Biomedical subjects

Y Stern

Publications and source records attributed to Y Stern.

At least 19 recordsLinked to original sources

PubMed2006

Facilitation of performance in a working memory task with rTMS stimulation of the precuneus: frequency- and time-dependent effects.

Although improvements in performance due to TMS have been demonstrated with some cognitive tasks, performance improvement has not previously been demonstrated with working memory tasks. In the present study, a delayed match-to-sample task was used in which repetitive TMS (rTMS) at 1, 5, or 20 Hz was applied to either left dorsolateral prefrontal or midline parietal cortex during the retention (delay) phase of the task. Only 5 Hz stimulation to the parietal site resulted in a significant decrease in reaction time (RT) without a corresponding decrease in accuracy. This finding was replicated in a second experiment, in which 5 Hz rTMS at the parietal site was applied during the retention phase or during presentation of the recognition probe. Significant speeding of RT occurred in the retention phase but not the probe phase. This finding suggests that TMS may improve working memory performance, in a manner that is specific to the timing of stimulation relative to performance of the task, and to stimulation frequency.

Adult↗

PubMed2006

Longitudinal study of effects of patient characteristics on direct costs in Alzheimer disease.

OBJECTIVES: To estimate long-term trajectories of direct cost of caring for patients with Alzheimer disease (AD) and examine the effects of patients' characteristics on cost longitudinally. METHODS: The sample is drawn from the Predictors Study, a large, multicenter cohort of patients with probable AD, prospectively followed up annually for up to 7 years in three university-based AD centers in the United States. Random effects models estimated the effects of patients' clinical and sociodemographic characteristics on direct cost of care. Direct cost included cost associated with medical and nonmedical care. Clinical characteristics included cognitive status (measured by Mini-Mental State Examination), functional capacity (measured by Blessed Dementia Rating Scale [BDRS]), psychotic symptoms, behavioral problems, depressive symptoms, extrapyramidal signs, and comorbidities. The model also controlled for patients' sex, age, and living arrangements. RESULTS: Total direct cost increased from approximately 9,239 dollars per patient per year at baseline, when all patients were at the early stages of the disease, to 19,925 dollars by year 4. After controlling for other variables, a one-point increase in the BDRS score increased total direct cost by 7.7%. One more comorbid condition increased total direct cost by 14.3%. Total direct cost was 20.8% lower for patients living at home compared with those living in an institutional setting. CONCLUSIONS: Total direct cost of caring for patients with Alzheimer disease increased substantially over time. Much of the cost increases were explained by patients' clinical and demographic variables. Comorbidities and functional capacity were associated with higher direct cost over time.

Aged↗

PubMed2006

Clinical features associated with costs in early AD: baseline data from the Predictors Study.

BACKGROUND: Few studies on cost of caring for patients with Alzheimer disease (AD) have simultaneously considered multiple dimensions of disease costs and detailed clinical characteristics. OBJECTIVE: To estimate empirically the incremental effects of patients' clinical characteristics on disease costs. METHODS: Data are derived from the baseline visit of 180 patients in the Predictors Study, a large, multicenter cohort of patients with probable AD followed from early stages of the disease. All patients initially lived at home, in retirement homes, or in assisted living facilities. Costs of direct medical care included hospitalizations, outpatient treatment and procedures, assistive devices, and medications. Costs of direct nonmedical care included home health aides, respite care, and adult day care. Indirect costs were measured by caregiving time. Patients' clinical characteristics included cognitive status, functional capacity, psychotic symptoms, behavioral problems, depressive symptoms, extrapyramidal signs, comorbidities, and duration of illness. RESULTS: A 1-point increase in the Blessed Dementia Rating Scale score was associated with a $1,411 increase in direct medical costs and a $2,718 increase in unpaid caregiving costs. Direct medical costs also were $3,777 higher among subjects with depressive symptoms than among those who were not depressed. CONCLUSIONS: Medical care costs and unpaid caregiving costs relate differently to patients' clinical characteristics. Poorer functional status is associated with higher medical care costs and unpaid caregiving costs. Interventions may be particularly useful if targeted in the areas of basic and instrumental activities of daily living.

Aged↗

PubMed2006

Education and rates of cognitive decline in incident Alzheimer's disease.

BACKGROUND: Some (but not all) epidemiological studies have noted faster rates of progression in high education patients with Alzheimer's disease (AD), which has been attributed to harbouring/tolerating a higher pathological burden at the time of clinical dementia for subjects with higher education. We wanted to assess the relationship between education and rates of decline in AD. METHODS: During the course of a community based multiethnic prospective cohort study of individuals aged > or = 65 years living in New York, 312 patients were diagnosed with incident AD and were followed overall for 5.6 (up to 13.3) years. The subjects received an average of 3.7 (up to 9) neuropsychological assessments consisting of 12 individual tests. With the aid of a normative sample, a standardised composite cognitive score as well as individual cognitive domain scores were calculated. Generalised estimating equation models were used to examine the association between education and rates of cognitive decline. RESULTS: Composite cognitive performance declined by 9% of a standard deviation per year. Rates of decline before and after AD incidence were similar. For each additional year of education there was 0.3% standard deviation lower composite cognitive performance for each year of follow up. The association between higher education and faster decline was noted primarily in the executive speed (0.6%) and memory (0.5%) cognitive domains and was present over and above age, gender, ethnicity, differential baseline cognitive performance, depression, and vascular comorbidity. CONCLUSIONS: We conclude that higher education AD patients experience faster cognitive decline.

Aged↗

PubMed2005

Stress and pain responses in rats lacking CCK1 receptors.

UNLABELLED: CCK involvement in stress- and pain-responsiveness was examined by studying the behavior of infant (11-12-days-old) and adult OLETF rats that do not express CCK1 receptors. Infant odor- and texture-preferences were also assessed. We hypothesized that OLETF rats will show behavioral patterns similar to those previously observed after CCK1 antagonist administration. Rate of separation-induced ultrasonic vocalization was significantly greater in OLETF compared to controls, in two separate studies. Infant pups of the two strains did not differ in odor- and texture-preference tests. OLETF rats showed consistently longer hot-plate paw-lift (as infants, in two separate studies) and paw-lick (as adults) latencies. SUMMARY: OLETF pups vocalized in isolation more than controls and showed relative hypoalgesic responses, evident also in adulthood, in concordance with the pharmacological literature.

Aging↗

PubMed2005

Motor signs predict poor outcomes in Alzheimer disease.

OBJECTIVE: To examine whether the presence of motor signs has predictive value for important outcomes in Alzheimer disease (AD). METHODS: A total of 533 patients with AD at early stages (mean Folstein Mini-Mental State Examination [MMSE] 21/30 at entry) were recruited and followed semiannually for up to 13.1 years (mean 3) in five University-based AD centers in the United States and European Union. Four outcomes, assessed every 6 months, were used in Cox models: cognitive endpoint (Columbia Mini-Mental State Examination < or = 20/57 [ approximately MMSE < or = 10/30]), functional endpoint (Blessed Dementia Rating Scale > or = 10), institutionalization equivalent index, and death. Using a standardized portion of the Unified PD Rating Scale (administered every 6 months for a total of 3,149 visit-assessments, average 5.9 per patient), the presence of motor signs, as well as of individual motor sign domains, was examined as time-dependent predictor. The models controlled for cohort, recruitment center, sex, age, education, a comorbidity index, and baseline cognitive and functional performance. RESULTS: A total of 39% of the patients reached the cognitive, 41% the functional, 54% the institutionalization, and 47% the mortality endpoint. Motor signs were noted for 14% of patients at baseline and for 45% at any evaluation. Their presence was associated with increased risk for cognitive decline (RR, 1.72; 95% CI, 1.24 to 2.38), functional decline (1.80 [1.33 to 2.45]), institutionalization (1.68 [1.26 to 2.25]), and death (1.38 [1.05 to 1.82]). Tremor was associated with increased risk for reaching the cognitive and bradykinesia for reaching the functional endpoints. Postural-gait abnormalities carried increased risk for institutionalization and mortality. Faster rates of motor sign accumulation were associated with increased risk for all outcomes. CONCLUSIONS: Motor signs predict cognitive and functional decline, institutionalization, and mortality in Alzheimer disease. Different motor sign domains predict different outcomes.

Aged↗

PubMed2005

Neuropsychological predictors of dependency in patients with Alzheimer disease.

OBJECTIVE: To determine whether specific cognitive deficits can predict the progression of Alzheimer disease (AD). METHODS: Two hundred fifty-two patients with AD enrolled in the Predictors Study were followed at 6-month intervals for up to 4.5 years with neurologic, cognitive, and psychiatric examinations. Neuropsychological functions were assessed by the Modified Mini-Mental State Examination (mMMSE). Items of mMMSE were divided into five cognitive domains: temporospatial orientation, short-term memory, long-term memory, language, and visuoconstructive functions. Loss of autonomy was assessed by both the Dependency Scale (DS) and the Equivalent Institutional Care (EIC) rating. Cox proportional hazards models, adjusted for age, sex, estimated duration of illness at entry into the study, and presence of extrapyramidal signs and behavioral disturbances, were used to determine the predictive value of each neuropsychological domain on dependency outcomes. RESULTS: Global mMMSE, temporospatial orientation, and short-term memory scores were associated with a greater relative risk of moderate or severe dependency. The visuoconstructive score predicted the development of severe dependency. Long-term memory and language scores were not predictive of the EIC or DS endpoints. CONCLUSIONS: The presence of certain neuropsychological deficits at a patient's initial visit, such as short-term memory, temporospatial orientation, and constructive apraxia, predict more rapid dependency in patients with Alzheimer disease. Neuropsychological items have different weights in term of predictive power, and these effects are independent of the influence of age and disease duration at baseline.

Age Distribution↗

PubMed2005

Metacognitive theory and assessment in dementia: do we recognize our areas of weakness?

Anosognosia, disordered awareness of cognitive and behavioral deficits, is a striking and common symptom of Alzheimer's disease (AD), yet its etiology, clinical correlates, and prognostic value are unclear. Historically, disordered awareness has been a conceptually challenging phenomenon, evidenced by the numerous and diverse theories that aim to explain the manner in which this syndrome arises. We review many of these theories, focusing on the neuroanatomic substrates of awareness, and highlighting the potential roles of critical regions such as the right prefrontal and parietal cortices in enabling self-awareness. We then address methodological limitations such as use of subjective measurement tools that likely contribute to the conceptual ambiguity surrounding anosognosia. We argue that metacognitive techniques used in healthy adults, such as the Feeling of Knowing task, offer models for dissecting awareness into clear and identifiable cognitive components in patients with AD. We critique several studies that have pioneered such tasks in AD, and offer guidelines for future implementation of such methods. A final goal of this review is to advocate for a multidimensional approach to studying metacognitive skills that will facilitate the objective investigation of deficit awareness as it relates to a variety of disease variables such as prognosis, neuropsychological profile, neuropathological distribution, psychiatric symptoms, and clinical course.

Aged↗

PubMed2005

APOE related alterations in cerebral activation even at college age.

BACKGROUND: Associations between the APOE genotype and various medical conditions have been documented at a very young age. The association between the APOE genotype and cognitive performance varies at different ages. APOE related changes in brain activation have been recently reported for middle aged and elderly subjects. OBJECTIVE: To explore APOE related alterations during cognitive activation in a population of young adults. METHODS: Using H2(15)O positron emission tomography (PET), imaging was carried out in 20 healthy young adults (age 19 to 28 years; four epsilon4 carriers and 16 non-epsilon4 carriers) during a non-verbal memory task. Voxel-wise multiple regression analyses were undertaken, with the activation difference PET counts as the dependent variable and the APOE genotype as the independent variable. RESULTS: Brain regions were identified where epsilon4 carriers showed significantly lower or higher activation than non-carriers. CONCLUSIONS: The results suggest that APOE dependent modulation of cerebral flow may be present even at a young age. This may reflect an APOE related physiological heterogeneity which may or may not predispose to brain disease in the ensuing decades or, less likely, the effect of very early Alzheimer's disease related pathological changes.

Adult↗

PubMed2004

Evaluation of HIV RNA and markers of immune activation as predictors of HIV-associated dementia.

OBJECTIVE: To evaluate whether baseline levels of plasma and CSF HIV RNA, tumor necrosis factor alpha (TNFalpha), monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase-2 (MMP-2), or macrophage colony stimulating factor (M-CSF) are predictors of incident HIV-associated dementia (HIVD) in a cohort with advanced HIV infection. METHODS: A total of 203 nondemented subjects with CD4 lymphocyte counts less than 200/muL, or <300/microL but with cognitive impairment, underwent semiannual neurologic, cognitive, functional, and laboratory assessments. HIVD and minor cognitive motor disorder (MCMD) were defined using American Academy of Neurology criteria. The cumulative incidence of HIVD was estimated using Kaplan-Meier curves. Cox proportional hazards regression models were used to examine the associations between biologic variables and time to HIVD, adjusting for age, sex, years of education, duration of HIV infection, type of antiretroviral use, premorbid IQ score, and presence of MCMD. RESULTS: After a median follow-up time of 20.7 months, 74 (36%) subjects reached the HIVD endpoint. The dementia was mild in 70% of cases. The cumulative incidence of HIVD was 20% at 1 year and 33% at 2 years. Highly active antiretroviral therapy (HAART) was used by 73% of subjects at baseline. A plasma HIV RNA level was undetectable in 23% of subjects and a CSF HIV RNA level was undetectable in 48% of subjects. In adjusted analyses, neither plasma nor CSF HIV RNA levels (log10) were associated with time to HIVD; log10 levels of plasma TNFalpha (HR 3.07, p = 0.03) and CSF MCP-1 (HR = 3.36, p = 0.06) tended to be associated with time to HIVD. CONCLUSION: The lack of association between baseline plasma and CSF HIV RNA levels and incident dementia suggests highly active antiretroviral therapy may be affecting CNS viral dynamics, leading to lower HIV RNA levels, and therefore weakening the utility of baseline HIV RNA levels as predictors of HIV-associated dementia.

AIDS Dementia Complex↗

PubMed2004

Motor signs during the course of Alzheimer disease.

BACKGROUND: Motor signs (MOSIs) are common in Alzheimer disease (AD) and may be associated with rates of cognitive decline, mortality, and cost of care. OBJECTIVE: To describe the progression and identify predictors of individual MOSIs in AD. METHODS: A cohort of 474 patients with AD at early stages was followed semiannually for up to 13.1 years (mean 3.6 years) in five centers in Europe and the United States. MOSIs were rated using a standardized portion of the Unified Parkinson's Disease Rating Scale. Overall, 3,030 visits/assessments of MOSIs (average 6.4/patient) were performed. Prevalence and incidence rates were calculated, and cumulative risk graphs were plotted for individual non-drug-induced MOSI domains. Rates of change over time taking into account potential covariates were also estimated. With use of each MOSI domain as outcome in Cox models, predictors of MOSI incidence were identified. RESULTS: At least one MOSI was detected in 13% of patients at first examination and in 36% for the last evaluation. Total MOSI score increased at an annual rate of 3% of total possible score. Rates of annual change for speech/facial expression (4%), rigidity (2.45%), posture/gait (3.9%), and bradykinesia (3.75%) were of similar magnitude, and their occurrence increased from first (3 to 6%) to last (22 to 29%) evaluation. Tremor was less frequent throughout the course of the disease (4% at first and 7% at last evaluation) and worsened less (0.75% increase/year). CONCLUSIONS: Most motor signs occur frequently and progress rapidly in Alzheimer disease. Tremor is an exception in that it occurs less frequently and advances at slower rates.

Aged↗

PubMed2004

APOE-dependent PET patterns of brain activation in Alzheimer disease.

Using H2(15)O PET, the authors imaged 13 patients with Alzheimer disease (AD) while performing a serial nonverbal recognition memory task. Patterns of brain activation differed as a function of APOE genotype: epsilon4 carriers exhibited lower activation in the left lingual gyrus and higher activation in left cuneus, precuneus, parahippocampal, and right precentral gyrus. The APOE genotype seems to play a role in cerebral physiologic activity even after onset of clinical manifestations of AD.

Age of Onset↗

PubMed2004

Genetic influences on memory performance in familial Alzheimer disease.

OBJECTIVE: To investigate the heritability of memory and other cognitive measures in families with multiple individuals with Alzheimer disease (AD) to determine if neuropsychological measures can be used to better understand genetic contributions to AD. METHODS: The genetic contributions to the variation in declarative memory, attention, abstract reasoning, language, and visuospatial function using a variance component method were estimated. For memory scores, the proportion of genetic contribution was estimated, controlling for APOE. RESULTS: The unadjusted heritability estimates for the declarative memory tasks ranged from 0.47 for delayed recall to 0.25 for delayed recognition, where a heritability estimate of 1 indicates that genetic factors explain all of the phenotypic variance and a heritability score of 0 indicates that genetic factors explain none. When adjusted for sex, age, education, and general intelligence, the heritability estimates increased to 0.60 for delayed recall and 0.41 for delayed recognition. None of the other cognitive tests showed heritability estimates as high as that observed for memory. When the influence of APOE was taken into account, the heritability estimates changed modestly for delayed recall and consistent long-term retrieval, whereas the estimates for other memory scores did not change, suggesting that APOE contributes little to these memory scores. CONCLUSIONS: Declarative memory in familial AD is under strong genetic influence, only part of which is attributable to APOE. Memory performance should prove to be a useful phenotypic component in the investigation of the genetic basis of AD.

Aged↗

PubMed2004

T cell vaccination in multiple sclerosis relapsing-remitting nonresponders patients.

Myelin autoreactive T cells are involved in the pathogenesis of multiple sclerosis (MS) and lead to propagation of the disease. We evaluated the efficacy of T cell vaccination (TCV) therapy for patients with aggressive relapsing-remitting MS who failed to respond to immunomodulatory treatments. Twenty nonresponders relapsing-remitting MS patients were immunized with autologous attenuated T cell lines after activation with synthetic myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein (MOG) encephalitogenic peptides. Each patient received three vaccinations in 6- to 8-week intervals. Annual relapse rate decreased from 2.6 to 1.1, P = 0.026. Neurological disability stabilized as compared with the 2- and 1-year pretreatment progression rates. Significant reduction in the number and volume of active lesions, as well as reduction in T2 lesion burden, was demonstrated by quantitative MRI analysis. No serious adverse events were observed. Our findings suggest that TCV has beneficial clinical effects in MS patients who, in spite of immunomodulatory treatments, continue to deteriorate. TCV could serve as a potential alternative therapy for this subgroup of nonresponders patients.

Adult↗

PubMed2004

Fine mapping of 10q and 18q for familial Alzheimer's disease in Caribbean Hispanics.

Familial Alzheimer's disease (AD [MIM 104300]) has been a focus of intense investigation, primarily in Caucasian families from Europe and North America families. Although the late-onset form of familial AD, beginning after age 65 years, has been linked to regions on chromosomes 10q and 12p, the specific genetic variants have not yet been consistently identified. Using a unique cohort of families of Caribbean Hispanics ancestry, we screened the genome using 340 markers on 490 family members from 96 families with predominantly late-onset AD. We observed the strongest support for linkage on 18q (LOD=3.14). However, 17 additional markers (chromosomes 1-6, 8, 10, 12, and 14) exceeded a two-point LOD score of 1.0 under the affecteds-only autosomal dominant model or affected sibpair model. As we previously reported the fine-mapping effort on 12p showing modest evidence of linkage, we focused our fine-mapping efforts on two other candidate regions in the current report, namely 10q and 18q. We added 31 family members and eight additional Caribbean Hispanic families to fine map 10q and 18q. With additional microsatellite markers, the evidence for linkage for 18q strengthened near 112 cM, where the two-point LOD score for D18S541 was 3.37 and the highest NPL score in that region was 3.65 (P=0.000177). This narrow region contains a small number of genes expressed in the brain. However, at 10q (134-138 cM), the NPL score decreased from 3.15 (P=0.000486) to 2.1 (P=0.0218), but two broad peaks remained overlapping with previously reported peaks. Our results provide modest support for linkage on 10q and 12p in this cohort of Caribbean Hispanic families with familial Alzheimer's disease, and strong evidence for a new locus on 18q.

Aged↗

PubMed2003

Plasma A[beta]40 and A[beta]42 and Alzheimer's disease: relation to age, mortality, and risk.

BACKGROUND: Plasma amyloid [beta]-peptide (A[beta]) 40 and A[beta]42 levels are increased in persons with mutations causing early-onset familial Alzheimer's disease (AD). Plasma A[beta]42 levels were also used to link microsatellite genetic markers to a putative AD genetic locus on chromosome 10 and were observed in patients with incipient sporadic AD. METHODS: The authors measured plasma A[beta]40 and A[beta]42 levels using a sandwich ELISA after the initial examination of 530 individuals participating in an epidemiologic study of aging and dementia. Participants were examined at 18-month intervals, and plasma A[beta]40 and A[beta]42 levels were repeated in 307 subjects 3 years after baseline. RESULTS: Compared with individuals who never developed AD, patients with AD at baseline and those who developed AD during the follow-up had significantly higher A[beta]42, but not A[beta]40, plasma levels. The risk of AD in the highest quartile of plasma A[beta]42 was increased by more than twofold over that in the lowest quartile. The highest plasma A[beta]42 levels were observed in patients with AD who died during the follow-up. Plasma A[beta]42, but not A[beta]40, levels decreased over time in patients with newly acquired AD. CONCLUSIONS: Plasma A[beta]40 and A[beta]42 increase with age and are strongly correlated with each other. Plasma A[beta]40 and A[beta]42 levels are elevated in some patients before and during the early stages of AD but decline thereafter. High plasma A[beta]42 levels may also be associated with mortality in patients with AD.

Age Distribution↗

PubMed2003

Cognition following bilateral implants of embryonic dopamine neurons in PD: a double blind study.

OBJECTIVES: To determine if bilateral transplantation of embryonic mesencephalic dopamine cells into the putamen of patients with PD significantly affected their cognitive functioning when compared with patients receiving sham surgery and to examine the effect of age on cognitive performance after implantation. METHODS: Forty patients (19 women, 21 men; age 34 to 75 years) with idiopathic PD of at least 7 years' duration (mean 14 years) who had disabling motor signs despite optimal drug management were randomly assigned to tissue implants or sham craniotomies in a double-blind design. Neuropsychological tests assessing orientation, attention, language, verbal and visual memory, abstract reasoning, executive function, and visuospatial and construction abilities were administered before and 1 year after surgery. Treatment groups did not differ at baseline in demographic, neuropsychological, motor, depression, or levodopa equivalent measures. RESULTS: Postsurgical change in cognitive performance was not significantly different for real or sham surgery groups. Performance in both groups remained unchanged at follow-up for most measures. CONCLUSIONS: Embryonic dopamine producing neurons can be implanted safely into the putamen bilaterally without impairing cognition in patients with PD, but within the first year, improved cognition should not be expected.

Adult↗

PubMed2003

Inter-rater reliability of a clinical staging of HIV-associated cognitive impairment.

OBJECTIVE: To determine the inter-rater reliability of a modification of the Memorial Sloan-Kettering (MSK) Staging for HIV-associated cognitive impairment. METHODS: Data were abstracted on neurologic, neuropsychological, and functional status on 100 individuals participating at four sites in the Northeast AIDS Dementia (NEAD) Consortium cohort study, a longitudinal study of predictors of cognitive impairment in HIV-infected individuals. Neuropsychological performance was defined 1) based on the neuropsychologist's global impression and 2) solely based on neuropsychological test scores. Raters at each site used the abstracted data to assign an MSK stage to each subject blind to any identifying information. Inter-rater reliability was assessed using kappa statistics. Agreement between computer-generated ratings and site-generated ratings was also assessed. RESULTS: Kappa statistics for pair-wise agreement among the sites regarding MSK stage ranged from 0.70-0.91, representing good to excellent agreement between sites. Agreement between computer-generated ratings and site-generated ratings was in the good to excellent range (0.62-0.79). CONCLUSIONS: The authors have modified the MSK rating scale and developed a reliable instrument that can be used in multicenter studies. This instrument will be useful in staging HIV-dementia in future longitudinal studies and will be valuable in increasing accuracy of clinicopathologic studies.

AIDS Dementia Complex↗