Subjective working and declarative memory in dementia and normal aging

The Challenge of Subjective Cognitive Complaints and Executive Functions in Middle-Aged Adults as a Preclinical Stage of Dementia: A Systematic Review

Subjective cognitive complaints correspond to a heterogeneous construct that frequently occurs in the early stages of older adult life. Despite being a common source of worry for middle-aged people, it can be underestimated when clinical and neuropsychological assessments discard any underlying pathological processes. Negative age stereotyping but also self-stereotyping can contribute to doing so. Although its diagnosis is a challenge, its implication as a possible predictor of mild cognitive impairment or dementia increases the interest in its early diagnosis and intervention. The present systematic review analyzes the empirical data on the relationship between these complaints and early executive dysfunction with possible predictive value for preclinical stages of dementia. The sixteen papers obtained from the PubMed and Embase databases were exploratory, cross-sectional and prospective in scope. The studies corroborated the relationship between subjective cognitive complaints and some executive processes, which is noteworthy since many people with subjective executive complaints progress to dementia. The relational studies confirmed that impaired executive performance is associated with CSF biomarkers and reduced cortical volume in specific brain regions. However, the heterogeneity of reports in these studies demands stronger efforts in future research with specific tools applied in clinical and neuropsychological assessments and analyzed under a gender perspective.

Spatial working memory in rats: Crucial role of the hippocampus in the allothetic place avoidance alternation task demanding stimuli segregation

Working memory is a construct that contains goal maintenance, interference control and memory capacity domains. Spatial working memory in presence of conflicting stimuli requires segregation and maintenance of the relevant information about a goal over a short period of time. Besides the prefrontal cortex, the hippocampus is an anatomical substrate for the working memory. We hypothesized that in a highly challenging task, where spatial stimuli are in a conflict and only some of them describe the goal location, the spatial working memory will be strongly dependant on the hippocampus. To verify this, we used an allothetic place avoidance alternation task (APAAT). Performance of this task demands a small number of entries and a long maximum time avoided between consecutive entries to the shock sector. These parameters reflected both domains of working memory. The experiment was conducted on hippocampal lesioned (HIPP n = 12) and sham-operated (CTRL n = 8) rats trained in four APAAT days, each consisting of four 5-minute stages: habituation, stage1 (st1) and stage2 (st2) of memory training, a 5-minute break followed by a retrieval test. The position of the shock sector was changed each day. The HIPP rats were impaired on both stages of memory training, whereas CTRL rats presented significant memory improvement on stage2. In HIPP rats the cognitive skill learning measured as shock per entrance ratio was compromised. Hippocampal lesions did not impair locomotor activity. In summary, even slight bilateral damage to the hippocampus is blocking working memory formation in a difficult task.

New Contemplation Upon Subjective Memory Complaints as a Self- Report Criterion for MCI Diagnosis

BACKGROUND

Subjective memory complaints are a key component in mild cognitive impairment (MCI) diagnosis. However, studies that examined memory awareness among MCI participants have published contradictory results. One possible explanation for the inconsistent findings could be the disregard from the multidimensional structure of subjective memory.

OBJECTIVES

The present study is directed at assessing subjective memory among healthy and MCI participants, referring to three main types of memory: episodic, semantic, and working memory.

METHODS

Participants were 123 adults (aged 50-90). They were divided into two groups, the MCI group, and the control group, according to their objective cognitive performance in RAVL or Mo- CA tests. All participants filled a subjective memory questionnaire, assessing their awareness of episodic, semantic, and working memory.

RESULTS

MCI participants estimated their semantic memory as significantly lower in comparison to the estimation of the healthy controls. By contrast, MCI participants showed an overestimation of their episodic memory capabilities compared to the control group. No significant difference was found between groups (MCI and healthy controls) in evaluating their working memory. In addition, for both groups, Pearson's correlation revealed a significant negative correlation between age and semantic memory evaluation. Such correlation was not found for subjective episodic memory.

DISCUSSION

Findings suggest that while people with MCI exhibit poor awareness of their episodic and working memory capabilities, their awareness of their decrease in semantic memory is apparently intact. Therefore, it is suggested that when using the self-report criterion for MCI diagnosis, clinicians should consider the patient's' semantic memory complaints.

Subjective working memory predicts objective memory in cognitively normal aging: a HUNT study

BACKGROUND

Recent studies have shown that subjective memory is multi-, rather than uni-dimensional, in line with the results of objective memory tests. The purpose of this study was to investigate whether there is an association between aspects of memory measured by the subjective Meta-Memory Questionnaire (MMQ) and aspects of memory measured by the objective Wechsler Memory Scale-III (WMS-III) and Wechsler Adult Intelligence Scale-III (WAIS-III) tests in cognitively normal older adults.

METHOD

The study subjects (n = 106) were cognitively normal, were aged 57-89 years and had participated in the third wave of the North-Trøndelag Health survey (HUNT3). All subjects had completed the MMQ, the WMS-III and the WAIS-III. Previous results from the MMQ (measured as the total MMQ score; the Component I score, related to long-term explicit declarative memory; and the Component II score, related to working/short-term memory) were compared with objective results from WMS-III (Logical Memory) and WAIS-III (Vocabulary and Letter-Number Sequencing) subtests. We conducted linear regression analyses with each objective memory test result as the dependent variable, and subjective memory measures and demographics as independent variables, as well as analyses of MMQ items vs. objective memory.

RESULTS

Subjective working memory impairment (Component II) was significant related to poor performance in objective episodic memory, according to correlation and regression analyses with demographic covariates. In contrast, ratings of impaired subjective declarative memory (Component I) were not related to poor objective memory performance.

CONCLUSIONS

Specific aspects of subjective memory related differentially to performance in specific objective memory tests. Clinicians and researchers might consider targeting working memory aspects of subjective memory tests, when seeking an estimate of objective memory performance.