Biomedical subjects

Wiebo H Brouwer

Publications and source records attributed to Wiebo H Brouwer.

13 recordsLinked to original sources

PubMed2006

Psychological and physical activity training for older persons: who does not attend?

BACKGROUND: Interventions to promote successful aging include psychological and physical activity programs. Identification of determinants of attendance of older persons may be useful to develop strategies to improve attendance. For physical activity programs determinants of attendance have been investigated extensively. For psychological programs hardly any knowledge is available. Determinants of attendance at psychological and physical activity programs have never been investigated simultaneously. OBJECTIVE: To identify demographic, physical and psychological determinants of attendance of older subjects following multifaceted psychological training - aimed at promoting active social participation - and physical activity training and to compare the variation of these determinants between the two training programs. METHOD: 118 subjects aged 65-92 years were randomized over psychological and physical activity training. Determinants of attendance were obtained at pretest with questionnaires and performance-based tests. RESULTS: Mean attendance was 62%. Attendance was not related to type of program. Having chronic diseases facilitated attendance in the psychological training group and limited attendance in the physical activity training group. Low and high levels of Activities of Daily Living performance (ADLs) and walking endurance were related to a high attendance in the psychological training group. A low level of activities of daily living (ADL) and a low walking endurance were related to a low attendance in the physical activity training group. For both training groups, persons living with a partner had higher attendance rates than persons living alone, and persons with a low level of anxiety had higher attendance rates than persons with a moderate or a high level of anxiety. CONCLUSION: Psychological training may be more suitable for frail older persons with chronic diseases, low ADL levels and low walking endurance than physical activity training, and may help to prepare such persons for physical activity.

Activities of Daily Living↗

PubMed2006

Walking trajectory in neglect patients.

A lateral deviation of the walking trajectory is often observed in stroke patients with unilateral spatial neglect. However, existing research appears to be contradictory regarding the direction of this deviation. The aim of the present study was to gain more insight into the walking trajectory of neglect patients. Twelve right hemisphere stroke patients (six neglect, six no neglect), eight left hemisphere stroke patients (none neglect) and 10 healthy control subjects were instructed to walk towards a target while a two-dimensional ultrasonic positioning system recorded their walking trajectory. Patients' recovery of walking ability was assessed and they were tested for the presence of neglect. Neglect patients showed a larger lateral deviation in their walking trajectory compared to stroke patients without neglect or controls. Neglect patients with good walking ability showed a deviation to the contralesional side. Neglect patients with limited walking ability showed a deviation to the ipsilesional side. Within the neglect group we found no relation between the severity of neglect and lateral deviation. Differences in walking ability may account for the contradictory results between studies regarding the lateral deviation in neglect patients' walking trajectory. We suggest that when a neglect patient's walking ability is limited, walking towards a target becomes a dual task: heading control and walking. A limited walking ability will cause a higher task priority of walking compared to heading control. This shift in task priority may be causing the change in walking trajectory deviation.

Adult↗

PubMed2005

Differences between participants and non-participants in an RCT on physical activity and psychological interventions for older persons.

BACKGROUND AND AIMS: Volunteer bias in intervention studies on successful aging has been poorly explored. This paper investigated differences between participants and non-participants of the Groningen Intervention Study on Successful Aging (GISSA) over a wide range of demographic, physical, psychological and social subject characteristics. METHODS: Subjects were recruited among a longitudinal cohort study (Groningen Longitudinal Aging Study) and included 558 men and 711 women, aged 65-96 years, who were invited to participate in the GISSA. Measures were obtained by questionnaires at the moment of invitation and eight years before invitation. Participants were compared with three groups of non-participants: persons who refused to participate, those who did not respond after a reminder, and those who intended to participate but withdrew before pre-test. RESULTS: At the moment of invitation, participants were younger, better educated, and functionally and physically more active than the three groups of non-participants. They also had better scores on the physical functioning subscale of the medical outcome scale, better ADL, iADL and vigorous ADL functions and fewer depressive symptoms, and perceived less social support in everyday and problem situations. Participants reported a less strong rate of decline in physical and psychological functioning in the eight years prior to the invitation than did the other groups. CONCLUSION: Due to volunteer bias, results of intervention studies on successful aging may have limited generalizability.

Activities of Daily Living↗

PubMed2005

Effect of ageing on the ability to adapt to a visual distortion during walking.

Degradation of major sensory systems such as proprioception, the vestibular system and vision may be a factor that contributes to the decline in walking stability in older people. In the present study this was examined by introducing a visual distortion by means of prism glasses shifting subject's view 10 degrees to the right while subjects walked towards a target (exposure condition). Shifting the view while walking towards a target will cause subjects to alter their heading in such a way that their walking trajectory describes a curvilinear path. It was expected that older people, when compared to young people, would have greater difficulty adjusting their heading and would show a greater decrease in heading stability, quantified by means of the standard deviation of the lateral position (SDLP). This was indeed the case. When performance in a pre- and post-exposure condition, in which subjects walked without prism glasses, were compared to each other, older people (O group) showed a greater decrease in heading stability than young people (Y group) and middle aged people (M group). Furthermore, it appeared that during the exposure condition adaptation effects were present in the Y and M group, which were absent in the O group. It is discussed that this adaptation is a form of realignment of the proprioceptive and visual system. The absence of realignment in the O group is argued to be caused by degradation of the proprioceptive system, which results in a lowering of the proprioceptive bias of vision.

Adaptation, Physiological↗

PubMed2005

Cognitive, physiological, and personality correlates of recurrence of depression.

BACKGROUND: The risk of recurrence in depressive disorder is high and increases with the number of episodes. We investigated whether individuals with a history of recurrent depression deviate from individuals with a single episode, as regards risk-related variables in 3 different domains of depression research. METHODS: Participants were 102 outpatients with major depressive disorder remitted from an episode (60 recurrent, 42 nonrecurrent). We assessed the perception of emotions from vocal stimuli, 24-h urinary free cortisol, and neuroticism. RESULTS: The recurrent group had higher cortisol levels than the nonrecurrent group, and recurrent women also had a more negative perception than nonrecurrent women. These results were independent of each other, and could also not be accounted for by neuroticism or residual symptoms. Gender differences were found in all 3 domains. LIMITATIONS: The cross-sectional design limits the possibility to draw conclusions on the causality of the observed effects. CONCLUSIONS: Remitted outpatients with recurrent depression deviate from remitted outpatients with single episode depression as regards physiology and social cognition, in a way that may increase their risk of the development of subsequent episodes. The results may have implications for prophylactic treatment strategies.

Adult↗

PubMed2005

P300 component identification in auditory oddball and novel paradigms using source analysis techniques: reduced latency variability in the elderly.

P300 latency variability in normal subjects limits its diagnostic applicability as a test for cognitive function. One of the causes of variation is the overlap in P300 (P3A and P3B) components resulting in inaccurate latency determination. Recently, we have shown that identification of P3A and P3B components using source analysis techniques significantly reduces P300 latency variability in healthy younger subjects. Here, we included a novel paradigm to enhance sensitivity and investigated the efficiency of the source analysis technique in reducing the P300 latency variability in healthy older subjects. Data were recorded with a 128-channel EEG system in 28 healthy subjects (aged 53-82 years, 12 males). We used a standard two-tone and a novel three-tone auditory oddball paradigm and an established source analysis technique, and compared the latencies to those obtained with conventional P300 analysis. The source analysis method identified both P3A and P3B components in a substantially larger percentage of subjects (93% versus 32%) than the conventional method. Both for the standard and novel paradigm, the source analysis method yielded a later mean P3B latency (361.4 versus 344.2 milliseconds, P = 0.017, and 374.4 milliseconds versus 354.3 milliseconds, P = 0.014, respectively) with a smaller standard deviation (15.8 versus 26.2 milliseconds, P = 0.013, and 18.9 versus 30.0 milliseconds, P = 0.052, borderline significant, respectively) than the conventional P300 method, for subjects aged 50 to 70 years. When applying the source analysis technique, as in young healthy subjects, a considerable reduction of P300 latency variability was thus found in healthy older subjects aged 50 to 70 years for both paradigms. This may have important consequences for applications of clinical event-related potential research in the early diagnosis of dementia, because the first signs of this disease are mostly observed in this age category.

Acoustic Stimulation↗

PubMed2004

Functional recovery of gait and joint kinematics after right hemispheric stroke.

OBJECTIVE: To gain insight into the relation between changes in gait patterns over time and functional recovery of walking ability in stroke patients. DESIGN: Cohort study. SETTING: Inpatient rehabilitation center of a university hospital in the Netherlands. PARTICIPANTS: Thirteen stroke patients admitted, or awaiting admission, for inpatient rehabilitation 3 weeks poststroke, and 16 healthy control subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: At 3, 6, 12, 24, and 48 weeks poststroke, functional recovery of walking ability was assessed with the Rivermead Mobility Index (RMI) and the Functional Ambulation Categories (FAC). When possible, kinematics of the knee, hip, and pelvis were assessed through gait analysis in an 8 x 4 m gait laboratory. Minimal scores of 8 on the RMI and 4 on the FAC were necessary before patients were classified as functionally recovered. RESULTS: Patients whose joint kinematics during ambulation had recovered to within the range of the control group showed functional recovery of walking ability. However, some patients whose kinematics had developed toward an abnormal pattern also showed functional recovery. CONCLUSIONS: Recovery of joint kinematics toward a normal pattern is not required for functional recovery of walking ability. Early recognition of compensatory walking patterns that facilitate functional recovery may have implications for rehabilitation programs.

Adult↗

PubMed2004

Age-related changes in the functional visual field: further evidence for an inverse Age x Eccentricity effect.

We assessed the performance of younger and older individuals by using the Attended Field of View test, a visual search task in which eye movements were allowed. When adjusting for slower processing in the older age group by log transformation, we observed significant effects of age, eccentricity, and Age x Eccentricity. Contrary to most previous findings, the Age x Eccentricity effect was "inverted" in that the difference between the age groups decreased as a function of eccentricity. The finding that the eccentricity effect of younger individuals was larger than that of older individuals was caused by large age-related differences in sensitivity for centrally located targets, even though differences with regard to foveal resolution were controlled. The results further indicated that, given a brief amount of time, older persons could process a smaller field of view than younger persons. Consequently, older persons were forced to resort to serial scanning for a larger part of the display, whereas younger persons could process a larger area in parallel.

Adult↗

PubMed2004

Predicting practical fitness to drive in drivers with visual field defects caused by ocular pathology.

Vision, viewing efficiency, visual attention, and on-road driving performance were assessed in 100 participants with central and/or peripheral visual field defects caused by ocular pathology. Driving was evaluated by the Dutch driving license authority making use of the protocol for investigating practical fitness to drive. A smaller percentage of participants with central visual field defects passed the on-road driving test, in comparison with participants with peripheral or mild field defects. The predictive power of a model based on the current vision requirements for driving significantly increased when taking compensatory viewing efficiency into account. The results of the latter model were comparable to those of a model based on tests of visual attention and contrast sensitivity. Despite the increased explained variance of practical fitness to drive when taking higher-order visual functions into account, sensitivity and specificity remained quite low, limiting the use of these tests in identifying unfit drivers. Actual or potential applications of this research include the development of training programs to improve practical fitness to drive in drivers with visual field defects.

Accidents, Traffic↗

PubMed2002

The effect of visual field defects on driving performance: a driving simulator study.

OBJECTIVES: To investigate the effect of visual field defects on driving performance, and to predict practical fitness to drive. METHODS: The driving performance of 87 subjects with visual field defects due to ocular abnormalities was assessed on a driving simulator and during an on-road driving test. OUTCOME MEASURES: The final score on the on-road driving test and simulator indexes, such as driving speed, viewing behavior, lateral position, time-headway, and time to collision. RESULTS: Subjects with visual field defects showed differential performance on measures of driving speed, steering stability, lateral position, time to collision, and time-headway. Effective compensation consisted of reduced driving speed in cases of central visual field defects and increased scanning in cases of peripheral visual field defects. The sensitivity and specificity of models based on vision, visual attention, and compensatory viewing efficiency were increased when the distance at which the subject started to scan was taken into account. CONCLUSIONS: Subjects with visual field defects demonstrated differential performance on several driving simulator indexes. Driving examiners considered reduced speed and increased scanning to be valid compensation for central and peripheral visual field defects, respectively. Predicting practical fitness to drive was improved by taking driving simulator indexes into account.

Adult↗

PubMed2002

Age-related changes in event-related prospective memory performance: a comparison of four prospective memory tasks.

The primary purpose of the study was to identify event-based prospective-memory tasks that provide sensitive and reliable tools for assessing effects of normal aging in prospective-memory performance. Four prospective-memory tasks were selected from the literature or were newly developed, with the tasks differing on various dimensions that, for theoretical reasons or based on previous evidence, might determine task sensitivity to age effects on prospective-memory performance: perceptual saliency of prospective target events, frequency of occurrence of prospective target events, complexity of prospective-memory instructions, and provision of feedback after prospective-memory errors. Two of the four tasks yielded large and robust age effects on prospective-memory performance. Correlational analyses suggested that these age effects on prospective-memory performance were mediated, at least in part, by a reduced ability of older adults to maintain prospective intentions in a highly activated state and not by age effects on basic mental speed alone.

Adolescent↗

PubMed2002

The effect of visual field defects on eye movements and practical fitness to drive.

Eye movements of subjects with visual field defects due to ocular pathology were monitored while performing a dot counting task and a visual search task. Subjects with peripheral field defects required more fixations, longer search times, made more errors, and had shorter fixation durations than control subjects. Subjects with central field defects performed less well than control subjects although no specific impairment could be pinpointed. In both groups a monotonous relationship was observed between the visual field impairment and eye movement parameters. The use of eye movement parameters to predict viewing behavior in a complex task (e.g. driving) was limited.

Adult↗

PubMed2002

Attention and driving in traumatic brain injury: a question of coping with time-pressure.

BACKGROUND: Diffuse and focal traumatic brain injury (TBI) can result in perceptual, cognitive, and motor dysfunction possibly leading to activity limitations in driving. Characteristic dysfunctions for severe diffuse TBI are confronted with function requirements derived from the hierarchical task analysis of driving skill. OBJECTIVE: Specifically, we focus on slow information processing, divided attention, and the development of procedural knowledge. Also the effects of a combination of diffuse and focal dysfunctions, specifically homonymous hemianopia and the dysexecutive syndrome, are discussed. Finally, we turn to problems and challenges with regard to assessment and rehabilitation methods in the areas of driving and fitness to drive.

Adaptation, Psychological↗