Structural relationships between measures based on heart beat intervals: potential for improved risk assessment

Decreased left ventricular ejection fraction is the most commonly used risk factor for identification of patients at high-risk for lethal ventricular arrhythmic events. Twenty-four-hour electrocardiographic (ECG) approaches to risk stratification include: counts of ventricular premature contractions (VPCs), measures of heart rate variability (HRV), and heart rate turbulence (HRT) which has two components, turbulence onset and turbulence slope (TS). Refinement of these ECG risk stratifiers could enhance their clinical utility. We explored the structural relationships between heart rate (HR) and HRV and HRT measures. Our goal was to separate out the component of these measures due to the underlying average heart rate (HR), thus potentially reducing the variability of the measures and increasing their power to stratify risk. We proposed re-scaling tachograms of heart-beat intervals so that the re-scaled tachogram has a HR of 75 (or equivalently an average interval of 800 ms) and calculating HRV and HRT from the rescaled time series. We also explored the relationship between the number of VPCs and HRT. We showed that TS is structurally related to the number of VPCs (and hence to the length of the ECG recording). We proposed an adjusted TS that is independent of the number of VPCs. We also addressed the ability of shorter ECG recording to estimate HRV and HRT measures. We evaluated standard and rescaled HRV and HRT measures using qualifying ambulatory ECG recordings from 744 patients in the Cardiac Arrhythmia Suppression Trial. We found that measures based on the rescaled tachogram had reduced variance (20% to 40%). Correlations between measures were also substantially reduced. We also found substantial circadian effects on some, but not all HRV indices, not explained by the circadian pattern in HR and possibly pointing to additional measures for risk prediction. In conclusion, we found that adjusting for HR and the number of VPCs in heart-beat related ambulatory ECG measures has the potential to significantly improve the power of these measures to risk stratify cardiac patients.     

Categorization of novel animals by patients with Alzheimer's disease and corticobasal degeneration.

We taught a novel animal category by rule-based and similarity-based processes to participants with Alzheimer's disease (AD), corticobasal degeneration (CBD), and healthy age-matched participants. Healthy participants successfully categorized by either process. AD patients' rule-based categorization was impaired, while their similarity-based categorization resembled that of healthy participants. Correlations of AD patients' performance with measures of executive functioning suggested a deficit in the cognitive resources necessary for engaging rule-based categorization. The contribution of limited executive resources to categorization difficulty in AD was further demonstrated in a second experiment in which features determining category membership were of lower salience. CBD patients were relatively impaired at similarity-based processing, suggesting that qualitatively distinct categorization processes can be selectively compromised in patients with focal neurodegenerative diseases. Moreover, AD patients' impaired categorization correlated with performance on a measure of semantic memory, implicating this categorization deficit in AD patients' semantic memory difficulty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-disclosure, paranoia, and unaware racism: Another look at the Black client and the White therapist.

Suggests that C. R. Ridley (see record 1985-26063-001), in his attempt to dissuade the reader from maintaining stereotypic views of Black clients, may be unintentionally perpetuating some of those views. Ridley's use of the term healthy cultural paranoiacs and the language and terminology of the article are discussed in this context. The concept of unaware racism and its effects on the White therapist–Black client relationship are discussed. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correspondence of supervisor and subordinate perspectives during major organizational change.

Staff members (N?=?2,605) and supervisors (N?=?55) of 39 administrative units in 2 healthcare organizations completed a survey measuring confidence in the organization, engagement with their work, and occupational hazards. A correlational analysis determined correspondence between the perspectives of supervisors with those of staff reporting to them as their facilities adjusted to major organizational changes. Supervisors' scores were significantly and positively correlated with the corresponding scores of staff members on cynicism, meaningfulness, acceptance of change, goals, hospital reputation, and health risks. Regression analysis found that relationships were relatively domain specific: Supervisor engagement with work was positively related to that of their staff members, and supervisor evaluations of the organization were positively related to those of their staff members. Supervisor assessment of occupational hazards was related to all 3 areas of staff perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Patterns and correlates of binge drinking trajectories from early adolescence to young adulthood.

Latent growth mixture modeling was used to identify developmental trajectories (described in terms of demographics, exposure and resistance to a pro-drug environment, and deviant behavior) of binge drinking among 5,694 individuals who completed 6 surveys from ages 13 to 23 years: nonbingers (32%); moderate stables (37%), who had consistently low levels of bingeing; steady increasers (16%), who increased from the lowest to highest level of bingeing; adolescent bingers (9%), whose early rise in bingeing was followed by a decrease to a moderate level; and early highs (6%), who decreased from the highest level of bingeing to a moderate level. Results show considerable diversity in binge drinking patterns and the correlates of bingeing across trajectory classes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measuring Developmental Changes in Alcohol Expectancies.

The goal of this study was to measure shifts in alcohol expectancies from childhood into adolescence while controlling for changes in the psychometric properties of the instrument. One thousand nine hundred ninety-three 4th-grade and 1,632 9th-grade students from South Dakota rated the likelihood that 23 outcomes would result from alcohol use. These expectancies were modeled using a 2-factor confirmatory factor analysis. After differences in the psychometric properties of the instrument were controlled, the cohorts were distinguished by a large difference in Alcohol Positivity, with older participants viewing alcohol's effects more positively. Additionally, older participants displayed greater Alcohol Potency, believing that alcohol has a larger impact on all outcomes. There were also significant differences in the interpretation of the alcohol expectancies items across cohorts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting achievement early and late in the semester: The role of motivation and use of learning strategies.

Relations among motivation, learning strategy use, and achievement were examined. Questionnaires were group administered to 283 high school students in geometry classes early and late in the semester. Path analyses were used to determine the effects of motivation (ability perceptions, expectancies, and perceived value) and use of learning strategies (metacognitive, general cognitive, geometry specific, and effort) on achievement early and late in the semester. Early, both expectancies and value predicted the use of strategies; expectancies and use of geometry specific and effort strategies influenced grades. Later, value predicted strategy use; geometry self-concept and metacognitive strategy use influenced grades. No sex differences were found. Results concerning motivation are congruent with previous reports. Strategy use findings suggest that teachers emphasize the use of content specific strategies early in a new course and metacognitive strategies later. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cultural Differences in Young Children's Vulnerability to Injuries: A Risk and Protection Perspective.

Interview data from 100 lower income Hispanic and 50 White mothers from a nutritional service clinic extended prior research on cultural differences in the risk for unintentional pediatric injuries. Group differences were expected in reported injury incidence and in the prevalence and impact of contributing factors. As predicted, White mothers reported more injuries for a young child, and among Hispanic mothers, English language preference and use were associated with more reported injuries. Hierarchical regression analysis revealed that risky behaviors, mother's judgment about child compliance, and stressful life events were better predictors of injuries than housing quality, but among Hispanics, the impact of certain factors (e.g.. child temperament) was qualified by mother's acculturation level. Stress and child temperament explained injury differences between more- and less-acculturated Hispanic families but only partially accounted for differences between White mothers and less-acculturated Hispanics. Pediatric injury risk and protective factors seemed to operate in concert with cultural processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental aspects of gender role flexibility and traditionality in middle childhood and adolescence.

Explored developmental patterns of gender traditionality and flexibility in 479 Ss across middle childhood and early and late adolescence and assessed the correlates of gender flexibility at these 3 developmental periods. Gender flexibility was differentiated into 2 dependent variables: self-related gender preferences and attitudes toward others. Varying theoretical developmental trends have been posited with regard to gender flexibility, but relationships obtained between age and gender flexibility were mostly positive. Several negative relationships, however, underscored the complexity of gender-related responses. Most variables assessed contributed significantly and cumulatively to the prediction of gender flexibility; socialization variables proved to be the strongest predictors of all 3 developmental levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of density and format on letter discrimination by beginning readers with different learning styles.

Investigated the processing requirements in letter discrimination for 40 1st graders with reflective-impulsive and field-dependent-field-independent learning styles. Field dependence was measured by the Children's Embedded Figures Test, and impulsivity was measured by the Matching Familiar Figures Test. The discrimination task, presented in vertical and horizontal formats and in high- and low-density arrangements, consisted of matching each of 12 letterlike symbols with 1 of its 12 transformations. Results support all a priori hypotheses: (a) Impulsivity-reflectivity was related only to number of errors and latency. (b) Field dependency-independency was unrelated to latency but interacted with contextual arrangements. Field dependents made more errors than field independents on high-density and horizontal presentations. Interpretations are made in terms of the feature analysis processes employed by beginning readers with different learning styles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)