Prospective memory function and cue salience in mild cognitive impairment: Findings from the Sydney Memory and Ageing Study

Time-Based and Event-Based Prospective Memory in Mild Cognitive Impairment and Alzheimer's Disease Patients: A Systematic Review and Meta-analysis

Prospective memory (PM) is the ability to remember to perform planned actions in a future moment and it is of fundamental importance for an independent and autonomous lifestyle from development to late adulthood. Deficits in episodic memory and executive functions, which are involved in PM are characteristic features of mild cognitive impairment (MCI) and Alzheimer's disease (AD). Considering that the number of older adults is drastically increasing over the next decades, it is of great interest to understand how PM decline in healthy older adults and patients with different degree of cognitive decline. The present meta-analysis included 46 studies investigating PM performance in AD patients (17 studies) and people with MCI (24 studies); 5 studies included both clinical conditions in the same article. The 46 studies contributed a total of 63 independent samples and 129 effect sizes from 4668 participants (2115 patients and 2553 controls). Unlike previous reviews of the literature, our results with a larger and updated sample of studies confirmed lower PM abilities in AD compared to MCI and controls, although we did not observe conclusive differences between event-based and time-based PM in patients. Surprisingly, PM deficits shown by MCI and AD patients have decreased across years, in parallel to a reduction of the evidence of publication bias and an increase in the number of observations per task. We propose the use of more reliable research designs as one plausible explanation for the reduction of PM impairments.

Neurophysiological markers of prospective memory and working memory in typical ageing and mild cognitive impairment

OBJECTIVE

Prospective memory (PM) -the memory of delayed intentions- is impacted by age-related cognitive decline. The current event-related potential study investigates neural mechanisms underpinning typical and atypical (Mild Cognitive Impairment, MCI) age-related decline in PM.

METHODS

Young adults (YA, n = 30, age = 24.7, female n = 13), healthy older adults (OA, n = 39, age = 72.87, female n = 24) and older adults with MCI (n = 27, age = 77.54, female n = 12) performed two event-based PM tasks (perceptual, conceptual) superimposed on an ongoing working memory task. Electroencephalographic data was recorded from 128 electrodes. Groups were compared for P2 (higher order perceptual processing), N300/frontal positivity (cue detection), the parietal positivity (retrieval), reorienting negativity (RON; attention shifting).

RESULTS

Participants with MCI had poorer performance (ongoing working memory task, conceptual PM), lower P2 amplitudes, and delayed RON (particularly for perceptual PM) than YA and OA. MCI had lower parietal positivity relative to YA only. YA had earlier latencies for the parietal positivity than MCI and OA, and lower amplitudes for N300 (than OA) and frontal positivity (than OA and MCI).

CONCLUSIONS

Impaired attention and working memory may underpin PM deficits in MCI.

SIGNIFICANCE

This is the first study to document the role of RON in PM and to investigate neurophysiological mechanisms underpinning PM in MCI.

Alcohol Hangover Has Detrimental Impact Upon Both Executive Function and Prospective Memory

The alcohol hangover (AH) is a state of general malaise following an evening of heavy episodic drinking when the blood alcohol concentration of the person reaches/approaches zero. The aim of the current study was to investigate what impact the AH has upon both executive function (EF) and prospective memory (PM). Previous research has shown that the AH has a detrimental effect upon cognitive abilities, including attention, working memory, and PM. The current study focused upon what impact AH might have upon both EF and related PM in the same cohort, both of which underpin everyday remembering. The current study compared an AH group (AHG) with a non-hangover group (NHG) on both EF and PM measures. Forty-one participants aged 18-29 years were tested; 19 comprised the AHG and 22 of whom made up the NHG (individuals who reported no heavy drinking the day before and did not report any significant hangover symptoms). A Verbal Fluency task measured EF and the Prospective Remembering Video Procedure measured PM. The Acute Hangover Rating Scale measured AH symptoms and severity, and a Digital Breath Analyzer Test measured their blood alcohol concentration (BAC). A Recreational Drug Use Questionnaire measured alcohol and other drug use. Anyone reporting having used an illicit substance across their lifetime (e.g., cannabis, ecstasy) or who smoked heavily were omitted from the study. Two univariate analyses of covariance compared the AHG and NHG groups on Verbal Fluency and Prospective Remembering Video Task scores (controlling for age, total alcohol units consumed per week, and the number of years spent drinking). The AHG recalled significantly fewer items on the Verbal Fluency task [F (1, 36) = 7.42, p < 0.01] and on the Prospective Remembering Video Task NHG [F (1, 36) = 14.9, p < 0.001] when compared with the NHG. Overall, it appeared that a state of AH significantly impaired both EF and PM. Given the importance of EF and PM to everyday remembering, these findings may have farther-reaching implications.

Evaluating aged mice in three touchscreen tests that differ in visual demands: Impaired cognitive function and impaired visual abilities

Normal aging is often accompanied by reductions in cognitive abilities as well as impairments in visual acuity in men and mice. In preclinical models of human cognition this concomitance can make it difficult to assess the relative contributions of declined vision and cognitive ability on behavioral measures of cognition. To assess the influence of age on cognition and the impact of visual decline on the performance of touchscreen-based behavioral paradigms in mice, aged (11, 12, 16, 17, 19 and 21 months old) male C57BL/6J mice were compared to young (3 or 4 months old) male C57BL/6J mice using three tests of cognition as well as an assessment of visual acuity. Performance of a Visual Discrimination, Spatial Reversal, and an Automated Search Task were all affected by age. However, there was no relationship between reduced visual acuity and the observed performance impairments. Moreover, the visual acuity of animals with profound cognitive impairments overlapped with those showing normal cognitive ability. Despite the potential confound of impaired visual ability, it appears that the touchscreen approach might be particularly effective in studying age-related cognitive decline. This approach will increase the utility of aged mice as a model of decreased cognitive flexibility and may be particularly important for the study of age-related disorders such as Alzheimer's disease.