Influence of memory strategies on memory test performance: A study in healthy and pathological aging

ABSTRACT

The ability to generate memory strategies is a key factor in the performance of episodic memory tasks. Whether the ability to generate memory strategies exerts an influence in the performance of memory tests in the elderly population is still a matter of debate. Here we present results from an experimental memory task (Test of Memory Strategies, TMS), comprised of five lists of words starting from an incidental learning task, and four more lists which progressively gain in their external organization of the material, reducing the necessity of mobilizing complex memory strategies. TMS has been applied to four groups of elderly patients (amnestic Mild Cognitive Impairment – aMCI, multidomain (mMCI), and Vascular Cognitive Impairment – VCI and Depression) and a healthy aging group. In conditions with low organization of the material, the mMCI and VCI groups (both showing a greater executive function impairment) have shown lower performance. However, as the material was progressively organized, they improved their performance. The aMCI group showed similar performance to the control group at the lower level of external organization but did not improve performance in conditions with a high level of external organization. The mMCI and VCI groups showed lower performance on all TMS conditions compared with controls. Discriminant analysis revealed 90% sensitivity and specificity to differentiate between groups based on TMS conditions. These results indicate how executive functions influence performance on memory tasks in elderly subjects with different neuropsychological profiles.     

Modeling and estimating recall processing capacity: Sensitivity and diagnostic utility in application to mild cognitive impairment

We investigate the potential for using latency-based measures of retrieval processing capacity to assess changes in performance specific to individuals with mild cognitive impairment (MCI), a reliable precursor state to Alzheimer’s Disease. Use of these capacity measures is motivated in part by exploration of the effects of atrophy on a computational model of a basic hippocampal circuit. We use this model to suggest that capacity may be a more sensitive indicator of the underlying atrophy than speed of processing, and test this hypothesis by adapting a standard behavioral measure of memory (the free and cued selective reminding test, FCSRT) to allow for the collection of cued recall latencies. Participants were drawn from five groups: college-aged, middle-aged, healthy elderly, those with a diagnosis of MCI, and a sample of MCI control participants. The measure of capacity is shown to offer increased classificatory sensitivity relative to the standard behavioral measures, and is also shown to be the behavioral measure that correlated most strongly with hippocampal volume.     

Response to Algarabel et al., 2012 “Recognition memory deficits in mild cognitive impairment”. Reconsidering claims of familiarity disruptions in mild cognitive impairment

There is some debate over the relative impairment of recollection and familiarity in mild cognitive impairment (MCI). A recent publication by Algarabel et al. (2012, Recognition memory deficits in mild cognitive impairment, Aging, Neuropsychology, and Cognition, 19, 608–619) claims to undermine previous studies reporting preserved familiarity in patients with MCI. Here, we respond to their main criticisms, concluding that they are not sufficiently supported by the data presented. The role of recollection and familiarity in MCI remains unresolved and further work will be required to disentangle the mixed literature.     

Subjective cognitive complaint in healthy older adults: Identification of major domains and relation to objective performance

This study analyzed complaints across a range of memory domains in middle-aged and older adults, as well as assessed their relationship with objective cognitive performance and personal characteristics. A total of 115 community-dwelling, healthy adults between the ages of 45 and 87 completed the Self-Evaluation Questionnaire (QAM) and were tested with a comprehensive neuropsychological battery. A principal component analysis identified seven dimensions of complaint. Difficulty inhibiting internal and external sources of interference when learning or remembering something was the main area of complaint and it was correlated with word-list recall and Digit Symbol. We identified complaints related to a set of memory failures that appear to be more detrimental to autonomy and safety. These were correlated with a measure of functional autonomy and might, therefore, indicate more severe difficulties. Overall, this study provides indications regarding the main domains of memory complaints and identifies which complaints are most reflective of objective cognitive problems.     

Neuropsychological function in a group of patients 25 years after sustaining minor head injuries as children and adolescents

Previous studies suggest that neuropsychological impairment following mild to moderate pediatric head injury may become persistent and interrupt the normal course of intellectual development. In this study 45 subjects were assessed with a standardized neuropsychological test battery 25 years after sustaining mild to moderate head injury as children. Although the group scores in the normal range, significant relations between head injury severity and current neuropsychological function were found. The most important predictor of poor outcome was length of PTA at injury, EEG pathology, and loss of consciousness at injury. No significant influence of pre- and post-injury risk factors on current neuropsychological function was evident. The findings support the view that complicated mild and moderate paediatric head injury may heighten the risk of developing subtle neuropsychological problems later in life.     

Spatial navigation deficits in amnestic mild cognitive impairment with neuropsychiatric comorbidity

Aims: To find out whether neuropsychiatric comorbidity (comMCI) influences spatial navigation performance in amnestic mild cognitive impairment (aMCI).

Methods: We recruited aMCI patients with (n = 21) and without (n = 21) neuropsychiatric comorbidity or alcohol abuse, matched for global cognitive impairment and cognitively healthy elderly participants (HE, n = 22). They completed the Mini-Mental State Examination and a virtual Hidden Goal Task in egocentric, allocentric, and delayed recall subtests.

Results: In allocentric navigation, aMCI and comMCI performed significantly worse than HE and similarly to each other. Although aMCI performed significantly worse at egocentric navigation than HE, they performed significantly better than patients with comMCI.

Conclusions: Despite the growing burden of dementia and the prevalence of neuropsychiatric symptoms in the elderly population, comMCI remains under-studied. Since trials often assess “pure” aMCI, we may underestimate patients’ navigation and other deficits. This finding emphasizes the importance of taking account of the cognitive effects of psychiatric disorders in aMCI.     

The role of probe trial distractors in the production/removal of the spatial negative priming effect

When a current (probe trial) target arises at a location formerly occupied by a distractor event (prime trial; ignored-repetition trial), its reaction time is slower than when it occurs at a previously empty location (control trial), revealing a spatial negative priming (SNP) effect. Here, we examined the influence of prime- and probe trial distractor identity similarity on the retrieval of the stored representations of prime trial processing (i.e., indexed by SNP production), in a context where the prevention of the SNP phenomenon had been motivated (via low probability of probe distractor presence—.25). Two results were important. One, the SNP effect was evident when the prime–probe distractor identities fully matched, but not when they partially or totally mismatched, showing a retrieval role for the probe distractor. Two, target-repeat trial latency facilitation showed the same pattern, indicating that representations of prime target and distractor processing are retrieved together, indicative of an episodic storage format. Since target identity remained fixed, the role of a matching probe distractor identity in SNP production was to presumably complete the triggering requirement (i.e., full event identity matching) for accessing the episodically stored representations.     

Physiological, psychological and behavioral consequences of activating autobiographical memories

Activating an autobiographical memory for a specific childhood event can have immediate and robust physiological, psychological, and behavioral consequences. The target behavior was public speaking, a vital skill about which many people are socially anxious. In this study, it was suggested to subjects that they had a positive public speaking experience in early childhood; they then thought about and retrieved details of this true childhood memory. Compared to a control condition in which a different suggestion was made, subjects in the treatment group exhibited superior public speaking performance on the Trier Social Stress Test (TSST). Further, physiological measures of cortisol and a self-report measure of anxiety (STAI-S) reflected a significantly smaller increase in anxiety from before to after the TSST in the treatment than control condition. Activating autobiographical memory for an event increases the accessibility of that memory and consequently affects performance on related behaviors.     

Serum β-Amyloid Correlates with Neuropsychological Impairment

ABSTRACT

Aims: Evidence suggests a relationship between peripheral Aβ and AD. We hypothesized that higher levels of serum Aβ_1–42 would be associated with memory impairment, thought to occur early in the disease, and rises in serum Aβ_1–40, which occur later, would be associated with impairment in non-memory measures. Methods: Using a cross-sectional design, we examined the relationship of serum Aβ_1–40, Aβ_1–42, and the ratio of Aβ_{1–42/1–40} to neuropsychological measures in 40 cognitively normal controls, 13 MCI subjects, and 25 AD patients. Results: Serum Aβ_1–42 and the ratio of Aβ_{1–42/1–40} were significantly higher in the MCI group compared to the controls. A significant relationship in the hypothesized direction (poorer scores associated with higher Aβ_1–40 serum levels) was found between Aβ_1–40 and measures of executive functions across the entire cohort of individuals tested and with measures of language and processing speed in the AD group. Regression analysis found that neuropsychological measures accounted for 26% of the variance in serum Aβ_1–40, in the MCI/AD but not the controls. Furthermore that language and executive measures were significant predictors. Conclusions: Results provide preliminary data to partially support our hypotheses and suggest that changes in serum Aβ levels may be attributed to pathological changes within the brain.     

Opposing effects of age and reading ability on pseudoword priming

Repetition priming refers to the facilitation of stimulus processing due to prior processing of the same or similar stimulus, and is one of the most primitive ways in which experience and practice can affect performance. Previous studies have produced contradictory results regarding the stability of repetition priming across development. Drawing on models of word priming that suggest decreased priming with increased reading ability, the present experiment investigated the possibility that null effects of age in priming are due to opposing effects of age and reading ability on priming magnitude. Forty-eight participants between 7 and 22 years old read aloud primed and unprimed pseudowords, after completing a reading ability assessment. In line with predictions, the magnitude of priming for pseudowords increased with increased age when reading ability was controlled, and decreased with increased reading ability when age was controlled. Moreover, neither the age nor ability effect was significant when tested without the other. Results were not influenced by explicit memory for primed pseudowords. Thus, the present experiment provides evidence for developmental increases in word priming, as well as a potential explanation for the lack of developmental effects in previous studies.