Longitudinal changes in serum immunoglobulin levels in older humans.
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[Statistical study of the longitudinal changes in the spectrum of potentials of the electroencephalogram of humans at psycho-sensory rest].
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Action Potentials↗
Longitudinal changes in intellectual and social development of non-institutionalized retardates.
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Age Factors↗
Longitudinal changes in intolerance and authoritarianism for subjects differing in amount of college education over four years.
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Adult↗
Physiological basis of longitudinal changes in human milk yield and composition.
Currently in Western Australia more than 85% of women are breast-feeding after discharge from the hospital. Breast milk is the only fluid consumed by 64% of infants at 6 months of age, and 25% of infants are still breast-fed at 12 months of age. Therefore, many Western Australian mothers have optimized the art of breast-feeding and thereby provide an ideal population for studies of the physiological, pathological, and pharmacological factors affecting lactation. Reports from other countries conclude that the maximum milk yield of well-nourished women is 700-900 ml/24 h. Our studies have found the average milk yield of mothers breast-feeding single infants was in excess of 1100 ml/24 h for the first 6 months of lactation. Furthermore, mothers breast-feeding twins produced in excess of 2100 ml/24 h over this period, which demonstrates that the potential milk yield for mothers is much higher than 700-900 ml/24 h. Substantial alterations in the composition of breast milk occur at the initiation of lactation and after the cessation of suckling. During established lactation it is generally believed that there is only a slight variation in the composition of the milk. However, intensive studies have revealed acute changes in the concentrations of lactose, glucose, sodium, potassium, and chloride 5-6 days before and 6-7 days after ovulation. These findings suggest that unknown hormonal events associated with the reproductive cycle in women also influence breast milk composition.
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Longitudinal changes in the orientation of trabecular bone in relation to the location in the distal radius.
The aim of this study was to examine changes in orientation of trabecular bone during growth and development in relation to the location of trabeculae between the epiphysial growth plate and the marrow cavity. Five annual hand-wrist radiographs of 57 children between 4-9 years of age, originating from the Nijmegen Growth Study, were analysed by a digital image processing system. Analysis was carried out on four adjacent areas of 7 mm x 7 mm located in the distal head of the radius between the epiphyseal growthplate and the marrow cavity. The orientation of the trabecular pattern was measured in twelve directions. The orientation of trabeculae at a standardized distance from the epiphysial growth plate did not change significantly during growth and development. The orientation in directions perpendicular to the long axis of the radius was higher in newly formed trabecular bone, which is located just below the epiphysial growthplate, than in older trabecular bone at a larger distance from the epiphysial growth plate. Observation of one single area during five years of growth and development showed a comparable development.
Aging↗
The severe impairment battery: concurrent validity and the assessment of longitudinal change in Alzheimer's disease. The Alzheimer's Disease Cooperative Study.
Measurement of cognitive dysfunction in the early stages of Alzheimer's disease (AD) has been well studied and there are many objective tests in use for this purpose. However, with the exception of clinical rating scales, such as the Clinical Dementia Rating Scale, Global Deterioration Scale, and Functional Assessment Staging, there are few objective measures of cognition in the more advanced stages of AD. Given a renewed interest in potential AD therapies, objective measures of mental functioning are needed to adequately assess change in more advanced AD patients. As part of an effort by the NIA-Alzheimer's Disease Cooperative Study to evaluate new measures of efficacy for their utility in treatment studies, the Severe Impairment Battery (SIB) was examined in a 1-year evaluation of change across a wide range of AD severity. The data suggest that the SIB is a reliable and valid measure of progression, particularly in persons with moderate to severe AD. The SIB may therefore be a useful outcome measure in clinical trials that include patients with more advanced stages of AD.
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Blomqvist revisited: how and when to test the relationship between level and longitudinal rate of change.
Longitudinal studies are often interested in assessing the relationship between severity (level) and rate of change (slope). Blomqvist describes an estimator of this relationship that has been used in a variety of contexts. This paper reviews and generalizes the Blomqvist method. Most published applications of the Blomqvist method contain substantial bias because they fail to consider and accommodate confounding due to the pooling of multiple age cohorts in a single analysis. We describe this bias, and present an unbiased algorithm consistent with the intentions of Blomqvist. We also explore when it is appropriate to apply the Blomqvist analysis, and what inferences can be made using this statistic. Aetiological inference about premorbid level of function predicting future rate of decline is often desired, but may not be justified when modelling chronic progressive conditions, since differential progression prior to the start of longitudinal follow-up can induce a relationship between level and rate of decline, even in the absence of an aetiologically relevant association. We conclude that aetiological inference by the Blomqvist analysis is not appropriate in most investigations of chronic progressive disease. Using the model to develop descriptive and predictive equations in these circumstances, however, remains appropriate, as does testing simply for clinical heterogeneity in longitudinal rate of decline.
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Ageing with spinal cord injury: cross-sectional and longitudinal effects.
STUDY DESIGN: Longitudinal and cross-sectional. OBJECTIVE: To determine whether, for studies of ageing with a spinal cord injury, the cross-sectional differences in outcomes across both age and years post injury (YPI) differ from the longitudinal change. SETTING: Two SCI centres in England: the National Spinal Injuries Centre in Aylesbury, and the Regional Spinal Injuries Centre in Southport. METHODS: A total of 315 people who sustained spinal cord injuries prior to 1971 underwent comprehensive health and psychosocial status interviews at one or more of the study assessments (1990, 1993, 1996, and 1999). A range of continuous and dichotomous outcomes was analyzed to detect both cross-sectional differences by age and average individual changes over multiple measurements. RESULTS: Frequently, outcomes changed longitudinally without showing any cross-sectional differences. Cross-sectional age was more commonly associated with the worsening of a condition while cross-sectional YPI was commonly associated with improvement. After controlling for cross-sectional effects, psychological measures generally showed minor deterioration, measures of community integration both improved and deteriorated, upper extremity pain increased, lower enxtremity pain decreased, and participants tended to quit smoking. CONCLUSION: Using longitudinal findings that control for cross-sectional differences produces a more complete description of ageing with a spinal cord injury.
Activities of Daily Living↗
Slice thickness in the assessment of medial and lateral tibial cartilage volume and accuracy for the measurement of change in a longitudinal study.
OBJECTIVE: The optimal magnetic resonance image (MRI) slice thickness required to assess cartilage volume accurately and efficiently in cross-sectional and longitudinal studies is unknown. We compared cartilage volume measured from MRI of the knees using different slice thicknesses (1.5 to 7.5 mm) and assessed longitudinal change. METHODS: A total of 123 subjects with osteoarthritis had baseline and followup MRI on their symptomatic knee at 2 years. Medial and lateral tibial cartilage volumes were calculated using increasing slice thickness by extracting each second, third, fourth, or fifth slice area to calculate total volume, which was compared to the "gold standard" volume calculated from the original 1.5 mm slices. RESULTS: There was little difference in the average medial and lateral tibial cartilage volume observed as the slice thickness increased from 1.5 to 7.5 mm; medial tibial cartilage volume ranged from 1750 microl to 1787 microl and lateral tibial cartilage volume ranged from 1949 microl to 2007 microl. There was also little absolute difference in the average change in medial and lateral tibial cartilage volume measured over 2 years. However, with increasing slice thickness, there was a decreased correlation between the tibial cartilage volume change calculated from the increased slice thickness, with the lowest correlation being 0.77 (p < 0.001) when the lateral cartilage volume calculated from the 7.5 mm slice was compared to the 1.5 mm slices. CONCLUSION: Increasing slice thickness may provide sufficiently accurate measurement of tibial cartilage volume and change over time in some studies. This would result in reduction in MRI scanning and postimaging processing time, which has the potential of increasing the feasibility of this technique.
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Longitudinal weight changes over four years and associated health factors in 629 men and women aged over 65.
OBJECTIVES: (1) To assess changes in body weight longitudinally over 4 years in a representative group of men and women aged over 65 years, living in their own homes. (2) To assess whether initial weight (or weight in proportion to skeletal size) was associated with health 4 years later. (3) To assess whether any changes found in body weight were associated with changes in physical or mental health. (4) To compare the cross-sectional age-related changes in weight found in the initial survey with the longitudinal changes found over 4 years. DESIGN: A large randomised age-stratified survey using a structured questionnaire and measurements of body weight and demispan (for skeletal size), with a 4-year follow-up. SETTING: The survey was conducted in the respondents' own homes. SUBJECTS: 958 subjects age over 65 years, who were recruited from the Nottingham general practitioners' lists, took part in the initial survey; 629 of these subjects completed the second survey 4 years later. RESULTS: (1) The mean 4-year change in body weight was a small but significant loss; in women (n = 385) it was 1.56kg (P <0.001, 95% CI 1.02-2.10) and in men (n = 244) 0.85kg (P = 0.010, 95% CI 0.21-1.49). (2) Initial weight did not predict mortality, new morbidity nor health 4 years later. (3) There were no robust associations between weight change ans either absolute measures of physical health or changes in these measures. (4) The longitudinal change in weight was similar to that predicted by the cross-sectional data. CONCLUSIONS: (1) Ageing, in old age, is associated with loss of body weight, but with a large intra-individual variation. (2) Neither initial body weight nor the change, was associated with mortality or morbidity over 4 years in a large representative sample of old people living in their own homes in a food-rich country.
Age Factors↗
Interpretation of change and longitudinal validity of the quality of life for respiratory illness questionnaire (QoLRIQ) in inpatient pulmonary rehabilitation.
The quality of life for respiratory illness questionnaire (QoLRIQ) is an outcome measure for patients with asthma or chronic obstructive pulmonary disease (COPD). This study assessed the longitudinal validity, reliability of the change score and the interpretation of changes on the QoLRIQ in inpatient pulmonary rehabilitation, completed by 108 patients with moderate to severe asthma (39) or COPD (69). Domains and total score of the QoLRIQ changed significant (all p < 0.0002) with standardized response means from 0.46 to 0.90. All QoLRIQ-change scores were significantly correlated with self-rated change in health and in disease symptoms and with change in self-assessed health status (r from 0.2 to 0.61). There were several significant correlations between QoLRIQ-change scores and change in experienced invalidity, emotional well-being, anxiety, depressive symptoms and Rand-36-domains (r from 0.2 to 0.68). The intraclass correlation coefficient of change was 0.90. The size of a minimal important difference (MID), computed from a retrospective global rating of change by the patients and with the standard error of measurement, was 0.5 points on a 7-point response scale. Computation of the MID from retrospective assessment of change may not be valid because this change was significantly correlated to post-treatment health status and significantly higher than serial assessment of change. We conclude that the QoLRIQ is sensitive to change, longitudinally valid and reliable, with a MID of 0.5 points. These results enable the use of the QoLRIQ as an outcome measure in clinical trials with patients with moderate to severe asthma or COPD. The longitudinal measurement properties in less severe patients still need to be studied.
Adult↗
Comparison of methods for measuring longitudinal brain change in cognitive impairment and dementia.
PURPOSE: The goal of this project was to compare MRI measures of hippocampal, entorhinal cortex (ERC), and whole brain longitudinal change in cognitively normal elderly controls (C), non-demented subjects with cognitive impairment (CI), and demented (D) subjects. METHODS: 16 C, 6 CI, and 7 D subjects of comparable age were studied with MRI twice, at least 1 year apart. Longitudinal change in total brain size was measured by several methods, including computerized segmentation, non-linear warping, and change in the fluid/tissue boundaries between cerebrospinal fluid (CSF) and brain. Change in hippocampal volume was measured by semi-automated methods, and ERC volumes were manually measured. RESULTS: The annual rate of atrophy was greater in D versus C and D versus CI for cortical gray matter (cGM) (P=0.009 and 0.002), hippocampus (P=0.0001 and 0.002), and for the change in the fluid/tissue boundary (P=0.03 and 0.03). The annual rate of atrophy of ERC was greater in both CI and D versus C (P=0.01 and 0.0002). No significant differences between groups were found using non-linear warping. CONCLUSIONS: In CI, the greatest annual rates of atrophy were in ERC, while in D the greatest annual rates of atrophy were in hippocampus and cortex. Progressive ERC atrophy was observed with a greater degree of cognitive impairment, while hippocampal and cortical atrophy were only observed in demented subjects.
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Longitudinal force and stress of rat's esophagus: age-related changes.
Longitudinal force-length relationship of the rat esophagus was studied in vitro in three age groups: 1 mo, 3 mo, and 12 mo. The length of maximum force development (MFD) occurs at 1.4-1.5 times the in vivo length for all age groups. The active force developed at MFD increases markedly with age. The difference in the active forces in the 3-mo and 12-mo age groups is due to differences in cross section because the active stress of the esophagus in the longitudinal direction is approximately equal for the two age groups. The active stress in the 1-mo-old rats is lower than in the 3-mo-old rats, suggesting an increased contractility of the esophagus with age in this period of development.
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Longitudinal personality changes among presymptomatic Huntington disease gene carriers.
OBJECTIVE: To determine whether longitudinal changes in personality as measured by the Minnesota Multiphasic Personality Inventory (MMPI) can be detected among clinically presymptomatic individuals carrying the expanded Huntington disease (HD) allele. BACKGROUND: Emotional symptoms are considered one of the cardinal features of HD. However, the literature is replete with conflicting reports of psychiatric symptoms in presymptomatic HD gene carriers. METHODS: A longitudinal, case-control, double-blind study comparing presymptomatic gene carriers and nongene carriers at risk for HD evaluated with an abbreviated MMPI and a quantified neurologic rating scale examined an average of 3.7 years apart. RESULTS: Presymptomatic gene carriers (PSGC) had a greater increase in abnormality over time for the MMPI scales, cynical hostility (repeated-measures ANOVA, = 0.04) and irritability (repeated measures ANOVA, = 0.005), when compared with the nongene carriers (NGC). Among both the PSGCs and NGCs, no significant correlation was found between the number of CAG repeats and the change in MMPI score between visits. CONCLUSIONS: This study provides significant evidence for increasing irritability and cynical hostility in presymptomatic gene carriers before the onset of overt clinical symptoms.
Adult↗
Longitudinal age changes in vigilance over an eighteen year interval.
An 18-year longitudinal repeat of the Mackworth Clock vigilance experiment was conducted. Skin potential response latencies (SPRL) and reaction times were taken from 33 men during the vigilance task. The longitudinal change in this study reproduced the earlier cross-sectional relationship. The 51 to 69 year olds showed faster reaction times, the 70 to 88 year olds showed slower reaction times and, the 70 to 88 year olds detected significantly fewer targets than when 18 years younger. It was found that the greater the change noted in this study reflected previously determined cross-sectional SPRL effect. However, the SPRL outcome was equivocated by a time-of-measurement effect. It was concluded that at about age 70 years a noticeable reduction in vigilance performance occurs, and this is accompanied by a reduction in autonomic and central nervous system reactivity.
Adult↗
Structural modeling of dynamic changes in memory and brain structure using longitudinal data from the normative aging study.
This is an application of new longitudinal structural equation modeling techniques to time-dependent associations of memory and brain structure measurements. There were 225 participants aged 30-80 years at baseline who were measured again after a 7-year interval on both the lateral ventricular size and Wechsler memory score. Multiple regression analyses show nonlinear associations with age but no relationships among longitudinal changes. Mixed-effects latent growth curve analyses and analyses based on latent difference scores indicate that longitudinal changes in both variables are reasonably well described by an exponential or dual change model. Bivariate dynamic structural equation modeling analyses indicate age-lagged changes operate in a coupled-over-time fashion, with the brain measure (lateral ventricular size) as a leading indicator in time of memory (Wechsler memory score) declines.
Adult↗
Longitudinal dietary change from adolescence to adulthood: perceptions, attributions and evidence.
Dietary patterns and change in eating habits are influenced by multiple factors from an individual's internal and external environment. A longitudinal dietary survey study provided quantitative evidence of dietary change and investigated factors influencing dietary change from adolescence to adulthood, using sociodemographic data and participants' own perceptions of, and attributions for, their dietary change. Longitudinal dietary data were obtained in 1980 and 2000 (average age 11.6 and 32.5 years, respectively). Two questionnaires (2000) and 2 x 3-day food diaries (1980 and 2000) were collected from 198 participants. Foods consumed were assigned to one of the five food groups from The Balance of Good Health (a UK food guide). Questionnaire responses were used to examine how subjects perceived their own dietary change and the factors to which they attributed such change. Six key factors were identified from the questionnaire: parents, partners, children, nutritional awareness, employment and lack of time. Demographic and key factors were associated with degree of change in intake. The complex process of change in food consumption can be linked with an individual's attributions for change.
Adult↗