Domains of awareness in Alzheimer's disease: The influence of executive function

Awareness of Disease and Its Domains in Young-onset and Late-onset Dementia: The Role of Executive Function

INTRODUCTION

Executive function (EF) involves a general cognitive process linked to strategic organization and control of complex goal-oriented tasks. In young-onset dementia (YOD), especially Alzheimer's disease, the symptoms that stand out in the initial stage are deficits in attention, visual-spatial function, praxis, and language. The present study aims to investigate what components of EF differ in young and late-onset dementia (LOD) and its impact on awareness and its domains.

METHODS

Using a cross-sectional design, we included 44 people with YOD and 70 with LOD. We assessed awareness and its domains, cognition, dementia severity, EF, functionality, and neuropsychiatric symptoms.

RESULTS

The YOD group was more impaired in general cognition ( P =0.017) and had a worse performance in Wechsler Digit Span Backward (DSB) ( P =0.007) and Phonemic fluency task (FAS) ( P =0.046) tests. In the LOD group, deficits in EF had a greater impact on awareness and on most domains (awareness total score, cognitive functioning and health condition, functional activity impairments and social function).

CONCLUSIONS

Our study findings support the heterogeneity of awareness, not only with regard to the difference between the domains and the measures of EF, but also to the groups studied.

Predictors of Awareness of Functional Ability in People with Dementia: The Contribution of Personality, Cognition, and Neuropsychiatric Symptoms - Findings from the IDEAL Program

INTRODUCTION

Discrepancy scores reflecting the difference between parallel ratings made by people living with dementia (PwD) in the mild-to-moderate stages and by their informants provide a way to investigate awareness of functional ability in relation to activities of daily living (ADL).

METHODS

Two measures of ADL (Functional Activities Questionnaire; Dependence Scale) were completed by 1,227 PwD and their informants in the IDEAL cohort study baseline assessment. Self-rated and informant-rated scores were used to calculate discrepancies, which were used as an indicator of awareness of functional ability. Smaller discrepancy scores were considered to reflect greater awareness on the part of PwD. PwD completed questionnaires on depression, personality, comorbidities, neuropsychiatric symptoms, and completed a measure of cognition. Informants provided ratings of stress. Univariable and multiple regressions were used to investigate factors related to ADL discrepancy.

RESULTS

A similar pattern of associations were found for both ADL discrepancy scores. Smaller discrepancy scores were associated with higher levels of depression, higher neuroticism, fewer neuropsychiatric symptoms, higher comorbidity, lower carer stress, and receipt of less than 1 hour of care per day from the informant.

DISCUSSION/CONCLUSION

There was a clear pattern of factors that were associated with greater awareness for both measures of functional ability. These factors associated with smaller discrepancy scores could be used to identify PwD who might benefit from targeted interventions to support their independence.

Cognitive Stimulation in Moderate Alzheimer's Disease

Cognitive stimulation is one of the non-pharmacological therapies recommended for dementia intervention. The present study evaluated the efficacy of an intervention based on cognitive stimulation in people with moderate Alzheimer's disease. Fifty-nine subjects with moderate dementia were randomly assigned to the stimulation group (N = 36) and the control group (N = 35). The treatment group received 16 intervention sessions cognitive tasks. All participants were evaluated with a battery of neuropsychological tests at three time points (pre, post, and follow-up). The treatment group showed significant increases in the three domains studied (memory, attention, and executive functions), although some of these effects were not maintained at follow-up. The control group progressively worsened. Cognitive stimulation was found to be an effective intervention for people with moderate Alzheimer's disease because it helped to maintain memory function, executive functions, and attention. However, the effects were minimized at the 3-month follow-up.

Altered Interplay Among Large-Scale Brain Functional Networks Modulates Multi-Domain Anosognosia in Early Alzheimer’s Disease

Decline in self-awareness is a prevalent symptom in Alzheimer’s disease (AD). Current data suggest that an early breakdown in the brain’s default mode network (DMN) is closely associated with the main symptomatic features in AD patients. In parallel, the integrity of the DMN has been shown to be heavily implicated in retained self-awareness abilities in healthy individuals and AD patients. However, the global contribution to awareness skills of other large-scale networks is still poorly understood. Resting-state functional magnetic resonance imaging (rs-fMRI) scans were acquired and pre-processed from 53 early-stage AD individuals. A group-level independent component analysis was run to isolate and reconstruct four intrinsic connectivity large-scale brain functional networks, namely left and right central executive fronto-parietal networks (FPN), salience network, and anterior and posterior DMN. Hypothesis-driven seed-based connectivity analyses were run to clarify the region-specific underpinnings of multi-domain anosognosia. Multiple regression models were run on large-scale network- and seed-based connectivity maps, including scores of memory, non-memory and total anosognosia obtained via the Measurement of Anosognosia Questionnaire. Memory anosognosia scores were associated with selective lower fronto-temporal connectivity and higher parieto-temporal connectivity. Non-memory anosognosia scores were associated with higher connectivity between the anterior DMN and the cerebellum, between the left medial prefrontal seeds and the contralateral prefrontal cortex, and between the left hippocampal seed and the left insula; lower connectivity was observed between the right prefrontal cortex and the right lingual seed. Lastly, total anosognosia scores were associated with large-scale network alterations, namely reduced left-FPN expression in the left posterior cingulate, reduced right-FPN expression in the left inferior lingual gyrus and adjacent inferior occipital cortex, and increased right-FPN expression in the right anterior cingulate. Seed-based analyses yielded significant connectivity differences only in the connectivity pattern associated with the left hippocampal seed by displaying lower intercommunication with the right prefrontal cortex, but higher connectivity with the left caudate nucleus. These findings support the hypothesis that alterations in functional connectivity of frontal lobe regions involved in executive-related mechanisms represent the neural correlates of domain-specific anosognosia in early AD. Up-regulated connectivity with subcortical structures appears to contribute to changes in the network dynamics interplay and fosters the appearance of anosognosia.