PubMed Health⌕ Search

Biomedical subjects

Yaakov Stern

Publications and source records attributed to Yaakov Stern.

At least 37 records · Page 2Linked to original sources
PubMed2006

Clinical characteristics and longitudinal changes of informal cost of Alzheimer's disease in the community.

Most estimates of the cost of informal caregiving in patients with Alzheimer's disease (AD) remain cross-sectional. Longitudinal estimates of informal caregiving hours and costs are less frequent and are from assessments covering only short periods of time. The objectives of this study were to estimate long-term trajectories of the use and cost of informal caregiving for patients with AD and the effects of patient characteristics on the use and cost of informal caregiving. The sample is drawn from the Predictors Study, a large, multicenter cohort of patients with probable AD, prospectively followed annually for up to 7 years in three university-based AD centers in the United States (n=170). Generalized linear mixed models were used to estimate the effects of patient characteristics on use and cost of informal caregiving. Patients' clinical characteristics included cognitive status (Mini-Mental State Examination), functional capacity (Blessed Dementia Rating Scale (BDRS)), comorbidities, psychotic symptoms, behavioral problems, depressive symptoms, and extrapyramidal signs. Results show that rates of informal care use and caregiving hours (and costs) increased substantially over time but were related differently to patients' characteristics. Use of informal care was significantly associated with worse cognition, worse function, and higher comorbidities. Conditional on receiving informal care, informal caregiving hours (and costs) were mainly associated with worse function. Each additional point on the BDRS increased informal caregiving costs 5.4%. Average annual informal cost was estimated at $25,381 per patient, increasing from $20,589 at baseline to $43,030 in Year 4.

Aged↗
PubMed2006

Single-dose levodopa administration and aging independently disrupt time production.

We tested the hypothesis that age-related time production deficits are dopamine-mediated. The experiment was conducted double-blind, and with random assignment of 32 healthy aged and 32 healthy young participants to either inert placebo or levodopa (200 mg) groups. The procedure included training participants to produce two target time intervals (6 and 17 sec) in separate blocks, drug/placebo administration, a 1-hr delay, and then delayed free-recall time production retesting without feedback. Participants also performed a speeded choice reaction time (RT) task, as a control for potential dopaminergic and aging effects on attention and psychomotor speed. Results indicate that during retesting, aged participants show duration-dependent timing errors that are larger than those shown by the young participants. Levodopa administration yielded lengthened time production of both target intervals. The aging and levodopa effects did not interact. Also, aging slowed RT and increased RT variability, but levodopa had no effect on the RT. These results suggest that at this dosage and under these specific conditions, timing is dopamine-mediated but the effect of aging on time production is not. Moreover, the levodopa timing effect cannot be attributed to the effects of dopaminergic function on psychomotor speed.

Adult↗
PubMed2005

Increased sympathetic and decreased parasympathetic cardiovascular modulation in normal humans with acute sleep deprivation.

Cardiovascular autonomic modulation during 36 h of total sleep deprivation (SD) was assessed in 18 normal subjects (16 men, 2 women, 26.0 +/- 4.6 yr old). ECG and continuous blood pressure (BP) from radial artery tonometry were obtained at 2100 on the first study night (baseline) and every subsequent 12 h of SD. Each measurement period included resting supine, seated, and seated performing computerized tasks and measured vigilance and executive function. Subjects were not supine in the periods between measurements. Spectral analysis of heart rate variability (HRV) and BP variability (BPV) was computed for cardiac parasympathetic modulation [high-frequency power (HF)], sympathetic modulation [low-frequency power (LF)], sympathovagal balance (LF/HF power of R-R variability), and BPV sympathetic modulation (at LF). All spectral data were expressed in normalized units [(total power of the components/total power-very LF) x 100]. Spontaneous baroreflex sensitivity (BRS), based on systolic BP and pulse interval powers, was also measured. Supine and sitting, BPV LF was significantly increased from baseline at 12, 24, and 36 h of SD. Sitting, HRV LF was increased at 12 and 24 h of SD, HRV HF was decreased at 12 h SD, and HRV LF/HF power of R-R variability was increased at 12 h of SD. BRS was decreased at 24 h of SD supine and seated. During the simple reaction time task (vigilance testing), the significantly increased sympathetic and decreased parasympathetic cardiac modulation and BRS extended through 36 h of SD. In summary, acute SD was associated with increased sympathetic and decreased parasympathetic cardiovascular modulation and decreased BRS, most consistently in the seated position and during simple reaction-time testing.

Adolescent↗
PubMed2005

Sources of errors on visuoperceptual tasks: role of education, literacy, and search strategy.

The current study explored possible sources of demographic effects through analyses of errors from modified formats of the Benton Visual Retention Test (BVRT) completed by African American elders. Results indicate that: (1) reading level was a stronger predictor of BVRT performance than years of education; (2) on the single-item matching format of the task, individuals with lower reading levels disproportionately produced errors on items that differed in geometric, rather than spatial features; and (3) on a multiple-choice matching format, individuals with lower reading levels committed more errors on items where the target was located in the lower half of a 2 x 2 matrix.

Black or African American↗
PubMed2005

Delusions and hallucinations are associated with worse outcome in Alzheimer disease.

BACKGROUND: Delusions and hallucinations are common in Alzheimer disease (AD) and there are conflicting reports regarding their ability to predict cognitive decline, functional decline, and institutionalization. According to all previous literature, they are not associated with mortality. OBJECTIVE: To examine whether the presence of delusions or hallucinations has predictive value for important outcomes in AD. DESIGN, SETTING, AND PARTICIPANTS: A total of 456 patients with AD at early stages (mean Folstein Mini-Mental State Examination [MMSE] score of 21 of 30 at entry) were recruited and followed up semiannually for up to 14 years (mean, 4.5 years) in 5 university-based AD centers in the United States and Europe. Using the Columbia University Scale for Psychopathology in AD (administered every 6 months, for a total of 3266 visit-assessments, average of 7.2 per patient), the presence of delusions and hallucinations was extracted and examined as time-dependent predictors in Cox models. The models controlled for cohort effect, recruitment center, informant status, sex, age, education, a comorbidity index, baseline cognitive and baseline functional performance, behavioral symptoms, and use of neuroleptics and cholinesterase inhibitors. MAIN OUTCOME MEASURES: Cognitive (Columbia MMSE score of < or =20/57 [approximate Folstein MMSE score of < or =10/30]), functional (Blessed Dementia Rating Scale [parts I and II] score of > or =10), institutionalization equivalent index, and death. RESULTS: During the full course of follow-up, 38% of patients reached the cognitive, 41% the functional, 54% the institutionalization, and 49% the mortality end point. Delusions were noted for 34% of patients at baseline and 70% at any evaluation. Their presence was associated with increased risk for cognitive (risk ratio [RR], 1.50; 95% confidence interval [CI], 1.07-2.08) and functional decline (RR, 1.41; 95% CI, 1.02-1.94). Hallucinations were present in 7% of patients at initial visit and in 33% at any visit. Their presence was associated with increased risk for cognitive decline (RR, 1.62; 95% CI, 1.06-2.47), functional decline (RR, 2.25; 95% CI, 1.54-2.27), institutionalization (RR, 1.60; 95% CI, 1.13-2.28), and death (RR, 1.49; 95% CI, 1.03-2.14). CONCLUSIONS: Delusions and hallucinations are very common in AD and predict cognitive and functional decline. Presence of hallucinations is also associated with institutionalization and mortality.

Aged↗
PubMed2005

Implementing diagnostic criteria and estimating frequency of mild cognitive impairment in an urban community.

BACKGROUND: Reported rates of mild cognitive impairment (MCI) range widely depending on methodologic differences, including specific sample characteristics, cognitive measures used, normative samples used for neuropsychological tests, and diagnostic criteria. OBJECTIVES: To operationalize diagnostic criteria for MCI and examine the frequency of MCI in ethnically and linguistically diverse elders (individuals older than 65 years). DESIGN: Prospective, community-based longitudinal cohort study. SETTING: Northern Manhattan, New York, NY. PARTICIPANTS: A cohort of 1315 nondemented elderly participants. MAIN OUTCOME MEASURE: A diagnosis of MCI was assigned retrospectively on the basis of comprehensive neuropsychological, functional, and neurologic assessments. Amnestic MCI, as well as forms of mild impairment with other cognitive characteristics, were classified. RESULTS: The frequency of amnestic MCI was 5.0% (95% confidence interval, 3.8-6.2). Other subtypes of MCI ranged in frequency from 2.1% to 6.2%. Mild cognitive impairment was more common among those older than 75 years compared with those aged 65 to 75 years. Individuals with fewer than 9 years of schooling were more likely to meet MCI criteria. Apolipoprotein (APOE) E4 allele was more frequent among those with amnestic MCI. CONCLUSIONS: When proper normative values are used, only age and education, and not race or ethnicity, are associated with higher frequency of MCI. The proportion of nondemented elders with isolated memory deficits is smaller than the proportion with deficits in multiple cognitive domains. The strong association of the APOE E4 allele with only amnestic MCI suggests that there are likely to be multiple causes of cognitive impairment and differential rates of conversion to Alzheimer disease within the cognitive subtypes of MCI.

Activities of Daily Living↗
PubMed2005

Predictive utility of apolipoprotein E genotype for Alzheimer disease in outpatients with mild cognitive impairment.

BACKGROUND: In cognitively impaired patients without dementia, the utility of apolipoprotein E (APOE) genotyping is unclear. OBJECTIVE: To evaluate the predictive utility of the APOE epsilon4 genotype for conversion to probable Alzheimer disease (AD). DESIGN: Naturalistic, longitudinal study. SETTING: Memory disorders outpatient clinic. PATIENTS: A total of 136 patients with memory complaints were determined to have mild cognitive impairment and were evaluated every 6 months. Fifty-seven age- and sex-matched healthy controls were evaluated annually. MAIN OUTCOME MEASURES: Primary outcome measures included conversion to AD. Secondary outcome measures included change over time in Mini-Mental State Examination (MMSE) score and Selective Reminding Test (SRT) delayed recall score. RESULTS: The APOE epsilon4 allele was present in 25% of patients and 21% of healthy controls. During a mean +/- SD follow-up of 35.2 +/- 24.3 months, 35 of 136 patients converted to AD. APOE epsilon4 carrier status did not differ between converters (31%) and nonconverters to AD (23%, P = .3) and did not affect the time trend in MMSE or SRT scores in the entire sample. Four of 5 APOE epsilon4 homozygotes converted to AD compared with 7 of 29 heterozygotes (P = .02). In a Cox proportional hazards model stratified by age quartiles, after controlling for sex, education, MMSE score, and SRT delayed recall score, APOE epsilon4 increased the risk of AD in patients 70 to 85 years old (n = 57; risk ratio, 2.77; 95% confidence interval, 1.1-7.3; P = .03) but not in patients 55 to 69 years old (n = 79; P = .7). CONCLUSIONS: APOE epsilon4 carrier status was associated with conversion to AD in older outpatients after controlling for known demographic and clinical risk factors, and APOE epsilon4 homozygosity was associated with increased risk of conversion to AD. However, APOE epsilon4 carrier status by itself did not predict cognitive decline or conversion to AD, indicating that APOE genotyping in patients with mild cognitive impairment may have limited clinical applicability for prediction of outcome.

Aged↗
PubMed2005

A 10-item smell identification scale related to risk for Alzheimer's disease.

University of Pennsylvania Smell Identification Test data from control subjects (n = 63), patients with mild cognitive impairment (n = 147), and patients with Alzheimer's disease (n = 100) were analyzed to derive an optimal subset of items related to risk for Alzheimer's disease (ie, healthy through mild cognitive impairment to early and moderate disease stages). The derived 10-item scale performed comparably with the University of Pennsylvania Smell Identification Test in classifying subjects, and it strongly predicted conversion to Alzheimer's disease on follow-up evaluation in patients with mild cognitive impairment. Independent replication is needed to validate these findings.

Aged↗
PubMed2005

Predicting age-related dual-task effects with individual differences on neuropsychological tests.

This study examined the relation of dual-task performance to individual differences on neuropsychological tests. Neuropsychological test scores from 16 young and 16 older participants were simultaneously submitted to a factor analysis that yielded 2 factors (Attention/Executive and Memory) that differed by age and 2 (Motor Speed and Cognitive Status) that did not. Regression analyses revealed that these factors were significant predictors of performance on a delayed visual recognition task, but the relationship varied as a function of task condition. The Memory and Motor Speed factors were the strongest predictors of single-task performance, but the Attention/Executive factor was the most important predictor of dual-task performance. The authors conclude that compromised central executive may underlie age-related decline in dual-task performance.

Adult↗
PubMed2005

Brain networks associated with cognitive reserve in healthy young and old adults.

In order to understand the brain networks that mediate cognitive reserve, we explored the relationship between subjects' network expression during the performance of a memory test and an index of cognitive reserve. Using H2(15)O positron emission tomography, we imaged 17 healthy older subjects and 20 young adults while they performed a serial recognition memory task for nonsense shapes under two conditions: low demand, with a unique shape presented in each study trial; and titrated demand, with a study list size adjusted so that each subject recognized shapes at 75% accuracy. A factor score that summarized years of education, and scores on the NART and the WAIS-R Vocabulary subtest was used as an index of cognitive reserve. The scaled subprofile model was used to identify a set of functionally connected regions (or topography) that changed in expression across the two task conditions and was differentially expressed by the young and elderly subjects. The regions most active in this topography consisted of right hippocampus, posterior insula, thalamus, and right and left operculum; we found concomitant deactivation in right lingual gyrus, inferior parietal lobe and association cortex, left posterior cingulate, and right and left calcarine cortex. Young subjects with higher cognitive reserve showed increased expression of the topography across the two task conditions. Because this topography, which is responsive to increased task demands, was differentially expressed as a function of reserve level, it may represent a neural manifestation of innate or acquired reserve. In contrast, older subjects with higher cognitive reserve showed decreased expression of the topography across tasks. This suggests some functional reorganization of the network used by the young subjects. Thus, for the old subjects this topography may represent an altered, compensatory network that is used to maintain function in the face of age-related physiological changes.

Adult↗
PubMed2005

Medicaid home care services and survival in New York City.

PURPOSE: New York City's Medicaid Home Care Services Program provides an integrated program of housekeeping and personal assistance care along with regular nursing assessments. We sought to determine if this program of supportive care offers a survival benefit to older adults. DESIGN AND METHODS: Administrative data from New York City's Medicaid Home Care Services Program were merged with epidemiologic and diagnostic data collected in a community study of older adults living in northern Manhattan. Of 866 older adults with Medicaid coverage living in the community, 288 (33.3%) received Medicaid home care services in the period from 1994 to 1996. Mortality was tracked through the end of 1999. RESULTS: In proportional hazards models that adjusted for differences in sociodemographic, medical, and functional status, use of Medicaid home care service was associated with a significantly reduced risk of death in people with disability in activities of daily living. IMPLICATIONS: Because the program has distinctive features (greater number of weekly hours than other programs, integration with nursing assessments), it is a special case of community-based long-term care. Still, results from this observational cohort suggest that mortality risk in the most vulnerable elderly population can be reduced through a program of supportive care.

Activities of Daily Living↗
PubMed2005

Depressive symptoms in Alzheimer's disease: natural course and temporal relation to function and cognitive status.

OBJECTIVES: To examine the natural course of depressive symptoms in patients with probable Alzheimer's disease (AD), specifically, the temporal relationship between depressive symptoms, function, and cognitive status. DESIGN: Multicenter cohort study with follow-up of up to 14 years. SETTING: Patients from the two Multicenter Study of Predictors of Disease Course in Alzheimer's Disease (Predictors Study) cohorts were recruited at five sites in the United States and Europe. PARTICIPANTS: Patients diagnosed with probable AD (n=536) enrolled in a longitudinal study (Predictors Study). MEASUREMENTS: Depressive symptoms were evaluated at 6-month intervals using the Columbia Scale for Psychopathology in Alzheimer's Disease. The Modified Mini-Mental State (3MS) and Blessed Dementia Rating Scale (BDRS) were used to assess cognitive status and functional activity, respectively. RESULTS: The prevalence of depressive symptoms was stable over the first 3 years of follow-up, at approximately 40%. There was a significant drop to 28% and 24% in the fourth and fifth years of follow-up, respectively. Time-dependent Cox analysis revealed that functional activity (BDRS) but not cognitive status (3MS) was a significant predictor of the first episode of depressive symptoms during follow-up. Generalized estimating equation analyses showed that AD duration and functional activity but not cognitive status were significantly related to depressive symptoms over the entire follow-up period. CONCLUSION: Depressive symptoms are common in AD, but their prevalence decreases over time. Examination of the temporal relationship between depressive symptoms and risk factors suggests that decline in function but not in cognition precedes the first episode of depressive symptoms in patients with probable AD.

Activities of Daily Living↗
PubMed2005

A new approach to spatial covariance modeling of functional brain imaging data: ordinal trend analysis.

In neuroimaging studies of human cognitive abilities, brain activation patterns that include regions that are strongly interactive in response to experimental task demands are of particular interest. Among the existing network analyses, partial least squares (PLS; McIntosh, 1999; McIntosh, Bookstein, Haxby, & Grady, 1996) has been highly successful, particularly in identifying group differences in regional functional connectivity, including differences as diverse as those associated with states of awareness and normal aging. However, we address the need for a within-group model that identifies patterns of regional functional connectivity that exhibit sustained activity across graduated changes in task parameters. For example, predictions of sustained connectivity are commonplace in studies of cognition that involve a series of tasks over which task difficulty increases (Baddeley, 2003). We designed ordinal trend analysis (OrT) to identify activation patterns that increase monotonically in their expression as the experimental task parameter increases, while the correlative relationships between brain regions remain constant. Of specific interest are patterns that express positive ordinal trends on a subject-by-subject basis. A unique feature of OrT is that it recovers information about functional connectivity based solely on experimental design variables. In particular, there is no requirement by OrT to provide either a quantitative model of the uncertain relationship between functional brain circuitry and subject variables (e.g., task performance and IQ) or partial information about the regions that are functionally connected. In this letter, we provide a step-by-step recipe of the computations performed in the new OrT analysis, including a description of the inferential statistical methods applied. Second, we describe applications of OrT to an event-related fMRI study of verbal working memory and H(2)15O-PET study of visuo-motor learning. In sum, OrT has potential applications to not only studies of young adults and their cognitive abilities, but also studies of normal aging and neurological and psychiatric disease.

Adult↗
PubMed2005

H215O PET study of impairment of nonverbal recognition with normal aging.

Little research has been conducted regarding age-related changes in nonverbal memory. Using positron emission tomography (PET), the authors studied 17 elderly volunteers and 20 young volunteers, during nonverbal recognition task performance, to examine differences in brain blood flow. The subjects were asked to recognize a study list size (SLS) of shapes that was adjusted so that each subject performed at approximately 75% accuracy. Positron emission tomography results showed that, relative to younger individuals, elderly subjects engaged different regions, including the insula, during recognition. Elderly subjects did not show the relationship between parahippocampal flow and SLS, which was observed in younger subjects. These differences suggest that age-related functional brain changes partly explain performance deficits.

Adult↗
PubMed2005

Cognitive decline and literacy among ethnically diverse elders.

Researchers on genetic and environmental influences on risk for Alzheimer's disease must be prepared for the growing ethnic and racial diversity of our participants. Within the investigation, years of education has typically served as a proxy for cognitive reserve, which may be one factor in influencing risk of cognitive decline among aging people. However, among ethnic minorities, years of education is a poor reflection of the value of educational experience and native ability. This study was conducted among 1002 ethnically diverse English-speaking residents of Northern Manhattan who were cognitively and functionally normal at a baseline evaluation. We found that literacy level was a better predictor of decline in memory, executive function, and language skills than was years of education. The results of this study suggest that in an ethnically diverse cohort, literacy level should be considered as a mediator of the interactions of biological and environmental factors on cognitive decline.

Aged↗
PubMed2004

The effects of aging on time reproduction in delayed free-recall.

The experiments presented here demonstrate that normal aging amplifies differences in time production occurring in delayed free-recall testing. Experiment 1 compared the time production ability of two healthy aged groups as well as college-aged participants. During the test session, which followed a 24-h delay and omitted all feedback and examples of the two target intervals, the two groups of aged participants' over-produced a 6s interval. This effect is similar in form to errors shown by young participants, but twice the magnitude. Productions of a 17 s interval were generally accurate overall. However, further analysis indicated that the majority of aged participants over-produced the 17 s interval while a minority greatly under-produced the 17 s interval. Furthermore, aged participants showed violations of the scalar property of timing variability in the training session, while in the test session, only those who under-produced the 17 s interval showed this tendency. In contrast, training session performance was good for all participants. Experiments 2 and 3 investigated the ability of the participants in Experiment 1 to reproduce the length of a line from memory, under conditions analogous to those of the time production experiments. These experiments provided tests of the specificity of the errors observed in Experiment 1. Performance in the older participants was accurate, if more variable, compared to the young participants, in contrast to the time production results, indicating that production inaccuracy in free-recall is specific to interval timing in the current context.

Adolescent↗
PubMed2004

An event-related fMRI study of the neural networks underlying the encoding, maintenance, and retrieval phase in a delayed-match-to-sample task.

Memory loads exceeding the limited capacity of working memory (WM) have been shown to expand the prefrontal areas that participate in WM and have revealed substantial individual differences in performance. We used a delayed-match-to-sample (DMS) task in an event-related fMRI study to map the full extent of the expanded regional activations associated with supracapacity loads. A 6-letter study array was compared to arrays of 1 and 3 letters. The task comprised separate encoding, retention, and retrieval fMRI epochs. A brain-wide spatial covariance analysis was applied to the data of all task epochs to identify patterns of correlated regional activations whose expression increased monotonically across 3 memory-load levels on a subject-by-subject basis. Such load-related activation patterns were in all task phases. Of greatest interest is the activation pattern that was obtained during the maintenance phase: increasing activation with memory load was found not only in the lateral PFC (BA 9,44) but also in the parietal lobe (BA 7,40), anterior cingulate (BA 32), and cerebellum. Decreasing activation was found in the occipito-temporal lobe (BA 19,39) as well as the medial prefrontal cortex (BA 9,10). Subject increases in pattern expression from 1 to 6 items were positively correlated with the corresponding reaction time increases (p<0.05) and negatively correlated with NARTIQ (p<0.05), indicating that people who were faster in their responses and had higher NARTIQ had to increase their subject expression of the memory-load-related activation pattern less and were more efficient at the cognitive task. Our method thus not only reproduced findings of other WM studies but also addressed the issue of interactions between lateral PFC and other parts of the brain during the task, for the retention of the to-be-remembered information. The load-related activation patterns from encoding and retrieval phase and their relationship to behavior are also discussed.

Adult↗