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Biomedical subjects

D Galasko

Publications and source records attributed to D Galasko.

At least 55 records · Page 3Linked to original sources
PubMed1998

High cerebrospinal fluid tau and low amyloid beta42 levels in the clinical diagnosis of Alzheimer disease and relation to apolipoprotein E genotype.

OBJECTIVE: To evaluate cerebrospinal fluid (CSF) levels of amyloid beta protein ending at amino acid 42 (Abeta42) and tau as markers for Alzheimer disease (AD) and to determine whether clinical variables influence these levels. DESIGN: Cohort study. SETTING: Six academic research centers with expertise in dementia. SUBJECTS: Eighty-two patients with probable AD, including 24 with very mild dementia (Mini-Mental State Examination score >23/30) (AD group); 60 cognitively normal elderly control subjects (NC group); and 74 subjects with neurological disorders, including dementia (ND group). MAIN OUTCOME MEASURES: Levels of Abeta42 and tau were compared among AD, NC, and ND groups. Relationships of age, sex, Mini-Mental State Examination score, and apolipoprotein E (Apo E) genotype with these levels were examined using multiple linear regression. Classification tree models were developed to optimize distinguishing AD from NC groups. RESULTS: Levels of Abeta42 were significantly lower, and levels of tau were significantly higher, in the AD group than in the NC or ND group. In the AD group, Abeta42 level was inversely associated with Apo E epsilon4 allele dose and weakly related to Mini-Mental State Examination score; tau level was associated with male sex and 1 Apo E epsilon4 allele. Classification tree analysis, comparing the AD and NC subjects, was 90% sensitive and 80% specific. With specificity set at greater than 90%, the tree was 77% sensitive for AD. This tree classified 26 of 74 members of the ND group as having AD. They had diagnoses difficult to distinguish from AD clinically and a high Apo E epsilon4 allele frequency. Markers in CSF were used to correctly classify 12 of 13 patients who later underwent autopsy, including 1 with AD not diagnosed clinically. CONCLUSIONS: Levels of CSF Abeta42 decrease and levels of CSF tau increase in AD. Apolipoprotein E epsilon4 had a dose-dependent relationship with CSF levels of Abeta42, but not tau. Other covariates influenced CSF markers minimally. Combined analysis of CSF Abeta42 and tau levels discriminated patients with AD, including patients with mild dementia, from the NC group, supporting use of these proteins to identify AD and to distinguish early AD from aging. In subjects in the ND group with an AD CSF profile, autopsy follow-up will be required to decide whether CSF results are false positive, or whether AD is a primary or concomitant cause of dementia.

Adult↗
PubMed1998

Cognitive profiles of autopsy-confirmed Lewy body variant vs pure Alzheimer disease.

OBJECTIVE: To compare the cognitive profiles of patients with autopsy-confirmed Alzheimer disease (AD), with or without concomitant Lewy bodies, on 2 dementia screening measures. METHODS: Profiles on subtests of the Mattis Dementia Rating Scale (range, 105-125) and of component items of the Mini-Mental State Examination were compared between 23 patients with uncomplicated AD and 23 patients with concomitant AD and Lewy body pathology (Lewy body variant [LBV]). RESULTS: Although the groups did not differ significantly regarding age, years of education, total Mini-Mental State Examination score, or total Mattis Dementia Rating Scale score, the AD group performed significantly worse than the LBV group on the Mattis Dementia Rating Scale Memory subscale (P < .005). In contrast, the LBV group demonstrated poorer performance than the pure AD group on the Initiation/Perseveration subscale (P < .02). The groups did not differ significantly on the Attention, Construction, or Conceptualization subscales. The same overall pattern of results was obtained when subgroups with mild to moderate and moderate to severe dementia were examined separately, with the additional finding that in the mild-to-moderate range patients with dementia and LBV performed worse than patients with pure AD on the Construction subscale. CONCLUSIONS: The difference in pattern of cognitive deficits among patients with pure AD vs those with AD and LBV is similar to that seen between AD and more subcortical/frontal dementias (eg, Huntington disease) This suggests that the concomitant Lewy body pathology significantly contributes to the presentation of the cognitive dysfunction in individuals with LBV.

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PubMed1998

Pronounced impact of Th1/E47cs mutation compared with -491 AT mutation on neural APOE gene expression and risk of developing Alzheimer's disease.

Possession of the apolipoprotein E (APOE) epsilon4 allele is the most frequently associated genetic susceptibility factor for Alzheimer's disease (AD). Recently, new polymorphisms in the regulatory region of the APOE gene have been described. We analysed the effects of three of these mutations (-491 AT, -427 CT and Th1/E47cs) on disease risk in a large case-control study, and tested their impacts on APOE allelic expression in brain tissues. The Th1/E47cs T allele was associated with an increased risk of occurrence of AD, while the -491 T allele was associated with a decreased risk, independently of the APOE epsilon2/epsilon3/epsilon4 polymorphism effect. However, the impact of the Th1/E47cs mutation was the strongest. The -427 CT polymorphism was not associated with the disease. In AD subjects heterozygous for the epsilon4 allele, analysis of allelic expression showed that the relative expression levels of the epsilon4 allele were higher than those of the corresponding controls. Consistent with epidemiological data, the relative level of expression of the epsilon4 allele was modified accordingly to the presence or absence of the two main promoter polymorphisms, indicating, in vivo, the deleterious effect of the Th1/E47cs T allele and the protective effect of the -491 T allele in population. These data indicate that in addition to the qualitative effect of the APOE epsilon2/epsilon3/epsilon4 polymorphisms on the AD occurrence, the quantitative variation of expression of these alleles due to functional APOE promoter mutations, is a key determinant of AD development.

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PubMed1998

Cognitive decline is faster in Lewy body variant than in Alzheimer's disease.

OBJECTIVES: To quantify the rate of cognitive decline on the Mini-Mental State Examination (MMSE) in autopsy-diagnosed Lewy body variant (LBV) of Alzheimer's disease (AD) cases. We hypothesized that LBV patients would have a faster cognitive decline and shorter survival compared with patients with pure AD. BACKGROUND: Prior reports have shown extrapyramidal signs to be associated with a poorer prognosis in AD. It has been suggested that LBV is often characterized by a rapidly progressive course. Few data are available regarding the rate of cognitive decline in autopsy-confirmed LBV dementia cases. METHODS: We searched the databases of the University of California-San Diego Alzheimer's Disease Research Center and the Consortium to Establish a Registry in Alzheimer's Disease (CERAD) for dementia cases with 1) an autopsy diagnosis of definite or probable AD (CERAD criteria) with concomitant Lewy bodies and 2) longitudinal MMSE assessments. This resulted in a series of 40 LBV cases and 148 AD cases without Lewy bodies, with comparable baseline MMSE scores, age, and education. The rate of cognitive decline was calculated as the baseline MMSE -- final MMSE. Methods were devised to reduce floor effects on the MMSE. RESULTS: The average rate of cognitive decline was -5.8 +/- 4.5 points/y in LBV and -4.1 +/- 3.0 points/y in AD (t-test, p < 0.01). The LBV group declined a similar amount on the MMSE (means, -10.0 versus -9.6 points) over a significantly shorter time interval (1.9 versus 2.7 years; p = 0.005) than did AD patients. At baseline, the mean MMSE scores were nearly identical (18.2 in LBV; 17.8 in AD), but on follow-up examinations approximately 1, 2, and 3 years later, there were intergroup mean differences of 1.8 points (two-tailed p = 0.19), 4.2 points (p = 0.04), and 5.6 points (p = 0.03), respectively. The LBV cases had shorter survival time from the onset of cognitive symptoms (7.7 +/- 3.0 years versus 9.3 +/- 3.5 years; p = 0.007) and a shorter mean survival after entry/baseline, which was of marginal significance (3.6 versus 4.1 years; p = 0.11). CONCLUSIONS: This study demonstrates that LBV is characterized by a faster cognitive decline and accelerated mortality compared with AD.

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PubMed1998

Cerebrospinal fluid levels of A beta 42 and tau: potential markers of Alzheimer's disease.

CSF levels of proteins related to the lesions of Alzheimer's Disease (AD) may be informative. These include the microtubule-associated protein tau, an integral component of neurofibrillary tangles, and A beta, a 4kDa protein that accumulates in senile plaque amyloid. Many studies have found that CSF tau is increased in AD compared to normal controls (NC). CSF tau may be increased in a minority of patients with destructive neurological disorders or several neurodegenerative conditions, making its use in differential diagnosis less clear. CSF tau consists of fragments that lack extensive phosphorylation. CSF levels of A beta species ending at residue 40 are unchanged in AD. However species ending at residue 42 (A beta 42) are significantly decreased in AD compared to NC. Decreased A beta 42 may be found in patients with other dementias, some of whom may harbor AD pathology. Simultaneous measurement of CSF A beta 42 and tau may improve discrimination between AD and NC, and may facilitate the diagnosis of early stage AD.

Alzheimer Disease↗
PubMed1997

Mutations in mitochondrial cytochrome c oxidase genes segregate with late-onset Alzheimer disease.

Mounting evidence suggests that defects in energy metabolism contribute to the pathogenesis of Alzheimer disease (AD). Cytochrome c oxidase (CO) is kinetically abnormal, and its activity is decreased in brain and peripheral tissue in late-onset AD. CO is encoded by both the mitochondrial and the nuclear genomes. Its catalytic centers, however, are encoded exclusively by two mitochondrial genes, CO1 and CO2 (encoding CO subunits I and II, respectively). We searched these genes, as well as other mitochondrial genes, for mutations that might alter CO activity and cosegregate with AD. In the present study, specific missense mutations in the mitochondrial CO1 and CO2 genes but not the CO3 gene were found to segregate at a higher frequency with AD compared with other neurodegenerative or metabolic diseases. These mutations appear together in the same mitochondrial DNA molecule and define a unique mutant mitochondrial genome. Asymptomatic offspring of AD mothers had higher levels of these mutations than offspring of AD fathers, suggesting that these mutations can be maternally inherited. Cell lines expressing these mutant mitochondrial DNA molecules exhibited a specific decrease in CO activity and increased production of reactive oxygen species. We suggest that specific point mutations in the CO1 and CO2 genes cause the CO defect in AD. A CO defect may represent a primary etiologic event, directly participating in a cascade of events that results in AD.

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PubMed1997

Early-onset Alzheimer's disease with a presenilin-1 mutation at the site corresponding to the Volga German presenilin-2 mutation.

We describe a new mutation causing Alzheimer's disease (AD) in presenilin-1 (N135D) that is at the homologous site to the presenilin 2 mutation (N141I) in Volga German kindreds. The phenotype of PS1 N135D is an early-onset (34-38 years) disease. The mutation forms part of, and extends, the alpha-helical array of mutations in transmembrane 2 of the presenilins and leads to the suggestion that disruption of this helical face is the molecular insult that leads to disease.

Adult↗
PubMed1997

The tau protein in human cerebrospinal fluid in Alzheimer's disease consists of proteolytically derived fragments.

Previous studies have shown that the levels of the microtubule-associated protein tau in the CSF of patients with Alzheimer's disease (AD) are elevated compared with age-matched controls. In spite of these findings, the nature of tau in CSF has not been well documented. In the present study, tau was immunoprecipitated from CSF of patients with AD or acute stroke, as well as normal elderly controls, followed by immunoblot analysis. In all cases, CSF tau consisted primarily of a band migrating at 26-28 kDa. In AD and stroke patients, several smaller tau fragments were also detected. No intact tau was detected in any of the CSF samples examined. Further immunoprecipitation studies showed that the majority of the tau fragments contained the amino terminus of the molecule. Treatment of CSF tau with alkaline phosphatase did not alter the electrophoretic properties of the fragments. These studies clearly demonstrate that CSF tau is truncated rather than intact.

Alzheimer Disease↗
PubMed1997

Distortion of allelic expression of apolipoprotein E in Alzheimer's disease.

The APOE epsilon4 allele is a strong genetic susceptibility factor for Alzheimer's disease. Interaction with other biological factors may modulate the effect of the apoE isoforms. However, previous work suggested that other genetic variability within the APOE locus, influencing the effect of the epsilon4 allele, may exist. Such variability could modify the expression of the APOE gene and, in particular, the level of expression of APOE alleles could be an important determinant of disease pathogenesis. To test this hypothesis we examined the levels of expression of APOE in heterozygotes with AD and in controls, using a new method of semi-quantitation. We report that relative epsilon4 mRNA expression is increased in AD compared with controls and suggest that genetic variability in the neural expression of APOE contributes to disease risk.

Aged↗
PubMed1997

Assessment of CSF levels of tau protein in mildly demented patients with Alzheimer's disease.

CSF levels of tau protein are increased in many patients with Alzheimer's disease (AD). Studies disagree on whether the increase is found in moderate or severe AD to a greater extent than in mild AD, and in two reports there was an inverse correlation between tau levels and cognitive scores. To readdress this question, we measured CSF tau in a group of mildly impaired patients with AD (Mini-Mental State Examination [MMSE] scores > or =20/30) and compared their tau levels with those in age-comparable normal and neurologic controls. We found that the mean level of CSF tau was significantly increased in the AD group compared with the controls, and 29 of 36 patients with AD had levels that exceeded a cutoff determined in a previous study. CSF tau levels did not correlate with MMSE scores. These findings and those of previous studies show that elevated CSF tau levels are found in most patients with AD, occur early in the course of dementia, and may be useful in supporting the diagnosis of AD.

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PubMed1997

The impact of apolipoprotein E4 on cause of death in Alzheimer's disease.

OBJECTIVE: We tested the hypothesis that the apolipoprotein E epsilon 4 (apoE4) allele is associated with an increased proportion of vascular-related mortality in Alzheimer's disease (AD). BACKGROUND: ApoE4 is associated with an increased risk of developing AD, with an earlier onset, and may predispose to vascular dementia as well. In the general population, apoE4 has been associated with increased coronary artery disease and shorter lifespan. There is a paucity of data regarding the effect of the apolipoprotein E (apoE) genotype upon the contributing causes of death in AD. METHODS: Death certificates of 114 AD cases were reviewed blind to apoE genotype. Deaths due to ischemic heart disease (IHD), cerebrovascular disease (CVD), vascular disease (either IHD or CVD), pneumonia, and other causes were analyzed as a function of apoE genotype. Logistic regression analyses were employed to control for age and gender effects. RESULTS: The likelihood of vascular disease contributing to death increased in association with the epsilon 4 allele (29% in cases without an epsilon 4 allele, 43% in cases with one epsilon 4 allele, 53% in epsilon 4/4 homozygous cases; p = 0.035 after corrections for age and gender). This increase appeared largely due to an increase in ischemic heart disease, which was reported more frequently on death certificates of cases with one or more epsilon 4 allele (adjusted odds ratio [OR] = 1.85 per epsilon 4 allele; p < 0.05). There were nonsignificant trends for apoE4 to be associated with increased mortality related to cerebrovascular disease (OR = 1.45) and decreased mortality related to pneumonia (OR = 0.77) and AD itself (OR = 0.72). The epsilon 4/4 cases had significantly earlier age of onset (mean = 64.5 yr), earlier death, and longer duration of disease (mean = 10.1 yr). Cases with one or more epsilon 4 allele tended to have lower mean MMSE scores prior to death (6.6 versus 9.5) and were more often female (54% versus 45%). CONCLUSIONS: The apoE4 allele appears to increase the risk of vascular and ischemic heart disease-related death in patients with AD.

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PubMed1997

A multicenter evaluation of new treatment efficacy instruments for Alzheimer's disease clinical trials: overview and general results. The Alzheimer's Disease Cooperative Study.

Evaluating treatment efficacy in Alzheimer's disease (AD) clinical trials requires optimal assessment methods to determine the extent and clinical meaningfulness of potential therapeutic effects of pharmacologic agents. Development of improved outcome measures for AD clinical trials is a major objective of the Alzheimer's Disease Cooperative Study (ADCS), an NIA-sponsored, multisite clinical trials consortium. The ADCS Instrument Development Project evaluated the sensitivity, reliability and validity of new or improved measures in each of five assessment domains: (a) cognition (immediate and delayed memory, praxis, attention, and executive function); (b) clinical global change; (c) activities of daily living; (d) behavioral symptoms (agitation and other noncognitive symptoms); and (e) cognition in severely impaired patients. A total of 306 English-speaking subjects were enrolled in the study, including AD patients stratified by disease severity and cognitively normal, age-matched elderly subjects. Half were retested at 1 month and 2 months after baseline, and all received 6- and 12-month follow-up assessments. Spanish versions of these new measures are currently being evaluated. The development of this multisite study, the common methods and procedures, and a detailed description of the cohort are provided in this overview article. This multisite project demonstrates the feasibility of a consortium approach to instrument development. We were able to develop new instruments and efficiently evaluate their reliability and sensitivity to longitudinal change by capitalizing on the experience and patient resources of the participating ADCS research sites.

Aged↗
PubMed1997

An inventory to assess activities of daily living for clinical trials in Alzheimer's disease. The Alzheimer's Disease Cooperative Study.

We developed a set of informant-based items describing performance of activities of daily living (ADL) by patients with Alzheimer's disease (AD) to identify which ADL are useful for assessment of patients in clinical trials. Evaluation of ADL is an important outcome measure in AD clinical trials. For clinical trial measurement, ADL should have broad applicability, good test-retest reliability, scaling to cover a range of performance, and sensitivity to detect change in disease progression. A total of 45 ADL items developed from literature review and clinical experience were administered to informants of 242 AD patients and 64 elderly controls as part of the multicenter Alzheimer's Disease Cooperative Study Instrument protocol. Half of the subjects were re-evaluated at 1 and 2 months and all at 6 and 12 months. Controls performed virtually all ADL items optimally at baseline and at 12 months. Among subjects with AD, 27 of the 45 ADL were widely applicable, i.e., performed at baseline or premorbidly by > 90% of subjects; showed good test-retest reliability between baseline and 1 and 2 months; correlated with MMSE scores of AD patients cross-sectionally; and showed a decline in performance from baseline to 12 months in at least 20% of AD patients. ADL could be identified that capture change in functional ability in patients across the entire range of the MMSE. The remaining 18 ADL included several that may be useful for trials that target specific populations, e.g., women with AD. Because change on specific items depends on baseline MMSE, ADL evaluation should include items relevant to the severity of dementia of patients enrolled in a clinical trial.

Activities of Daily Living↗
PubMed1997

Multicenter evaluation of new instruments for Alzheimer's disease clinical trials: summary of results. The Alzheimer's Disease Cooperative Study.

The Instrument Development Project of the Alzheimer's Disease Cooperative Study (ADCS) evaluated new assessments in five domains: (a) cognitive function; (b) clinical global change; (c) activities of daily living; (d) behavioral symptoms, and (e) cognition in severely impaired patients. These new instruments demonstrate excellent discrimination between normal controls and patient groups and show adequate validity and reliability. Stability of measurement and sensitivity to longitudinal change were also demonstrated in each of these areas. Examination of several domain-specific questions also contributed new information on the measurement of cognitive function with different subtasks across AD severity levels, the stability of clinical ratings of global change, and the applicability of behavioral assessment across severity levels. The success of this project enhances the state of the art in the measurement of efficacy in AD clinical trials and also provides a basis for future research on improving AD outcome measures.

Activities of Daily Living↗
PubMed1996

Neuropsychological assessment of severely demeted elderly: the severe cognitive impairment profile.

BACKGROUND: Although the assessment of cognitive functioning in the late stages of Alzheimer's Disease (AD) is important for identifying abilities that may improve communication and interactions with severely impaired patients in clinical and institutional settings and for assessing the efficacy of pharmacologic agents and behavioral interventions for the treatment of AD, few adequate instruments exist for measuring the cognitive capacities of these severely demented individuals. OBJECTIVES: To evaluate the reliability and validity of the Severe Cognitive Impairment Profile (SCIP), a measure of neuropsychological functioning in severely demented patients, and compare it with other available instruments. DESIGN AND METHODS: We administered the Mattis Dementia Rating Scale (DRS), Mini-Mental State Examination (MMSE), SCIP, and Severe Impairment Battery (SIB) to 41 severely demented patients with AD participating in an AD research center. We used (1) Spearman rank correlation coefficients to assess interrater and test-retest reliability and construct validity of the SCIP; (2) one-way analysis of variance with post hoc comparisons to examine performance on the SCIP and the SIB at different levels of dementia severity; and (3) descriptive statistics to establish the sensitivity of the SCIP to cognitive functioning in a subgroup of very severely demented patients. RESULTS: Interrater and test-retest reliability correlation coefficients were highly significant for total SCIP score (r=0.99 and r=0.96, respectively) as well as for all SCIP subscales. High correlations were also found between SCIP scores and two widely used tests of global cognitive functioning, the DRS (r=0.91) and the MMSE (r=0.84), suggesting good construct validity. The SCIP was able to significantly differentiate between four groups of severely impaired patients divided by level of dementia severity, while the SIB was unable to differentiate between the less severely demented groups. A subgroup of 16 very severely demented patients (DRS score, <50 points) obtained an average of 45% of total possible points on the SCIP, compared with an average of 1% and 21% of total possible points on the MMSE and DRS, respectively. After approximately 1 year of decline, 12 severely demented patients with AD were able to correctly answer an average of more than 58% of the items on the SCIP, compared with only 30% on the DRS and 20% on the MMSE. CONCLUSIONS: The SCIP is a reliable, valid measure of neuropsychological functioning in severely demented patients with AD with the ability to avoid both floor and ceiling effects and to evaluate a wider range of cognitive abilities than other tests used with severely impaired individuals.

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PubMed1996

Neuropsychological deficits associated with diffuse Lewy body disease.

Diffuse Lewy body disease (DLBD), in its pure form, is a neuropathologic condition in demented patients that is characterized by subcortical and diffusely distributed neocortical Lewy bodies with little or no concomitant Alzheimer's disease (AD) pathology. Clinically, DLBD patients initially present with dementia of insidious onset and subsequently develop mild extrapyramidal motor dysfunction. The present study retrospectively examined the neuropsychological test performance of five patients with DLBD and compared their performance to that of equally demented patients with neuropathologically confirmed "pure" AD. The results showed that the DLBD patients were globally demented with deficits in memory, attention, language, psychomotor performance, and "executive" functions, and a strikingly severe deficit in visuospatial and visuoconstructive abilities. The visuoconstructive and psychomotor impairments of the DLBD patients were significantly worse than those of the AD patients, whereas the memory performance of the AD patients was worse than that of the DLBD patients. These results indicate that DLBD without concomitant AD pathology can produce a global dementia with aspects of both cortical and subcortical dysfunction and suggests that Lewy body pathology contributes importantly to the clinical manifestation of the Lewy body variant of AD.

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PubMed1996

Clinical and neuropathological findings in Lewy body dementias.

We compared clinical features in three groups of pathologically defined patients evaluated for dementia during life: (i) Alzheimer's disease (AD); (ii) Lewy body variant of Alzheimer's Disease (LBV), with Lewy bodies (LB) and AD; (iii) diffuse Lewy body disease (DLBD), with LB alone. All three groups had similar initial cognitive symptoms. LBV and DLBD had Parkinsonian signs, though resting tremor was extremely rare. Delusions and hallucinations were relatively more frequent in LBV and DLBD than in AD. On neuropsychological testing, the LBV group had relatively greater impairment than AD on visuospatial and executive tests. LB therefore contribute to the clinical picture of dementia.

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