Visual Integration and the Role of Structural and Functional Brain Changes in the Age-Related Associative Memory Deficit

In the present set of experiments, we investigated the effects of visual integration, and age-related changes in brain structure and function on associative memory for objects and scenes. The results of experiment 1 demonstrated improved associative memory when objects and scenes were visually integrated, through an increase in hits without a corresponding increase in false alarms. This profile was interpreted to reflect an increase in recollection-based responding when associative pairs were visually integrated. Although processing of visually integrated stimuli resulted in greater activation across medial temporal lobe (MTL) structures (e.g. hippocampus (HC), perirhinal cortex (PRC), parahippocampal cortex (PHC)) compared to non-integrated pairs and their respective controls, no difference in MTL or prefrontal (PFC) activation was observed after accounting for control activation. In young adults, activation across all three MTL structures predicted discrimination for non-integrated pairs, but only PRC activation predicted discrimination for visually integrated pairs. In older adults, MTL activation was not related to performance for non-integrated pairs, but HC and VLPFC activation predicted performance for visually integrated pairs. In experiment 2, we investigated differences in reaction time based on visual integration, and the neural correlates of associative recognition. Both young and older adults responded faster to visually integrated than non-integrated pairs, reflecting increased recollection-based responding. However, the difference between conditions was greater in older adults. While both groups exhibited a reduction in right HC and left PRC activation during recognition of visually integrated compared to non-integrated pairs, an interaction occurred in left medial HC. Young adults exhibited reduced activation in this region for visually integrated pairs, whereas high functioning older adults activated this region more for visually integrated than non-integrated pairs. Similar to results from encoding (Experiment 1), HC activation was associated with recognition of non-integrated pairs in young adults, but no MTL region predicted performance for visually integrated pairs. In contrast, HC and PHC activation was only related to memory for visually integrated pairs in older adults. Contrary to findings from the verbal unitization literature that demonstrate improved memory in older adults through increased familiarity-based responding (Zheng et al., 2015; Ahmad et al., 2015), our findings suggest that visual integration improves performance across age-groups through an increased reliance on recollection. Notably, the neural correlates of this shift vary based on age. Finally, in experiment 3, we examined the role of white matter integrity in the tracts connecting frontal and temporal brain regions in predicting associative memory. White matter integrity in the fornix, uncinate fasciulucs, and PHC cingulum predicted associative memory in older adults, even after controlling for global white matter changes. The present findings demonstrate the benefit of visual integration as a strategy to improve associative memory across age groups. Further, we identified age-related changes in brain function and structure that are related to memory for visual pairs of objects and scenes

Social participation predicts cognitive functioning in aging adults over time: comparisons with physical health, depression, and physical activity

Objectives: Several risk and protective factors are associated with changes in cognitive functioning in aging adults - including physical health, depression, physical activity, and social activities - though the findings for participation in social activities are mixed. This study investigated the longitudinal association between social participation and two domains of cognitive functioning, memory and executive function. A primary goal of our analyses was to determine whether social participation predicted cognitive functioning over-and-above physical health, depression, and physical activity in a sample with adequate power to detect unique effects. Method: The sample included aging adults (N = 19,832) who participated in a large, multi-national study and provided data across six years; split into two random subsamples. Unique associations between the predictors of interest and cognitive functioning over time and within occasion were assessed in a latent curve growth model. Results: Social participation predicted both domains of cognitive functioning at each occasion, and the relative magnitude of this effect was comparable to physical health, depression, and physical activity level. In addition, social participation at the first time point predicted change in cognitive functioning over time. The substantive results in the initial sample were replicated in the second independent subsample. Conclusion: Overall, the magnitude of the association of social participation is comparable to other well-established predictors of cognitive functioning, providing evidence that social participation plays an important role in cognitive functioning and successful aging.European Commission [QLK6-CT-2001-00360, RII-CT-2006-062193, CIT5-CT-2005-028857, CIT4-CT-2006-028812, 211909, 227822, 261982]; U.S. National Institute on Aging [U01 AG09740-13S2, P01 AG005842, P01 AG08291, P30 AG12815, R21 AG025169, Y1-AG-4553-01, IAG BSR06-11, OGHA 04-064]; German Ministry of Education and Research12 month embargo; Published online: 01 Sep 2015This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Social participation predicts cognitive functioning in aging adults over time: comparisons with physical health, depression, and physical activity

Objectives: Several risk and protective factors are associated with changes in cognitive functioning in aging adults - including physical health, depression, physical activity, and social activities - though the findings for participation in social activities are mixed. This study investigated the longitudinal association between social participation and two domains of cognitive functioning, memory and executive function. A primary goal of our analyses was to determine whether social participation predicted cognitive functioning over-and-above physical health, depression, and physical activity in a sample with adequate power to detect unique effects. Method: The sample included aging adults (N = 19,832) who participated in a large, multi-national study and provided data across six years; split into two random subsamples. Unique associations between the predictors of interest and cognitive functioning over time and within occasion were assessed in a latent curve growth model. Results: Social participation predicted both domains of cognitive functioning at each occasion, and the relative magnitude of this effect was comparable to physical health, depression, and physical activity level. In addition, social participation at the first time point predicted change in cognitive functioning over time. The substantive results in the initial sample were replicated in the second independent subsample. Conclusion: Overall, the magnitude of the association of social participation is comparable to other well-established predictors of cognitive functioning, providing evidence that social participation plays an important role in cognitive functioning and successful aging.European Commission [QLK6-CT-2001-00360, RII-CT-2006-062193, CIT5-CT-2005-028857, CIT4-CT-2006-028812, 211909, 227822, 261982]; U.S. National Institute on Aging [U01 AG09740-13S2, P01 AG005842, P01 AG08291, P30 AG12815, R21 AG025169, Y1-AG-4553-01, IAG BSR06-11, OGHA 04-064]; German Ministry of Education and Research12 month embargo; Published online: 01 Sep 2015This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

APOE moderates the effect of hippocampal blood flow on memory pattern separation in clinically normal older adults.

Pattern separation, the ability to differentiate new information from previously experienced similar information, is highly sensitive to hippocampal structure and function and declines with age. Functional MRI studies have demonstrated hippocampal hyperactivation in older adults compared to young, with greater task-related activation associated with worse pattern separation performance. The current study was designed to determine whether pattern separation was sensitive to differences in task-free hippocampal cerebral blood flow (CBF) in 130 functionally intact older adults. Given prior evidence that apolipoprotein E e4 (APOE e4) status moderates the relationship between CBF and episodic memory, we predicted a stronger negative relationship between hippocampal CBF and pattern separation in APOE e4 carriers. An interaction between APOE group and right hippocampal CBF was present, such that greater right hippocampal CBF was related to better lure discrimination in noncarriers, whereas the effect reversed directionality in e4 carriers. These findings suggest that neurovascular changes in the medial temporal lobe may underlie memory deficits in cognitively normal older adults who are APOE e4 carriers