Decline in Memory, Visuospatial Ability, and Crystalized Cognitive Abilities in Older Adults: Normative Aging or Terminal Decline?

The aim of this study is to explore the pattern of change in multiple measures of cognitive abilities in a sample of oldest-old adults, comparing two different time metrics (chronological age and time to death) and therefore examining both underlying conceptual assumptions (age-related change and terminal decline). Moreover, the association with individual characteristics as sex, education, and dementia diagnosis was also examined. Measures of cognitive status (Mini-Mental State Examination and the Swedish Clock Test) and tests of crystallized (knowledge and synonyms), memory (verbal memory, nonverbal long-term memory, recognition and correspondence, and short-term memory), and visuospatial ability were included. The sample consisted of 671 older Swedish adult participants of the OCTO Twin Study. Linear mixed models with random coefficients were used to analyse change patterns and BIC indexes were used to compare models. Results showed that the time to death model was the best option in analyses of change in all the cognitive measures considered (except for the Information Test). A significant cognitive decline over time was found for all variables. Individuals diagnosed with dementia had lower scores at the study entrance and a faster decline. More educated individuals performed better in all the measures of cognition at study entry than those with poorer education, but no differences were found in the rate of change. Differences were found in age, sex, or time to death at baseline across the different measures. These results support the terminal decline hypothesis when compared to models assuming that cognitive changes are driven by normative aging processes.

Contribution of cognitive abilities to performance and improvement on a substitution coding task.

Age-related performance variance on substitution coding tests has been found to account for much of the age-related variance in tests of fluid and other abilities, leading to the conclusion that cognitive decline is due to slowing. Although it is an easy task, which could easily be performed accurately given adequate time, the substitution coding task is not a pure measure of cognitive speed. Evidence from growth curve analyses involving 3,708 volunteers (49-95 years of age) from the Manchester and Newcastle Studies of Cognitive Aging (P. Rabbitt, C. Donlan, N. Bent, L. McInnes, & V. Abson, 1993) indicates that, with practice on this task, improvement is related more to memory than to age, reasoning, vocabulary, or perceptual speed. In other words, faster performances are related primarily to memory. Operational similarities between speeded measures and measures of higher order abilities, which weaken the argument for causal relationships, are discussed.

Analysis of structure and discriminative power of the Mattis Dementia Rating Scale.

The study examines the factor structure and provides test of the discriminative properties of the 38-item Mattis Dementia Rating Scale (MDRS). The MDRS was designed a priori to measure five broad domains of cognitive abilities: attention, initiation/perseveration, conceptualization, construction, and memory. Complete item level data were collected at the USC Alzheimer Disease Research Center from 19 probable Alzheimer's Disease (AD) patients, 17 cases with dementia of various etiologies (e.g., multiple infarct), and 49 contrast subjects. Factor analyses, with rotation to equamax criterion, were performed on education partialled data. Five and six factor solutions accounted for most of the reliable variance and permitted simple structure theoretical description for separate subscales. These factors, similar to Mattis' design, can be characterized as Memory (Recall)/Verbal Fluency, Construction, Memory (short-term), Initiation/Perseveration, and Simple Commands. Cross-validated discriminant analyses performed on five unit-weighted composite variables derived from factor analysis provided better classification (72% vs 62%) than the 38 Mattis items alone.

Resistance-skills training and onset of alcohol use: evidence for beneficial and potentially harmful effects in public schools and in private Catholic schools.

Recent research suggests that the success of social influence prevention programs is due to enhancing an adolescent's ability to resist passive social pressure (e.g., social modeling and overestimation of peer use), and is not due to teaching refusal skills for combating active social pressure (i.e., alcohol and drug offers). Using 4 waves of longitudinal data (collected in the 5th, 6th, 7th, and 8th grades) from 11,995 students participating in the Adolescent Alcohol Prevention Trial, resistance-skills training was found to be an effective strategy for preventing the onset of alcohol use when program assumptions were met. However, a counterproductive effect was found for adolescents attending public school who received a resistance training only condition.

Analysis with missing data in drug prevention research.

Missing data problems have been a thorn in the side of prevention researchers for years. Although some solutions for these problems have been available in the statistical literature, these solutions have not found their way into mainstream prevention research. This chapter is meant to serve as an introduction to the systematic application of the missing data analysis solutions presented recently by Little and Rubin (1987) and others. The chapter does not describe a complete strategy, but it is relevant for (1) missing data analysis with continuous (but not categorical) data, (2) data that are reasonably normally distributed, and (3) solutions for missing data problems for analyses related to the general linear model in particular, analyses that use (or can use) a covariance matrix as input. The examples in the chapter come from drug prevention research. The chapter discusses (1) the problem of wanting to ask respondents more questions than most individuals can answer; (2) the problem of attrition and some solutions; and (3) the problem of special measurement procedures that are too expensive or time consuming to obtain for all subjects. The authors end with several conclusions: Whenever possible, researchers should use the Expectation-Maximization (EM) algorithm (or other maximum likelihood procedure, including the multiple-group structural equation-modeling procedure or, where appropriate, multiple imputation, for analyses involving missing data [the chapter provides concrete examples]); If researchers must use other analyses, they should keep in mind that these others produce biased results and should not be relied upon for final analyses; When data are missing, the appropriate missing data analysis procedures do not generate something out of nothing but do make the most out of the data available; When data are missing, researchers should work hard (especially when planning a study) to find the cause of missingness and include the cause in the analysis models; and Researchers should sample the cases originally missing (whenever possible) and adjust EM algorithm parameter estimates accordingly.

Children's recall of aggressive and withdrawn behaviors: recognition memory and likability judgments.

This study examined children's recognition memory for descriptions of maladjusted behaviors displayed by hypothetical peers. 144 first-, third-, fifth-, and seventh-grade children (mean ages 6.4, 8.4, 10.5, and 12.5 years, respectively) listened to descriptions of hypothetical aggressive, withdrawn, and nonmaladjusted peers, following which they were asked to identify these descriptions from among a second list of descriptions. The children were also asked about the desirability of these hypothetical peers as friends. Whereas children accurately identified the aggressive and nonmaladjusted descriptors at all grade levels, only at grades 5 and 7 were they equally accurate for withdrawal descriptors. Across grade, they also showed an increasing tendency to identify erroneously novel withdrawal and aggression items, but not nonmaladjusted items, as previously displayed by the hypothetical peer. Finally, whereas the aggressive character was low in likability at all grades, the withdrawn character was viewed as increasingly less likable as grade increased. The relevance of these findings to children's peer assessments of aggression and withdrawal is discussed.