Objective: To examine the neuropsychological profile of dementia patients fro m a community- based autopsy sample of dementia, comparing Alzheimer disease (A D), Lewy body pathology (LBP) alone, and LBP with coexisten...Objective: To examine the neuropsychological profile of dementia patients fro m a community- based autopsy sample of dementia, comparing Alzheimer disease (A D), Lewy body pathology (LBP) alone, and LBP with coexistent AD (AD/LBP). Methods: The authors reviewed 135 subjects from a community- based study of dementia for wh om autopsy and brain tissue was available. Diagnostic groups were determined acc ording to standard neuropathologic methods and criteria, and the presence of LBs was determined using α - synuclein immunostaining. Neuropathologically define d diagnostic groups of AD, AD/LBP, and LBP were examined for differences on neur opsychological test performance at the time of initial study enrollment. Results : There were 48 patients with AD alone, 65 with LB and AD pathology (AD/LBP), an d 22 with LBP alone (LBP alone). There were no significant differences between g roups demographically or on performance of enrollment Mini- Mental State Examin ation (MMSE) or Dementia Rating Scale (DRS). AD patients performed worse than th e LBP patients on memory measures (Fuld Object Memory Evaluation Delayed Recall, Wechsler Memory Scale Logical Memory Immediate and Delayed Recall; p < 0.05) an d a naming task (Consortium to Establish a Registry for Alzheimer’ s Disease Na ming; p < 0.05). LBP patients were more impaired than AD patients on executive f unction (Trail Making Test Part B; p < 0.05) and attention tasks (Wechsler Adult Intelligence Scale- Revised Digit Span; p < 0.05). Decline in MMSE and DRS sco res over time were greatest in the patients with AD/LBP. Conclusions: In a commu nity- based sample of older, medically complicated patients with dementia, ther e are neuropsychological differences between dementia subtypes at the time of di agnosis. In particular, patients with Alzheimer disease (AD) alone and AD/Lewy b ody pathology (LBP) had more severe memory impairment than patients with LBP. LB P alone was associated with more severe executive dysfunction. Patients with AD/ LBP had the most rapid rate of cognitive decline.展开更多
Objective： The functional relationship between calculated alpha band spectral power and inter-/intra-hemispheric coherence during a three-level working memory task of patients with mild cognitive impairment （MCI） w...Objective： The functional relationship between calculated alpha band spectral power and inter-/intra-hemispheric coherence during a three-level working memory task of patients with mild cognitive impairment （MCI） was investigated. Methods：Subjects included 35 MCI patients according to the DSM-Ⅳ criteria （mean age： 62.3, SD： 6.5） and 34 healthy controls （mean age：57.4, SD： 4.0） were selected from the community at large. All subjects performed a simple calculation and recall task with three levels of working memory load while electroencephalograph （EEG） signal was recorded. The spectral EEG power was computed over alphal （8.0～10.0 Hz） and alpha2 （10.5～13.0 Hz） frequency bands and was compared between rest stage and working memory processing stage by two-way ANOVA. Post hoc testing analyzed the differences between each two levels of working memory load during task processing. The inter-hemisphere EEG coherence of frontal （F3-F4）, central （C3-C4）, parietal （P3-P4）, temporal （T5-T6） as well as occipital （O1-O2） was compared between MCI patients and normal controls. The EEG signals from F3-C3,F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs resulted from the intra-hemispheric action for alphal and alpha2 frequency bands. Result： There was significantly higher EEG power from MCI patients than from normal controls both at rest and during working memory processing. Significant differences existed between rest condition and three-level working memory tasks （P〈0.001）. The inter- and intra-hemispheric coherence during working memory tasks showed a ＂drop to rise＂ tendency compared to that at rest condition. There was significantly higher coherence in MCI patients than in the controls.When task difficulties increased, the cortical connectivity of intra-hemispheric diminished while the inter-hemispheric connectivity dominantly maintained the cognitive processing in MCI patients. Conclusion： The results of the present study indicate that the alpha frequency band may be the characteristic band in distinguishing MCI patients from normal controls during working memory tasks. MCI patients exhibit greater inter-hemispheric connectivity than intra-hemispheric connectivity when memory demands increase. MCI patients mobilize a compensatory mechanism to maintain the processing effectiveness while the processing efficiency is reduced.展开更多
文摘Objective: To examine the neuropsychological profile of dementia patients fro m a community- based autopsy sample of dementia, comparing Alzheimer disease (A D), Lewy body pathology (LBP) alone, and LBP with coexistent AD (AD/LBP). Methods: The authors reviewed 135 subjects from a community- based study of dementia for wh om autopsy and brain tissue was available. Diagnostic groups were determined acc ording to standard neuropathologic methods and criteria, and the presence of LBs was determined using α - synuclein immunostaining. Neuropathologically define d diagnostic groups of AD, AD/LBP, and LBP were examined for differences on neur opsychological test performance at the time of initial study enrollment. Results : There were 48 patients with AD alone, 65 with LB and AD pathology (AD/LBP), an d 22 with LBP alone (LBP alone). There were no significant differences between g roups demographically or on performance of enrollment Mini- Mental State Examin ation (MMSE) or Dementia Rating Scale (DRS). AD patients performed worse than th e LBP patients on memory measures (Fuld Object Memory Evaluation Delayed Recall, Wechsler Memory Scale Logical Memory Immediate and Delayed Recall; p < 0.05) an d a naming task (Consortium to Establish a Registry for Alzheimer’ s Disease Na ming; p < 0.05). LBP patients were more impaired than AD patients on executive f unction (Trail Making Test Part B; p < 0.05) and attention tasks (Wechsler Adult Intelligence Scale- Revised Digit Span; p < 0.05). Decline in MMSE and DRS sco res over time were greatest in the patients with AD/LBP. Conclusions: In a commu nity- based sample of older, medically complicated patients with dementia, ther e are neuropsychological differences between dementia subtypes at the time of di agnosis. In particular, patients with Alzheimer disease (AD) alone and AD/Lewy b ody pathology (LBP) had more severe memory impairment than patients with LBP. LB P alone was associated with more severe executive dysfunction. Patients with AD/ LBP had the most rapid rate of cognitive decline.
基金Project (No.2003B070) supported by the Science and TechnologyProgram of Zhejiang Province, China
文摘Objective： The functional relationship between calculated alpha band spectral power and inter-/intra-hemispheric coherence during a three-level working memory task of patients with mild cognitive impairment （MCI） was investigated. Methods：Subjects included 35 MCI patients according to the DSM-Ⅳ criteria （mean age： 62.3, SD： 6.5） and 34 healthy controls （mean age：57.4, SD： 4.0） were selected from the community at large. All subjects performed a simple calculation and recall task with three levels of working memory load while electroencephalograph （EEG） signal was recorded. The spectral EEG power was computed over alphal （8.0～10.0 Hz） and alpha2 （10.5～13.0 Hz） frequency bands and was compared between rest stage and working memory processing stage by two-way ANOVA. Post hoc testing analyzed the differences between each two levels of working memory load during task processing. The inter-hemisphere EEG coherence of frontal （F3-F4）, central （C3-C4）, parietal （P3-P4）, temporal （T5-T6） as well as occipital （O1-O2） was compared between MCI patients and normal controls. The EEG signals from F3-C3,F4-C4, C3-P3, C4-P4, P3-O1, P4-O2, T5-C3, T6-C4, T5-P3 and T6-P4 electrode pairs resulted from the intra-hemispheric action for alphal and alpha2 frequency bands. Result： There was significantly higher EEG power from MCI patients than from normal controls both at rest and during working memory processing. Significant differences existed between rest condition and three-level working memory tasks （P〈0.001）. The inter- and intra-hemispheric coherence during working memory tasks showed a ＂drop to rise＂ tendency compared to that at rest condition. There was significantly higher coherence in MCI patients than in the controls.When task difficulties increased, the cortical connectivity of intra-hemispheric diminished while the inter-hemispheric connectivity dominantly maintained the cognitive processing in MCI patients. Conclusion： The results of the present study indicate that the alpha frequency band may be the characteristic band in distinguishing MCI patients from normal controls during working memory tasks. MCI patients exhibit greater inter-hemispheric connectivity than intra-hemispheric connectivity when memory demands increase. MCI patients mobilize a compensatory mechanism to maintain the processing effectiveness while the processing efficiency is reduced.
