Subjective and Objective Memory Changes in Old Age across Five Years.

Typically, subjective memory assessments (be it in form of single items or questionnaires) in old age only weakly correlate with the performance in objective memory tests at cross-section. It thus appears as if individual differences in subjective memory assessments hardly reflect individual differences in memory in old age. A shortcoming of cross-sectional studies, however, is that subjective assessments may rely on different individual standards, which are not taken into account. One solution to this problem has been to investigate subjective and objective memory longitudinally, thereby focusing on individual differences in intraindividual changes. Results from studies using this approach have been mixed, with some studies showing a significantly stronger relation between changes than between levels, and other studies showing no such significant difference. Using data from the Zurich Longitudinal Study on Cognitive Aging (n=236), we find that 5-year changes in subjective assessments of memory capacity and memory changes correlate with objective memory changes of 0.54 and -0.44, respectively. These correlations are significantly stronger than at cross-section. After controlling for age, depressive affect, and subjective health at the first measurement occasion, correlations are slightly attenuated, but the basic findings remain the same.

Individual differences in subjective organization and verbal learning in old age.

UNLABELLED: BACKGROUND/STUDY CONTEXT: Previous research has shown an increase of subjective organization of stimuli and of recall performance across learning trials. However, up to date, it has not been examined whether subjective organization and recall performance are positively related also at the level of the individual. To close this gap, parameters of verbal learning were regressed on growth parameters of subjective organization. METHODS: The sample for this investigation involved N = 205 subjects (65 to 80 years old). Participants learned a word list containing 27 unrelated words, presented randomly across five trials. Subjective organization was measured by using the Paired Frequency measure. RESULTS: Overall, there were reliable individual differences with regard to both subjective organization and verbal learning. RESULTS showed that the learning parameters were positively correlated with the initial level and linear slope of subjective organization. Furthermore, growth parameters of subjective organization turned out to be reliable predictors of verbal learning. CONCLUSION: The present study emphasized the role of analyzing individual differences in subjective organization. Implications are discussed, in particular, regarding the interdependency of subjective organization and verbal learning in old age.

Individual differences in task-specific paired associates learning in older adults: the role of processing speed and working memory.

UNLABELLED: BACKGROUND/STUDY CONTEXT: The role of processing speed and working memory was investigated in terms of individual differences in task-specific paired associates learning in a sample of older adults. Task-specific learning, as distinct from content-oriented item-specific learning, refers to gains in performance due to repeated practice on a learning task in which the to-be-learned material changes over trials. METHODS: Learning trajectories were modeled within an intensive repeated-measures design based on participants obtained from an opt-in Internet-based sampling service (M(age) = 65.3, SD = 4.81). Participants completed an eight-item paired associates task daily over a 7-day period. RESULTS: Results indicated that a three-parameter hyperbolic model (i.e., initial level, learning rate, and asymptotic performance) best described learning trajectory. After controlling for age-related effects, both higher working memory and higher processing speed had a positive effect on all three learning parameters. CONCLUSION: These results emphasize the role of cognitive abilities for individual differences in task-specific learning of older adults.

Individual differences in criterion-based dropout learning in old age: the role of processing speed and verbal knowledge.

In the present study, individual differences in criterion-based dropout learning in old age were investigated. The predictive role of processing speed and verbal knowledge for individual differences in this type of learning was analyzed. Learning trajectories were modeled using a multilevel approach based on N = 47 older participants (Mage = 69.3, SD = 6.4). Participants learned five lists of eight cue-target word pairs across six study-test cycles maximally possible. Results indicate that there were reliable individual differences in the initial level, speed of learning, and quadratic growth of learning. After adjusting for age-related effects, both higher verbal knowledge and higher processing speed had a positive effect on speed of learning. Additionally, verbal knowledge had a negative effect on quadratic growth of learning. Speed of learning and quadratic growth had a positive effect on a delayed recall test after adjusting for effects of processing speed and verbal knowledge. These results emphasize the role of cognitive abilities for individual differences in criterion-based dropout learning in old age.

Individual differences and predictors of forgetting in old age: the role of processing speed and working memory.

The goal of the present study was to examine whether individual differences in basic cognitive abilities, processing speed, and working memory, are reliable predictors of individual differences in forgetting rates in old age. The sample for the present study comprised 364 participants aged between 65 and 80 years from the Zurich Longitudinal Study on Cognitive Aging. The impact of basic cognitive abilities on forgetting was analyzed by modeling working memory and processing speed as predictors of the amount of forgetting of 27 words, which had been learned across five trials. Forgetting was measured over a 30-minute interval by using parceling and a latent change model, in which the latent difference between recall performance after five learning trials and a delayed recall was modeled. Results implied reliable individual differences in forgetting. These individual differences in forgetting were strongly related to processing speed and working memory. Moreover, an age-related effect, which was significantly stronger for forgetting than for learning, emerged even after controlling effects of processing speed and working memory.

A new Mint1 isoform, but not the conventional Mint1, interacts with the small GTPase Rab6.

Small GTPases of the Rab family are important regulators of a large variety of different cellular functions such as membrane organization and vesicle trafficking. They have been shown to play a role in several human diseases. One prominent member, Rab6, is thought to be involved in the development of Alzheimer's Disease, the most prevalent mental disorder worldwide. Previous studies have shown that Rab6 impairs the processing of the amyloid precursor protein (APP), which is cleaved to ß-amyloid in brains of patients suffering from Alzheimer's Disease. Additionally, all three members of the Mint adaptor family are implied to participate in the amyloidogenic pathway. Here, we report the identification of a new Mint1 isoform in a yeast two-hybrid screening, Mint1 826, which lacks an eleven amino acid (aa) sequence in the conserved C-terminal region. Mint1 826, but not the conventional Mint1, interacts with Rab6 via the PTB domain. This interaction is nucleotide-dependent, Rab6-specific and influences the subcellular localization of Mint1 826. We were able to detect and sequence a corresponding proteolytic peptide derived from cellular Mint1 826 by mass spectrometry proving the absence of aa 495-505 and could show that the deletion does not influence the ability of this adaptor protein to interact with APP. Taking into account that APP interacts and co-localizes with Mint1 826 and is transported in Rab6 positive vesicles, our data suggest that Mint1 826 bridges APP to the small GTPase at distinct cellular sorting points, establishing Mint1 826 as an important player in regulation of APP trafficking and processing.