Eisuke Segawa

Full-Information Item Bifactor Analysis of Graded Response Data

A plausible factorial structure for many types of psychological and educational tests exhibits a general factor and one or more group or method factors. This structure can be represented by a bifactor model. The bifactor structure results from the constraint that each item has a nonzero loading on the primary dimension and, at most, one of the group factors. The authors develop estimation procedures for fitting the graded response model when the data follow the bifactor structure. Using maximum marginal likelihood estimation of item parameters, the bifactor restriction leads to a major simplification of the likelihood equations and (a) permits analysis of models with large numbers of group factors, (b) permits conditional dependence within identified subsets of items, and (c) provides more parsimonious factor solutions than an unrestricted full-information item factor analysis in some cases. Analysis of data obtained from 586 chronically mentally ill patients revealed a clear bifactor structure.

The Natural History of Cognitive Decline in Alzheimer's Disease

The study aim was to describe the temporal course of cognitive decline in Alzheimers disease (AD). We selected 226 persons from 2 longitudinal clinical-pathological studies who were cognitively healthy at baseline, followed at least 4 years (M = 10.2, SD = 3.5), and clinically diagnosed with AD at some point during follow-up. Each evaluation included a battery of 17 cognitive tests from which a previously established composite measure of global cognition was derived. In those who died, a uniform neuropathologic examination established the pathological diagnoses of Alzheimers disease and other common conditions that impair cognition. Mixed-effects models with 2 change points were used to assess trajectories of cognitive decline. In the main analysis, there was no change in cognitive function until a mean of 7.5 years before dementia was diagnosed (95% confidence interval [CI]: -8.3, -6.7). The global cognitive measure declined a mean of 0.087-unit per year (95% CI: -0.099, -0.073) until a mean of 2.0 years before the diagnosis (95% CI: -2.2, -1.7) when it increased more than 4-fold to a mean loss of 0.370-unit per year (95% CI: -0.417, -0.334). Of 126 individuals who died and underwent autopsy, 101 (80%) met pathologic criteria for AD, of whom 67 had at least one other pathologic condition. Pathologic measures of AD and cerebral infarction were not strongly related to cognitive trajectories. The results indicate that cognitive decline in AD begins many years before dementia is diagnosed and accelerates during the course of the disease.

Influence of late-life cognitive activity on cognitive health

Objective: To test the hypothesis that late-life participation in mentally stimulating activities affects subsequent cognitive health. Methods: Analyses are based on 1,076 older persons without dementia at study onset participating in a longitudinal cohort study. They completed annual clinical evaluations for a mean of 4.9 years. Each evaluation included administration of a self-report scale about participation in mentally stimulating activities and a battery of cognitive performance tests. Previously established measures of cognitively stimulating activity and cognitive function were derived. We assessed the temporal sequence of activity changes in relation to functional changes in a series of cross-lagged panel models adjusted for age, sex, and education. Results: During the observation period, cognitive activity participation (estimate of mean annual change = −0.066, SE = 0.005, p < 0.001) and cognitive functioning (estimate = −0.077, SE = 0.005, p < 0.001) declined at rates that were moderately correlated (r = 0.44, p < 0.001). The level of cognitive activity in a given year predicted the level of global cognitive function in the following year, but the level of global cognition did not predict the subsequent level of cognitive activity participation. Cognitive activity showed the same pattern of unidirectional associations with measures of episodic and semantic memory, but its associations with working memory were bidirectional. Conclusions: The results suggest that more frequent mental stimulation in old age leads to better cognitive functioning.

The influence of cognitive decline on well-being in old age.

This study addressed the hypothesis that late life cognitive decline leads to loss of well-being. Participants are older persons from the Rush Memory and Aging Project. Beginning in 2001, they underwent annual clinical evaluations that included detailed cognitive performance testing and a 10-item self-report measure of purpose in life, an aspect of well-being. Initial analyses involved 1,049 individuals who were without dementia at baseline and followed a mean of 5.0 years. The intercepts and slopes of global cognition and purpose were positively correlated, and level of cognition at a given evaluation predicted level of purpose at the subsequent evaluation, consistent with the study hypothesis. Purpose also predicted subsequent cognition. These findings persisted in analyses that excluded mild cognitive impairment or controlled for time varying levels of depressive symptoms or disability. To see whether cognitive declines correlation with purpose differed from its correlation with other aspects of well-being, we conducted additional analyses on a subgroup of 560 persons without dementia who completed a multidimensional measure of well-being once between 2008 and 2011. More rapid cognitive decline in the period preceding well-being assessment (M = 5.5 years, SD = 2.8) was associated with lower level of nearly all aspects of well-being (5 of 6 measures), but the extent of the association varied across well-being dimensions and was stronger for purpose than for self-acceptance and autonomy. The results support the hypothesis that cognitive aging leads to diminished well-being, particularly aspects such as purpose in life that involve behavioral regulation.

Cognitive decline impairs financial and health literacy among community-based older persons without dementia.

Literacy is an important determinant of health and well-being across the life span but is critical in aging, when many influential health and financial decisions are made. Prior studies suggest that older persons exhibit lower literacy than younger persons, particularly in the domains of financial and health literacy, but the reasons why remain unknown. The objectives of this study were to: (a) examine pathways linking diverse resources (i.e., education, word knowledge, cognitive function, and decision making style) to health and financial literacy among older persons and determine the extent to which the relation of age with literacy represents a direct effect versus an indirect effect due to decrements in specific cognitive functions (i.e., executive functions and episodic memory); and (b) test the hypothesis that declines in executive function and episodic memory are associated with lower literacy among older persons without dementia. Six-hundred and forty-five community-based older persons without dementia underwent detailed assessments of diverse resources, including education, word knowledge, cognitive function (i.e., executive function, episodic memory) and decision making style (i.e., risk aversion), and completed a measure of literacy that included items similar to those used in the Health and Retirement Study, such as numeracy, financial concepts such as compound inflation and knowledge of stocks and bonds, and important health concepts such as understanding of drug risk and Medicare Part D. Path analysis revealed a strong effect of age on literacy, with about half of the effect of age on literacy due to decrements in executive functions and episodic memory. In addition, executive function had an indirect effect on literacy via decision making style (i.e., risk aversion), and education and word knowledge had independent effects on literacy. Finally, among (n = 447) persons with repeated cognitive assessments available for up to 14 years, regression analysis supported the association of multiple resources with literacy; moreover, more rapid declines in executive function and episodic memory over an average of 6.4 years prior to the literacy assessment predicted lower literacy scores (ps < 0.02), but rate of decline in word knowledge did not. These findings suggest that diverse individual resources contribute to financial and health literacy and lower literacy in old age is partially due to declines in executive function and episodic memory.

EVALUATION OF THE EFFECTS OF THE ABAN AYA YOUTH PROJECT IN REDUCING VIOLENCE AMONG AFRICAN AMERICAN ADOLESCENT MALES USING LATENT CLASS GROWTH MIXTURE MODELING TECHNIQUES

This study employs growth mixture modeling techniques to evaluate the preventive effects of the Aban Aya Youth Project in reducing the rate of growth of violence among African American adolescent males (N = 552). Results suggest three distinct classes of participants: high risk (34%), medium risk (54%), and low risk (12%) based on both the participants’ initial violence scores and their growth of violence over time. Results further show significant effects (almost 3 times as large as the effect found in the regular one-class analysis) for the high-risk class but not for the medium- or low-risk classes.

Terminal dedifferentiation of cognitive abilities

Objective: To test the cognitive dedifferentiation hypothesis that cognitive abilities become increasingly correlated in late life. Methods: Participants are 174 older persons without dementia at the beginning of a longitudinal clinical-pathologic cohort study. At annual intervals for 6 to 15 years prior to death, they completed a battery of cognitive performance tests from which previously established composite measures of episodic memory, semantic memory, working memory, and perceptual speed were derived. At death, there was a uniform neuropathologic assessment and levels of diffuse plaques, neuritic plaques, and neurofibrillary tangles were summarized in a composite measure. Change in the 4 cognitive outcomes was analyzed simultaneously in a mixed-effects model that allowed rate of decline to accelerate at a variable point before death. Results: On average, cognitive decline before the terminal period was relatively gradual, and rates of change in different cognitive domains were moderately correlated, ranging from 0.25 (episodic memory–working memory) to 0.46 (episodic memory–semantic memory). By contrast, cognition declined rapidly during the terminal period, and rates of change in different cognitive functions were strongly correlated, ranging from 0.83 (working memory–perceptual speed) to 0.89 (episodic memory–semantic memory, semantic memory–working memory). Higher level of plaques and tangles on postmortem examination was associated with faster preterminal decline and earlier onset of terminal decline but not with rate of terminal decline or correlations between rates of change in different cognitive functions. Conclusion: In the last years of life, covariation among cognitive abilities sharply increases consistent with the cognitive dedifferentiation hypothesis.

Trajectories of smoking among freshmen college students with prior smoking history and risk for future smoking: Data from the University Project Tobacco Etiology Research Network (UpTERN) study

AIMS Little is known about smoking during the transition to college. The current study examined trajectories of smoking among college freshmen, how trajectories predicted later smoking and the social context of smoking. DESIGN Weekly assessments of daily smoking were collected via the web during the first year of college for a large cohort with a previous history of smoking. PARTICIPANTS AND SETTING A total of 193 college freshmen from a large public university with a previous history of smoking who smoked frequently enough to be included in trajectory analysis. MEASUREMENTS Measures included weekly reports of daily smoking, family smoking, perceived peer attitudes and smoking, social norms and social smoking environment. FINDINGS Seven trajectories were identified: one of low-level sporadic smoking, one of low-level smoking with a small increase during the year, two classes with a substantial decrease during the year, two classes with relatively small decreases and one class with a substantial increase in smoking. Trajectories of smoking in the freshman year predicted levels of sophomore year smoking, and some social context variables tended to change as smoking increased or decreased for a given trajectory class. CONCLUSIONS The transition into college is marked by changes in smoking, with smoking escalating for some students and continuing into the sophomore year. Shifts in social context that support smoking were associated with trajectories of smoking. Despite the focus of developmental models on smoking in early adolescence, the transition into college warrants further investigation as a dynamic period for smoking.

Conscientiousness, Dementia Related Pathology, and Trajectories of Cognitive Aging

The study aim was to determine the contribution of dementia related pathologies to the association of conscientiousness with late-life cognitive health. At enrollment in 2 longitudinal clinical-pathologic cohort studies, 309 older individuals without cognitive impairment completed a standard conscientiousness measure. Annually thereafter, they completed a battery of 17 cognitive tests. On death, they underwent a uniform neuropathologic examination from which measures of neurofibrillary tangles, Lewy bodies, chronic gross cerebral infarction, and hippocampal sclerosis were derived. The relation of conscientiousness and the neuropathologic markers to cognitive decline was assessed in mixed-effects change point models to accommodate nonlinear cognitive decline. During a mean of 10.7 years of follow-up, annual decline on a composite measure of global cognition (baseline M = 0.082, SD = 0.499) was gradual (estimated M = -0.036, 95% CI [-0.046, -0.025]) until a mean of 3.2 years before death (95% CI [-3.6, -2.8]) when it accelerated to a mean annual loss of 0.369 unit (95% CI [-0.426, -0.317]), a tenfold increase. Higher conscientiousness (baseline M = 33.6, SD = 5.1) was associated with slower terminal decline (estimate = 0.064, 95% CI [0.024, 0.103]) but not preterminal decline (estimate = 0.005, 95% CI [-0.003, 0.013]). After adjustment for neuropathologic burden, conscientiousness was still related to terminal decline (estimate = 0.057, 95% CI [0.019, 0.094]) and accounted for 4% of the variance in terminal slopes. In addition, the association of neocortical Lewy bodies with terminal cognitive decline was attenuated in those with higher conscientiousness. The results suggest that higher conscientiousness is protective of late-life cognitive health.

Terminal decline in motor function.

The study aim was to test the hypothesis that motor function undergoes accelerated decline proximate to death. As part of a longitudinal clinical-pathologic study, 124 older Roman Catholic nuns, priests, and monks completed at least 7 annual clinical evaluations, died, and underwent brain autopsy and uniform neuropathologic examination. Each evaluation included administration of 11 motor tests and 19 cognitive tests from which global measures of motor and cognitive function were derived. The global motor measure (baseline M = 0.82, SD = 0.21) declined a mean 0.024 unit per year (95% confidence interval [CI]: -0.032, -0.016) until a mean of 2.46 years (95% CI: -2.870, -2.108) before death when rate of decline increased nearly fivefold to -0.117 unit per year (95% CI: -0.140, -0.097). The global cognitive measure (baseline M = 0.07, SD = 0.45) declined a mean of 0.027-unit per year (95% CI: -0.041, -0.014) until a mean of 2.76 years (95% CI: -3.157, -2.372) before death when rate of decline increased more than 13-fold to -0.371 unit per year (95% CI: -0.443, -0.306). Onset of terminal motor decline was highly correlated with onset of terminal cognitive decline (r = .94, 95% CI: 0.81, 0.99), but rates of motor and cognitive change were not strongly correlated (preterminal r = .20, 95% CI: -0.05, 0.38; terminal r = .34, 95% CI: 0.03, 0.62). Higher level of plaques and tangles was associated with earlier onset of terminal decline in motor function, but no pathologic measures were associated with rate of preterminal or terminal motor decline. The results demonstrate that motor and cognitive functions both undergo a period of accelerated decline in the last few years of life.