Biomedical subjects

M P van Boxtel

Publications and source records attributed to M P van Boxtel.

15 recordsLinked to original sources

PubMed2001

Visual determinants of reduced performance on the Stroop color-word test in normal aging individuals.

It is unknown to what extent the performance on the Stroop color-word test is affected by reduced visual function in older individuals. We tested the impact of common deficiencies in visual function (reduced distant and close acuity, reduced contrast sensitivity, and color weakness) on Stroop performance among 821 normal individuals aged 53 and older. After adjustment for age, sex, and educational level, low contrast sensitivity was associated with more time needed on card I (word naming), red/green color weakness with slower card 2 performance (color naming), and reduced distant acuity with slower performance on card 3 (interference). Half of the age-related variance in speed performance was shared with visual function. The actual impact of reduced visual function may be underestimated in this study when some of this age-related variance in Stroop performance is mediated by visual function decrements. It is suggested that reduced visual function has differential effects on Stroop performance which need to be accounted for when the Stroop test is used both in research and in clinical settings. Stroop performance measured from older individuals with unknown visual status should be interpreted with caution.

Aged↗

PubMed2000

Pesticide exposure and risk of mild cognitive dysfunction.

Little is known about the adverse effects of substances, such as pesticides and metals, on the development of mild cognitive dysfunction (MCD). Cross-sectional and prospective data from the Maastricht Aging Study were used to find out the potential neurotoxicity of particular substances. Exposure to pesticides, for example by arable farmers and gardeners, was associated with increased risks of MCD. Exposure to metals and organic solvents was not associated with MCD. Our findings might reflect subtle changes in brain function among people exposed to pesticides.

Aged↗

PubMed2000

Does migraine headache affect cognitive function in the elderly? Report from the Maastricht Aging Study (MAAS).

The aim of this study was to examine two aspects of cognitive functioning-information processing speed and memory-in both young/middle-aged and older subjects with and without migraine, using data from a large population-based sample. We found that, although age had a large effect on processing speed and memory, migraine did not influence cognitive performance. In addition, there was no significant interaction between age and migraine on processing speed and memory. Our results suggest that, in the general population, migraine does not seriously affect cognitive functioning in young/middle-aged or older adults.

Adult↗

PubMed2000

Mild hearing impairment can reduce verbal memory performance in a healthy adult population.

We studied to what extent immediate and delayed recall in an auditory verbal learning paradigm was affected by basic information processing speed (digit copying) and hearing acuity (average hearing acuity at 1, 2 and 4 KHz at the better ear). A group of 453 individuals in the age between 23 and 82 years with no overt hearing pathology was recruited from a larger study of cognitive aging (Maastricht Aging Study, MAAS). After controlling for age, sex, educational level, and processing speed it was found that a mild to moderate hearing loss predicted lower verbal memory performance. Auditory administered verbal memory tests can underestimate true memory performance, particularly in older individuals with unknown hearing status.

Adult↗

PubMed2000

Tryptophan depletion impairs memory consolidation but improves focussed attention in healthy young volunteers.

Animal and human studies have provided evidence for serotonergic modulation of cognitive processes. However, the exact nature of this relationship is not clear. We used the acute tryptophan depletion (ATD) method to investigate the effects of lowered serotonin synthesis on cognitive functions in 17 healthy young volunteers. The study was conducted according to a placebo-controlled, double-blind, crossover design. Cognitive performance and mood were assessed at baseline and 5 and 9 h after administration of ATD. A specific impairment of word recognition, without effects on short-term memory, occurred during ATD. No memory deficits were seen if ATD was induced after acquisition of new words. The Stroop Test and dichotic listening task demonstrated a modality independent improvement of focussed attention after ATD. Fluency was also improved after ATD. ATD did not alter speed of information processing, divided attention or planning functions. These results indicate that serotonin is essential in the process of long-term memory consolidation, primarily in the first 30 min after acquisition. Improvement of specific cognitive processes by lowered 5-HT function may be linked to the removal of inhibitory actions of 5-HT in the cortex.

Adult↗

PubMed1998

Effects of age on performance in a finger-precuing task.

This study investigated age-related precuing effects in the finger-precuing task (J. Miller, 1982). In this task, a spatial precue provides partial advance information about which fingers to use for responding. Results indicated a substantial age-related deficit in preparing 2 fingers on 2 hands, but not on 1 hand. This disparate set of findings does not provide strong support for A. A. Hartley's (1993) hypothesis that anterior brain attention systems responsible for selection-for-action are compromised with advancing age. Finally, the authors report that advancing age increasingly slows reaction time more to the inner than to the outer stimulus-response positions. A possible mechanism of this age-related bowed stimulus-response position effect is discussed.

Adult↗

PubMed1998

The relation between morbidity and cognitive performance in a normal aging population.

BACKGROUND: Factors related to physical health have been implicated in both normal and pathological aging of cognitive abilities. To substantiate this notion, we studied existing morbidity, as diagnosed by the general practitioner according to well-defined criteria, as a potential predictor of cognitive test performance. METHODS: A sample of 1360 individuals, aged 24-81 years and living in the community, was stratified for age, sex, and general ability. Active and total morbidity in this group were classified according to the International Classification of Primary Care. Neurocognitive tests were used to assess the domains of verbal memory, sensorimotor speed, and cognitive flexibility. RESULTS: Multiple regression analyses with adjustment for age, sex, and educational level showed both insulin-dependent and noninsulin-dependent diabetes to be negatively associated with all cognitive measures. More specific negative associations were found for chronic bronchitis (performance speed) and presbyacusia (memory). Single or aggregated cardiovascular morbidity (including hypertension) was unrelated to test performance. CONCLUSIONS: Existing morbidity as a whole contributes only modestly (up to 3.5%) to total variance in cognitive function. However, some specific, relatively common diseases of the elderly, such as diabetes and chronic bronchitis, may aggravate the age-related decline in cognitive ability.

Adult↗

PubMed1998

Is nondipping in 24 h ambulatory blood pressure related to cognitive dysfunction?

OBJECTIVE: Associations between the outcome of 24 h ambulatory monitoring and cognitive performance were studied in order to evaluate the potential relevance of ambulant blood pressure status to brain function. It was hypothesized that a small daytime-night-time difference in mean blood pressure (nondipping) is associated with reduced cognitive performance, in line with studies in hypertensive subjects that have reported associations between nondipping and target-organ damage. METHODS: The study followed a cross-sectional design and was part of a larger research programme on determinants of cognitive aging (Maastricht Aging Study, MAAS). A group of 115 community residents aged 28-82 years was recruited from a general practice population and screened for cardiovascular events and medication use. All underwent 24 h blood pressure monitoring. Cognitive performance was measured with tests of verbal memory, attention, simple speed and information processing speed. RESULTS: Mean daytime or night-time levels of both systolic and diastolic blood pressure were unrelated to cognitive outcome, when age, sex and educational level were controlled for. Differences between mean daytime and night-time blood pressure (based on both narrow and wide measurement intervals for day and night-time periods) were positively associated with memory function (5-9% of additional variance explained) and one sporadic positive association was found on the sensorimotor speed score (4%). Nondippers (n=15) showed lower levels of both memory and sensorimotor speed scores. CONCLUSIONS: Ambulatory blood pressure status was not associated with cognitive performance. A reduced nocturnal blood pressure drop was associated with quite specific cognitive deficits, but the underlying mechanism remains to be determined.

Adult↗

PubMed1998

[The Maastricht aging study (MAAS). The longitudinal perspective of cognitive aging].

The Maastricht Aging Study (MAAS) was designed to specify the usual and pathological aging of cognitive function. In short, the main questions of MAAS are: who deteriorates when in which aspects of cognitive function, and what biomedical or psychosocial factors can be identified that may act as mediators in this process? The study comprises four independent panel studies in which a group of 1,900 initially healthy individuals are followed for a period of 12 years with respect to health characteristics and neurocognitive status. For this purpose a sample was drawn from a patient register of collaborating general practitioners, stratified by age (range 24 to 81 years), sex and general ability level. Rationale and design of MAAS are discussed and some findings from the cross-sectional baseline measurement are summarized: general aspects of memory and attention in aging, cognitive functioning after brain trauma and general anesthesia, physical condition (fitness, morbidity and vascular risk factors, such as blood pressure) as predictors of cognitive function, and finally cognitive complaints and metamemory.

Adult↗

PubMed1997

Can the blood pressure predict cognitive task performance in a healthy population sample?

OBJECTIVES: To study the relation between the blood pressure and the neurocognitive function within the full adult age range in a large population sample. DESIGN: A cross-sectional study of 936 healthy adults who were recruited from a register of family practices, stratified for age (24-81 years), sex, and occupational level, who took part in a medical and neurocognitive test program. METHODS: The blood pressure status was studied in relation to five measures of cognitive ability, including verbal memory and speed of information processing. Other vascular risk factors were treated as control variables and included smoking, alcohol intake, body mass index, and body fat distribution. The blood pressure was measured five times using an automatic recording technique (with a Dinamap 8100 device). RESULTS: After adjustment for age, sex, and educational level in a hierarchical regression analysis, we found no unequivocal association between the mean systolic and diastolic blood pressures (or any other studied vascular risk factor) and cognitive test performance both for the whole group and for the subgroup of subjects who were not being administered antihypertensive medication and whose medical history did not include cardiovascular events. Stratified analysis within four age levels revealed no age-specific associations between the blood pressure and the cognitive function. Subjects whose blood pressure was within the hypertensive range performed worse than did matched controls at letter digit copying, but not according to other cognitive measures. CONCLUSIONS: With a population-based sample unselected for blood pressure status we found no linear relationship between the actual blood pressure level and various aspects of cognitive performance. Prospective studies are needed to investigate the possibility that the systemic blood pressure load over time is associated with a decline in specific cognitive abilities.

Adult↗

PubMed1997

Aerobic capacity and cognitive performance in a cross-sectional aging study.

In a population unselected for aerobic fitness status, aerobic fitness (VO2max) and its interaction with age were used to predict performance on several cognitive measures known to be affected by chronological age. It was hypothesized that, in particular, cognitively demanding tasks would be sensitive to aerobic capacity. Healthy subjects between 24 and 76 yr of age (N = 132) were recruited from a larger study into determinants of cognitive aging (Maastricht Aging Study-MAAS). All participants took part in a submaximal bicycle ergometer protocol and an extensive neurocognitive examination, including tests of intelligence, verbal memory, and simple and complex cognitive speed. Participants engaged more hours a week in aerobic sports and felt healthier than the nonparticipants of the same age did. No group differences were found in the basic anthropometric characteristics height, weight, and BMI. Two of four subtasks that reflect complex cognitive speed (Stroop color/word interference and Concept Shifting Test) showed main and interaction effects with age of aerobic capacity in a hierarchical regression analysis, accounting for up to 5% of variance in parameter score after correction for age, sex, and intelligence main effects. These findings fit well within a moderator model of aerobic fitness in cognitive aging. They add to the notion that aerobic fitness may selectively and age-dependently act on cognitive processes, in particular those that require relatively large attentional resources.

Adult↗

PubMed1996

Effects of age and gender on discrete and reciprocal aiming movements.

Using a cross-sectional design, this study determined the time course of aging effects on rapid discrete and reciprocal aiming movements in men and women. A total of 80 men and 61 women in good health were classified into six age groups (25, 35, 45, 55, 65, and 75 years). The discrete task required participants to make one discrete aiming movement, whereas the reciprocal task required a series of back-and-forth movements. Results indicated for both aiming tasks that greater age was strongly associated with slower movement times. The significant interaction between age and task indicated that the discrete task showed much larger aging effects (54%) than the reciprocal task (25%). This finding is tentatively interpreted in terms of a reduced efficiency of "on-line" control processes.

Adult↗

PubMed1996

Repeated automatic versus ambulatory blood pressure measurement: the effects of age and sex in a normal ageing population.

OBJECTIVES: To study blood pressure adaptation in relation to age and sex. In a subsample, laboratory blood pressure measurements were compared with ambulatory daytime blood pressure measurements to determine the degree of agreement between the two methods. The night-time blood pressure reduction was analysed as a function of blood pressure status, age and sex. DESIGN: A cross-sectional study in 469 healthy volunteers, aged 23-82 years, stratified for age, sex and educational level. METHODS: Laboratory blood pressure was measured automatically (Dinamap 8100) five times during a 20 min recording session. Cardiovascular events in the medical history were identified in order to treat the cardiovascular event-free group separately in subsequent analyses. Within 3 weeks after laboratory blood pressure measurement, ambulatory blood pressure was measured for 24 h in 135 volunteers from the main study. RESULTS: Both diastolic and systolic blood pressure varied markedly in a single measurement session as a function of age, independent of mean pressure level. After 15 min no further blood pressure decrease was observed. On the basis of the average of the final two blood pressure measurements, 18.8% of the subjects were in the hypertensive range (WHO/ISH guidelines). Ambulatory blood pressure measurements were in accord with earlier findings and correlated 0.74 and 0.73 with laboratory diastolic and systolic blood pressure, respectively, but weighted kappa values indicated only moderate agreement (0.42 and 0.51). Women showed a more profound reduction in cnight-time blood pressure than did men. CONCLUSIONS: There is a substantial change in blood pressure during a single measurement session which is greater in older age groups. The moderate agreement between the two methods of blood pressure measurement supports the notion that blood pressure measured in a single session has limited generalizability to average daytime levels in a population sample.

Adult↗

PubMedDate not supplied

The relation between global and limbic brain volumes on MRI and cognitive performance in healthy individuals across the age range.

The present study investigated the range of age-related changes in brain morphology and the relation with performance on memory and other cognitive tests in a healthy population. A group of 61 subjects (21 to 81 years old, mean = 55.7), free from cognitive and medical deficits, underwent MRI scanning and neuropsychological assessment encompassing memory and other cognitive tests. Volumetry of the hippocampus, parahippocampal gyrus, mamillary bodies, third ventricle, and total brain matter was performed. The results indicate that in healthy individuals increases in ventricular volume and volume decreases in total brain matter, hippocampus and parahippocampal gyrus, but not mamillary bodies, are clearly apparent with increasing age. However, no relation could be established between the brain volumes and test performance when controlling for the effects of age. To conclude, variations in total and limbic brain volumes do not seem predictive for cognitive performance independent of age.

Adult↗

PubMedDate not supplied

Self-reported physical activity, subjective health, and cognitive performance in older adults.

The literature to date suggests a positive relationship between physiological indicators of physical fitness (such as aerobic capacity) and indices of cognitive performance. However, the complexity and cost of methods to measure physical fitness prohibit their use in large-population studies in cognitive aging research. In this study, a questionnaire measuring habitual physical activity was used as an indirect estimate of physical fitness, to predict performance in several cognitive domains in an age- and sex-stratified sample of 80 healthy older adults (55 years and older). Age effects were found on several measures of cognitive speed and fluency, but not on memory performance. Women were slower in sensorimotor speed than men but scored higher on memory tasks. No main effects of activity on cognitive measures were found, but two measures that assessed cognitive speed were sensitive to the age-by-activity interaction term. Subjective health also appeared to contribute to the explained variance in the same two indices of cognitive speed. Limitations of the use of activity questionnaires in cognitive aging research are discussed.

Aged↗