Biomedical subjects

J Jolles

Publications and source records attributed to J Jolles.

193 records · Page 11Linked to original sources

PubMedDate not supplied

On the involvement of prefrontal networks in cognitive ageing.

Normal ageing is associated with a wide variety of disturbances in the structure and function of the human brain. Recent neuroimaging studies suggest that the prefrontal cortex (PFC) is particularly vulnerable to the effects of ageing. These findings are compatible with the so-called 'frontal ageing hypothesis' which has been formulated on the basis of neuropsychological research on non-pathological ageing. We will argue on the basis of recent structural and functional neuroimaging studies that this hypothesis needs to be refined, especially to acknowledge the possible relevance of a distinction between subregions within the PFC. In addition, findings with regard to a differential involvement of grey versus white matter suggest that both have to be considered in relation to age-related cognitive decline. Hence, neural networks and larger systems of interconnected brain regions and the functional activity in these circuits may be more important than specific cortical regions to explain age effects on cognitive functioning. Finally, it is important to consider individual variability due to sex differences and age-extrinsic biomedical factors in research which examines the relationship between brain structure or function and cognitive ageing.

Aged↗

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

Serum cholesterol, precursors and metabolites and cognitive performance in an aging population.

The present study investigated if a causal relation exists between serum concentrations of precursors and metabolites of cholesterol and cognitive performance in a healthy aging population. Cognitive function addressing four domains of 144 individuals (30-80 years) was tested at baseline and after 6 years of follow-up. Serum concentrations of different sterols related to cholesterol were measured. Serum levels of lathosterol and lanosterol correlated negatively with cognitive performance on the Word Learning tests for verbal learning and memory. This was observed at baseline and follow-up and was independent of age, sex and educational level. Furthermore, the levels of lathosterol and lanosterol at baseline correlated with performance on the Stroop test and Word Learning tests over the 6-year follow-up period. Serum levels of 27-hydroxycholesterol and 24S-hydroxycholesterol showed inconsistent correlations, while cholesterol, desmosterol, sitosterol and campesterol were not related to cognitive performance.Thus, relative high serum ratios of the cholesterol precursors lanosterol and lathosterol, indicative for a high rate of endogenous cholesterol synthesis, are associated with relatively low memory performance in this aging population.

Adult↗

PubMedDate not supplied

Stroop interference: aging effects assessed with the Stroop Color-Word Test.

A large, cross-sectional aging investigation of performance on the Stroop Color-Word Test (SCWT) was carried out. Subjects were 247 volunteers, ages 20-80 in seven age levels. Although all subjects thought themselves to be normal and healthy, a post hoc division could be made on the basis of biological life events (BLE). BLE are mild biological or environmental factors, such as repeated experiences of general anesthesia, that can hamper optimal brain functioning. Apart from the anticipated age effects, performance was poorer in subjects who had experienced one or more BLE: The slowing due to BLE was comparable to the effect of age, especially on the task involving language interference in color-naming. Education had a significant effect on performance: More highly educated subjects performed better than less educated subjects. No sex differences were observed. These findings replicate observations made with other tests in parallel studies. They are also in line with several other studies reporting interactions between the effects of aging and physical fitness. This study questions some of the validity of cognitive aging research, as our data suggest that screening for BLE as age-extrinsic factors in nondiseased subjects can reduce many of the performance deficits usually ascribed to aging per se.

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↗

PubMedDate not supplied

Evidence for a selective decrease in type 1 phosphatidylinositol kinase activity in brains of patients with Alzheimer's disease.

We have previously shown that phosphatidylinositol (PI) kinase activity is 40-50% lower in cytosolic fractions of neocortical regions from brains of patients with Alzheimer's disease (AD) in contrast to phosphatidylinositol phosphate (PIP) kinase activity, which was not affected. After preparing different enzyme fractions by solubilization, the PI kinase activity in the salt-solubilized protein preparation of the temporal cortex of AD brains was predominantly affected (70% decrease). PIP kinase activity in AD brains was not different from that of control brains in any of the fractions tested. PI kinase in the salt-solubilized fractions was inhibited (-75%) by 1% Triton X-100, whereas the PI kinase in the detergent solubilized protein preparation was stimulated (+80%) by 1% Triton X-100. PI kinase activity in the salt-solubilized protein preparation was almost unaffected by adenosine in contrast to PI kinase activity in the detergent solubilized protein preparation, which was strongly inhibited by adenosine. These results indicate that the PI kinase that is specifically affected in AD is the PI 3-kinase, or type 1 PI kinase, because the fraction which was affected most severely has (1) a cytosolic localization; (2) a high sensitivity to inhibition by the non-ionic detergent Triton X-100, and (3) an insensitivity to adenosine inhibition, which are characteristic features of type 1 PI kinase. The relevance of our findings is that type 1 PI kinase is thought to be involved in the regulation of cytoskeletal turnover processes.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Phosphatidylinositol 4-Kinase↗

PubMedDate not supplied

Reduced phosphatidylinositol kinase activity in Alzheimer's disease: effects of age and onset.

Phosphatidylinositol kinase (PI kinase) and phosphatidylinositol phosphate kinase (PIP kinase) were assayed in a membrane-free cytosolic fraction prepared from the medial temporal cortex of patients with Alzheimer's disease (AD) and nondemented controls, with exogenous lipids as substrate. 32P-PIP formation appeared to be reduced by 21% in patients with AD who died before 80 years, compared to matched controls. In addition, there was an age-related decrease in PI kinase activity in the control group. In the AD patients there was no age-related decrease. Very old AD patients (older than 80 when they died) with a short duration of the disease were characterized by increased PI kinase activity. No differences were found in the closely related enzyme PIP kinase. The results are indicative for heterogeneity in AD.

1-Phosphatidylinositol 4-Kinase↗

PubMedDate not supplied

Differential diagnosis of dementia: intra- and interdiscipline agreement.

Ninety clinicians from six disciplines diagnosed ten case descriptions of patients, judged by a multidisciplinary expert committee to suffer from dementia. Five cases were diagnosed before and five after a consensus meeting on the diagnosis of dementia. A significant change in the level of agreement between the disciplines could not be established. The analysis did show a significant difference between the disciplines in the use of etiologic diagnoses. The results indicated that, in order to avoid possible bias caused by medical specialization, a multidisciplinary approach for this type of patient is recommended.

Aged↗

PubMedDate not supplied

Coping styles, cortisol reactivity, and performance in a vigilance task of patients with persistent postconcussive symptoms after a mild head injury.

Some patients experience persistent postconcussive symptoms (PCS) after a mild head injury (MHI). According to the coping hypothesis, PCS result from the increased stress that head-injured patients experience when they are not able to cope with environmental demands. This study examined the coping ability and cortisol reactivity of MHI patients with and without PCS and in uninjured controls. Patients with PCS 12-34 months after injury were individually matched with MHI patients without PCS (N = 11) and healthy controls (N = 11) for the time elapsed since the injury, age, sex, education, and IQ. First, we found that patients with PCS reported being less able to cope with problems. These patients appeared to be inferior in active problem solving and had a more depressive attitude toward problems than subjects of the two control groups. Second, we found no differences between the three groups in the mean cortisol response during a vigilance task. These results only partly support the coping hypothesis. With respect to cognitive performance, we found that decrements in a vigilance task were related to an increased cortisol response during this task, especially in apparently "recovered" (asymptomatic) MHI patients. The latter finding may point to an increased cognitive vulnerability of apparently recovered MHI patients when exposed to a CNS stressor.

Adaptation, Psychological↗

PubMedDate not supplied

Post-traumatic and emotional symptoms in different subgroups of patients with mild head injury.

Post-concussional symptoms, such as headache, dizziness and irritability, are thought to result from the emotional stress associated with decreased cognitive performance after a head injury. A questionnaire-based investigation was carried out in 71 patients with mild head injury (MHI), using a heterogeneous item pool in order to study the interrelationships between traditional post-concussive complaints, cognitive problems, and more emotional and functional complaints. Factor analysis indicated that post-concussive symptoms loaded together with items on problems associated with decreased work performance and fatigability on a first factor, whereas psychovegetative and emotional complaints loaded together on a second factor. Two rating scales were constructed from the relevant items and were used to compare between subgroups of MHI patients and non-concussed controls. Patients with uncomplicated MHI had significantly higher scores than non-concussed subjects on the post-concussive-cognitive scale, but not on the emotional-vegetative scale. Patients with multiple head injuries or pre-existing emotional problems had higher scores on both the post-concussive-cognitive scale and the emotional-vegetative scale than MHI patients without a history of emotional problems. Reliable rating scales may be useful in multidiagnostic studies of MHI patients.

Adult↗

PubMedDate not supplied

Late outcome of mild head injury: results from a controlled postal survey.

There is insufficient information about the long-term sequelae of mild head injury (postconcussional symptoms, PCS). Therefore, a questionnaire-based investigation was carried out in patients 1-5 years after mild head injury (MHI) and in non-concussed subjects in order to study the nature of long-term complaints after MHI. A three-factor model of residual subjective and psychological complaints that contained a dysthymic factor, a vegetative/bodily complaints factor, and a cognitive performance factor were identified in the patient population. Three rating scales were constructed from the relevant items or factors, and were used to compare the MHI patients with non-concussed controls. It was found that the profile of distresses and discomforts mentioned by a population of MHI patients 1-5 years after the trauma was similar to that of a non-concussed control population. These symptoms were indistinguishable from those encountered in ordinary everyday life. These symptoms were significantly more severe in the MHI patients. Stepwise regression analysis in the patient population indicated that a number of parameters were statistically of predictive importance: comorbidity, sex, and neurological complication at the time of the trauma. The results support the hypothesis that MHI may not ever be completely reversible.

Adult↗

PubMedDate not supplied

Influence of age and sex on 19 blood variables in healthy subjects.

Normal values exist for all clinical chemical tests, but it is not very clear what is normal for healthy elderly subjects. Therefore, routine blood variables were determined in 80 ambulatory, disease-free persons who had undergone rigorous health screening. The subjects were divided into the following age groups: 20 (+/- 3), 40 (+/- 3), 60 (+/- 3), and 80 (+/- 5) years, with 10 males and 10 females per age group. Blood variables were determined after an overnight fast. It was found that even with conservative statistical measures more than half of the variables were significantly affected by age or sex. Significant age differences were found for total cholesterol, triglycerides, sodium, and ASAT. Urea, creatinine, gamma-GT, phosphate, alkaline phosphatase, and albumin were characterized by both age and sex differences. No age or sex differences were found for glucose, potassium, chloride, calcium, calcium ion, iron, magnesium, total protein, and ALAT. The findings suggest that the age or sex-related changes of a number of blood variables such as cholesterol, triglycerides, and liver enzymes are not only of statistical significance, but are also of clinical relevance.

Adolescent↗

PubMedDate not supplied

Levels of trace elements in blood in healthy aging subjects.

The effects of age and sex on the serum levels of trace elements were determined after an overnight fast in 80 ambulatory, disease-free adults who had undergone rigorous health screening. Significant age and sex differences were found for Mn. Blood levels of Cu and Zn showed both age and sex differences. No age or sex differences were found for Pb, Cd, Cr, Ni, Se, and Al.

Adolescent↗