Processing speed and adult age differences in activity memory

The NIH Toolbox Pattern Comparison Processing Speed Test: Normative Data

The NIH Toolbox Pattern Comparison Processing Speed Test was developed to assess processing speed. While initial validation work provides preliminary support for this test in both children and adults, more work is needed to ensure dependability and generalizability. Thus, this replication study examines descriptive data (including age effects), test-retest reliability, and construct validity in n = 4,859 participants ages 3-85 years (matched to 2010 census data). Although the Pattern Comparison was not appropriate for all 3 and 4 years old, by ages 5 and 6, more meaningful scores were apparent. There was evidence for convergent and discriminant validity. There was also a moderate practice effect (i.e., increase of 5.5 points) over a 1-week time frame. Pattern Comparison exhibits a number of strengths: it is appropriate for use across the lifespan (ages 5-85), it is short and easy to administer, and there is support for construct validity.

Memory for positive, negative and neutral events in younger and older adults: Does emotion influence binding in event memory?

When remembering an event, it is important to remember both the features of the event (e.g., a person and an action) and the connections among features (e.g., who performed which action). Emotion often enhances memory for stimulus features, but the relationship between emotion and the binding of features in memory is unclear. Younger and older adults attempted to remember events in which a person performed a negative, positive or neutral action. Memory for the action was enhanced by emotion, but emotion did not enhance the ability of participants to remember which person performed which action. Older adults were more likely than younger adults to make binding errors in which they incorrectly remembered a familiar actor performing a familiar action that had actually been performed by someone else, and this age-related associative deficit was found for both neutral and emotional actions. Emotion not only increased correct recognition of old events for older and younger adults but also increased false recognition of events in which a familiar actor performed a familiar action that had been performed by someone else. Thus, although emotion may enhance memory for the features of an event, it does not increase the accuracy of remembering who performed which action.

Effects of training of processing speed on neural systems

Processing speed (PS) training improves performance on untrained PS tasks in the elderly. However, PS training's effects on the PS of young adults and on neural mechanisms are still unknown. In humans, we investigated this issue using psychological measures, voxel-based morphometry, the n-back task [a typical task for functional magnetic resonance imaging (fMRI) studies with conditions of 0-back (simple cognitive processes) and 2-back tasks (working memory; WM)], resting-state fMRI for the analysis of functional connectivity between brain regions during rest (resting-FC), and intensive adaptive training of PS. PS training was associated with (1) significant or substantial improvement in the performance of PS measures, (2) changes in the gray matter structures of the left superior temporal gyrus and the bilateral regions around the occipitotemporal junction, (3) changes in functional activity that are related to simple cognitive processes (but not those of WM) in the left perisylvian region, and (4) increased resting-FC between the left perisylvian area and the area that extends to the lingual gyrus and calcarine cortex. These results confirm the PS-training-induced plasticity in PS and the training-induced plasticity of functions and structures that are associated with speeded cognitive processes. The observed neural changes caused by PS training may give us new insights into how PS training, and possibly other cognitive training, can improve PS.

Comparable sensitivity of postmenopausal and young women to the effects of intranasal insulin on food intake and working memory

CONTEXT

We have previously shown that enhancing brain insulin signaling by intranasal administration of a single dose of the hormone acutely reduces food intake in young men but not women, whereas its improving effects on spatial and working memory are restricted to young women.

OBJECTIVE

Against the background of animal studies suggesting that low estrogen concentrations are a prerequisite for the anorexigenic impact of central nervous insulin, we extended our foregoing study by assessing intranasal insulin effects in postmenopausal women with comparatively low estrogen concentrations, expecting them to be more sensitive than young women to the anorexigenic effects of the hormone.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION

In a within-subject, double-blind comparison performed at the University of Lübeck, 14 healthy postmenopausal women (body mass index, 23.71±0.6 kg/m2; age, 57.61±1.14 yr) were intranasally administered 160 IU regular human insulin or vehicle.

MAIN OUTCOME MEASURES

Subjects performed a working memory task (digit span) and a hippocampus-dependent visuospatial memory task. Subsequently, free-choice food intake from an ad libitum breakfast buffet was measured.

RESULTS

Contrary to expectations, results in postmenopausal women mirrored those found in young women (22.44±0.63 yr), i.e. insulin administration did not affect food intake (P>0.46), but did enhance performance in the prefrontal cortex-dependent working memory task (P<0.05).

CONCLUSIONS

Low estrogen levels as present in postmenopausal women do not modulate the effects of intranasal insulin in females, suggesting that in humans as opposed to rats, estrogen signaling does not critically alter central nervous system sensitivity to the effects of insulin on energy homeostasis and cognition.

Learning and memory in amnestic mild cognitive impairment: contribution of working memory

In addition to deficits in delayed recall, recent research suggests that participants with amnestic mild cognitive impairment (aMCI) demonstrate diminished use of strategic encoding strategies during learning. Few studies have explored the cognitive mechanisms underlying this deficit. The aim of this study was to investigate in aMCI whether components of working memory (executive attention--attention set-shifting, dividing and focusing attention; and episodic buffer functions--strategic retrieval and manipulation of information) predict strategic encoding strategies during learning (semantic clustering). Thirty-three participants with aMCI and 33 healthy older adults (HOA) were administered neuropsychological tests assessing word-list learning and working memory. The aMCI group demonstrated significant impairment in acquisition, retrieval of information, and decreased use of semantic clustering strategies. Use of semantic clustering in the aMCI group was not predicted by measures of executive attention or phonemic verbal fluency, but was predicted by semantic verbal fluency performance. In the HOA group, semantic clustering was strongly related to semantic verbal fluency. These findings suggest that in aMCI, diminished strategic encoding strategies during learning (semantic clustering) is selectively related to the strategic function of the episodic buffer, but only when in interaction with the manipulation and retrieval of semantic associations.

Aging and Memory for Self-Performed Tasks: Effects of Task Difficulty and Time Pressure

An increase in task difficulty or time pressure during the performance of cognitive tasks decreased the ability of older adults to recall the tasks. In Experiments 1 and 2, adult age differences in recall of cognitive tasks were smaller for easier than for more difficult tasks, and, in Experiment 3, adult age differences were smaller for recall of cognitive tasks without time pressure than for recall of cognitive tasks with time pressure. During difficult or time-pressured cognitive tasks, older adults may become anxious about their performance, and they may have trouble inhibiting negative self-evaluative thoughts about their performance. Older adults may thus devote less attention to aspects of the cognitive tasks that would be beneficial for task recall.

The effect of education on cognitive performances and its implication for the constitution of the cognitive reserve

Some studies have suggested that people with a high educational level have a lower risk of developing dementia compared to people with a low educational level. This protective effect of education has been explained by the constitution of a cognitive reserve which might delay the cognitive and functional expression of neurodegenerative illnesses. The aim of this study is, on the one hand, to evaluate the impact of education on cognitive functioning, which is thought to support the cognitive reserve capacity, and on the other, to determine the extent to which cognitive functioning is affected by other explanatory variables. The analysis was conducted on 1022 individuals without physical or neurological disorders in the Personnes Ages Quid study. These participants were aged 66 and over and had completed a neuropsychological battery. The effect of some demographic and socioeconomic variables on cognitive performance was also analyzed. Multivariate analysis showed a significant effect of education on most neuropsychological performances, independently of the other variables, and more particularly, in the high-attention-demanding tests. A principal component analysis demonstrated that education specifically increases 2 cognitive components: controlled processes and conceptualization ability. More-over, mental stimulation occurring after the education years, such as high-complex-activity occupations, seems to increase the controlled component. All these results suggest that the effect of education on cognitive reserve may be explained by an in-crease in controlled processes and conceptualization abilities. These 2 cognitive components might delay the clinical expression of neurodegenerative illnesses by maintaining global cognitive efficiency. Of these 2 components, controlled processes were also influenced by high attention-demanding occupations.