Autobiographical Memory Performance in Alzheimer’s Disease Depends on Retrieval Frequency

Cognitive Decline in Alzheimer's Disease

Deficits in memory, language, and other cognitive domains that impact an individual's ability to perform necessary tasks of daily living are symptoms of dementia, which is a major cause of death and disability in older adults. As the global population continues to age, deepening our understanding of dementia is crucial. Alzheimer's disease is the leading cause of dementia and accounts for between 60% and 80% of total dementia cases. Declines in episodic memory are considered a hallmark of Alzheimer's disease and occur early in disease progression. The cognitive effects of Alzheimer's disease differ from the cognitive changes expected in nonpathological or normal aging. While some cognitive changes are expected as a part of the aging processes, the declines in cognition associated with Alzheimer's disease are to a degree that the individual diagnosed with the disease is unable to function independently in activities of daily living. In this review, we will discuss how cognition is impacted by both normal and pathological aging, with a focus on Alzheimer's disease. We describe the progressive nature of Alzheimer's disease, as well as the effects of each stage of the disease on cognition.

Speech patterns in responses to questions asked by an intelligent virtual agent can help to distinguish between people with early stage neurodegenerative disorders and healthy controls

Previous research has provided strong evidence that speech patterns can help to distinguish between people with early stage neurodegenerative disorders (ND) and healthy controls. This study examined speech patterns in responses to questions asked by an intelligent virtual agent (IVA): a talking head on a computer which asks pre-recorded questions. The study investigated whether measures of response length, speech rate and pausing in responses to questions asked by an IVA help to distinguish between healthy control participants and people diagnosed with Mild Cognitive Impairment (MCI) or Alzheimer's disease (AD). The study also considered whether those measures can further help to distinguish between people with MCI, people with AD, and healthy control participants (HC). There were 38 people with ND (31 people with MCI, 7 people with AD) and 26 HC. All interactions took place in English. People with MCI spoke fewer words compared to HC, and people with AD and people with MCI spoke for less time than HC. People with AD spoke at a slower rate than people with MCI and HC. There were significant differences across all three groups for the proportion of time spent pausing and the average pause duration: silent pauses make up the greatest proportion of responses from people with AD, who also have the longest average silent pause duration, followed by people with MCI then HC. Therefore, the study demonstrates the potential of an IVA as a method for collecting data showing patterns which can help to distinguish between diagnostic groups.

Episodic and Semantic Autobiographical Memory in Mild Cognitive Impairment (MCI): A Systematic Review

INTRODUCTION

Mild cognitive impairment (MCI) is a syndrome defined as a decline in cognitive performance greater than expected for an individual according to age and education level, not interfering notably with daily life activities. Many studies have focused on the memory domain in the analysis of MCI and more severe cases of dementia. One specific memory system is represented by autobiographical memory (AM), which has been largely studied in Alzheimer's disease and its effect on AM; however, the impairment of AM in moderate forms of decline, such as MCI, is still controversial.

OBJECTIVE

The main aim of this systematic review is to analyze the functioning of autobiographical memory in patients with MCI, considering both the semantic and the episodic components.

MATERIALS

The review process was conducted according to the PRISMA statement. The search was conducted until 20 February 2023 in the following bibliographical databases: PubMed, Web of Science, Scopus, and PsycInfo, and twenty-one articles were included.

RESULTS

The results highlight controversial findings concerning the semantic component of AM since only seven studies have found a worse semantic AM performance in patients with MCI compared to the HC group. The results of impaired episodic AM in individuals with MCI are more consistent than those concerning semantic AM.

CONCLUSIONS

Starting from the evidence of this systematic review, further studies should detect and investigate the cognitive and emotional mechanisms that undermine AM performance, allowing the development of specific interventions targeting these mechanisms.

Change in the psychological self in people living with dementia: A scoping review

Alterations in one's sense of self are often considered a significant psychological symptom of dementia. However, the self is not a unified construct; it consists of a set of closely connected, yet substantive, manifestations which might not be equally impacted by dementia. Recognising the multidimensional nature of the self, the current scoping review aimed to explore the nature and scope of the evidence demonstrating change in the psychological self in people living with dementia. Adopting a cognitive psychological framework, a hundred and five (105) quantitative and qualitative studies were reviewed, and findings were organised into three main types of self-manifestations: high-order manifestations, functional aspects of the self, and foundational manifestations. Overall, the results show that although there are alterations in some of these different manifestations of the self, these do not imply a global loss of selfhood. Despite notable cognitive changes during dementia, it seems that preserved aspects of self may be enough to compensate for potential weakening of some self-processes such as autobiographical recall. Better understanding alterations in selfhood is key to addressing psychological symptoms of people living with dementia, such as feelings of disconnection and reduced agency, and may inform new pathways for dementia care interventions.

DMapp: a developing promising approach to monitor symptoms progression and stimulate memory in Italian people with cognitive impairments

BACKGROUND

Based on recent researches on the use of natural language processing techniques for very early detection of cognitive decline and the benefits of cognitive stimulation for people with cognitive impairments, the Dementia Monitoring application (DMapp) is developed inside the Memento project.

AIMS

The aims of this work are: (1) to present DMapp; (2) to report the results of two preliminary studies on DMapp; (3) to describe the clinical and experimental potentiality of DMapp.

METHODS

Italian people with the diagnosis of mild cognitive impairment due to Alzheimer's disease or dementia due to Alzheimer's Disease with a Mini-Mental-State-Examination between 24 and 28 (inclusive) were involved in the DMapp development prototype during the Lab Trial (4 subjects) and Filed Trial (5 subjects) of the Memento project. Qualitative and quantitative data were collected to evaluate participants' opinions, the DMapp ability to perform the automatic analysis of the speech and participants' visible emotional state effective. Ad hoc interviews, the Observed Emotion Rating Scale and performance metrics to solve different tasks were used. The relation between cognitive measures (global cognitive measures) and linguistic indexes values was considered using Euclidean distances between the participants.

RESULTS

Linguistic indexes were calculated and seemed to classify the participants' performance as expected from cognitive measures. The DMapp was appreciated by people with cognitive impairment. Positive emotions were present.

CONCLUSION

DMapp seems an interesting approach to monitor dementia symptoms progression and stimulate memory. Possible developments and open questions are discussed.

A Longitudinal Study of Episodic and Semantic Autobiographical Memory in aMCI and Alzheimer's Disease Patients

BACKGROUND

The main objective of this study was to analyze the evolution of autobiographical memory (both episodic and semantic) in patients with mild cognitive impairment, patients with Alzheimer's disease, and a healthy control group. We compared these groups at two time points: first, at baseline, and in a follow-up after 18 months.

METHOD

Twenty-six healthy older adults, 17 patients with mild amnestic cognitive impairment, and 16 patients with Alzheimer's disease, matched on age and educational level, were evaluated at both time points with the Autobiographical Memory Interview.

RESULTS

The results showed significant longitudinal deterioration in episodic and semantic autobiographical memory in patients with mild cognitive impairment and in patients with Alzheimer's disease, but not in healthy older adults.

CONCLUSIONS

The deterioration of episodic and semantic autobiographical memory in AD is confirmed; however, although the episodic was impaired in aMCI, a pattern that evolved toward deterioration over a period of eighteen months was observed for the semantic autobiographical memory.

Characterising spoken responses to an intelligent virtual agent by persons with mild cognitive impairment

The diagnosis of Mild Cognitive Impairment (MCI) characterises patients at risk of dementia and may provide an opportunity for disease-modifying interventions. Identifying persons with MCI (PwMCI) from adults of a similar age without cognitive complaints is a significant challenge. The main aims of this study were to determine whether generic speech differences were evident between PwMCI and healthy controls (HC), whether such differences were identifiable in responses to recent or remote memory questions, and to determine which speech variables showed the clearest between-group differences. This study analysed recordings of 8 PwMCI (5 females, 3 males) and 14 HC of a similar age (8 females, 6 males). Participants were recorded interacting with an intelligent virtual agent: a computer-generated talking head on a computer screen which asks pre-recorded questions when prompted by the interviewee through pressing the next key on a computer keyboard. Responses to recent and remote memory questions were analysed. Mann-Whitney U tests were used to test for statistically significant differences between PwMCI and HC on each of 12 speech variables, relating to temporal characteristics, number of words produced and pitch. It was found that compared to HC, PwMCI produce speech for less time and in shorter chunks, they pause more often and for longer, take longer to begin speaking and produce fewer words in their answers. It was also found that the PwMCI and HC were more alike when responding to remote memory questions than when responding to recent memory questions. These findings show great promise and suggest that detailed speech analysis can make an important contribution to diagnostic and stratification systems in patients with memory complaints.

The Petrified Self 10 Years After: Current Evidence for Mnemonic anosognosia

Lack of awareness about disease, its symptoms and consequences, also termed anosognosia, is a common feature of Alzheimer's disease (AD). It has been hypothesized that memory disorder may be a key contributing factor to anosognosia, with people with AD not being able to update their personal information about performance and relying on older consolidated material about ability. This potentially outdated sense of self has been named, as a metaphor, the petrified self. In the current review, evidence from the past 10 years in relation to this concept is critically appraised. In particular, focus is given to empirical evidence produced on anterograde memory deficits about performance, the profile of autobiographical retrograde memory loss and the role of frontal lobes in anosognosia in AD. Finally, wider consequences of this metaphor for the understanding of selfhood in dementia are discussed.

Correlation Between Hippocampal Volume and Autobiographical Memory Depending on Retrieval Frequency in Healthy Individuals and Patients with Alzheimer's Disease

The hippocampus plays an indispensable role in episodic memory, particularly during the consolidation process. However, its precise role in retrieval of episodic memory is still ambiguous. In this study, we investigated the correlation of hippocampal morphometry and the performance in an autobiographical memory task in 27 healthy controls and 24 patients suffering from Alzheimer's disease (AD). Most importantly, correlations were defined separately and comparatively for memory contents with different retrieval frequency in the past. In healthy subjects, memory performance for seldom retrieved autobiographical events was significantly associated with gray matter density in the bilateral hippocampus, whereas this correlation was not present for events with high retrieval frequency. This pattern of findings confirms that retrieval frequency plays a critical role in the consolidation of episodic autobiographical memories, thereby making them more independent of the hippocampal system. In AD patients, on the other hand, successful memory retrieval appeared to be related to hippocampal morphometry irrespective of the contents' retrieval frequency, comprising events with high retrieval frequency, too. The observed differences between patients and control subjects suggest that AD-related neurodegeneration not only impairs the function, but also decreases the functional specialization of the hippocampal memory system, which, thus, may be considered as marker for AD.