GRAPHICAL APPROACH TO AGE-PERIOD-COHORT ANALYSIS

The paper presents the graphical approach to decomposition of APC effect in cohort studies (mainly applied to demographic phenomena) using multilevel or accelerated longitudinal design. The aim of the paper is to present and visualize the pure age, period and cohort effects based on simulated data with an increment of five for each successive age, period and cohort variation. In cohort analysis on real data all of the effects are usually interrelated. The analysis shows basic patterns of two-variate APC decomposition (age within period, age within cohort, cohort within period, period within age, cohort within age, period within cohort) and reveals the trajectory of curves for each of the pure effects. The APC plots are developed using apc library of R package.

Shift-&-Persist and discrimination predicting depression across the life course: An accelerated longitudinal design using MIDUSI-III

Life course theorists posit that sensitive periods exist during life span development where risk and protective factors may be particularly predictive of psychological outcomes relative to other periods in life. While there have been between-cohort studies trying to examine differences in discrimination and depressive symptoms, these studies have not been designed to identify these sensitive periods, which are best modeled by examining intra-individual change across time. To identify sensitive periods where discrimination and shift-&-persist (S&P) – a coping strategy that may protect against the negative impact of discrimination – are most strongly predictive of depressive symptoms, we employed latent growth curve modeling using an accelerated longitudinal design to track intra-individual change in depressive symptoms from ages 20–69. Participants were 3,685 adults measured at three time points ~10 years apart from the Midlife in the United States study (Mage = 37.93, SD = 6.948 at Wave I). Results identified two sensitive periods in development where high levels of S&P interacted with discrimination to protect against depressive symptoms; during the 30s and a lagged effect where 40's S&P protected against depressive symptoms when participants were in their 50s. Implications for the life course study of discrimination, coping, and depression are discussed.

Establishing Measurement Invariance across Time within an Accelerated Longitudinal Design

The chapter provides a review of the potential value of accelerated longitudinal designs (ALD) for research, through (i) a systematic literature review, and (ii) an original investigation showing in particular the importance of evaluation of measurement invariance. It empirically draws on a large-scale UK study with a substantial aim to map teaching practices with students’ learning outcomes (including dispositions) in mathematics during secondary school. The focus here is on the methodological implications of combining the separate cohorts of students’ outcomes into a longitudinal model of progression for the whole secondary school trajectory and in particular the measurement methods involved to make this possible. Other challenges are also explored in the context of a comprehensive procedure that covers the validation of the construct of mathematics disposition and subsequent multilevel modelling to account for the complex longitudinal design.

Abnormal brain development in child and adolescent carriers of mutant huntingtin

ObjectiveThe huntingtin gene is critical for the formation and differentiation of the CNS, which raises questions about the neurodevelopmental effect of CAG expansion mutations within this gene (mHTT) that cause Huntington disease (HD). We sought to test the hypothesis that child and adolescent carriers of mHTT exhibit different brain growth compared to peers without the mutation by conducting structural MRI in youth who are at risk for HD. We also explored whether the length of CAG expansion affects brain development.MethodsChildren and adolescents (age 6–18) with a parent or grandparent diagnosed with HD underwent MRI and blinded genetic testing to confirm the presence or absence of mHTT. Seventy-five individuals were gene-expanded (GE) and 97 individuals were gene-nonexpanded (GNE). The GE group was estimated to be on average 35 years from clinical onset. Following an accelerated longitudinal design, age-related changes in brain regions were estimated.ResultsAge-related striatal volume changes differed significantly between the GE and GNE groups, with initial hypertrophy and more rapid volume decline in GE. This pattern was exaggerated with CAG expansion length for CAG > 50. A similar age-dependent group difference was observed for the globus pallidus, but not in other major regions.ConclusionOur results suggest that pathogenesis of HD begins with abnormal brain development. An understanding of potential neurodevelopmental features associated with mHTT may be needed for optimized implementation of preventative gene silencing therapies, such that normal aspects of neurodevelopment are preserved as neurodegeneration is forestalled.

Longitudinal Changes in Empathy Across the Life Span in Six Samples of Human Development

The development of empathy is a hotly debated topic. Some studies find declines and others an inverse U-shaped pattern in empathy across the life span. Yet other studies find no age-related changes. Most of this research is cross sectional, and the few longitudinal studies have their limitations. The current study addresses these limitations by examining changes in empathy in six longitudinal samples (total N = 740, age 13–72). In a preliminary study ( N = 784), we created and validated a measure of empathy out of the California Adult Q-Sort. The samples were combined for multilevel analyses in a variant of an accelerated longitudinal design. We found that empathy increased across the life span, particularly after age 40, and more recent cohorts were higher in empathy.