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PubMed1991

Methylphenidate speeds evaluation processes of attention deficit disorder adolescents during a continuous performance test.

Forty-six Attention Deficit Disorder (ADD) adolescents took a Continuous Performance Test (CPT) under placebo and methylphenidate (35.33 mg/day). The task required pressing one button for targets (p = .133), and another button for nontargets. Subjects displayed a strong bias to make the more frequent negative response before completely evaluating stimuli. Consistent with this assumption, subjects responded faster (by an average of 87 ms) to nontargets than to targets. Methylphenidate increased accuracy and speeded reaction times (RTs) to targets. The drug also increased the amplitude of the P3b component of the event-related potential for nontargets and shortened the latency of P3b for both targets and nontargets. These results suggest increased capacity allocation to and faster evaluation of task stimuli. Finally, the stimulant lengthened relative motor processing time (RT-P3b latency) for nontargets, a finding implying that response processing was accomplished with the benefit of earlier completion of evaluation processes for these stimuli.

Adolescent↗
PubMed1991

Cognitive addition: strategy choice and speed-of-processing differences in young and elderly adults.

Sixty young and 60 elderly adults completed a pencil-and-paper addition test and solved 40 computer-presented simple addition problems. Strategies and problem solution times were recorded on a trial-by-trial basis and were classified in accordance with the distributions of associations model of strategy choices. The elderly group showed a performance advantage on the ability measure and for the developmental maturity of the mix of problem-solving strategies, but the young group showed an advantage for overall solution times. A componential analysis of the overall solution times for memory retrieval trials, however, showed no reliable age difference for rate of retrieving addition facts from long-term memory but did suggest that the elderly adults might have been slower than the younger adults for rate of encoding digits and verbally producing an answer. Overall results are interpreted within the context of the strategy choice model.

Adolescent↗
PubMed1992

The Ruff 2 and 7 Selective Attention Test: a neuropsychological application.

The neuropsychological application of the Ruff 2 and 7 Selective Attention Test as a measure of visual selective attention was investigated. The instrument was constructed as a paper-and-pencil approach to evaluate sustained attention utilizing different distractor conditions in the study of voluntary or intentional aspects of attention. Four patient groups with cerebral lesions confined to either the right or left anterior or left or right posterior region (ns = 8, 8, 8, 6) were studied. Patients with right-hemispheric lesions showed a greater over-all reduction in processing speed independent of the serial or parallel processing mode in comparison to individuals with left-sided lesions. Furthermore, as predicted, the two groups with anterior brain damage showed a larger discrepancy between serial and parallel processing modes than patients with posterior lesions. Specifically, the right frontal cases showed the greatest differential of accuracy on the serial and parallel tasks.

Adult↗
PubMed1991

The genetic correlation between intelligence and speed of information processing.

This study examined the contributions of genetic and environmental factors to the observed correlation between intelligence test scores and speed of information processing, based on data for same-sex adult twin pairs (age, 15-57). Verbal and performance IQ scores from the Multidimensional Abilities Battery, as well as 11 reaction-time measures derived from a battery of information-processing tasks, were available for 50 monozygotic and 32 dizygotic pairs of twins. Multivariate biometrical analyses were used to estimate genetic and environmental parameters underlying observed variances and covariances among intelligence test scores and a general speed of information-processing factor (based on a linear composite of the 11 reaction-time scores). A common-factor model with loadings on general speed of processing, verbal IQ, and performance IQ fit the data well. The common factor was influenced primarily by additive genetic effects, such that the observed relationships among the speed and IQ measures are mediated entirely by hereditary factors. There was additional specific genetic variance for Verbal IQ and specific shared-twin environmental variance for Performance IQ. However, twin similarity for general speed of processing was explained entirely by genetic factors related to intelligence. The results emphasize the importance of common, heritable, biological mechanisms underlying the speed-IQ association.

Adolescent↗
PubMed1992

On estimating processing variance: commentary and reanalysis of Kail's "Developmental functions for speeds of cognitive processes".

A recent paper by Kail (1988) in this journal appears to contain a significant error in the data analysis. The "goodness-of-fit" coefficients reported which suggest that overall about 94% of the variance can be accounted for by the model seem to be a substantial overestimation as a result of inappropriate procedures for statistical modeling. Using the data made available to us by Kail, we have reanalyzed these results. The corrected values range from 0.9 to 92.1% for the individual tasks with an overall average between 40 and 60%. We suggest that the support for the original conclusions is considerably weaker than reported.

Aptitude↗
PubMed1978

Methamphetamine and diphenhydramine effects on the rate of cognitive processing.

Three cognitive tasks in which performance depends primarily on the rate of cognitive processing were given to 24 male subjects before and after oral doses of methamphetamine (10 mg), diphenhydramine hydrochloride (100 mg), and placebo. Each subject was tested on Monday, Wednesday, and Friday of one week with drug orders balanced across subjects. Compared with placebo and diphenhydramine, methamphetamine increased the rate at which a visual display was scanned for a target stimulus. Methamphetamine affected neither a time-production task nor a divided attention task that required the subject to perform two cognitive tasks in a limited amount of time. This suggests that methamphetamine can increase cognitive processing speed on tasks involving familiar cognitive operations but that an increase is not likely in tasks involving more complicated decision processes. Compared with placebo and methamphetamine, diphenhydramine caused subjects no experience geophysical time as passing more slowly, but the drug had no significant effects on the visual search or divided-attention tasks. This suggests that time perception is more likely to be altered by diphenhydramine than is performance on tasks requiring short periods of rapid cognitive processing.

Adolescent↗
PubMed1992

ST analysis of Holter tapes.

In recent years, it has become increasingly clear that for an important subset of patients with coronary artery disease, many or all of their ischemic episodes are not accompanied by anginal pain. For these patients, it is desirable to detect these ischemic episodes as periods of ST-segment depression on Holter tapes. In the past, such detection has been difficult because the analysis methods were artifact-sensitive and failed to differentiate ischemic from nonischemic ST-segment changes. This work describes a new ST-segment analysis algorithm that has been added to the existing computer-based Holter analysis system. This system is highly artifact-resistant and has been designed to minimize the loss of processing speed while maintaining extremely high accuracy.

Algorithms↗
PubMed1992

Spatial code interference on directional responses.

The interference from an irrelevant position cue was compared in a reaction-time paradigm using voice and manual responses. The subjects were required to say 'left' or 'right' or to press left or right keys in response to arrow directions, and the arrows were presented at left or right side display positions irrelevant to the task. Display position significantly increased latency when it did not match the response to the relevant direction cue for both spatial (key-press) and non-spatial (voice) responses (73 and 59 ms, respectively). When presented alone, the position cue was processed faster than the direction cue for both manual and verbal responses. Results are discussed in terms of a common abstract mediator for left-right responses between modes and the processing speed difference between the relevant and irrelevant cue. The irrelevant left-right position code may occupy some limited-capacity channel ahead of the left-right code derived from processing the relevant direction cue.

Humans↗
PubMed1992

Cognitive impairment following closed head injury.

Cognitive impairments are usually the most disabling sequelae of CHI. The earliest stage of recovery from moderate to severe closed head injury is a period of PTA that typically includes memory loss for events preceding and surrounding the injury and memory loss for events occurring since the injury. Following resolution of PTA, deficits may be present in a number of cognitive domains. Memory and attention/information processing speed and efficiency are typically the cognitive domains most severely affected by head injury. Intellectual, language, and perceptual skills tend to be relatively preserved. Neurologic variables such as pupillary reactivity and worst GCS score are prognostic of cognitive impairment at 1 to 2 years postinjury. Following mild head injury, impairments of memory and information processing may be apparent within the first week of recovery. These deficits usually resolve in 1 to 3 months, although chronic complaints persist in a minority of individuals. The long-term cognitive effects of CHI are typically more severe for younger children than older children. Neuropsychologic assessment provides an objective way to measure the presence and severity of cognitive impairment.

Adult↗
PubMed1992

Vision, aging, and driving: the problems of older drivers.

Although there are well-recognized declines in visual functioning with age, their contribution to the problems of older persons on tasks in the natural environment, including driving, are largely unknown. Adults ranging in age from 22-92 years were surveyed in regard to their visual difficulties when driving and performing everyday tasks. The visual problems of drivers increased with age along five different visual dimensions: unexpected vehicles, vehicle speed, dim displays, windshield problems, and sign reading. Several of the age-related visual problems that were reported appear to be related to the types of automobile accidents more common among older drivers. The study also replicated the findings from an earlier investigation of non-driving tasks that showed visual declines with age on five dimensions: visual processing speed, light sensitivity, dynamic vision, near vision and visual search. These findings indicate promising areas of research regarding the effects of visual aging on tasks in the natural environment.

Adult↗
PubMed1992

Regularized linear method for reconstruction of three-dimensional microscopic objects from optical sections.

The inverse problem involving the determination of a three-dimensional biological structure from images obtained by means of optical-sectioning microscopy is ill posed. Although the linear least-squares solution can be obtained rapidly by inverse filtering, we show here that it is unstable because of the inversion of small eigenvalues of the microscope's point-spread-function operator. We have regularized the problem by application of the linear-precision-gauge formalism of Joyce and Root [J. Opt. Soc. Am. A 1, 149 (1984)]. In our method the solution is regularized by being constrained to lie in a subspace spanned by the eigenvectors corresponding to a selected number of large eigenvalues. The trade-off between the variance and the regularization error determines the number of eigenvalues inverted in the estimation. The resulting linear method is a one-step algorithm that yields, in a few seconds, solutions that are optimal in the mean-square sense when the correct number of eigenvalues are inverted. Results from sensitivity studies show that the proposed method is robust to noise and to underestimation of the width of the point-spread function. The method proposed here is particularly useful for applications in which processing speed is critical, such as studies of living specimens and time-lapse analyses. For these applications existing iterative methods are impractical without expensive and/or specially designed hardware.

Computer Simulation↗
PubMed1992

Neuropsychological assessment in MS: clinical, neurophysiological and neuroradiological relationships.

We assessed cognitive performance and its relationship with clinical and anatomic disease severity in MS with mild to moderate handicap; 34 definite MS and 18 healthy subjects matched for age and education were submitted to a neuropsychological test battery. Both groups were examined for anxiety. MS patients underwent magnetic resonance imaging examination. MS performed worse than controls on all WAIS-P subtests and had learning, short- and long-term verbal memory impairment. Cognitive deficits were not related to abnormal emotional states, but were found to be associated with attentional process and information-processing speed impairment. Cognitive impairment did not correlate with severity of physical disability. The most severe memory deficits were found in patients with extensive periventricular damage.

Adult↗
PubMed1992

Automatic film processing: analysis of 9 years of observations.

A survey method known as the sensitometric technique for the evaluation of processing (STEP) has been used to monitor processing speed of over 2,000 automatic film processors in hospitals, private offices, and mammography facilities since 1981. Analysis of data obtained through this program revealed underprocessing at 33% (76 of 231) of observed hospitals in 1987, 7% (13 of 179) of mammography facilities in 1988, and 42% (101 of 241) of private practices in 1989. Underprocessing at mammography facilities decreased from 18% (25 of 139) in 1985, which was contrary to the trend in hospitals. The consequence of underprocessing is higher radiation exposure and a degradation in film contrast. Evaluation of automatic film processors is a necessary part of any comprehensive evaluation of a diagnostic radiography facility. The STEP procedure was designed only as a field survey test; to ensure optimal conditions for obtainment of diagnostic quality radiographs, facilities should perform quality assurance evaluations of their processing equipment and verify that processing recommendations of manufacturers are being followed.

Technology, Radiologic↗
PubMed1992

Plasma vitamin B12 level as a potential cofactor in studies of human immunodeficiency virus type 1-related cognitive changes.

Studies of cognitive function in subjects with human immunodeficiency virus type 1 (HIV-1) infection who remain relatively asymptomatic (ie, Centers for Disease Control stages II and III) have provided widely variable estimates of cognitive impairment. In view of the finding that approximately 25% of asymptomatic HIV-1-infected subjects demonstrate either marginal or overt vitamin B12 deficiency, we have investigated plasma vitamin B12 status as a potential cofactor in studies of HIV-1-related cognitive impairment. When cognition was assessed in asymptomatic (Centers for Disease Control stages II and III) HIV-1-infected participants taking into consideration vitamin B12 status, those subjects with low plasma vitamin B12 levels (less than 180 pmol/L) performed more poorly than did those with normal (greater than or equal to 180 pmol/L) vitamin B12 status on specific measures of information processing speed and visuospatial problem-solving skills. These findings suggest that concurrent vitamin B12 deficiency may be a cofactor in subtle cognitive changes observed in the asymptomatic stages of HIV-1 infection. These differences in prevalence of low plasma vitamin B12 levels may help to explain differences among studies in the proportion of HIV-1-infected subjects showing cognitive impairment.

Adult↗
PubMed2026

Wearable Sleep Monitoring in Pediatric Acute Lymphoblastic Leukemia: Associations With Subjective Sleep Ratings and Neurocognitive Functioning.

BACKGROUND: Sleep disturbances are associated with increased fatigue, reduced quality of life, and neurocognitive dysfunction and have emerged as a common complication among pediatric cancer survivors. Sleep disturbances are particularly concerning given their potential to exacerbate existing neurocognitive impacts of cancer treatments. This pilot study examined the feasibility and acceptability of a home-wearable EEG-based sleep device (Sleep ProfilerTM) for acute lymphoblastic leukemia (ALL) survivors as well as associations between specific sleep parameters and neurocognitive functioning. PROCEDURE: Children (ages 8-12; M = 10 years, SD = 1.6; N = 23) >6 months post-treatment for ALL were enrolled at clinical visits and wore the Sleep ProfilerTM for two consecutive nights at home, followed by neurocognitive testing of attention, inhibitory control, working memory, and processing speed. Parents completed subjective measures of child sleep, anxiety, depression, and acceptability. Feasibility reflected the percentage of children wearing the device at least one night and the percentage of nights with good EEG quality data. RESULTS: All participants wore the device both nights, with 84% meeting the threshold for good quality measurement. Few children met recommended quantity and quality sleep thresholds based on objective measurement, including 5 patients with elevated snoring levels; 43.5% of subjective ratings fell above the threshold for sleep disturbance. Greater sleep latency was associated with worse inhibitory control (r = -0.42, p = 0.046), and total sleep time was positively associated with inhibitory control and attention. CONCLUSIONS: Findings confirm the feasibility and acceptability of home EEG sleep monitoring in school-age survivors, and associations of sleep latency and snoring with reduced neurocognitive functioning may offer modifiable risk factors for aspects of neuropsychological dysfunction common in pediatric survivorship. CLINICAL TRIAL REGISTRATION: At the time this study was conducted, we were not required to register the study on ClinicalTrials.gov. It was a single-institution feasibility study without intervention, which was not considered a clinical trial.

Humans↗
PubMed1991

Cumulative cognitive impairment following recurrent severe hypoglycaemia in adult patients with insulin-treated diabetes mellitus.

To examine the hypothesis that episodes of severe hypoglycaemia may cause cumulative cognitive impairment. 100 Type 1 (insulin-dependent) diabetic patients were examined. Their age range was 25-52 years, and the onset of diabetes had occurred after the age of 19 years. Patients with evidence of organic brain disease, including cerebrovascular disease, were excluded. A questionnaire was used to assess the number, frequency and severity of hypoglycaemic episodes experienced during treatment with insulin and the accuracy of this retrospective information was verified from general practice and hospital case-notes. A detailed neuropsychological assessment was undertaken, including tests of pre-morbid and present IQ (Wechsler-Revised), memory and information-processing speed. Significant correlations were observed between the frequency of severe hypoglycaemia and the magnitude of intellectual decline, Performance IQ, inspection time and reaction time (patients with the more frequent hypoglycaemia had poorer performance). Two sub-groups of patients were identified on the basis of their experience of severe hypoglycaemia, and were balanced for pre-morbid IQ, age and duration of diabetes. One sub-group (n = 23) had never experienced severe hypoglycaemia (Group A), whilst the other sub-group (n = 24) had suffered at least five episodes of severe hypoglycaemia (Group B). Group B had greater intellectual impairment than Group A, and Group B also had a significantly slower mean reaction time and higher reaction time variance when compared with Group A.

Adult↗
PubMed1992

Amitriptyline, clovoxamine and cognitive function: a placebo-controlled comparison in depressed outpatients.

No longer prescribed only for vegetative signs of depression, tricyclic antidepressants also lessen depressive cognitive distortions. Less clear is whether they ameliorate depressed patients' other cognitive deficits in memory, information processing speed, and psychomotor performance. We tested the alternative hypothesis that amitriptyline, because of its anticholinergic and sedative properties, would exacerbate depressed patients' cognitive disturbances. Depressed outpatients received double-blind placebo (n = 15), amitriptyline (n = 10), or clovoxamine fumarate (n = 10), a serotonin reuptake inhibitor relatively lacking in anticholinergic properties. Depression, memory, and psychomotor performance were assessed at baseline and after 7 and 28 days of drug treatment. Depression was alleviated after all treatments, including placebo. Only amitriptyline impaired performance on tests of memory, producing a significant decrement, relative to placebo, after 4 weeks of treatment. None of the treatments adversely affected performance on psychomotor tasks. These findings add to the evidence that antidepressant drugs with high anticholinergic activity can impair memory, despite alleviation of depression.

Acoustic Stimulation↗