Faculty Bibliography

BACKGROUND: Patients with dementia of the Alzheimer type (DAT) respond variably to treatment with acetylcholinesterase inhibitors. OBJECTIVE: To determine whether measures of hippocampal volume and shape predict the response to donepezil in patients with DAT. DESIGN: T1-weighted, magnetic resonance images were obtained from patients with DAT, who subsequently underwent treatment with donepezil. Brain-mapping algorithms were used to quantify hippocampal volume and shape, and growth curves were used to estimate clinical outcome. SETTING: A referral outpatient center specializing in treatment of dementia. PATIENTS: Thirty-seven patients with very mild or mild DAT received donepezil therapy for up to 4 weeks before magnetic resonance imaging and for 24 to 96 weeks after magnetic resonance imaging. INTERVENTION: Donepezil, 10 mg/d. MAIN OUTCOME MEASURE: Rate of change in the cognitive portion of the Alzheimer's Disease Assessment Scale total scores. RESULTS: Smaller hippocampal volume and inward variation of the lateral and inferomedial portions of the hippocampal surface were correlated with a poorer response to donepezil therapy. CONCLUSIONS: Measures of hippocampal volume and surface variation can be used to predict the response of patients with DAT to the acetylcholinesterase inhibitor donepezil

To evaluate molecular events associated with the aging process in animal models and human tissues, microarray analysis is performed at the regional and cellular levels to define transcriptional patterns or mosaics that may lead to better understanding of the mechanism(s) that drive senescence. In this review, we outline the experimental and analytical issues associated with high-throughput genomic analyses in aging brain and other tissues for a comprehensive evaluation of the current state of microarray analysis in aging paradigms. Ultimately, the goal of these studies is to apply functional genomics and proteomics approaches to aging research to develop new tools to assess age in cell- and tissue-specific manners in order to develop aging biomarkers for pharmacotherapeutic interventions and disease prevention

OBJECTIVE: To investigate the cognitive decline in dementia with Lewy bodies (DLBs) and characterize the contribution of Lewy bodies (LBs) to cognitive impairment in the presence of concurrent Alzheimer disease (AD). METHODS: Cognitive deficits and rates of progression attributable to DLB and AD neuropathology were investigated in three groups of participants from the longitudinal cohort of the Alzheimer Disease Research Center at Washington University with autopsy-confirmed diagnoses of pure DLB (n = 9), mixed DLB/AD (n = 57), and pure AD (n = 66). Factor analysis was used to recover latent constructs in a comprehensive psychometric test battery, analysis of variance was used to test group differences on the observed dimensions, and random effects models were used to test longitudinal rates of cognitive decline. RESULTS: Patients with AD pathology performed worse on the verbal memory dimension. Patients with LB pathology performed worse on the visuospatial dimension. Combined pathology affected visuospatial performance but not verbal memory. The rate of cognitive decline in the DLB, DLB/AD combined, and the pure AD groups was equivalent. CONCLUSIONS: The comorbid presence of DLB and AD alters the cognitive presentation of visuospatial deficits in dementia but does not alter dementia progression. Both visuospatial and verbal abilities declined at similar rates across the three patient groups. DLB diagnosis may be improved, particularly when there is comorbid AD, by using domain-specific testing

BACKGROUND: Brief measures that accurately discriminate normal cognitive aging from very mild dementia are lacking. Cognitive tests often are insensitive to very mild dementia. Informant-based measures may be more sensitive in detecting early dementia. OBJECTIVE: To identify informant-reported clinical variables that differentiate cognitively normal individuals from those with very mild dementia. METHODS: A 55-item battery of informant queries regarding an individual's cognitive status was derived from a semistructured interview and a consensus panel of dementia experts. The battery was evaluated with informants for 189 consecutive participants of a longitudinal study of memory and aging and compared with an independently obtained Clinical Dementia Rating (CDR) score for the participant. Multiple regression and receiver operator characteristic curves assessed subsets of the items to discriminate between CDR 0 (no dementia) and CDR 0.5 (very mild dementia). RESULTS: The final version (AD8) querying memory, orientation, judgment, and function was administered to an additional sample of 112 CDR 0 and 68 CDR 0.5 participants. Using a cut-off of two items endorsed, the area under the curve was 0.834, suggesting good to excellent discrimination, sensitivity was 74%, and specificity was 86% (prevalence of 0.38 for very mild dementia). Inclusion of 56 additional individuals with mild to severe dementia (increasing dementia prevalence to 0.53) increased sensitivity to 85%. CONCLUSIONS: The AD8 is a brief, sensitive measure that reliably differentiates between nondemented and demented individuals. Use of the AD8 in conjunction with a brief assessment of the participant could improve diagnostic accuracy in general practice

BACKGROUND: To understand the earliest signs of cognitive decline caused by Alzheimer disease (AD) and other illnesses causing dementia, information is needed from well-characterized individuals without dementia studied longitudinally until autopsy. OBJECTIVE: To determine clinical and cognitive features associated with the development of AD or other dementias in older adults. DESIGN: Longitudinal study of memory and aging. SETTING: Alzheimer's Disease Research Center, St Louis, Mo. MAIN OUTCOME MEASURES: Clinical Dementia Rating, its sum of boxes, and neuropathologic diagnosis of dementia. PARTICIPANTS: Eighty control participants who eventually came to autopsy. RESULTS: Individuals who did not develop dementia showed stable cognitive performance. Entry predictors of dementia were age, deficits in problem solving as well as memory, slowed psychomotor performance, and depressive features. Minimal cognitive decline occurred prior to dementia diagnosis, after which sharp decline was noted. Even individuals who were minimally cognitively impaired (Clinical Dementia Rating = 0.5) typically had neuropathologic AD at autopsy. Histopathologic AD also was present in 34% of individuals who did not have dementia at death; these individuals without dementia showed an absence of practice effects on cognitive testing. CONCLUSIONS: Increased age, depressive features, and even minimal cognitive impairment, as determined clinically by Clinical Dementia Rating sum of boxes and by slowed psychomotor performance, identify older individuals without dementia who develop dementia. Older adults who do not develop dementia have stable cognitive performance. The absence of practice effects may denote the subset of older adults without dementia with histopathologic AD, which may reflect a preclinical stage of the illness

BACKGROUND: Extrapyramidal signs (EPS) are common in Alzheimer disease (AD) and increase in prevalence as AD advances. The neuropathologic substrate responsible for EPS in AD remains to be fully characterized. METHODS: Subjects had a clinical diagnosis of AD confirmed by neuropathologic examination. EPS during life were documented by clinical methods assessing bradykinesia, cogwheel rigidity, rest tremor, and parkinsonian gait. Subjects with EPS and previous neuroleptic exposure were excluded. Twenty-eight subjects were in the EPS group and 104 subjects were without EPS. Neuron loss, alpha-synuclein (ASYN)-labeled pathology, and tau-labeled pathology in the substantia nigra were measured using semiquantitative techniques such that higher scores represented increased pathologic burden. RESULTS: Presence of nigral ASYN-labeled pathology was more common (50 vs 28.9%; p < 0.05) in the EPS group than in those without EPS. There was more nigral neuron loss in the EPS group (1.50 vs 1.11 in no-EPS group; p < 0.05). Tau-labeled burden was not different by group comparisons; however, EPS onset at later stages of dementia severity was associated with increased tau-labeled pathology (Kendall tau-B = 0.48, p < 0.01) and this association remained after controlling for dementia severity at death. Additionally, moderate to severe tau burden was more common in the subgroup with 'pure AD' (definite AD without other neuropathology) with EPS (81.8%) than cases without EPS (49.0%; p < 0.05). Four subjects with EPS (14.3%) had little to no significant nigral pathologic changes. CONCLUSIONS: Clinically detected extrapyramidal signs (EPS) in Alzheimer disease (AD) are associated with substantia nigra pathology including alpha-synuclein aggregation, hyperphosphorylated tau accumulation, and neuron loss that may account for the increasing prevalence of EPS as AD progresses. In some cases, limited nigral pathology suggests extranigral factors in the clinical symptoms of EPS

Expression profiling data is available for many diverse tissues throughout the body, allowing for exciting hypothesis testing of critical concepts such as cellular development, differentiation, normative function, and disease pathogenesis. The central nervous system is an ideal structure to evaluate relationships between functional genomics and expression data. Recent developments in gene array technologies, specifically cDNA microarray platforms, have made it easier to try to understand the multiplicity of gene alterations that occur within the brains of animal models and postmortem human tissues. However, unlike structures have one principal cell type, the brain contains diverse populations of phenotypically distinct cell types. A goal of modern molecular and cellular neuroscience is to assay gene expression from homogeneous populations of cells within a defined region without potential contamination by expression profiles of adjacent neuronal subtypes and non-neuronal cells. This is a difficult task that demands a multidisciplinary approach that is highlighted in this review within the context of neurodegenerative pathology

The aggregation of neuronal proteins as inclusions is emerging as a common mechanistic theme in neurodegenerative diseases. The presence of these 'disease-specific' pathologic changes in the brains of patients with neurodegenerative diseases assist pathologists in the diagnosis and characterization of dementing illnesses. However, these same inclusions may provide valuable clues toward understanding common pathologic roots and shared abnormalities in protein folding across disorders. Such an investigation will likely provide insights into disease mechanisms underlying neurodegenerative disorders characterized by abundant filamentous lesions. This review focuses on two themes: (i) Neurodegenerative disorders are characterized by shared and distinct histopathological and biochemical abnormalities, and (ii) the presence of abnormal protein aggregates may alter a gene, and hence protein expression in inclusion-bearing neurons predisposes them to dysfunction and eventual neuronal degeneration. The pathologic features of neurodegenerative diseases are first discussed followed by a rationale behind sampling mRNA species from single cells rather than from whole-brain homogenates to explore disease mechanisms