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PubMed2006

Diffusion tensor imaging in the corpus callosum in children after moderate to severe traumatic brain injury.

Diffusion tensor imaging (DTI) is a recent imaging technique that assesses the microstructure of the cerebral white matter (WM) based on anisotropic diffusion (i.e., water molecules move faster in parallel to nerve fibers than perpendicular to them). Fractional anisotropy (FA), which ranges from 0 to 1.0, increases with myelination of WM tracts and is sensitive to diffuse axonal injury (DAI) in adults with traumatic brain injury (TBI). However, previous DTI studies of pediatric TBI were case reports without detailed outcome measures. Using mean FA derived from DTI fiber tractography, we compared DTI findings of the corpus callosum for 16 children who were at least 1 year (mean 3.1 years) post-severe TBI and individually matched, uninjured children. Interexaminer and intraexaminer reliability in measuring FA was satisfactory. FA was significantly lower in the patients for the genu, body, and splenium of the corpus callosum. Higher FA was related to increased cognitive processing speed and faster interference resolution on an inhibition task. In the TBI patients, higher FA was related to better functional outcome as measured by the dichotomized Glasgow Outcome Scale (GOS). FA also increased as a function of the area of specific regions of the corpus callosum such as the genu and splenium, and FA in the splenium was reduced with greater volume of lesions in this region. DTI may be useful in identifying biomarkers related to DAI and outcome of TBI in children.

Adolescent↗

PubMed2005

Effect of regular Tai Chi and jogging exercise on neuromuscular reaction in older people.

OBJECTIVES: to investigate the effects of regular Tai Chi (TC) or jogging exercise on neuromuscular reaction in older people. DESIGN: cross-sectional study. SETTING: university biomechanics laboratory. SUBJECTS: 21 long-term elderly TC practitioners were compared with 18 regular elderly joggers and 22 sedentary counterparts. MEASUREMENTS: electromyography (EMG) was used to detect the neuromuscular reaction of the leg muscles to an unexpected ankle inversion perturbation. The latency of the muscles, which was defined as the time that the moment of perturbation began to the onset of the EMG response, was evaluated. RESULTS: a one-way ANOVA revealed that there were significant differences in the latency of the rectus femoris (R) and anterior tibialis (T) muscles between the three groups, but that there were no differences in the latency of the semitendinosus (S) and gastrocnemius (G) muscles. Further tests indicated that the R and T muscles in the TC and jogging groups were activated significantly faster than those in the control group. No significant difference was found for the muscle onset latencies between the TC and jogging groups. CONCLUSION: maintaining information processing speed during ageing is important, because of the role that it plays in many everyday events. The R and T muscles in the regular TC and jogging groups showed faster responses to unexpected ankle inversion perturbations, which is helpful for the timely correction of postural disturbances, than those in the sedentary control group.

Aged↗

PubMed2006

Homocysteine, folate, and vitamin B-12 and cognitive performance in older Chinese adults: findings from the Singapore Longitudinal Ageing Study.

BACKGROUND: The relations of elevated homocysteine, low folate, and vitamin B-12 with cognitive performance in nondemented elderly are not well established. Limited research data suggest differential effects of homocysteine and folate on specific cognitive domains. OBJECTIVE: The aim was to examine the independent associations of homocysteine, folate, and vitamin B-12 with cognitive performance in high-functioning elderly Chinese. DESIGN: Homocysteine, folate, and vitamin B-12 concentrations were measured in fasting blood samples of 451 Chinese aged >or=55 y with Mini-Mental State Examination scores >or=24 and who were considered fully independent based on Activities of Daily Living score. Cognitive functions were assessed by a neuropsychological test battery. Independent associations (standardized beta) were determined in multiple linear regression models that simultaneously controlled for potential confounders. RESULTS: Log-transformed homocysteine was inversely associated with performance on Block Design (beta = -0.319, P = 0.006) and the written Symbol Digit Modality Test (beta = -0.129, P = 0.031). Log-transformed folate was significantly associated with Rey Auditory Verbal Learning Test delayed recall (beta = 0.139, P = 0.010), verbal learning (beta = 0.112, P = 0.038), percentage of forgetting (beta = -0.139, P = 0.013), and the Categorical Verbal Fluency test (beta = 0.104, P = 0.042). Vitamin B-12 was not significantly associated with any cognitive test score. CONCLUSIONS: In this high-functioning elderly Chinese population, elevated homocysteine is associated with deficits in constructional ability and processing speed and folate is associated with measures of episodic memory and language. Our results provide support for differential effects of homocysteine and folate on specific cognitive functions.

Aged↗

PubMed2007

MinSet: a general approach to derive maximally representative database subsets by using fragment dictionaries and its application to the SCOP database.

MOTIVATION: The size of current protein databases is a challenge for many Bioinformatics applications, both in terms of processing speed and information redundancy. It may be therefore desirable to efficiently reduce the database of interest to a maximally representative subset. RESULTS: The MinSet method employs a combination of a Suffix Tree and a Genetic Algorithm for the generation, selection and assessment of database subsets. The approach is generally applicable to any type of string-encoded data, allowing for a drastic reduction of the database size whilst retaining most of the information contained in the original set. We demonstrate the performance of the method on a database of protein domain structures encoded as strings. We used the SCOP40 domain database by translating protein structures into character strings by means of a structural alphabet and by extracting optimized subsets according to an entropy score that is based on a constant-length fragment dictionary. Therefore, optimized subsets are maximally representative for the distribution and range of local structures. Subsets containing only 10% of the SCOP structure classes show a coverage of >90% for fragments of length 1-4. AVAILABILITY: http://mathbio.nimr.mrc.ac.uk/~jkleinj/MinSet. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Algorithms↗

PubMed1992

Acute optic neuritis. A cognitive and magnetic resonance imaging study.

Forty-two patients with acute optic neuritis (ON) (mean duration of symptoms 14.5 d) were compared with a matched, normal control group on a battery of tests of attention and information processing speed. Approximately half the sample (55%) had brain abnormalities shown by magnetic resonance imaging (MRI) and were more impaired across a variety of tests compared with those patients without brain lesions or normal controls. There was no difference in psychometric performance other than the pegboard task between the normal control group and those ON patients without brain involvement. Significant correlations were found between total lesion area in the brain and some tests of attention. Results from the Symbol Digit-Substitution Test were particularly sensitive in this regard and could correctly identify 70% of the sample with brain lesions.

Adult↗

PubMed1993

A serial study of psychometric and magnetic resonance imaging changes in multiple sclerosis.

Over a 6-month period, five patients with early relapsing--remitting multiple sclerosis and five with long-standing, benign multiple sclerosis underwent serial psychometric testing and contrast enhanced magnetic resonance imaging of the brain at 2-weekly or monthly intervals, respectively. All patients were individually matched with healthy controls who completed the same psychometric battery at the same time intervals. As a group, multiple sclerosis patients either made more errors or performed slower on all psychometric tasks than controls. In the control subjects and those patients with a stable brain lesion score, no consistent deterioration occurred in any test and the overall pattern was one of improvement over time commensurate with practice effects. However, patients with a deteriorating lesion score either showed a fall-off in performance on some psychometric tasks (patients 2, 3) or else an impaired ability to improve with practice on certain tests of attention and information-processing speed (patient 10).

Adult↗

PubMed2003

Neuropsychological long-term sequelae after posterior fossa tumour resection during childhood.

The importance of the cerebellum for non-motor functions is becoming more and more evident. The influence on cognitive functions from acquired cerebellar lesions during childhood, however, is not well known. We present follow-up data from 24 patients, who were operated upon during childhood for benign cerebellar tumours. The benign histology of these tumours required neither radiotherapy nor chemotherapy. Post-operatively, these children were of normal intelligence with a mean IQ of 99.1, performance intelligence quotient (PIQ) of 101.3 and verbal intelligence quotient (VIQ) of 96.8. However, 57% of patients showed abnormalities in subtesting. In addition, more extensive neuropsychological testing revealed significant problems for attention, memory, processing speed and interference. Visuo-constructive problems were marked for copying the Rey figure, but less pronounced for recall of the figure. Verbal fluency was more affected than design fluency. Behavioural deficits could be detected in 33% of patients. Attention deficit problems were marked in 12.5%, whereas others demonstrated psychiatric symptoms such as mutism, addiction problems, anorexia, uncontrolled temper tantrums and phobia. Age at tumour operation and size of tumour had no influence on outcome. Vermis involvement was related to an increase in neuropsychological and psychiatric problems. The observation that patients with left-sided cerebellar tumours were more affected than patients with right-sided tumours is probably also influenced by a more pronounced vermian involvement in the former group. In summary, this study confirms the importance of the cerebellum for cognitive development and points to the necessity of careful follow-up for these children to provide them with the necessary help to achieve full integration into professional life.

Adolescent↗

PubMed2002

Differential rates of regional brain change in callosal and ventricular size: a 4-year longitudinal MRI study of elderly men.

Brain structure changes in size with normal aging, but the rate at which different structures change is controversial. We used magnetic resonance imaging (MRI) performed twice, 4 years apart, to compare rates of age-related size change of the corpus callosum, which has been inconsistently observed to thin with age, with change in the lateral ventricles, which are well established to enlarge. Subjects were 215 community dwelling, elderly men (70-82 years old at initial MRI), who were participants in a longitudinal study of cardiovascular risk factors. Percent change in size was significant for both the callosal and ventricular measures, but annual rate of ventricular expansion (2.9%) was significantly greater than annual rate of callosal thinning (-0.9%). Callosal regions showed statistically equivalent rates of shrinkage; ventricular dilatation was symmetrical. Neither callosal and ventricular rates of change correlated with each other (r = 0.01), nor did genu and splenium rates of change correlate with each other (r = 0.05). Tests of speeded processing were administered contemporaneously with both MRIs to examine functional ramifications of observed brain changes. Decline in the Mini-Mental State Examination was related to thinning of the splenium, and decline in Stroop test word reading was selectively related to thinning of the callosal body. These longitudinal data support the contentions that differential rates of change occur in different brain regions in normal aging, age-related callosal thinning contributes to functional declines, and rate of change in one region can be independent of rate of change in another region, even within a brain structure.

Aged↗

PubMed1999

A 3D computer-aided design system applied to diagnosis and treatment planning in orthodontics and orthognathic surgery.

The purpose of this article is to describe a newly developed 3D computer-aided design (CAD) system for the diagnostic set-up of casts in orthodontic diagnosis and treatment planning, and its preliminary clinical applications. The system comprises a measuring unit which obtains 3D information from the dental model using laser scanning, and a personal computer to generate the 3D graphics. When measuring the 3D shape of the model, to minimize blind sectors, the model is scanned from two different directions with the slit-ray laser beam by rotating the mounting angle of the model on the measuring device. For computed simulation of tooth movement, the representative planes, defined by the anatomical reference points, are formed for each individual tooth and are arranged along a guideline descriptive of the individual arch form. Subsequently, the 3D shape is imparted to each of the teeth arranged on the representative plane to form an arrangement of the 3D profile. When necessary, orthognathic surgery can be simulated by moving the mandibular dental arch three-dimensionally to establish the optimum occlusal relationship. Compared with hand-made set-up models, the computed diagnostic cast has advantages such as high-speed processing and quantitative evaluation on the amount of 3D movement of the individual tooth relative to the craniofacial plane. Trial clinical applications demonstrated that the use of this system facilitated the otherwise complicated and time-consuming mock surgery for treatment planning in orthognathic surgery.

Algorithms↗

PubMed1995

Genetic and environmental influences on functional age: a twin study.

Twin analyses were conducted to determine the relative influence of genetic and environmental factors on functional aging. As part of the ongoing Minnesota Twin Study of Adult Development and Aging (MTSADA), measures of 30 demographic, cognitive, physiological, personality, and behavioral variables were available from 140 monozygotic twin pairs and 97 dizygotic twin pairs ranging in age from 27 to 88 years. Functional age was based on a general linear regression model with chronological age as the dependent variable. Stepwise regression determined the subset of variables by MTSADA providing the best prediction of chronological age. Factor analysis of these 12 variables resulted in three factors: physiological measures, cognitive abilities, and processing speed. When entered into, a regression equation, the three factors accounted for 66% of the variance in chronological age. Analysis of twin similarity for components of functional age suggested the relative influence of genetic and environmental factors varies greatly for different components of functional aging. In addition, the genetic and shared environmental influences on the three components were common to all three, while the nonshared environmental influences were specific to each component.

Adult↗

PubMed1996

Interrelations of age, visual acuity, and cognitive functioning.

It has recently been suggested that a large proportion of the age-related influences on many measures of cognitive functioning is mediated through a single common factor. This hypothesis has been supported by the discovery that much of the age-related variance in different cognitive measures is shared, and is not distinct or independent. These earlier results were replicated in this project, and it was also discovered that measures of corrected visual acuity and processing speed share a very large proportion of the age-related variance in measures of working memory, associative learning, and concept identification. The apparent implication is that the common factor that appears to contribute to age-related differences in many cognitive measures is quite broad and may reflect a relatively general reduction in central nervous system functioning.

Adult↗

PubMed2004

Age-related differences in arithmetic problem-verification strategies.

To test age-related differences in split and problem-difficulty effects, adults between the ages of 20 and 80 years (N = 138) performed a simple and a complex inequality verification task (e.g., 6 + 3 < 11, 271 + 182 < 458; true or false?). Split effects in verification tasks (i.e., better performance for large-split than for small-split problems) reflect strategy selection between nonexhaustive verification (e.g., evaluation of plausibility; estimation) and exhaustive verification (e.g., retrieval; calculation). Problem-difficulty effects (i.e., better performance for easy than hard problems) reflect calculation processing. Results showed decreased split effects across age groups, particularly in the complex task. Moreover, problem-difficulty effects did not vary across age groups. Age-related changes were mostly mediated by age-related declines in processing speed.

Adult↗

PubMed1988

Visual changes in daily life throughout adulthood.

A pair of surveys asked healthy adults about their everyday visual problems. Participants ranged in age from 18 to 100 and were screened for major visual impairment. Respondents rated the frequency of difficulty they had performing visual tasks such as reading, recognizing objects, picking out a face in a crowd, seeing in dimly lit environments, seeing moving objects, and so on. The surveys revealed five dimensions that declined with increasing age: visual processing speed, light sensitivity, dynamic vision, near vision, and visual search. The percentage of respondents reporting a decline in these visual dimensions increased two- to sixfold across the adult life span. Varying rates of visual decline for different tasks suggest that various aspects of vision age at different rates.

Activities of Daily Living↗

PubMed1992

Four to ten milliseconds per year: age-related slowing of visual word identification.

This experiment examined the age-related slowing of visual word identification. Each of 108 subjects between 20 and 78 years of age performed a word/nonword discrimination (lexical decision) task in which the target was preceded by a single-word prime. Several aspects of the data were consistent with a generalized slowing model: There was a positive correlation between age and mean reaction time, the absolute magnitude of age differences increased as a function of task complexity, and the statistical control of a relatively task-independent index of processing speed attenuated the age-related variance in mean reaction time. The degree of age-related slowing was more pronounced for visually degraded targets (10 msec per year) than for intact targets (4 msec per year). Other aspects of lexical decision performance, however, suggested that some components of word identification, especially those involved in semantic activation, are relatively exempt from age-related slowing.

Adult↗

PubMed2006

Correlates of health literacy in patients with chronic heart failure.

PURPOSE: Many older adults have inadequate health-related literacy, which is associated with poor health outcomes. Thus, it is important to identify determinants of health literacy. We investigated relationships between health literacy and general cognitive and sensory abilities, as well as education, health, and demographic variables, in a community sample of middle-aged and older adults. DESIGN AND METHODS: Participants were 314 community-dwelling adults (67% female, 48% African American) diagnosed with chronic heart failure recruited for a pharmacist-based intervention study to improve adherence to chronic heart failure medications. We adminstered demographic, health, education, cognitive (e.g., processing speed, working memory), and sensory measures, and the Short Test of Functional Health Literacy in Adults (STOFHLA), as part of the baseline condition of this study. RESULTS: STOFHLA scores were lower for participants who were older, less educated, male, African American, had more comorbidities, or scored lower on all cognitive ability measures. Hierarchical linear regression analyses showed that education and cognitive ability were independently associated with the STOFHLA measure and explained age differences in health literacy. IMPLICATIONS: The association of cognitive abilities and literacy has important implications for health literacy models and for interventions to reduce the impact of low health literacy on health outcomes. For example, medication instructions should be designed to reduce comprehension demands on general cognitive abilities as well as literacy skills.

Aged↗

PubMed2006

Children's attentional skills 5 years post-TBI.

OBJECTIVE: While a small number of research papers have reported findings on attentional deficits following pediatric traumatic brain injury (TBI), no study to date has reported findings in this area at 5 years post-TBI in very young children. This study examined attentional skills in a group of children who had sustained a mild, moderate, or severe TBI between the ages of 2 and 7 years. METHODS: The sample comprised 70 children, 54 of these had sustained a TBI and 16 the non-injured control group. Children were assessed 5 years post-TBI, with focus on tests of attentional ability. RESULTS: Attentional and processing speed (PS) deficits do occur and persist up to 5 years post-TBI, particularly following severe TBI in early childhood. Predictors of attentional outcomes varied depending on the component of attention investigated. CONCLUSIONS: Those skills developing or emerging at time of injury (e.g., sustained attention, shifting attention, divided attention, PS) are more compromised and may not develop at a normal rate of post-injury.

Adolescent↗

PubMed2001

Verb comprehension in frontotemporal degeneration: the role of grammatical, semantic and executive components.

Verb comprehension has been associated with the left frontal cortex, but assessments of verb comprehension in frontotemporal degeneration (FTD) have been rare. This study assessed word-picture matching for verbs and nouns under two conditions: alone (baseline) and during concurrent performance of a secondary task. In addition, we correlated FTD patients' verb comprehension with their performance on measures of executive resources and language. We found that FTD patients were significantly less accurate and required significantly longer to make word-picture matching decisions about verbs compared with nouns at baseline. During concurrent performance of a secondary task, accuracy decreased and response latencies became prolonged for nouns to the point that these measures equaled the performance with verbs at baseline. Verb comprehension accuracy was significantly correlated with the performance on executive measures such as category naming fluency, the Stroop test, and the Trail Making Test Part B (Trails B test). Assessment of FTD patient subgroups revealed distinct profiles of performance, suggesting that several factors contribute to verb comprehension in FTD. Verb comprehension in FTD patients with a dysexecutive syndrome (EXEC, n = 10) was sensitive to concurrent performance of a secondary task, and their verb comprehension accuracy correlated with the time required to complete executive measures such as the Stroop test and the Trails B test. This suggested a relationship between impaired verb comprehension and limited information-processing speed in EXEC patients. Verb comprehension in patients with a progressive non-fluent aphasia (PNFA, n = 7) was not selectively influenced by executive resources. Instead, verb comprehension accuracy in PNFA was significantly correlated with sentence comprehension accuracy, suggesting that grammatical aspects of verbs play a crucial role in their verb comprehension difficulty. Although we studied only a small number of patients with semantic dementia (SD, n = 4), we observed significant verb comprehension difficulty that was minimally influenced by executive resources and was unrelated to sentence comprehension. It is possible that impaired verb comprehension in SD is related in part to the degradation of semantic feature knowledge.

Adult↗

PubMed2006

Psychomotor slowing in schizophrenia.

Psychomotor slowing (PS) is a cluster of symptoms that was already recognized in schizophrenia by its earliest investigators. Nevertheless, few studies have been dedicated to the clarification of the nature and the role of the phenomenon in this illness. Moreover, slowed psychomotor functioning is often not clearly delineated from reduced processing speed. The current, first review of all existing literature on the subject discusses the key findings. Firstly, PS is a clinically observable feature that is most frequently established by neuropsychological measures assessing speed of fine movements such as writing or tasks that require rapid fingertip manipulations or the maintenance of maximal speed over brief periods of time in manual activities. Moreover, the slowed performance on the various psychomotor measures has been demonstrated independent of medication and has also been found to be associated with negative symptoms and, to a lesser extent, with positive and depressive symptoms. Importantly, performance on the psychomotor tasks proved related to the patients' social, clinical, and functional outcomes. Several imaging studies showed slowed performance to coincide with dopaminergic striatal activity. Finally, conventional neuroleptics do not improve the patients' PS symptoms, in contrast to the atypical agents that do seem to produce modestly improving effects.

Antipsychotic Agents↗