Clock Test Research Articles

Clinical determinants of failure in balance tests in elderly subjects

We assessed the role of clinical and biological parameters on performance in four balance tests in elderly subjects. An observational study was conducted in the Center for Preventive Medicine of Nancy (France) in 2368 community-living elderly subjects aged 60 and older. Body mass index (BMI), Mini-Mental State Examination (MMSE), clock test, “Health score” and use of psychotropic drugs (UPD) were assessed. Participants performed four balance tests: “one-leg-stand” (OLS), “timed-up-and-go” (TUG), “rise-from-the-floor” (RFF) and “sit-to-stand” (STS). The statistical analysis showed that women were almost twice as likely to fail balance tests as men. In both women and men, the following determinant factors of the performance in balance tests were found: for OLS: age, BMI and health score; for TUG: age, BMI, clock test and health score; for RFF: BMI and health score. In addition, in women other determinant factors were: MMSE for OLS, UPD for TUG, age and clock test for RFF. In men, the clock test and the UPD were also significant determinant factors for OLS. Similar results were found for STS. In conclusion, female sex, overweight, low cognitive status, low self-perception of health and UPD were associated with a higher risk of failure in balance tests.

Comparison of the Clock Test and a questionnaire-based test for screening for cognitive impairment in Nigerians

Since it is projected that by 2020 seventy percent of the elderly will reside in developing countries, a reliable screening method for dementia and cognitive impairment in general in populations with diverse languages, culture, education and literacy will be needed. We sought to determine if the Clock Test, a screening test for dementia, was suitable for use in a Nigerian population. Cross-sectional survey of 54 men and 12 women from Northern Nigeria. Researchers administered two dementia screening tools: a questionnaire-based test adapted for use in a Nigerian population and the Clock Test. Overall, 53.0% of the subjects had an abnormal Clock Test whereas 10.6% of the subjects had an abnormal questionnaire score. Only 9.1% of the subjects had abnormal scores on both tests. Subjects with more schooling had a greater probability of having a positive clock concept (understanding that a circle represented a clock). Of those with more than 6 years of schooling, 91.0% had a positive clock concept. Subjects with a negative clock concept were more likely to have an abnormal Clock Test (93.3%) than a questionnaire (26.6%). The main finding of our study was the discrepancy between the results of the Clock Test and the questionnaire. Performance on the Clock Test appeared to have been heavily influenced by education level, indicating the test is not universally applicable across cultures. The questionnaire-based test appears to reduce the effects of illiteracy on assessing dementia in a Nigerian population. Larger studies should be done to control for how education affects the assessment of dementia.

Analysis of Test Generation Complexity for Stuck-At and Path Delay Faults Based on k-Notation

In this paper, we discuss the relationship between the test generation complexity for path delay faults (PDFs) and that for stuck-at faults (SAFs) in combinational and sequential circuits using the recently introduced τk-notation. On the other hand, we also introduce a class of cyclic sequential circuits that are easily testable, namely two-column distributive state-shiftable finite state machine realizations (2CD-SSFSM). Then, we discuss the relevant conjectures and unsolved problems related to the test generation for sequential circuits with PDFs under different clock schemes and test generation models.

Evaluation of Two Assessment Tools in Predicting Driving Ability of Senior Drivers

To evaluate Motor Free Visual Perceptual Test (MVPT) and Clock Drawing Task (clock test) as quick assessment tools in predicting driving capability of senior drivers for an on-road driving test. Senior drivers (> or = 55 yrs) referred for evaluation and recommendation for license renewal were given the MVPT, clock test, and an on-road driving test. Receiving operating characteristic (ROC) analysis and stepwise multivariate logistic regression (SMLR) were used to develop a probability model to differentiate between capable and incapable senior drivers. Data for 232 seniors who had completed all written tests and the on-road driving test were analyzed. Of the 232 seniors, 131 (56%) were classified as capable and 101 (44%) as incapable drivers on the road test. Mean scores for capable and incapable drivers were MVPT 32.0 +/- 4.0 vs. 28.4 +/- 4.6 and mean clock test score 3.5 +/- 0.8 vs. 2.7 +/- 1.2, and mean processing time was 7.1 + 6.5 vs. 10.6 + 5.5. The means of the three measurements were significantly different between the two groups (P value <0.001). ROC curve analysis revealed an optimal cut point of > or = 32 for MVPT score with 60% sensitivity and 83% specificity. The optimal cut point for clock test scores is > or = 3 with 70% sensitivity and 65% specificity. The optimal cut point for processing times is < or = 6.27 secs with 60% sensitivity and 80% specificity. SMLR showed that the most significant predictor of seniors' driving capabilities are the MVPT test scores and clock test scores. MVPT and clock test tools are significant predictors of driving capability on an on-road driving test.

Do Russian and American normal adults perform similarly on neuropsychological tests?: Preliminary findings on the relationship between culture and test performance

To learn how culture may affect neuropsychological performance, eight tests were administered to non-brain damaged adult volunteers in the United States and Russia. The tests included Ruff Figural Fluency Test (RFFT), Color Trails Test (CTT), Digit Span Forward and Backward, and Category Fluency Test. Verbal and Visual Memory measures and Blind Clock Test were selected from Luria's (1980) battery. Forty-two Russian and 42 American volunteers (age 18–44) were assessed. It was hypothesized that the American group would outscore the Russian on timed measures (RFFT & CTT) due to cultural differences in familiarity with timed testing procedures. Otherwise, significant differences between the two groups were not expected to emerge. Consistent with the hypotheses, significant effect of culture was found on CTT and RFFT in favor of the American group. ANCOVA suggested that intergroup differences were not fully explained by differences in subjective relevance of the tasks to culture-specific experiences. The rest of the tests appeared similar for potential application in both cultures.

Vigilance monitoring – review and practical aspects

Vigilance monitoring is increasingly important in the industrialised world because working tasks are becoming increasingly monotonous and less physically exhausting, resulting in a high risk of falling asleep unintentionally. Among existing tests for the assessment of vigilance, objectiveness plays the most important role in preventing volitional influence by the test subject. In addition, the tests should be simple so that a monotonous situation will emerge. This review gives an overview of important vigilance monitoring systems that are currently in use for research purposes and industrial application. The tests presented are the Mackworth clock test, the VIGIMAR, the Karolinska drowsiness test, tests based on blood pressure and heart rate changes, the psychomotor vigilance test, and experimental tests relying on pupillography and electrodermal activity.

Experiencia con el Eurotest en la exploración neuropsicológica. Un test de cribado

The increasing number of foreign patients being attended in our health centres makes it necessary to have tests that are compatible among different countries, especially in Europe. The objective of this study is to compare the Eurotest with other screening tests and to determine whether there are any differences between European (other than Spanish) and Spanish patients. We included patients who were referred because of complaints that were compatible with cognitive impairment and they were asked to carry out a protocol of tests that included the global deterioration scale (GDS), Folstein's MMSE (Mini-Mental State Examination), the Clock Test (CT) and the Eurotest. Epidemiological data were collected. The sample used in the study included 45 patients, 21 males and 24 females, with a mean age of 69.76 years; 34 were born in Spain and 11 abroad. Diagnoses were 17 with mild cognitive impairment, 8 with Alzheimer's disease, 6 with age-associated impairment, 5 with vascular dementia, 5 with a psychiatric disorder, 1 with mixed dementia and 1 with dementia with Lewy bodies. The distribution according to the GDS was as follows: 10 with a GDS of 2, 18 with a GDS of 3, and 17 with a GDS of 4. All the patients with a GDS 2 completed the tests correctly, those with a GDS 3 scored below the cut-off point 5 for the Eurotest, 4 for the MMSE and 3 for CT, and in the GDS 4 they were 9, 7 and 6, respectively. Results did not vary between Spaniards and foreigners, the kappa index between MMSE and the Eurotest was 0.39 and the Pearson coefficient was 0.67. The Eurotest was slightly more useful in patients with a greater degree of impairment.

Use of Subjective and Physiological Indicators of Sleepiness to Predict Performance during a Vigilance Task

Sleepiness is a major risk factor for serious injury and death in accidents. Although it is important to develop countermeasures to sleepiness to reduce risks, it is equally important to determine the most effective timing for these countermeasures. To determine optimum timing for necessary countermeasures, we must be able to predict performance errors. This study examined the predictability of subjective and physiological indicators of sleepiness during a vigilance task. Thirteen healthy male volunteers (mean age, 26.9 yr; SD = 5.98 yr; range 22-43 yr) participated in the study. Participants used the Karolinska sleepiness scale (KSS) to rate their subjective sleepiness every 4 min during a 40-min Mackworth clock test. Electrophysiological and performance data were divided into 10 epochs (i.e., 1 epoch lasted for 4 min). To estimate predictability, the data from the sleepiness indicators used for the correlation analysis were preceded by one epoch to the performance data. Results showed that sleepiness indicators (KSS score and electroencephalographic [EEG] alpha activity) and standard deviation of heart rate (SDNN) were significantly correlated with succeeding performance on the vigilance test. These findings suggest that the KSS score, EEG alpha activity, and SDNN could be used to predict performance errors.

Design of the cold atom PHARAO space clock and initial test results

In this paper we describe the cold atom clock PHARAO, designed for microgravity operation. All elements of the PHARAO engineering model have been manufactured and delivered to CNES, the French space agency. We present the clock design, its main characteristics, and initial science operation. PHARAO is one of the main components of the Atomic Clock Ensemble in Space payload that is scheduled to fly on board the International Space Station in 2010.

Test Scheduling of NoC-Based SoCs Using Multiple Test Clocks

Network-on-chip (NoC) is an emerging design paradigm intended to cope with future systems-on-chips (SoCs) containing numerous built-in cores. Since NoCs have some outstanding features regarding design complexity, timing, scalability, power dissipation and so on, widespread interest in this novel paradigm is likely to grow. The test strategy is a significant factor in the practicality and feasibility of NoC-based SoCs. Among the existing test issues for NoC-based SoCs, test access mechanism architecture and test scheduling particularly dominate the overall test performance. In this paper, we propose an efficient NoC-based SoC test scheduling algorithm based on a rectangle packing approach used for current SoC tests. In order to adopt the rectangle packing solution, we designed specific methods and configurations for testing NoC-based SoCs, such as test packet routing, test pattern generation, and absorption. Furthermore, we extended and improved the proposed algorithm using multiple test clocks. Experimental results using some ITC’02 benchmark circuits show that the proposed algorithm can reduce the overall test time by up to 55%, and 20% on average compared with previous works. In addition, the computation time of the algorithm is less than one second in most cases. Consequently, we expect the proposed scheduling algorithm to be a promising and competitive method for testing NoC-based SoCs.

P3-059: A preliminary study on the validation of Persian Clock Test in Iran

P3-059: A preliminary study on the validation of Persian Clock Test in Iran

Neural mechanisms underlying spatial judgements on seen and imagined visual stimuli in the left and right hemifields in men

We investigated the neural networks involved in spatial judgements on visual and imagined stimuli in the left and right hemifields. Twenty healthy male right-handers were scanned using fMRI. In an adaptation of the Mental Clock Test, subjects judged whether the angle between visually presented or to be imagined clock hands at a given time (e.g. “12:20”) was >90° or <90°. The angle formed by the clock hands was always located either on the left or right hemifield of the clock face, constituting a 2 × 2 factorial design with factors stimulus type (visual “V”, imagined “I”) and attention to spatial hemifield (left “L”, right “R”). The contrast I > V revealed a bilateral neural network which included the superior parietal, prefrontal and antero-dorsal cingulate cortex. While right superior parietal cortex was activated during both RV and LV, left superior parietal cortex was only active during RV. The contrast RI versus LI (and vice versa) did not reveal significant differences with respect to activation height. However, a masking procedure and the calculation of a laterality index showed that RI recruited larger areas in the left than in the right hemisphere, while LI led to symmetrical activations in both hemispheres. Our data thus confirm that there are hemifield-specific asymmetries in brain activity during spatial processing of both visual and imagined stimuli. Our data indicate, however, that these asymmetries are less clear and of a different nature in the latter. Overall, our findings converge with neuropsychological data showing that representational and visuospatial neglect do not always co-occur.

Evaluación de la versión española del Memory Impairment Screen

Screening tests for detecting dementias are usually long, sometimes difficult to apply, and require a certain amount of instruction prior to using them. The Memory Impairment Screen (MIS) is a fast (3-4 minutes), easy-to-apply screening test that evaluates short-term verbal memory.To evaluate the value of the MIS for screening for dementia in our population.We evaluated 101 subjects who were divided into two groups, one consisting of 49 individuals with dementia according to DMS-IV criteria and the other made up of 52 subjects with no cognitive impairment. Demographic variables (sex, age, schooling) were studied together with the results from the Global Deterioration Scale, the Folstein Mini-Mental State Examination (MMSE), the MIS, the Semantic Verbal Fluency (SVF) and the Command-Condition Clock Test (CCCT).demographic variables and the results from the tests for the two groups (with and without dementia) were compared, and the parameters for diagnostic usefulness and the areas under the ROC (aROC) were determined.No significant differences were found between the sociodemographic variables except for a higher mean age in the group with dementia. The MIS showed a sensitivity of 83.7% (95% CI: 71-97.9), which was higher than the SVF and the CCCT, and a specificity of 94.2% (95% CI: 84.4-98), which was higher than the MMSE and the SVF. The aROC of the MIS was 0.935 (95% CI: 0.954-1.006).These findings show that the MIS is a good test for screening for dementia, and its simplicity and quick application could make it suitable for use in our population.

The Mental Clock Test and its asymmetry

The Mental Clock Test and its asymmetry

Visual Spatial Abilities and Fall Risk

Risk of falling is a major concern of long-term care facilities with residents diagnosed with dementia. Use of a brief cognitive assessment focusing on visual spatial abilities could be one strategy in the prevention of falls in residents with dementia. The objective of this study was to determine if a clock test could predict a risk of falls in residents diagnosed with dementia. Three hundred sixty-four individuals with dementia participated (92 men and 272 women; ages 37 to 100, mean 80.5 years, median 83 years). Each participant was given the Reality Comprehension Clock Test (RCCT) three times, and Mini Mental-Status Examination (MMSE) two times to determine criterion-related validity, test-retest reliability, internal consistency; and to set and evaluate a risk of falls score based on the Visual Spatial Score (VSS) component produced by the RCCT. Significant findings included .72 (p < .01) correlation between the RCCT and the MMSE, .90 (p < .01) correlation between the first administration of the RCCT and the second administration of the RCCT; an alpha of .95 (p, < .001) and an F value of 7.6 (p < .001) producing a risk of falls initial VSS of 5 or lower compared to 9 or greater. Chi-square of 6.3 for 30 days (p,< .01), 11.08 for 60 days (p < .01) and 13.3 for 90 days (p < .01) indicated a significant difference in the number of falls occurring in the high risk group (VSS of 5 or lower) compared to the low/ no risk group (VSS of 9 or higher). A risk factor analysis suggested that residents in the higher risk group were three times more likely to have fallen than residents in the low risk group. Knowing a resident's visual spatial ability offers health care providers an opportunity to implement a resident-specific intervention that addresses their cognitive ability and visual spatial deficit that may reduce the resident's risk of falling.

Correlation of MMSE, SKT and clock test scores in patients with mild and moderate dementia.

The objective of our study was to assess the correlation of routine neuropsychological test results in elderly patients referred to a gerontopsychiatric ward. MMSEs, Clocktests (CT) and SKTs were performed in 94 patients (Age: Median = 74 ys, Range = 54-89 ys; 64 f, 30 m; MMSE < 25:45 and MMSE > 25:37) with mild to moderate dementia and evaluated retrospectively. Linear and multiple regression was used. The scores of all 3 tests used were reciprocally correlated (p < 0.05). Multiple regression analysis showed a maximum correlation of 0.87 and marked standardized beta values, if SKT was chosen as dependent variable. In conclusion, results of SKT, CT or MMSE in patients with dementia showed marked pairwise or multiple correlations and therefore it is not necessary to include more than two reliable tests in clinical psychogeriatric studies.

Comparative phylogeography of livebearing fishes in the genera Poeciliopsis and Poecilia (Poeciliidae: Cyprinodontiformes) in central Mexico

AbstractAim To test the hypothesis that the vicariant event responsible for north–south divergences in two clades of the fish genus Poeciliopsis Regan was also responsible for north–south divergences in the fish Poecilia butleri Jordan.Location Central Mexico.Methods Parsimony, distance, maximum likelihood and Bayesian phylogenetic analyses of a mitochondrial gene. Molecular clock test and Bayesian analyses of divergence time.Results We report concordant phylogeographical patterns between two clades in the genus Poeciliopsis (i.e. the other formed by P. latidens Garman and P. fasciata Meek, and the other formed by P. presidionis Jordan and P. turneri Miller) and the clade of Poecilia butleri, with northern and southern individuals within each clade grouping into separate lineages. There is also evidence for slower substitution rates in Poecilia compared with Poeciliopsis. After taking into account these substitution rate discrepancies with Bayesian relaxed molecular clock analyses, north–south divergences in Poecilia butleri were equivalent to those reported for Poeciliopsis latidens‐fasciata and P. presidionis‐turneri.Main conclusions The same Plio‐Pleistocene vicariant event associated with geological activity of the Trans‐Mexican Volcanic Belt (TMVB) appears to have caused divergence in three different freshwater fish lineages. This study is an example of how comparative phylogeography can strengthen inferences about vicariant events in regions of high biological diversity and complex geological history such as the TMVB.

Pelvic Floor Surgery in the Older Woman: Enhanced Compared With Usual Preoperative Assessment

To examine whether knowledge of deficits obtained in a preoperative geriatric assessment may benefit postoperative health outcomes in older women undergoing pelvic surgery. This study employed a pre-post intervention cohort design. Primary outcome was difference in scores of the Physical Component Summary and Mental Component Summary of the Medical Outcomes Study Short Form 36 Health Survey in 62 older women who had undergone "usual" compared with an "enhanced" preoperative assessment consisting of Activities of Daily Living, Instrumental Activities of Daily Living, Get Up and Go Test, Draw a Clock Test, Mini Nutritional Assessment, Geriatric Depression Scale, and Social Support Scale. The assessment results were placed on the participant's hospital chart. Repeated measures analysis was used. There were no significant differences in Mental Component Summary scores between the usual and enhanced assessment cohorts preoperatively (mean +/- standard deviation; 49.14 +/- 10.61 compared with 53.2 +/- 9.33), at 6 weeks (53.69 +/- 8.61 compared with 55.47 +/- 9.46), or at 6 months postoperatively (53.85 +/- 10.77 compared with 56.25 +/- 7.25); P = .120 for group effect and P = .798 for group by time interaction. Significant time effect was noted (P = .036). There was no significant difference in Physical Component Summary scores between the usual and enhanced assessment cohorts with respect to group effect (P = .986); there was a significant time effect (P = < .001) and a significant group by time interaction (P = .026). Satisfaction with treatment was high in both cohorts at 6 weeks and 6 months. A preoperative geriatric assessment did not seem to have differential benefit in healthy older women undergoing elective pelvic floor surgery. II-2.

Neuropsychological Correlates of Greek Alcoholic Patients Who Report Memory Disturbances

We studied 40 male and 37 female (M age=63 yr.) Greek alcoholic patients and an equal number of control subjects. Both groups were evaluated with the Mini-Mental State Examination, the Syndrome Short Test, the Verbal Fluency Test (Category & Letter), the Clock Test, and the Digit Span (Forward and Backward from the Wechsler Adult Intelligence Scale-Revised). Alcoholic patients had statistically significant lower scores on MMSE, Verbal Fluency Test, and Digit Span, and higher scores on the Syndrome Short Test, while positive correlations were found among MMSE, Verbal Fluency Test, Clock Test, Digit Span-Backward, and age. These findings point to frontal lobe dysfunction in Greek alcoholic patients which is not different from that shown in patients from diverse ethnic and cultural backgrounds.

Use of the Ten-Point Clock Test to Compare Executive Functioning across 24 Months in Patients with Subcortical Vascular Dementia

The Ten-point Clock Test can be used to identify early forms of Alzheimer's disease because it is reliable, well accepted, and easily administered at the bedside. Nevertheless, its clinical role in the detection of early dementia and its correlations with other cognitive processes is still under investigation. Vascular dementia is an uncertain nosological entity, in which unevenly distributed patterns of cognitive deficits comprising slowing of cognitive processing and impairment of executive function occur. The present study assessed how the Clock Test scores correlated with a number of other neuropsychological and functional tests in a sample of 144 patients with vascular dementia, who were followed for a period of 24 mo. At baseline, at 12 mo. and at 24 mo. subjects were administered a battery of tests, including the Mini-Mental State Examination, word fluency, visuospatial skills, an evaluation of hetero- and autotopognosia (knowledge of self), the Proverbs Test, and the Ten-point Clock Test. For these patients scores on the Clock Test correlated significantly with semantic abilities, with abstract reasoning capacities, visuospatial perception, and with right and left recognition.