Executive Dysfunction and Reduced Self-Awareness in Patients With Neurological Disorders. A Mini-Review

Mood moderates the effects of prefrontal tDCS on executive functions: A meta-analysis testing the affective state-dependency hypothesis

BACKGROUND

In recent decades, numerous studies have investigated the effects of transcranial direct current stimulation (tDCS) on cognitive functioning. However, results of these studies frequently display inconsistency and pose challenges regarding replicability. The present work aimed at testing the hypothesis of mood as potential moderator of prefrontal tDCS effects on executive functions (EF). This hypothesis refers to the relationship between mood and EF, as well as to the association of mood with the dorsolateral prefrontal cortex (dlPFC) activity.

METHODS

We conducted a meta-analysis of 11 articles where the dlPFC was stimulated with anodal tDCS, EF were measured, and mood was assessed prior to the stimulation. We then conducted a meta-regression to examine whether mood moderated the tDCS effects on EF.

RESULTS

While no significant effect of tDCS on EF emerged from the meta-analysis, the meta-regression indicated that mood plays a significant role as moderator, with greater tDCS effects on EF in individuals with higher depressive symptoms.

LIMITATIONS

The limited number of studies included, the heterogeneous samples considered, and the limited generalizability to other non-invasive brain stimulation techniques and affective states.

CONCLUSIONS

Findings suggest that evaluating mood prior to stimulation could increase the sensitivity and specificity of tDCS application, and provide the first meta-analytic evidence in favor of the affective state-dependency hypothesis.

Components of self-awareness affecting caregiver burden: a long-term follow-up study

OBJECTIVE

Studies utilizing the discrepancy model of the Mayo-Portland Adaptability Inventory-4 (MPAI-4) have commonly used the cognitive and physical domains to estimate self-awareness. This study included other aspects of self-awareness such as awareness of one's social and emotional status and daily functioning to explore their effects on caregiver burden for ABI survivors.

METHODS

We studied 64 patient-caregiver pairs up to 29 years post-discharge from a holistic, milieu-oriented outpatient neurorehabilitation program. Discrepancy scores between ABI survivors' and caregivers' reports on the MPAI-4 subscales (i.e. Abilities, Adjustment, and Participation) and Total Score were used to determine self-awareness. Caregiver burden was measured using the Zarit Burden Interview (ZBI).

RESULTS

Exploratory linear regression analyses revealed that caregiver burden derived from the ZBI was predicted by the discrepancy scores generated from the Abilities (p < 0.0001), Adjustment (p < 0.01), Participation subscales (p = 0.01), and Total Score (p < 0.001), respectively. Among the exploratory models generated, the Total Score model had the highest predictive value (R2 = .33) for caregiver burden.

CONCLUSIONS

Measures of self-awareness should be comprehensive by considering diverse components of self-awareness. Increasing ABI survivors' self-awareness in different domains has the potential to effectively alleviate caregiver burden.

Unawareness of Apathy in Parkinson's Disease: The Role of Executive Dysfunction on Symptom Recognition

Altered self-awareness or anosognosia may impact patients' everyday life by interfering with their safe and independent functioning. Symptom awareness has been linked to executive dysfunctions caused by damage to frontal regions. Apathy is a frequent neuropsychiatric manifestation of Parkinson's disease (PD) and is considered a consequence of altered functioning of cortico-subcortical circuitries connecting the prefrontal cortex (PFC) with the basal ganglia. Thus, apathetic PD patients may be not be fully aware of their condition due to shared neuropathophysiological mechanisms. The present study aimed to explore the awareness of apathy in PD patients by comparing the self-reported evaluations with their caregivers' ratings. Moreover, we explored the clinical predictors of possible discrepancies and their consequences on patients' self-reported evaluation of quality of life (QoL). We found a fair agreement between patients' self-reports and caregivers' ratings on apathy scores, with patients reporting less severe apathetic symptoms, especially those related to executive and auto-activation processing, compared to their caregivers' reports. Executive functioning was found to mediate the relationship between disease stage and awareness of the apathetic state. Awareness of executive apathy impacted patients' self-reported QoL. Therefore, PD patients might be unaware of their apathetic symptoms, especially those with worse executive functioning, which plays a key role in metacognitive processes such as self-monitoring and error detection. Anosognosia for apathy in PD patients may affect their QoL perception and leads to misleading self-report evaluations that delay diagnosis and treatment.

The self and self-knowledge after frontal lobe neurosurgical lesions

BACKGROUND

Evidence suggests that damage to the frontal lobes can be associated with changes in cognitive and behavioral functioning and reduced awareness that such changes have occurred. In the current study, the Cognitive Awareness Model was used as a theoretical framework to explore knowledge of the self in people with acquired frontal lesions.

METHODS

Fifteen individuals with focal frontal lobe lesions (FFL) and their nominated informants were compared with fifteen healthy matched control-informant dyads on questionnaire measures designed to assess awareness of difficulties. Questionnaires were adapted to ensure all enabled pre- and post-injury perspectives to be gained from both patient and informant, and to allow novel exploration of awareness of deficits from a third person perspective.

RESULTS

Individuals with frontal lobe lesions showed adequate awareness of their post-surgery changes, which was substantiated by their informant report. Compared to the control group, the patient group was found to acknowledge more difficulties in current functioning. Perspective-taking ability was limited with both patients and controls being comparatively unreliable in assessing how they were perceived by others.

CONCLUSION

These results demonstrate that FLL patients are engaging in more atypical behaviors compared to healthy controls, but suggest that they are aware of and acknowledge these difficulties. The importance of obtaining multiple viewpoints when examining an individual's level of awareness and the clinical implications of this are discussed.

Exploring impaired self-awareness of motor symptoms in Parkinson's disease: Resting-state fMRI correlates and the connection to mindfulness

OBJECTIVE

To further explore the phenomenon of impaired self-awareness of motor symptoms in patients with Parkinson's Disease by using an evaluated measurement approach applied in previous studies, while also examining its connection with dispositional mindfulness and possible correlates of functional connectivity.

BACKGROUND

Recently, the phenomenon of impaired self-awareness has been studied more intensively by applying different measurement and imaging methods. Existing literature also points towards a possible connection with mindfulness, which has not been examined in a cross-sectional study. There is no data available concerning correlates of functional connectivity.

METHODS

Non-demented patients with idiopathic Parkinson's Disease without severe depression were tested for impaired self-awareness for motor symptoms following a psychometrically evaluated approach. Mindfulness was measured by applying the German version of the Five Facet Mindfulness Questionnaire. A subset of eligible patients underwent functional MRI scanning. Spearman correlation analyses were performed to examine clinical data. Whole-brain voxelwise regressions between seed-based connectivity and behavioral measures were calculated to identify functional connectivity correlates of impaired self-awareness scores.

RESULTS

A total of 41 patients with Parkinson's Disease were included. 15 patients successfully underwent resting-state fMRI scanning. Up to 88% of patients showed signs of impaired self-awareness. Awareness for hypokinetic movements correlated with total mindfulness values and three facets, while awareness for dyskinetic movements did not. Three significant clusters between scores of impaired self-awareness in general and for dyskinetic movements were identified linking behavioral measures with the functional connectivity of the inferior frontal gyrus, the right insular cortex, the supplementary motor area, and the precentral gyrus among others. Impaired self-awareness for hypokinetic movements did not have any neural correlate.

CONCLUSIONS

Clinical data is comparable with results from previous studies applying the same structured approach to measure impaired self-awareness in Parkinson's Disease. Functional connectivity analyses were conducted for the first time to evaluate neural correlates thereof. This data does not support a connection between impaired self-awareness of motor symptoms and dispositional mindfulness.

Computer-assisted training of executive functions in adult patients with non-progressive acquired brain damage - a pilot study on efficacy of a new therapeutic application

Executive dysfunction is most often caused by post-traumatic or post-stroke damage to the prefrontal regions of the brain. The aim of this study was to compare the efficacy of two computer-assisted therapy programs for executive dysfunctions in patients with acquired brain injury. Patients were trained using either a newly developed application ExeSystem (designed to help improve the ability to manage and control one's own behavior by performing tasks imitating natural, everyday situations) or a combination of two commercial applications RehaCom and CogniPlus. Data collected after a three-week period of therapy conducted in two 15-person groups of participants indicated comparable efficacy of both therapy programs in improving quality of daily functioning, executive attention, as well as planning and problem-solving but not memory. The improvement in social competence (p = .028) was the only advantage of therapy with the ExeSystem. Therapeutic interactions using computer programs were shown to be positively evaluated by patients (p < .01). This study confirmed at least equal efficacy of computer-based executive function therapy using ExeSystem compared to RehaCom and CogniPlus. However, despite the implementation of a more ecological and comprehensive approach to the content of a new application, the benefits of this approach were limited.

Causal effects of cingulate morphology on executive functions in healthy young adults

In this study, we want to explore evidence for the causal relationship between the anatomical descriptors of the cingulate cortex (surface area, mean curvature-corrected thickness, and volume) and the performance of cognitive tasks such as Card Sort, Flanker, List Sort used as instruments to measure the executive functions of flexibility, inhibitory control, and working memory. We have performed this analysis in a cross-sectional sample of 899 healthy young subjects of the Human Connectome Project. To the best of our knowledge, this is the first study using causal inference to explain the relationship between cingulate morphology and the performance of executive tasks in healthy subjects. We have tested the causal model under a counterfactual framework using stabilized inverse probability of treatment weighting and marginal structural models. The results showed that the posterior cingulate surface area has a positive causal effect on inhibition (Flanker task) and cognitive flexibility (Card Sort). A unit increase (+1 mm² ) in the posterior cingulate surface area will cause a 0.008% and 0.009% increase from the National Institute of Health (NIH) normative mean in Flankers (p-value <0.001), and Card Sort (p-value 0.005), respectively. Furthermore, a unit increase (+1 mm² ) in the anterior cingulate surface area will cause a 0.004% (p-value <0.001) and 0.005% (p-value 0.001) increase from the NIH normative mean in Flankers and Card Sort. In contrast, the curvature-corrected-mean thickness only showed an association for anterior cingulate with List Sort (p = 0.034) but no causal effect.

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.

Executive Functions in Alzheimer’s Disease: A Systematic Review

Background: In Alzheimer’s disease, in addition to memory, attention has been given to cognitive testing due to its interface and connection with memory. Objective: The aim of this study is to take a global view of executive functions and place the concept within the theoretical framework of Alzheimer’s disease dementia, verifying their role in the cognitive functioning of the human mind, as well as how they are compromised in this pathology. Methods: An initial search was carried out in databases such as PubMed, ScienceDirect, and Web of Science. The guiding question presented at the end of the introduction was elaborated from the PICO/PIO/PEO strategy. The selected articles, therefore, answered the guiding question, were made available in full, and published in the period from 2000 to 2020. Studies without specific methodology and which correlated with other diseases or other types of dementia were excluded. To meet the objective, an integrative literature review was adopted. Results: The results indicate that, although the tests to verify the performance of cognitive functions have their limitations, they bring some evidence that they have been compromised, especially when analyzed periodically during the development of dementia. Conclusion: It is concluded that there is an interference of executive functions in function of Alzheimer’s and that memory and attention are the most evident in this type of dementia.

Neuropsychiatric Symptoms Mediated the Relationship Between Odor Identification and Cognition in Alzheimer's Disease Spectrum: A Structural Equation Model Analysis

Background: Odor identification dysfunction is an early predictor of the development of Alzheimer's disease (AD), but neuropsychiatric symptoms (NPS), which are common in AD and mild cognitive impairment (MCI), are also associated with odor identification dysfunction. Whether NPS affect the specificity of using odor identification dysfunction to predict cognitive decline in AD and MCI remains unclear.

Methods: Patients (233 with MCI and 45 with AD) and 45 healthy controls (HCs) underwent assessments of odor identification (Sniffin' Sticks), NPS (Neuropsychiatric Inventory-12), and cognitive function (global cognition, memory, language, executive function, visual-spatial skill, and attention). Structural equation modeling (SEM) with bootstrapping estimation was conducted to explore the relationships between odor identification, NPS, and cognition.

Results: Patients with NPS showed significantly worse performance in odor identification and cognition than patients without NPS and HCs. The SEM showed odor identification to be positively associated with cognition, and cognition had special indirect effects on odor identification through affective and psychosis symptoms (two factors extracted from Neuropsychiatric Inventory-12). Additionally, affective and psychosis symptoms partially mediated the effect of cognition on odor identification.

Conclusion: Neuropsychiatric symptoms are associated with odor identification dysfunction in patients with AD and MCI. Studies exploring the relationship between odor identification dysfunction and cognitive decline in patients with AD and MCI should include an assessment of affective and psychosis symptoms, and adjust their confounding effects.

Standardization and diagnostic utility of the Frontal Assessment Battery for healthy people and patients with dementia in the Chilean population

The Frontal Assessment Battery (FAB) is a screening test that measures executive functions. Although this instrument has been validated in several countries, its diagnostic utility in a Chilean population has not been studied yet.

Objectives

This study aimed to (1) adapt FAB in a Chilean population; (2) study the psychometric properties of the FAB in a Chilean population; (3) assess the sociodemographic influence in the performance of the FAB in a sample of healthy controls (HC); and (4) develop normative data for this healthy group.

Methods

A HC (n=344) and a group of patients with dementia (n=156) were assessed with the Chilean version of FAB.

Results

FAB showed good internal consistency (Cronbach's alpha=0.79) and acceptable validity based on the relationship with other variables. Factor analysis showed the unidimensionality of the instrument. Significant differences were found in the total FAB value between the HC and dementia groups. With the matched sample, the established cutoff point was 13.5, showing a sensitivity of 80.8% and a specificity of 90.4%. Regression analysis showed that education and age significantly predicted FAB performance in the healthy group. Finally, normative data are provided.

Conclusions

This study shows that FAB is a useful tool to discriminate between healthy people and people with dementia. However, further studies are needed to explore the capacity of the instrument to characterize the dysexecutive syndrome in people with dementia in the Chilean population.

Awareness of Performance on a Functional Cognitive Performance-Based Assessment Across the Adult Lifespan

As people age, their cognitive skills and ability to complete complex instrumental activities of daily living often decline in subtle ways. Older adults who are aware of these slight cognitive and functional changes spontaneously adapt and implement strategies to maximize performance. On the other hand, older adults with limited self-awareness are less likely to adjust performance or initiate compensatory strategies as they may not recognize the need to do so. This places them at higher risk of functional decline and loss of independence. Research on awareness of functional performance in healthy adults is, however, limited, and there is a paucity of assessment tools available to address questions of awareness and strategy use in functional tasks. We used the Weekly Calendar Planning Activity (WCPA) - a performance-based assessment of functional cognition including measures of awareness and strategy use - to investigate differences in performance, awareness, and strategy use across the adult lifespan. The WCPA requires examinees to schedule appointments into a weekly calendar while following rules designed to increase task demands. Healthy adults (n=342) from ages 18-92 were observed for strategy use and error recognition, while a post-test interview probed participants' reported strategy use and estimation of accuracy. The discrepancy between participant estimation and actual accuracy provided a measure of online awareness of performance where a larger estimation discrepancy indicated over-estimation of performance. Performance on the WCPA declined across the adult lifespan. Older adults were less likely to use self-monitoring strategies and used less effective strategies overall. Overestimation was associated with use of fewer strategies and lower accuracy in all age groups. Importantly, twice as many older adults overestimated compared to younger adults. Furthermore, the subset of older adults who had good awareness of performance was more likely to use effective strategies, to recognize errors, and achieved accuracy on par with their younger counterparts. Our results emphasize the importance of examining self-awareness of performance and analyzing the strategies used to perform a complex functional task. This information can provide a foundation for early detection of functional decline in aging and for designing interventions to maximize functional independence in aging.

New insights into neural networks of error monitoring and clinical implications: a systematic review of ERP studies in neurological diseases

Error monitoring allows for the efficient performance of goal-directed behaviors and successful learning. Furthermore, error monitoring as a metacognitive ability may play a crucial role for neuropsychological interventions, such as rehabilitation. In the past decades, research has suggested two electrophysiological markers for error monitoring: the error-related negativity (ERN) and the error positivity (Pe), thought to reflect, respectively, error detection and error awareness. Studies on several neurological diseases have investigated the alteration of the ERN and the Pe, but these findings have not been summarized. Accordingly, a systematic review was conducted to understand what neurological conditions present alterations of error monitoring event-related potentials and their relation with clinical measures. Overall, ERN tended to be reduced in most neurological conditions while results related to Pe integrity are less clear. ERN and Pe were found to be associated with several measures of clinical severity. Additionally, we explored the contribution of different brain structures to neural networks underlying error monitoring, further elaborating on the domain-specificity of error processing and clinical implications of findings. In conclusion, electrophysiological signatures of error monitoring could be reliable measures of neurological dysfunction and a robust tool in neuropsychological rehabilitation.

Alzheimer's Disease and Empathic Abilities: The Proposed Role of the Cingulate Cortex

In recent years there has been increasing interest in examining the role of empathic abilities in Alzheimer’s disease (AD). Empathy, the ability to understand and share another person’s feelings, implies the existence of emotional and cognitive processes and is a pivotal aspect for success in social interactions. In turn, self-empathy is oriented to one’s thoughts and feelings. Decline of empathy and self-empathy can occur during the AD continuum and can be linked to different neuroanatomical pathways in which the cingulate cortex may play a crucial role. Here, we will summarize the involvement of empathic abilities through the AD continuum and further discuss the potential neurocognitive mechanisms that contribute to decline of empathy and self-empathy in AD.

Virtual Reality as a Technological-Aided Solution to Support Communication in Persons With Neurodegenerative Diseases and Acquired Brain Injury During COVID-19 Pandemic

The COVID-19 poses an ongoing threat to lives around the world and challenges the existing public health and medical service delivery. The lockdown or quarantine measures adopted to prevent the spread of COVID-19 has caused the interruption in ongoing care and access to medical care including to patients with existing neurological conditions. Besides the passivity, isolation, and withdrawal, patients with neurodegenerative diseases experience difficulties in communication due to a limited access to leisure opportunities and interaction with friends and relatives. The communication difficulties may exacerbate the burden on the caregivers. Therefore, assistive-technologies may be a useful strategy in mitigating challenges associated with remote communication. The current paper presents an overview of the use of assistive technologies using virtual reality and virtual body ownership in providing communication opportunities to isolated patients, during COVID-19, with neurological diseases and moderate-to-severe communication difficulties. We postulate that the assistive technologies-based intervention may improve social interactions in patients with neurodegenerative diseases and acquired brain injury-thereby reducing isolation and improving their quality of life and mental well-being.

Psychometric properties of the Dysexecutive Questionnaire (DEX): a study with Brazilian older adults

Abstract This study aimed to verify the psychometric properties of the Dysexecutive Questionnaire (DEX) through exploratory factor analysis (EFA), evidence of reliability, and convergent validity, in a sample of neurologically preserved older adults. Participants were 345 older adults who answered, in addition to DEX, a sociodemographic and clinical questionnaire, the Mini-Mental State Examination (MMSE), and two verbal fluency tasks. The EFA was conducted through Parallel Analysis based on the generation of a polychoric correlation matrix, as well as Pearson’s correlation between the DEX scores, age, education, MMSE, and verbal fluency tasks. According to the EFA, the extraction of two factors (“Inhibition” and “Social Regulation and Planning”) was suggested and DEX was negatively associated with age and MMSE. In conclusion, DEX presented a satisfactory factorial structure for older adults, which can be considered a reliable self-report measure for complaints of executive functions.