SEARCH · PubMed Health

Results for “Longitudinal Studies”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1993

Issues in the long-term evaluation of diet in longitudinal studies.

Longitudinal studies are very useful for studying diet/disease relationships. The fundamental components of a longitudinal study are that: 1) data are collected for two or more distinct time periods; 2) the subjects are the same or comparable from one time period to the next; and 3) data are compared between or among time periods in the analysis. A longitudinal study is often assumed to be synonymous with a cohort study, but there are at least four possible definitions for a longitudinal study. While focusing on cohort studies, the paper describes the nature of longitudinal studies, including a discussion of how the different definitions differ from a cohort study and a set of important assumptions necessary to cohort studies. It also highlights some of the major issues associated with such studies, including the selection of a dietary survey methodology; data collection issues in multicultural, multilingual societies; the importance of nutrient databases; measurement error and misclassification in nutrient intake and energy adjustment.

Cohort Studies↗

PubMed1990

Next steps in describing aging and disease in longitudinal studies.

Longitudinal studies have contributed much to the understanding of aging. Traditionally, age-specific changes in physiological functioning are inferred from studies in which persons with disease processes believed to be relevant to the function in question are excluded from the results. The main theme of this review is that, in the future, studies of aging must better attempt to capture the interplay between disease and aging processes. A variety of research results, mostly from the Baltimore Longitudinal Study of Aging, are used to support this argument. Topics covered include: the role of longitudinal studies in aging research; the complexity of the aging process; the significance of cohort and secular changes for understanding both aging and disease processes; age changes over the adult life span in the significance of risk factors for disease; and age-related increases in morbidity in a longevous group of men.

Aging↗

PubMed2004

Vocal aging and the impact on daily life: a longitudinal study.

Longitudinal studies on vocal aging are scarce, and information on the impact of age-related voice changes on daily life is lacking. This longitudinal study reports on age-related voice changes and the impact on daily life over a time period of 5 years on 11 healthy male speakers, age ranging from 50 to 81 years. All males completed a questionnaire on vocal performance in daily life, and perceptual and acoustical analyses of vocal quality and analyses of maximum performance tasks of vocal function (voice range profile) were performed. Results showed a significant deterioration of the acoustic voice signal as well as increased ratings on vocal roughness judged by experts after the time period of 5 years. An increase of self-reported voice instability and the tendency to avoid social parties supported these findings. Smoking males had a lower speaking fundamental frequency compared with nonsmoking males, and this seemed reversible for males who stop smoking. This study suggests a normal gradual vocal aging process with clear consequences in daily life, which should be taken into consideration in clinical practice as well as in studies concerning communication in social life.

Acoustics↗

PubMed1989

Estimating intervention effects in longitudinal studies.

Longitudinal studies aimed at assessing the impact of interventions on disease risk factors often confront several statistical problems. These problems include 1) dependent variables measured by ordered categories, 2) numerous potentially relevant patterns of transition between outcome levels, 3) mixed units of analysis (e.g., assignment by social unit while theorizing in terms of individuals), 4) incomplete randomization, and 5) correlated estimates for successive occasions of longitudinal measurement. Longitudinal data on use of cigarettes, alcohol, and marijuana among adolescents (n = 1,244, complete data) from the Midwestern Prevention Project are used to demonstrate solutions to each of these problems: 1) a proportional odds regression model, 2) conditional logistic models of transitions with interactions between baseline level and intervention effect, 3) a logistic model estimated with linear regression methods on measures aggregated by social unit, 4) conditional and unconditional models of effect magnitude, and 5) a repeated measures logistic regression technique. Panel data fit to the various models yielded the following conclusions concerning intervention effects in the Midwestern Prevention Project: reduction in the prevalence of cigarette users in treatment schools compared with control schools (8% vs. 18% smoked in the last week at one year follow-up), mixed evidence of an effect on marijuana use, and no evidence of an effect on alcohol use.

Adolescent↗

PubMed2003

Multivariate modeling of two associated cognitive outcomes in a longitudinal study.

Longitudinal studies of Alzheimer's disease provide information about cognitive decline and predictors of this decline. However, overall cognitive function is comprised of many underlying processes, each of which may respond differently over time and may be affected by different predictors. In addition to studying how these processes decline independently, one might also be interested in how the processes decline together. Multivariate growth models, an extension and modification of random effects models, provide a means of dealing with these issues and enable assessing the association between the processes of interest. This technique allows for separate random effects and predictors for each process in the same model, thereby providing simultaneous estimates of the model parameters and variability for each process. We can then determine if factors associated with decline in one process are also associated with decline in another process and the extent to which the processes differ. We provide data that include information on two underlying processes of cognitive function, namely memory and executive function, to illustrate this methodology.

Aged↗

PubMed2005

[Cognitive abilities in older seniors: a longitudinal study].

Longitudinal studies of older seniors (over 80 years) are rare in the literature. This research was designed to study cognitive abilities in the oldest old at two different moments with a three-year interval. The research was quantitative, with a longitudinal and prospective design. The sample consisted of 66 individuals from 80 to 95 years of age, randomly selected for phase I, with 46 of these individuals tested again three years later, in phase II. The instruments used were: Geriatric Depression Scale, Subjective Perception of Memory Problems, Mini-Mental State Examination, Digit Span, Buschke Test of Free and Cued Recall, and the Verbal Fluency Test--Animal Category. The results indicated that there was a small downward trend in the older seniors' performance at the end of the three-year period. More leisure activities and more years of formal schooling were good predictors of smaller decline in cognitive performance during the three-year period. Despite their age, older seniors in this study showed only a slight decline in their cognitive abilities, with little impact on their cognitive patterns.

Aged, 80 and over↗

PubMed2003

Association of energy intake with prostate cancer in a long-term aging study: Baltimore Longitudinal Study of Aging (United States).

OBJECTIVES: To examine the association of total energy intake and macronutrient contributors to energy with prostate cancer risk among men in the Baltimore Longitudinal Study of Aging. METHODS: In the Baltimore Longitudinal Study of Aging cohort, 444 men completed at least one food frequency questionnaire (FFQ). At their earliest FFQ completion, men were 45 to 92 years old. The total number of prostate cancer cases (n = 68) consisted of men who were diagnosed with cancer before their FFQ completion (n = 46) and those who were diagnosed after their FFQ completion (n = 22). Multiple logistic regression analysis was used to calculate the odds ratio of prostate cancer and its 95% confidence interval. RESULTS: Total energy intake was positively associated with prostate cancer. Compared with the lowest quintile of energy intake, the odds ratio for the highest quintile was 3.79 (95% confidence interval 1.52 to 9.48, P TREND = 0.002). Energy-adjusted intakes of protein, fat, and carbohydrates were not statistically significantly associated with prostate cancer risk. CONCLUSIONS: This analysis, in which we used current energy intake as a surrogate for past prediagnostic intake, suggests a higher risk of prostate cancer with increased energy intake.

Aged↗

PubMed1998

Risk factors for nuclear opalescence in a longitudinal study. LSC Group. Longitudinal Study of Cataract.

This study evaluated risk factors for increases in nuclear opacification of the lens in the Longitudinal Study of Cataract (1989-1993; Boston, Massachusetts), which included 764 participants. Baseline data on demographic, medical, and other risk factors were available from an earlier case-control study; follow-up visits were completed yearly over a 4-year period. The lens photographs taken at baseline and at each follow-up visit were graded using the Lens Opacities Classification System III protocol. Analyses evaluated which risk factors collected at baseline were related to increased nuclear opacification at follow-up. The MULCOX2 method, an extension of Cox regression for nested event-time data, was used to estimate the effects of the risk factors. This method accounted for the correlation between fellow eyes. Results showed that the risk of nuclear opacification increased with each year of age (relative risk (RR) = 1.07), white race (RR = 2.94), lower education (RR = 1.50), use of gout medications (RR = 2.32), current smoking (RR = 1.58), family history of cataract (RR = 1.39), and preexisting posterior subcapsular opacities (RR = 6.67). An association with early use of eyeglasses was also suggested (RR = 1.37). In conclusion, nuclear opacification was related to demographic and other variables, including potentially modifiable factors such as current smoking and use of gout medications. Most risk factors identified by this longitudinal study confirm those found by the original case-control study. The increased risk of nuclear opacities in whites appears to be a new finding.

Adult↗

PubMed1999

Pertussis vaccination and wheezing illnesses in young children: prospective cohort study. The Longitudinal Study of Pregnancy and Childhood Team.

OBJECTIVES: To examine the relation between pertussis vaccination and the prevalence of wheezing illnesses in young children. DESIGN: Prospective cohort study. SETTING: Three former health districts comprising Avon Health Authority. SUBJECTS: 9444 of 14 138 children enrolled in the Avon longitudinal study of pregnancy and childhood and for whom data on wheezing symptoms, vaccination status, and 15 environmental and biological variables were available. MAIN OUTCOME MEASURES: Episodes of wheezing from birth to 6 months, 7-18 months, 19-30 months, and 31-42 months. These time periods were used to derive five categories of wheezing illness: early wheezing (not after 18 months); late onset wheezing (after 18 months); persistent wheezing (at every time period); recurrent wheezing (any combination of two or more episodes for each period); and intermittent wheezing (any combination of single episodes of reported wheezing). These categories were stratified according to parental self reported asthma or allergy. RESULTS: Unadjusted comparisons of the defined wheezing illnesses in vaccinated and non-vaccinated children showed no significant association between pertussis vaccination and any of the wheezing outcomes regardless of stratification for parental asthma or allergy. Wheeze was more common in non-vaccinated children at 18 months, and there was a tendency for late onset wheezing to be associated with non-vaccination in children whose parents did not have asthma, but this was not significant. After adjustment for environmental and biological variables, logistic regression analyses showed no significant increased relative risk for any of the wheezing outcomes in vaccinated children: early wheezing (0.99, 95% confidence interval 0.80 to 1.23), late onset wheezing (0.85, 0.69 to 1.05), persistent wheezing (0.91, 0.47 to 1.79), recurrent wheezing (0.96, 0.72 to 1.26), and intermittent wheezing (1.06, 0.81 to 1.37). CONCLUSIONS: No evidence was found that pertussis vaccination increases the risk of wheezing illnesses in young children. Further follow up of this population with objective measurement of allergy and bronchial responsiveness is planned to confirm these observations.

Cohort Studies↗

PubMed2006

Relations among mothers' expressivity, children's effortful control, and their problem behaviors: a four-year longitudinal study.

Longitudinal relations between mothers' expressivity, children's effortful control, and their problem behaviors were examined when children (N = 181) were 6.5-10 years old (T2) and again 2 (T3) and 4 (T4) years later. Mothers reported on their expression of positive and negative dominant emotion. Mothers and teachers reported on children's effortful control and externalizing and internalizing problem behaviors. In structural equation models, variables exhibited consistency over time. Further, the relation between mothers' expressivity (positive minus negative dominant emotion) at T2 and children's externalizing problems at T4 was mediated by T3 effortful control. The same process of mediation was significant for teacher- but not mother-reported internalizing problems. The results provide one explanation for how emotion-related socializing behaviors influence children's problem behaviors.

Adolescent↗

PubMed1993

Food restriction suppresses an age-dependent increase in the exhalation rate of pentane from rats: a longitudinal study.

Longitudinal age changes in the exhalation rates of ethane and pentane, which are used as the indices of in vivo lipid peroxidation, from rats under ad libitum feeding and food restriction were measured. The exhalation rate of ethane or pentane from old, ad libitum-fed rats is higher than that of the corresponding hydrocarbon from young, ad libitum-fed rats, as reported previously. There is no difference between the exhalation rates of each hydrocarbon from young, ad libitum-fed and food-restricted rats. However, the exhalation rate of pentane from old, food-restricted rats is significantly lower than that from old, ad libitum-fed rats, while the exhalation rate of pentane from old, food-restricted rats tends to be lower than that from old, ad libitum-fed rats. In addition, the exhalation rate of pentane from old, food-restricted rats is equivalent to that from young, ad libitum-fed rats. These results are consistent with the views that in vivo lipid peroxidation in rats is increased during aging, and that the age-dependent increase in in vivo lipid peroxidation is suppressed by food restriction.

Aging↗

PubMed1988

[Decrement of respiratory function indices in a case series of workers exposed to cement dust: a longitudinal study].

Longitudinal changes in some respiratory parameters (FEV1 and VC) have been examined in a sample of cement workers (163 male subjects differently exposed to cement dusts); the subjects have been surveyed over a period of 10 years performing yearly spirometric tests (Vital capacity--VC and Forced Expiratory Volume in 1 second--FEV1 measurements). Three possible risk indicators have been considered: occupational exposure, smoking habit and age. 65.6% and 60.7% of the cases showed significant individual annual decreases of VC and FEV1 throughout the time of follow up. According to our results the occupational risk indicator has not significantly influenced the normal trend of decreases of the respiratory parameters; instead age brings about an increase of longitudinal changes of VC and smoke habit an increase of longitudinal changes of FEV1, (but only in the younger group, people less than forty years old). 16 subjects characterized by abnormal losses (more than 100 ml/year) have been selected as "VC-FEV1, losers".

Adult↗

PubMed1982

Reciprocal effects of health and labor force participation among women: evidence from two longitudinal studies.

Longitudinal data were analyzed to provide information concerning the effects of health on women's labor force participation and the effects of labor force participation on women's health. The data were from a representative national sample of middle-aged women and a representative sample of women from Alameda County, California. Significant relationships were observed between self-reported health and subsequent changes in labor force participation. Women who reported poorer health were more likely to leave the labor force and less likely to join the labor force. In contrast, no significant relationships were observed between labor force participation and subsequent self-reported change in health. (These latter relationships could be tested only for married women in the national sample.) In conclusion, our analyses provide substantial evidence that health affects women's labor force participation (the healthy worker effect). In contrast, we did not find evidence that, on the average, labor force participation has either harmful or beneficial effects on the general health of middle-aged married women in the United States.

Adult↗

PubMed1976

Carbohydrate metabolism and capillary basement-membrane thickness in children. II. Longitudinal studies.

Longitudinal biochemical and histologic studies were carried out in 11 children receiving oral hypoglycemic agents. There were five "suspected" diabetics (with evidence of glucose intolerance but without repeated fasting hyperglycemia) and six diabetics. Mean fasting plasma glucose (FPG) values showed no significant change during treatment with phenformin alone. The mean FPG decreased significantly within six to 10 weeks after addition of tolazamide to the regimen, but the decrease was not sustained during long-term observation (seven months to four years). Glucose disappearance rate (K) generally increased as FPG decreased, but the number of observations was smaller, and mean values showed no significant change. Mean values for fasting plasma insulin and for peak insulin response to intravenously administered glucose did not change significantly. Changes in capillary basement membrane thickness (BMT) were found to be statistically significant in a number of individual instances. Decreasing BMTs were associated with increasing Ks and vice versa. A similar trend was apparent among other patients, in whom individual changes in BMT were not statistically significant. The pooled data were therefore subjected to chi-square analysis; K and average BMT were found to change in opposite directions (P less than 0.001); a similar relationship held for K and minimum BMT (P less than 0.05). But K and BMT did not correlate well as regards magnitude of change. Influences of phenformin and tolazamide on these changes could not be evaluated. Both BMT and K may be influenced by many complex variables, but the present findings indicate that glucose tolerance and BMT have a close interdependence.

Adolescent↗

PubMedDate not supplied

Image-guided MR spectroscopy volume of interest localization for longitudinal studies.

Longitudinal magnetic resonance spectroscopy (MRS) studies require accurate repositioning of the volume of interest (VOI) over which measurements are made. In this work we present and evaluate a method for the image-guided repositioning of brain volumes of interest. The point-based registration technique we developed allows the repositioning to be performed on-line (i.e. while the patient is in the scanner). MR image volumes were acquired from six subjects, three scans each over the course of a month. During the first scan, two spectroscopy VOIs are visually selected: one in the frontal white matter, the other in the superior cerebellar vermis. The coordinates of 13 internal brain landmarks are also identified. During both subsequent scans, the same 13 landmarks are identified, and the transformation that registers the first set of landmarks to the subsequent set is computed. This result is used to automatically map the position of the spectroscopy VOIs from the first volume to the current volume. For the six subjects evaluated to date, we show an average repositioning error of the spectroscopy VOIs in the order of 1 mm. This accuracy allows us to conclude that any variations in the MR spectra are unlikely to be due to repositioning error.

Algorithms↗

PubMed1988

Factors influencing the development of molar occlusion: a longitudinal study.

Longitudinal records, in the form of study casts, of 35 Class I cases were examined for factors associated with changes of sagittal molar relationship during childhood. These were studied at two phases: between the deciduous and mixed dentitions, and between the mixed and permanent dentitions. During the first of these periods, there was a small, but general move to a less post-normal occlusion, although some cases were found to show a slight reverse trend. In the second period, the permanent molar relationship became less post-normal, but this was reflected only weakly in that of the canines. Throughout development, asymmetry of occlusal relation became more marked with age, an unexplained bias towards less post-normal occlusion on the left side developing in the second phase. The amount of change in this period was related to variations of deciduous molar size, especially that of the upper second molar.

Adolescent↗

PubMed1985

Phonetic inventories, 15-24 months: a longitudinal study.

Longitudinal samples of meaningful speech of 34 normally developing children were analyzed to determine the range and types of consonantal phones produced at 15, 18, 21, and 24 months. Separate inventories for word-initial and word-final consonants were constructed for each child at each age level. Group analyses showed that early inventories in initial position were composed primarily of voiced anterior stops, nasals, and glides; by 24 months, voiceless stops, velars, and a few fricatives were also included. In final position, inventories consisted primarily of voiceless stops and alveolar consonants. There was a strong tendency for the voiced stops to appear first in initial position and for [t] and [r] to appear first in word-final. Individual analyses of place and manner of articulation revealed highly similar patterns across subjects. The findings are related to other longitudinal research in early phonological development and to studies of babbling of younger subjects and correct productions of older subjects.

Child Language↗

PubMedDate not supplied

Venturing a 30-year longitudinal study.

Longitudinal inquiry has long been recognized as a uniquely powerful method for seeking understanding of psychological development. A 30-year longitudinal venture is described--its theoretical motivation, methodological rationale, and details of implementation. Some of the novel and implicative findings the study has generated are briefly described. Common to all of the results is an absolute reliance on long-term, widely ranging, independent data. Although specific aspects of the study have appeared over the years, its intentions and scope are recounted only here. By and large, the organizing constructs of ego-control and ego-resiliency find impressive support in various empirical inquiries, here quickly described. Methodologically, a number of savvy research procedures useful and perhaps even necessary in longitudinal research are conveyed. The troublesome burdens but ever-alluring attractions of longitudinal inquiry are noted. A forthcoming Web site will contain the extensive 30-year longitudinal data bank together with explanatory information. Psychological investigators may find these imminently available data resources useful.

Ego↗