| 1. |
- Clouston, Sean A. P., et al.
(författare)
-
Cohort and Period Effects as Explanations for Declining Dementia Trends and Cognitive Aging
- 2021
-
Ingår i: Population and Development Review. - : WILEY. - 0098-7921 .- 1728-4457. ; 47:3, s. 611-637
-
Tidskriftsartikel (refereegranskat)abstract
- Studies have reported that the age-adjusted incidence of cognitive impairment and dementia have decreased over the past two decades. Aging is the predominant risk factor for Alzheimers disease and related dementias and for neurocognitive decline. However, aging alone cannot explain changes in the overall age-adjusted incidence of dementia. The objective of this position paper was to describe the potential for cohort and period effects in cognitive decline and incidence of dementia. Cohort effects have long been reported in demographic literature, but starting in the early 1980s researchers began reporting large historical cohort trends in cognitive function. At the same time, period effects have emerged in the form of economic factors and stressors in early and midlife that may result in reduced cognitive dysfunction. Recognizing that aging individuals today were once children and adolescents and that research has clearly noted that childhood cognitive performance are associated with old-age cognitive performance, this review proposes the need to connect these cohort effects with differences in late-life functioning.
|
|
| 2. |
- Mann, Frank D., et al.
(författare)
-
A novel approach to model cumulative stress: Area under the s-factor curve
- 2024
-
Ingår i: Social Science and Medicine. - : Elsevier. - 0277-9536 .- 1873-5347. ; 348
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Using a large longitudinal sample of adults from the Midlife in the United States (MIDUS) study, the present study extended a recently developed hierarchical model to determine how best to model the accumulation of stressors, and to determine whether the rate of change in stressors or traditional composite scores of stressors are stronger predictors of health outcomes. Method: We used factor analysis to estimate a stress-factor score and then, to operationalize the accumulation of stressors we examined five approaches to aggregating information about repeated exposures to multiple stressors. The predictive validity of these approaches was then assessed in relation to different health outcomes. Results: The prediction of chronic conditions, body mass index, difficulty with activities of daily living, executive function, and episodic memory later in life was strongest when the accumulation of stressors was modeled using total area under the curve (AUC) of estimated factor scores, compared to composite scores that have traditionally been used in studies of cumulative stress, as well as linear rates of change. Conclusions: Like endogenous, biological markers of stress reactivity, AUC for individual trajectories of self-reported stressors shows promise as a data reduction technique to model the accumulation of stressors in longitudinal studies. Overall, our results indicate that considering different quantitative models is critical to understanding the sequelae and predictive power of psychosocial stressors from midlife to late adulthood.
|
|
| 3. |
- O'Keefe, Patrick, et al.
(författare)
-
Cohort Changes and Sex Differences After Age 50 in Cognitive Variables in the English Longitudinal Study of Ageing
- 2023
-
Ingår i: The journals of gerontology. Series B, Psychological sciences and social sciences. - : OXFORD UNIV PRESS INC. - 1079-5014 .- 1758-5368. ; 78:10, s. 1636-1641
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives This paper models cognitive aging, across mid and late life, and estimates birth cohort and sex differences in both initial levels and aging trajectories over time in a sample with multiple cohorts and a wide span of ages. Methods The data used in this study came from the first 9 waves of the English Longitudinal Study of Ageing, spanning 2002-2019. There were n = 76,014 observations (proportion male 45%). Dependent measures were verbal fluency, immediate recall, delayed recall, and orientation. Data were modeled using a Bayesian logistic growth curve model. Results Cognitive aging was substantial in 3 of the 4 variables examined. For verbal fluency and immediate recall, males and females could expect to lose about 30% of their initial ability between the ages of 52 and 89. Delayed recall showed a steeper decline, with males losing 40% and females losing 50% of their delayed recall ability between ages 52 and 89 (although females had a higher initial level of delayed recall). Orientation alone was not particularly affected by aging, with less than a 10% change for either males or females. Furthermore, we found cohort effects for initial ability level, with particularly steep increases for cohorts born between approximately 1930 and 1950. Discussion These cohort effects generally favored later-born cohorts. Implications and future directions are discussed.
|
|
| 4. |
- OKeefe, Patrick, et al.
(författare)
-
Getting a Grip on Secular Changes: Age-Period-Cohort Modeling of Grip Strength in the English Longitudinal Study of Ageing
- 2022
-
Ingår i: The journals of gerontology. Series A, Biological sciences and medical sciences. - : OXFORD UNIV PRESS INC. - 1079-5006 .- 1758-535X. ; 77:7, s. 1413-1420
-
Tidskriftsartikel (refereegranskat)abstract
- Background Grip strength is a popular and valuable measure in studies of physical functional capabilities in old age. The influence of historical trends and differential period-specific exposures can complicate the interpretation of biomarkers of aging and health and requires careful analysis and interpretation of aging, birth cohort, and period effects. This study evaluates the effects of aging, period, and cohort on grip strength in a population of adults and older adults. Methods We use more than 27 000 observations for individuals at least 50 years of age, born in approximately 1910-1960, from the English Longitudinal Study of Ageing to examine a variety of multilevel and cross-classified modeling approaches to evaluate age, period, and cohort effects. Our results extended Hierarchical Age-Period-Cohort modeling and compared our results with a set of 9 submodels with explicit assumptions to determine the most reliable modeling approach. Results Findings suggest grip strength is primarily related to age, with minimal evidence of either period and/or cohort effects. Each years increase in a persons age was associated with a 0.40-kg decrease in grip strength, though this decline differs by gender. Conclusions We conclude that as the population ages, grip strength declines at a systematic and predictable rate equal to -0.40 kg per year (approximately -0.50 kg for men and -0.30 kg for women) in residents of England aged 50 and older. Age effects were predominant and most consistent across methodologies. While there was some evidence for cohort effects, such effects were minimal and therefore indicative that grip strength is a consistent physiological biomarker of aging.
|
|
| 5. |
- Robitaille, Annie, et al.
(författare)
-
Transitions across cognitive states and death among older adults in relation to education: A multistate survival model using data from six longitudinal studies
- 2018
-
Ingår i: Alzheimer's and Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 14:4, s. 462-472
-
Tidskriftsartikel (refereegranskat)abstract
- © 2017 the Alzheimer's Association. Introduction: This study examines the role of educational attainment, an indicator of cognitive reserve, on transitions in later life between cognitive states (normal Mini-Mental State Examination (MMSE), mild MMSE impairment, and severe MMSE impairment) and death. Methods: Analysis of six international longitudinal studies was performed using a coordinated approach. Multistate survival models were used to estimate the transition patterns via different cognitive states. Life expectancies were estimated. Results: Across most studies, a higher level of education was associated with a lower risk of transitioning from normal MMSE to mild MMSE impairment but was not associated with other transitions. Those with higher levels of education and socioeconomic status had longer nonimpaired life expectancies. Discussion: This study highlights the importance of education in later life and that early life experiences can delay later compromised cognitive health. This study also demonstrates the feasibility and benefit in conducting coordinated analysis across multiple studies to validate findings.
|
|
| 6. |
- Wänström, Linda, et al.
(författare)
-
It Runs in the Family: Testing for Longitudinal Family Flynn Effects
- 2023
-
Ingår i: JOURNAL OF INTELLIGENCE. - : MDPI. - 2079-3200. ; 11:3
-
Tidskriftsartikel (refereegranskat)abstract
- The Flynn effect refers to increases over time in measured (particularly fluid) intelligence of approximately 3 IQ points per decade. We define the Flynn effect at the family level, using longitudinal data and two new family-level cohort definitions. Multilevel growth curve analyses of the National Longitudinal Survey of Youth 1979 data showed that children in families with later-born mothers had higher average PIAT math scores, and lower average reading comprehension scores and growth, in young and middle childhood. Children in families where the first child was born later had higher average PIAT math, reading recognition, and reading comprehension scores, as well as larger developmental growth. The latter family-level Flynn effects were of higher magnitudes than the usual individual-level Flynn effect found in previous studies. Our results, showing family level-intercept and slope Flynn effects for both maternal birthyear and first child birthyear, have implications for research aiming to explain the Flynn effect.
|
|
