Christa Simon

Introduction: The use of compensatory strategies plays an important role in the ability of older adults to adapt to late-life memory changes. Even with the benefits associated with compensatory strategy use, little research has explored specific mechanisms associated with memory performance and compensatory strategies. Rather than an individual’s objective memory performance directly predicting their use of compensatory strategies, it is possible that some other variables are indirectly… Show more

Introduction: The use of compensatory strategies plays an important role in the ability of older adults to adapt to late-life memory changes. Even with the benefits associated with compensatory strategy use, little research has explored specific mechanisms associated with memory performance and compensatory strategies. Rather than an individual’s objective memory performance directly predicting their use of compensatory strategies, it is possible that some other variables are indirectly influencing that relationship. The purpose of this study was to: (a) examine the moderating effects of cognitive reserve (CR) and (b) evaluate the potential mediating effects of memory self-efficacy on the relationship between objective memory performance and compensatory strategy use. Method: Two structural equation models (SEM) were used to evaluate CR (latent moderator model) and memory self-efficacy (mediator model) in a sample of 155 community-dwelling older adults over the age of 55. Results: The latent variable moderator model indicated that CR was not substantiated as a moderator variable in this sample (p = .861). However, memory self-efficacy significantly mediated the association between objective memory performance and compensatory strategy use (β = .22, 95% confidence interval, CI [.002, .437]). More specifically, better objective memory was associated with lower compensatory strategy use because of its relation to higher memory self-efficacy. Conclusions: These findings provide initial support for an explanatory framework of the relation between objective memory and compensatory strategy use in a healthy older adult population by identifying the importance of an individual’s memory perceptions. Show less

Fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder, affects fragile X (FMR1) gene premutation carriers in late life. Studies have shown cognitive impairments in FXTAS including executive dysfunction, working memory and visuospatial deficits. However, less is known about cognition in females with FXTAS. Thus, we examined semantic processing and verbal memory in female FXTAS patients with event-related potentials (ERPs) and neuropsychological testing. Sixty-one… Show more

Fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder, affects fragile X (FMR1) gene premutation carriers in late life. Studies have shown cognitive impairments in FXTAS including executive dysfunction, working memory and visuospatial deficits. However, less is known about cognition in females with FXTAS. Thus, we examined semantic processing and verbal memory in female FXTAS patients with event-related potentials (ERPs) and neuropsychological testing. Sixty-one females (34 FXTAS, Mage = 62.7; 27 controls, Mage = 60.4) were studied with 32-channel ERPs during a category judgment task in which semantically congruous (50%) and incongruous items were repeated approximately 10–140 seconds later. N400 and P600 amplitude data were submitted to analysis of covariance. Neuropsychological testing demonstrated lower performance in verbal learning and executive function in females with FXTAS. Event-related potential analyses showed a significant reduction of the N400 congruity effect (incongruous − congruous) in the FXTAS group. The N400 congruity effect reduction in females with FXTAS was mainly due to increased N400 amplitude to congruous new words. No significant abnormalities of the N400 repetition effect or the P600 repetition effect were found, indicating preserved implicit memory and verbal memory, respectively, in females with FXTAS. The decreased N400 congruity effect suggests abnormal semantic expectancy and/or semantic network disorganization in female FXTAS patients. The enhanced N400 amplitude to congruous new words may reflect decreased cognitive flexibility among FXTAS women, making access to less typical category exemplar words more difficult. Show less

To evaluate the electrophysiological effects of chronic memantine therapy with cognitive ERPs related to language and memory. Patients with (FXTAS) manifest cognitive deficits which often progress to cause dementia. Memantine, an (NMDA) receptor non-competitive antagonist approved for Alzheimer's disease, might help block glutamate-associated excitotoxicity and/or facilitate glutamatergic-signaling in FXTAS. Our prior event-related potentials (ERPs) studies in FXTAS have found marked… Show more

To evaluate the electrophysiological effects of chronic memantine therapy with cognitive ERPs related to language and memory. Patients with (FXTAS) manifest cognitive deficits which often progress to cause dementia. Memantine, an (NMDA) receptor non-competitive antagonist approved for Alzheimer's disease, might help block glutamate-associated excitotoxicity and/or facilitate glutamatergic-signaling in FXTAS. Our prior event-related potentials (ERPs) studies in FXTAS have found marked attenuation of the N400 repetition effect, an electrophysiological index of semantic priming. 39 FXTAS participants, completed a 1 year randomized double-blinded placebo-controlled clinical trial of memantine and met all inclusion criteria. Subjects performed a category decision task during (EEG) recordings at baseline and 1 year later. Auditory category statements followed by an associated visual target word (50% 'congruous' category-exemplars, 50% 'incongruous' nouns) were repeated in a pseudo-randomized manner (~10-140 seconds later). ANOVAs were performed on the 'early' (270-430 ms) and 'late' portions (430-600 ms) of the N400 component. A significant timextreatmentxelectrode interaction was found for the early N400 repetition effect. Analyses of right posterior electrodes showed a significant timextreatment group interaction. Significant effects of treatment with increased early N400 repetition effect (mean amplitudes: pre-drug= -0.34 uV, post-drug=-1.22 uV) was found in the memantine-treated group (n=22), but not in the placebo group (n=17), who showed a diminished effect. Memantine therapy of 1 year duration in FXTAS was associated with an improvement in a language-related brain potential, specifically the early portion of the N400 became more sensitive to word repetition. The increased early N400 repetition effects suggest facilitation of implicit memory and automatic semantic activation processes. Show less

Abstract
Objective: To investigate the nature of cognitive impairments and underlying brain mechanisms in older female fragile X premutation carriers with and without fragile X-associated tremor/ataxia syndrome (FXTAS).
Methods: Extensive neuropsychological testing and cognitive event-related brain potentials (ERPs, particularly, the auditory P300) were examined in 84 female participants: 33 fragile X premutation carriers with FXTAS (mean age = 62.8), 25 premutation carriers without FXTAS… Show more

Abstract
Objective: To investigate the nature of cognitive impairments and underlying brain mechanisms in older female fragile X premutation carriers with and without fragile X-associated tremor/ataxia syndrome (FXTAS).
Methods: Extensive neuropsychological testing and cognitive event-related brain potentials (ERPs, particularly, the auditory P300) were examined in 84 female participants: 33 fragile X premutation carriers with FXTAS (mean age = 62.8), 25 premutation carriers without FXTAS (mean age = 55.4) and 26 normal healthy controls (mean age = 59.3).
Results: Both premutation groups exhibited executive dysfunction on the Behavioral Dyscontrol Scale (BDS), with subtle impairments in inhibition and performance monitoring in female carriers without FXTAS, and more substantial deficits in FXTAS women. However, the female carrier group without FXTAS showed more pronounced deficiencies in working memory.
Abnormal ERPs were recorded over the frontal lobes, where FXTAS patients showed both P300 amplitude reduction and latency prolongation, while only decreased frontal P300 amplitudes were found in carriers without FXTAS. These frontal P3 measures correlated with executive function and information processing speed.
Interpretation: The neuropsychological testing and ERP results of the present study provide support for the hypothesis that executive dysfunction is the primary cognitive impairment among older female premutation carriers both with and without FXTAS, although these deficits are relatively mild compared to those in FXTAS males. These findings are consistent with a synergistic effect of the premutation and aging on cognitive impairment among older female fragile X premutation carriers, even in those without FXTAS symptoms.
Show less

OBJECTIVE: The Nun Study showed that lower linguistic ability in young adulthood, measured by idea density (ID), increased the risk of dementia in late life. The present study examined whether ID measured in late life continues to predict the trajectory of cognitive change. Method. ID was measured in 81 older adults who were followed longitudinally for an average of 4.3 years. Changes in global cognition and 4 specific neuropsychological domains (episodic memory, semantic memory, spatial… Show more

OBJECTIVE: The Nun Study showed that lower linguistic ability in young adulthood, measured by idea density (ID), increased the risk of dementia in late life. The present study examined whether ID measured in late life continues to predict the trajectory of cognitive change. Method. ID was measured in 81 older adults who were followed longitudinally for an average of 4.3 years. Changes in global cognition and 4 specific neuropsychological domains (episodic memory, semantic memory, spatial abilities, and executive function) were examined as outcomes. Separate random effects models tested the effect of ID on longitudinal change in outcomes, adjusted for age and education. RESULTS: Lower ID was associated with greater subsequent decline in global cognition, semantic memory, episodic memory, and spatial abilities. When analysis was restricted to only participants without dementia at the time ID was collected, results were similar. Discussion. Linguistic ability in young adulthood, as measured by ID, has been previously proposed as an index of neurocognitive development and/or cognitive reserve. The present study provides evidence that even when ID is measured in old age, it continues to be associated with subsequent cognitive decline and as such may continue to provide a marker of cognitive reserve. Show less

Prompting technology can help individuals with cognitive impairments complete independent activities of daily living (IADL). Although the prompt delivery is an effective way to remind an adult to record a completed activity, this potential benefit may not be sufficient to motivate the adult to comply with the prompt on a consistent basis. In this work we extend activity-aware prompting techniques to utilize alternative reward structures. Our reward mechanism will allow adults to observe game… Show more

Prompting technology can help individuals with cognitive impairments complete independent activities of daily living (IADL). Although the prompt delivery is an effective way to remind an adult to record a completed activity, this potential benefit may not be sufficient to motivate the adult to comply with the prompt on a consistent basis. In this work we extend activity-aware prompting techniques to utilize alternative reward structures. Our reward mechanism will allow adults to observe game progress as a result of their decisions to comply with the prompts. In our study with volunteer participants, the activity-aware reward-based prompting method increased the compliance rate compared to activity-aware prompting without rewarding the adults. Show less