Psychological functioning in Parkinson's disease post-deep brain stimulation: Self-regulation and executive functioning

Deep Brain Stimulation in Parkinson Disease: A Meta-analysis of the Long-term Neuropsychological Outcomes

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or globus pallidum internus (GPi) improves motor functions in patients with Parkinson's disease (PD) but may cause a decline in specific cognitive domains. The aim of this systematic review and meta-analysis was to assess the long-term (1-3 years) effects of STN or GPi DBS on four cognitive functions: (i) memory (delayed recall, working memory, immediate recall), (ii) executive functions including inhibition control (Color-Word Stroop test) and flexibility (phonemic verbal fluency), (iii) language (semantic verbal fluency), and (iv) mood (anxiety and depression). Medline and Web of Science were searched, and studies published before July 2021 investigating long-term changes in PD patients following DBS were included. Random-effects model meta-analyses were performed using the R software to estimate the standardized mean difference (SMD) computed as Hedges' g with 95% CI. 2522 publications were identified, 48 of which satisfied the inclusion criteria. Fourteen meta-analyses were performed including 2039 adults with a clinical diagnosis of PD undergoing DBS surgery and 271 PD controls. Our findings add new information to the existing literature by demonstrating that, at a long follow-up interval (1-3 years), both positive effects, such as a mild improvement in anxiety and depression (STN, Hedges' g = 0,34, p = 0,02), and negative effects, such as a decrease of long-term memory (Hedges' g = -0,40, p = 0,02), verbal fluency such as phonemic fluency (Hedges' g = -0,56, p < 0,0001), and specific subdomains of executive functions such as Color-Word Stroop test (Hedges' g = -0,45, p = 0,003) were observed. The level of evidence as qualified with GRADE varied from low for the pre- verses post-analysis to medium when compared to a control group.

Heart rate variability in relation to cognition and behavior in neurodegenerative diseases: A systematic review and meta-analysis

Neurodegenerative diseases, which frequently present with neuropsychiatric symptoms related to prefrontal cortical dysfunction, can alter the integrity of the neural networks involved in central autonomic nervous system regulation, which is proposed to be indexed by heart rate variability (HRV). We systematically reviewed the characteristics, methodology and outcomes of 27 studies of HRV in relation to measures of cognition and behavior in neurodegenerative conditions, and assessed the strength of this relationship, cross-sectionally, across 18 studies. A significant, moderate effect was observed (r = 0.25), such that higher HRV was related to better cognitive and behavioral scores, which was not influenced by mean age or cognitive status. There was no evidence of small-study effects but we could not rule out publication bias, and other factors may have contributed to heterogeneity between studies. Our findings support the proposal that HRV may be a marker of self-regulatory processes in neurodegenerative conditions, and further research on this association is needed in relation to neuropsychiatric symptoms and alongside neuroimaging methods.

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Heart rate variability is proposed to be influenced by a neural network involved in autonomic regulation.

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Neurodegenerative processes alter the integrity of the central autonomic network.

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We reviewed studies of HRV and cognition/behavior in neurodegenerative diseases.

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We found a moderate correlation between HRV and measures of cognition/behavior.

Stability of Subjective Executive Functioning in Older Adults with aMCI and Subjective Cognitive Decline

OBJECTIVE

Subjective memory concerns are characteristic of individuals with amnestic mild cognitive impairment (aMCI) and subjective cognitive decline (SCD), though subjective changes in executive functions have also been reported. In a cohort study, we examined the temporal stability of subjective report of executive functioning in a high education (mean = 16.8 years) sample of cognitively normal (CN) older adults and those with aMCI or SCD.

METHOD

Participants (CN, n = 22; aMCI, n = 21; SCD, n = 24) and their informants completed the BRIEF-A and neuropsychological tests at two time points separated by approximately 1 year.

RESULTS

Analyses focused on those with diagnostic stability (95.7%). Participants with aMCI and SCD, and their informants, endorsed worse executive functions relative to CN at both time points. No group by time interaction was observed for subjective or objective measures of executive function.

CONCLUSIONS

Diagnostically stable CN older adults, and those with prodromal dementia conditions, report stable executive functioning at 1-year follow-up.

The Structure of Self-Regulation and Its Psychological and Physical Health Correlates in Older Adults

Self-regulation refers to effortful control over one's thoughts, emotions, choices, impulses, and behaviors, and has implications for older adults' health. Executive function, physiological, and subjective indices have all been proposed to reflect self-regulation. Pairwise associations among these indices have been previously examined; however, a self-regulation constellation encompassing all of these indices has never been tested in older adults. The present study described the relationships among indices of self-regulation and tested their between- and within-person associations with upstream personality factors (conscientiousness) and downstream psychological and physical health in 149 older adults aged 60-93 years, assessed semi-annually for five years (up to 10 waves). Indices of self-regulation were only modestly correlated with each other but were each associated with health. Better executive function was associated with better psychological and physical health between and within people, whereas higher heart rate variability was associated with psychological health within people. Better subjective self-regulation had the most between- and within-person associations with better psychological and physical health. Conscientiousness was associated with subjective self-regulation and better psychological and physical health. These findings support the non-unitary nature of self-regulation in older adults and the health relevance of each of its indices between and within older adults. The aging process may change how the indices relate to each other, and older adults may draw more on certain self-regulatory components over others, given limited resources. Subjective self-regulation may be an important final common pathway to psychological and physical health in older adults.

Goal-directed behavior in individuals with mild Parkinson's disease: Role of self-efficacy and self-regulation

Introduction

Deficits in goal-directed behavior are common in individuals with Parkinson's disease (PD) and have been ascribed to apathy. In addition to apathy, individuals' beliefs in their competence (self-efficacy) and capacity to regulate emotions, thoughts, and actions (self-regulation) are critical skills for goal-directed behavior. We investigated these skills and their relationship to motor and non-motor symptoms in individuals with PD. We also examined the neural correlates of these skills using functional magnetic resonance imaging (fMRI).

Methods

We enrolled 35 subjects with mild PD (Hoehn and Yahr stage ≤2.5) and used the new general self-efficacy (NGSES) and self-regulation scales (SRS). We correlated the scores on these scales with measures of cognition, anxiety, depression, apathy, fatigue, quality of life, and disease burden using stepwise regression analyses. We collected resting-state fMRI data in a 3-Tesla scanner and computed the pairwise functional connectivity among nodes of major networks. We correlated the connectivity maps with the NGSES and SRS scores.

Results

Our PD cohort demonstrated intact NGSES and SRS scores compared with respective population data. These scores showed significant negative correlation with apathy and disease burden. Stronger connectivity in the salience network and decoupling from the default mode network supported self-efficacy and self-regulation.

Conclusions

Self-efficacy and self-regulation capacity seems preserved, but vulnerable to disease-related factors in individuals with mild PD. Educational programs cultivating this capacity could improve the coping skills of these individuals. Functional connectivity changes in salience and default mode networks may serve as neurobiological markers to demonstrate the effectiveness of such interventions.

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Self-efficacy and self-regulation skills are critical for goal-directed behavior.

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These skills and their neural bases were tested in mild Parkinson's disease.

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These skills are intact and correlate negatively with apathy and disease burden.

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Functional connectivity among nodes of major neural networks supports these skills.

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These skills can be cultivated in educational programs for better health outcomes.