidence to support these empirical distinctions has not been rigorously sought. Methods - MRI analysis of 55 subjects included quantification of WMH volume, mapping onto a common anatomical image, and spatial localization of each WMH voxel. WMH locations were then divided into PVWMH and DWMH on the basis of distance from the lateral ventricles and correlations, with total WMH volume determined. Periventricular distance histograms of WMH voxels were also calculated. Results - PVWMH and DWMH were highly correlated with total WMH (R2 > 0.95) and with each other (R2 >0.87). Mapping of all WMH revealed smooth expansion from around central cerebrospinal fluid spaces into more distal cerebral white matter with increasing WMH volume. Conclusion - PVWMH, DWMH, and total WMH are highly correlated with each other. Moreover, spatial analysis failed to identify distinct subpopulations for PVWMH and DWMH. These results suggest that categorical distinctions between PVWMH and DWMH may be arbitrary, and conclusions regarding individual relationships between causal factors or behavior for PVWMH and DWMH may more accurately reflect total WMH volume relationships.展开更多
Background: Mild cognitive impairment (MCI) is widely viewed as the transition phase between normal aging and Alzheimer disease (AD). Given that MCI can also result from cerebrovascular disease (CVD), the authors used...Background: Mild cognitive impairment (MCI) is widely viewed as the transition phase between normal aging and Alzheimer disease (AD). Given that MCI can also result from cerebrovascular disease (CVD), the authors used clinical,MRI, and cognitive measures of AD and CVD to test the hypothesis that CVD increases the likelihood of progression from MCI to dementia within 3 years. Objective: To examine the impact of CVD on progression of MCI to dementia. Methods: Fifty two consecutive patients with MCI (71% men) including many with symptomatic CVD were longitudinally evaluated for 3.1 ± 1.3 years. MCI was defined as a Clinical Dementia Rating Scale (CDR) score of 0.5. Dementia was defined as progression to a CDR score of ≥ 1.0. Results: Forty four percent of the MCI patients had MRI infarcts, 50% of which were symptomatic. Thirty three percent of patients progressed to dementia, and 37.8% of these had MRI infarcts. Clinically probable or possible AD was diagnosed in approximately 82% of converters. Of the clinical and MRI measures, only hippocampal volume was associated with increased risk to progression (hazard ratio = 0.31 [95% CI 0.1 to 0.92], p = 0.03). When neuropsychological measures were included in the analysis,memory (HR = 0.90 [95% CI 0.84 to 0.96], p = 0.002) and executive function (HR= 0.96 [95% CI 0.92 to 1.0] p=0.045)were associatedwith increased risk of dementia progression, whereas APOE genotype, cerebrovascular risk factors, clinical stroke, presence or absence of lacunes, and extent of white matter hyperintensities did not predict progression. Conclusion: Within a heterogenous group of MCI patients, including many with clinically significant CVD, baseline memory and executive performance significantly predicted likelihood to develop dementia.展开更多
Objective: To analyze the effect of white matter lesions in different brain regions on regional cortical glucose metabolism, regional cortical atrophy, and cognitive function in a sample with a broad range of cerebrov...Objective: To analyze the effect of white matter lesions in different brain regions on regional cortical glucose metabolism, regional cortical atrophy, and cognitive function in a sample with a broad range of cerebrovascular disease and cognitive function. Methods: Subjects (n = 78) were recruited for a study of subcortical ischemic vascular disease (SIVD) and Alzheimer disease (AD) contributions to dementia. A new method was developed to define volumes of interest from high resolution three dimensional T1 weighted MR images. Volumetric measures of MRI segmented white matter signal hyperintensities (WMH) in five different brain regions were related to regional PET glucose metabolism (rCMRglc) in cerebral cortex, MRI measures of regional cortical atrophy, and neuropsychological assessment of executive and memory function. Results: WMH was significantly higher in the prefrontal region compared to the other brain regions. In all subjects, higher frontal and parietal WMH were associated with reduced frontal rCMRglc, whereas occipitotemporal WMH was only marginally associated with frontal rCMRglc. These associations were stronger and more widely distributed in nondemented subjects where reduced frontal rCMRglc was correlatedwithWMH for all regions measured. In contrast, there was no relationship between WMH in any brain region and rCMRglc in either parietal or occipitotemporal regions. WMHs in all brain regions were associated with low executive scores in nondemented subjects. Conclusions: The frontal lobes are most severely affected by SIVD. WMHs are more abundant in the frontal region. Regardless of where in the brain these WMHs are located, they are associated with frontal hypometabolism and exe cutive dysfunction.展开更多
Background: Latino individuals are the largest minority group and the fastest growing population group in the United States, yet there are few studies comparing the clinical features of Alzheimer disease (AD) in th is...Background: Latino individuals are the largest minority group and the fastest growing population group in the United States, yet there are few studies comparing the clinical features of Alzheimer disease (AD) in th is population with those found in Anglo (white non-Latino) patients. Objective: To compare the age at AD symptom onset in Latino and Anglo individuals. Design: Cross-sectional assessment using standardized methods to collect and compare a ge at AD symptom onset, demographic variables, and medical variables. Setting: F ive National Institute on Aging-sponsored Alzheimer’s Disease Centers with exp erience evaluating Spanish-speaking individuals. Patients: We evaluated 119 Lat ino and 55 Anglo patients who had a diagnosis of AD. Main Outcome Measure: Age a t symptom onset. Results: After adjusting for center, sex, and years of educatio n, Latino patients had a mean age at symptom onset 6.8 years earlier (95%confid ence interval, 3.5-10.3 years earlier) than Anglo patients. Conclusions: An ear lier age at symptom onset suggests that US mainland Latino individuals may exper ience an increased burden of AD compared with Anglo individuals. The basis for t he younger age at symptom onset remains obscure.展开更多
文摘Background and Purpose - MRI segmentation and mapping techniques were used to assess evidence in support of categorical distinctions between periventricular white matter hyperintensities (PVWMH) and deep WMH (DWMH). Qualitative MRI studies generally identify 2 categories of WMH on the basis of anatomical localization. Separate pathophysiologies and behavioral consequences are often attributed to these 2 classes of WMH. However, evidence to support these empirical distinctions has not been rigorously sought. Methods - MRI analysis of 55 subjects included quantification of WMH volume, mapping onto a common anatomical image, and spatial localization of each WMH voxel. WMH locations were then divided into PVWMH and DWMH on the basis of distance from the lateral ventricles and correlations, with total WMH volume determined. Periventricular distance histograms of WMH voxels were also calculated. Results - PVWMH and DWMH were highly correlated with total WMH (R2 > 0.95) and with each other (R2 >0.87). Mapping of all WMH revealed smooth expansion from around central cerebrospinal fluid spaces into more distal cerebral white matter with increasing WMH volume. Conclusion - PVWMH, DWMH, and total WMH are highly correlated with each other. Moreover, spatial analysis failed to identify distinct subpopulations for PVWMH and DWMH. These results suggest that categorical distinctions between PVWMH and DWMH may be arbitrary, and conclusions regarding individual relationships between causal factors or behavior for PVWMH and DWMH may more accurately reflect total WMH volume relationships.
文摘Background: Mild cognitive impairment (MCI) is widely viewed as the transition phase between normal aging and Alzheimer disease (AD). Given that MCI can also result from cerebrovascular disease (CVD), the authors used clinical,MRI, and cognitive measures of AD and CVD to test the hypothesis that CVD increases the likelihood of progression from MCI to dementia within 3 years. Objective: To examine the impact of CVD on progression of MCI to dementia. Methods: Fifty two consecutive patients with MCI (71% men) including many with symptomatic CVD were longitudinally evaluated for 3.1 ± 1.3 years. MCI was defined as a Clinical Dementia Rating Scale (CDR) score of 0.5. Dementia was defined as progression to a CDR score of ≥ 1.0. Results: Forty four percent of the MCI patients had MRI infarcts, 50% of which were symptomatic. Thirty three percent of patients progressed to dementia, and 37.8% of these had MRI infarcts. Clinically probable or possible AD was diagnosed in approximately 82% of converters. Of the clinical and MRI measures, only hippocampal volume was associated with increased risk to progression (hazard ratio = 0.31 [95% CI 0.1 to 0.92], p = 0.03). When neuropsychological measures were included in the analysis,memory (HR = 0.90 [95% CI 0.84 to 0.96], p = 0.002) and executive function (HR= 0.96 [95% CI 0.92 to 1.0] p=0.045)were associatedwith increased risk of dementia progression, whereas APOE genotype, cerebrovascular risk factors, clinical stroke, presence or absence of lacunes, and extent of white matter hyperintensities did not predict progression. Conclusion: Within a heterogenous group of MCI patients, including many with clinically significant CVD, baseline memory and executive performance significantly predicted likelihood to develop dementia.
文摘Objective: To analyze the effect of white matter lesions in different brain regions on regional cortical glucose metabolism, regional cortical atrophy, and cognitive function in a sample with a broad range of cerebrovascular disease and cognitive function. Methods: Subjects (n = 78) were recruited for a study of subcortical ischemic vascular disease (SIVD) and Alzheimer disease (AD) contributions to dementia. A new method was developed to define volumes of interest from high resolution three dimensional T1 weighted MR images. Volumetric measures of MRI segmented white matter signal hyperintensities (WMH) in five different brain regions were related to regional PET glucose metabolism (rCMRglc) in cerebral cortex, MRI measures of regional cortical atrophy, and neuropsychological assessment of executive and memory function. Results: WMH was significantly higher in the prefrontal region compared to the other brain regions. In all subjects, higher frontal and parietal WMH were associated with reduced frontal rCMRglc, whereas occipitotemporal WMH was only marginally associated with frontal rCMRglc. These associations were stronger and more widely distributed in nondemented subjects where reduced frontal rCMRglc was correlatedwithWMH for all regions measured. In contrast, there was no relationship between WMH in any brain region and rCMRglc in either parietal or occipitotemporal regions. WMHs in all brain regions were associated with low executive scores in nondemented subjects. Conclusions: The frontal lobes are most severely affected by SIVD. WMHs are more abundant in the frontal region. Regardless of where in the brain these WMHs are located, they are associated with frontal hypometabolism and exe cutive dysfunction.
文摘Background: Latino individuals are the largest minority group and the fastest growing population group in the United States, yet there are few studies comparing the clinical features of Alzheimer disease (AD) in th is population with those found in Anglo (white non-Latino) patients. Objective: To compare the age at AD symptom onset in Latino and Anglo individuals. Design: Cross-sectional assessment using standardized methods to collect and compare a ge at AD symptom onset, demographic variables, and medical variables. Setting: F ive National Institute on Aging-sponsored Alzheimer’s Disease Centers with exp erience evaluating Spanish-speaking individuals. Patients: We evaluated 119 Lat ino and 55 Anglo patients who had a diagnosis of AD. Main Outcome Measure: Age a t symptom onset. Results: After adjusting for center, sex, and years of educatio n, Latino patients had a mean age at symptom onset 6.8 years earlier (95%confid ence interval, 3.5-10.3 years earlier) than Anglo patients. Conclusions: An ear lier age at symptom onset suggests that US mainland Latino individuals may exper ience an increased burden of AD compared with Anglo individuals. The basis for t he younger age at symptom onset remains obscure.
