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At least 163 records · Page 9Linked to original sources
PubMed1996

Cognition and white matter hyperintensities in older depressed patients.

OBJECTIVE: The authors compared amounts of white matter hyperintensity in late- and early-onset depressed patients and never-depressed older subjects, compared neuropsychological function in these groups, and investigated the association between white matter hyperintensities and cognitive function in depression. METHOD: Sixty currently depressed patients whose first depression occurred after age 50 years, 35 depressed patients over age 50 whose first depression occurred before age 35, and 165 nonpsychiatrically ill subjects over age 50 underwent magnetic resonance imaging (MRI) and neuropsychological evaluation. Areas of white matter hyperintensity were measured from MRI images. RESULTS: The late-onset patients had more white matter hyperintensity than either of the other groups. Compared to the nondepressed subjects, the patients had significantly lower scores in the cognitive domains of nonverbal intelligence, nonverbal memory, constructional ability, executive ability, and information processing speed. The cognitive abnormalities were mostly confined to the late-onset patients, and the presence of a large amount of white matter hyperintensity was associated with significantly poorer executive skills. However, most of the scores were not in the significantly impaired range. CONCLUSIONS: Large amounts of white matter hyperintensity are more frequent in patients with late-onsetdepression than in elderly subjects with early-onset or no depression. Both late- and early-onset elderly depressed patients show mild decrements in some "right hemisphere" cognitive skills; the late-onset subjects also show deterioration in information processing speed and executive functions. Patients with large amounts of white matter hyperintensity have significantly poorer executive function.

Age Factors↗
PubMed1998

Dissociation of affect recognition and mood state from blunting in patients with schizophrenia.

The present study was designed to investigate the relationships between expression, perception, and experience of emotion in schizophrenic patients with and without affective blunting. Cognitive processing speed, emotional perception, and emotional experience were assessed in 25 schizophrenic patients grouped according to scores on a measure of overt emotional expression (Rating Scale for Emotional Blunting). Results showed dissociation of emotional expression from emotional perception and emotional experience. Blunted schizophrenic patients were no more impaired in the perception of emotion (Profile of Nonverbal Sensitivity) than non-blunted schizophrenic patients. In addition, groups did not differ in intensity of emotional experience as quantified on the self-report of arousal state (Positive and Negative Affect Scales). Accuracy of perception and reported experience of emotion did not differ between groups as a function of emotional valence. Cognitive processing speed (Symbol Digit Modalities Test; SDMT) was related to blunting score and to perception accuracy, although the SDMT did not differ between groups. Results are discussed in terms of a neuropathological basis for impairment of emotional expression.

Adult↗
PubMed1998

Recovery in pediatric brain injury: is psychostimulant medication beneficial?

OBJECTIVE: To assess the effects of methylphenidate on attention, memory, behavior, processing speed, and psychomotor skills of children with closed head injuries. DESIGN: Double-blind, placebo-controlled, crossover design. SETTING: An outpatient facility of a children's hospital medical center. PATIENTS: Ten pediatric subjects identified through chart review. Subjects met baseline scores for hyperactivity (Conner's Hyperactivity Index greater than or equal to 60) and intellectual functioning (Verbal Intelligence Quotient greather than or equal to 70) and achieved minimal scores on two psychometric tests. All subjects evidenced head injury by focal lesions on computed tomography scan and/or sequelae reported at the time of injury. Severity of injury ranged from mild to severe. All subjects were medically stable at the time of testing. Mean time post injury was 2 years, 8 months. INTERVENTION: Administration of methylphenidate and placebo. MAIN OUTCOME MEASURES: Percentage change in scores was calculated to assess differences between baseline and end of methylphenidate/placebo trials. RESULTS: No significant differences between methylphenidate and placebo on measures assessing behavior, attention, memory, and processing speed. CONCLUSIONS: The results of the study call into question the effectiveness of methylphenidate in the pediatric head injury population.

Adolescent↗
PubMed1989

[Psychological aspects of sleep related disorders of respiratory control].

An impaired ability to concentrate, loss of intellectual performance, and changes in personality are frequently-mentioned psychological symptoms of sleep apnoea. Apnea-associated disturbances of sleep structure as well as nocturnal cerebral hypoxia are possible causes. Twenty men and two women with an average age of 51.5 years underwent psychological testing. The average apnea index was 36 (range 11 to 92). The following psychodiagnostic procedures were used for screening; attention-strain test (d2) to measure short term concentration ability, numbers-connecting test (ZVT) for the evaluation of cognitive processing speed as an indication of intellectual performance, the Freiburg Personality Inventory FPI-R for assessing personality traits. As compared with the standard random sample of the d2, our patients' ability to concentrate over a period of five minutes does not seem to be impaired. Deficits in patients with sleep apnea are more likely to be found in the care of long-term concentration, especially in monotonous situations. The mean IQ score of our sample (93) is rather low as compared with the mean value of the age-matched sample (100). Patients with an Apnea index greater than 30 tended to have lower IQ-values (87.4) than those with less severe sleep apnea (97). Older patients had significantly lower age-corrected figures (87.2) than younger patients (98). Younger patients with high apnea activity (greater than median) had significantly (ANOVA: interaction alpha = 0.01) lower IQ scores (84.8) than younger patients with less severe sleep apnea (107). Sleep apnea seems to impair cognitive processing speed. Our sample turned out to be normal with respect to the twelve personality traits measured by means of the FPI-R.(ABSTRACT TRUNCATED AT 250 WORDS)

Arousal↗
PubMed1997

Infant expectations and reaction time as predictors of childhood speed of processing and IQ.

A longitudinal study investigated the relation between infant expectations and reaction time (RT) and childhood IQ and RT. Measures of visual anticipation and visual RT were taken at 3.5 months and 4 years of age. In addition, manual RT and verbal and performance IQ were measured at 4 years of age. Infant visual RT correlated reliably with childhood visual RT, and infant performance correlated significantly with childhood IQ. Childhood performance also correlated with concurrent childhood IQ. Children were slower to initiate eye movements when a manual choice button press was required than when it was not required. This load effect decreased as IQ increased. Visual RT and manual RT in childhood correlated only marginally. These are the first data to suggest stability in RT between early infancy and childhood or predictability from infant RT and anticipation in the first half-year of life to childhood IQ.

Child, Preschool↗
PubMed1990

Mechanism of age-related differences in frequency discrimination with backward masking: speed of processing or stimulus persistence?

In Experiment 1, frequency-discrimination thresholds were estimated in a 2-interval, forced-choice, backward masking procedure with a masker acoustically dissimilar to the targets. Young subjects were more efficient in escaping the effects of masking than were their elderly counterparts. In Experiment 2, young and elderly subjects performed the same task, with a masker acoustically similar to the targets and with a target-dissimilar masker. Under target-similar masking and at short target-masker intervals, the elderly demonstrated significant improvement, reaching the level of performance of the young, whereas under the target-dissimilar masker, the age-related differences were restored. Both age-related slowing of information processing and increase in stimulus persistence can account for the results of Experiment 1, but only increased stimulus persistence explains the results of Experiment 2.

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↗
PubMed1996

Speed of processing in the human visual system.

How long does it take for the human visual system to process a complex natural image? Subjectively, recognition of familiar objects and scenes appears to be virtually instantaneous, but measuring this processing time experimentally has proved difficult. Behavioural measures such as reaction times can be used, but these include not only visual processing but also the time required for response execution. However, event-related potentials (ERPs) can sometimes reveal signs of neural processing well before the motor output. Here we use a go/no-go categorization task in which subjects have to decide whether a previously unseen photograph, flashed on for just 20 ms, contains an animal. ERP analysis revealed a frontal negativity specific to no-go trials that develops roughly 150 ms after stimulus onset. We conclude that the visual processing needed to perform this highly demanding task can be achieved in under 150 ms.

Adult↗
PubMed1997

Speed of processing and stimulus complexity in low-frequency and high-frequency channels.

Studies of the microgenesis of perception led to the hypothesis that global aspects of objects are processed faster than their details. If one starts with the assumption that low-frequency information of objects corresponds to the global, and high-frequency information to the local aspects, recognising objects should rely at first on information from the low-frequency channels and afterwards from that of the high-frequency channels. The priming paradigm provides a mean of investigating experimentally the temporal availability of low-frequency and high-frequency information in object perception. In the experiments subjects had to respond to target objects preceded either by related or by unrelated priming stimuli, which consisted of low-pass-filtered and high-pass-filtered versions of the objects. With the influence of stimulus complexity controlled, pictures of objects were chosen that varied in the number of intensity changes in the high-frequency components, with those of the low-frequency components kept constant. The exposure duration of each prime was varied between 40 and 100 ms. The results indicated that target identification only profits more from low-frequency than from high-frequency primes if the high-frequency information has a high level of complexity. If the number of intensity changes in the high-frequency components of the prime is low, target identification is most strongly facilitated. The results are discussed in terms of models which focus on organising principles at different scales.

Humans↗
PubMedDate not supplied

An experimental and computational analysis of age differences in the recognition of fragmented pictures: inhibitory connections versus speed of processing.

Young and older adults were tested for the ability to identify degraded pictures presented either in a series of incremental steps with each step increasing the completeness of the visual information (ascending condition) or in one single exposure (fixed condition). Significant interference effects, indicated by a superiority of fixed over ascending presentations, appeared at a lower level of performance for the older adults than for the young adults. This finding was consistent with the notion of an inhibition deficit operating in normal aging. A computer simulation, based on simple connectionist architecture, demonstrated that an age-related inhibition deficit in the identification of fragmented pictures can be produced by slowed processing rates.

Adolescent↗
PubMed1998

Antisense drug discovery: can cell-free screens speed the process?

Many conditions must be satisfied for an antisense drug to function. It must colocalize with its target RNA at a sufficient concentration for a bimolecular reaction to occur, and it must have a structure that favors association with its target. In addition, if the antisense compound is to form Watson-Crick bonds with the target RNA, it must be complementary to sites that are amenable to binding. Unfortunately, the peculiarities that cause certain sites to be especially vulnerable to antisense compounds are undefined, as discussed previously (Branch, 1998). Because vulnerable target sites have no common properties allowing them to be identified by sequence analysis, most target sites and their antisense counterparts are found through a trial and error process in which oligomers--each complementary to a different site in the target RNA--are tested individually to find the one with the greatest specificity and lowest inhibitory concentration (IC50). However, testing antisense molecules one at a time can be a taxing process, and there is great interest in developing cell-free screening methods that can reduce the number of compounds that must be tested in cells and in whole animals. These cell-free screens are designed to generate short lists of target sites that include the ideal site--the site most vulnerable to antisense ablation in vivo. They are based on the unproven assumption that ideal sites have distinctive properties, such as susceptibility to RNase H-mediated cleavage, that allow them to be detected in cell-free assays. This is a review of data emerging from studies using RNase H-based screens and a summary of the challenges confronting these and any similar methods that use naked RNAs as surrogates for intracellular RNAs. It is not yet clear if cell-free screening methods will be effective.

Drug Evaluation, Preclinical↗