The Structural and Functional Neuroanatomy of Post-Stroke Depression and Executive Dysfunction: A Review of Neuroimaging Findings and Implications for Treatment

Vagus nerve stimulation for stroke rehabilitation: Neural substrates, neuromodulatory effects and therapeutic implications

Paired vagus nerve stimulation (VNS) has emerged as a promising strategy to potentiate recovery after neurological injury. This approach, which combines short bursts of electrical stimulation of the vagus nerve with rehabilitation exercises, received approval from the US Food and Drug Aministration in 2021 as the first neuromodulation-based therapy for chronic stroke. Because this treatment is increasingly implemented in clinical practice, there is a need to take stock of what we know about this approach and what we have yet to learn. Here, we provide a survey on the foundational basis of VNS therapy for stroke and offer insight into the mechanisms that underlie potentiated recovery, focusing on the principles of neuromodulatory reinforcement. We discuss the current state of observations regarding synaptic reorganization in motor networks that are enhanced by VNS, and we propose other prospective loci of neuromodulation that should be evaluated in the future. Finally, we highlight the future opportunities and challenges to be faced as this approach is increasingly translated to clinical use. Collectively, a clearer understanding of the mechanistic basis of VNS therapy may reveal ways to maximize its benefits.

Analysis of radiological features in patients with post-stroke depression and cognitive impairment

Post-stroke depression (PSD) and post-stroke cognitive impairment (PSCI) are common complications following a stroke, significantly impacting the quality of life and survival time of survivors. Currently, the comorbidity of PSCI and PSD is receiving increasing attention, as they share some common clinical characteristics, mechanisms, risk factors, radiological features, and treatment strategies. They influence each other, with the clinical prevalence of PSD comorbid with PSCI reaching as high as 26.15 %. The prevention, screening, diagnosis, and treatment of PSD and PSCI require collaboration across clinical, radiological, and neuropsychological evaluations. This paper aims to summarize the common radiological features of both conditions from a radiological perspective, which may aid in identifying early screening and predictive imaging biomarkers.

Pathophysiology, Assessment, and Management of Post-Stroke Cognitive Impairment, Depression, and Fatigue

Post-stroke cognitive impairment, depression, and fatigue are common, persistent, and disabling. This review summarizes current knowledge on the pathophysiology, assessment, and management of these debilitating neuropsychiatric sequelae of stroke. We briefly review evolving knowledge on the neural mechanisms and risk factors for each condition. We describe patient-reported outcome measures and clinician rating techniques that can be used to assist in screening and comprehensive assessment. We then discuss behavioral and pharmacologic management strategies. Heterogeneity of stroke remains a challenge in management and new research is still needed to optimize and personalize treatments for stroke survivors.

Research status and global trends of late-life depression from 2004 to 2023: bibliometric analysis

Background

Global research hotspots and future research trends in the neurobiological mechanisms of late-life depression (LLD) as well as its diagnosis and treatment are not yet clear.

Objectives

This study profiled the current state of global research on LLD and predicted future research trends in the field.

Methods

Literature with the subject term LLD was retrieved from the Web of Science Core Collection, and CiteSpace software was used to perform econometric and co-occurrence analyses. The results were visualized using CiteSpace, VOSviewer, and other software packages.

Results

In total, 10,570 publications were included in the analysis. Publications on LLD have shown an increasing trend since 2004. The United States and the University of California had the highest number of publications, followed consecutively by China and England, making these countries and institutions the most influential in the field. Reynolds, Charles F. was the author with the most publications. The International Journal of Geriatric Psychiatry was the journal with the most articles and citations. According to the co-occurrence analysis and keyword/citation burst analysis, cognitive impairment, brain network dysfunction, vascular disease, and treatment of LLD were research hotspots.

Conclusion

Late-life depression has attracted increasing attention from researchers, with the number of publications increasing annually. However, many questions remain unaddressed in this field, such as the relationship between LLD and cognitive impairment and dementia, or the impact of vascular factors and brain network dysfunction on LLD. Additionally, the treatment of patients with LLD is currently a clinical challenge. The results of this study will help researchers find suitable research partners and journals, as well as predict future hotspots.

Post-Stroke Depression in Older Adults: An Overview

Detailed data on post-stroke depression (PSD) in older adults are limited in spite of the high vulnerability of this population to stroke. In fact, PSD prevalence in older adults ranges from 16.0 to 43.9%; however, timing and instruments of evaluation often differ significantly across all available studies. The etiology, genetic and inflammatory factors, as well as structural brain alterations, are claimed as part of a multifaceted mechanism of action in PSD onset. Thus, the aim of this narrative review was to further elaborate on the prevalence, etiology, diagnosis, consequences and treatment of PSD in older adults. The consequences of PSD in older adults may be devastating, including a poor functional outcome after rehabilitation and lower medication adherence. In addition, lower quality of life and reduced social participation, higher risk of new stroke, rehospitalization, and mortality have been reported. In this scenario, treating PSD represents a crucial step to prevent these complications. Both pharmacological and non-pharmacological therapies are currently available. The pharmacological treatment utilizes antidepressant drugs, such as selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TAs) and new multimodal antidepressants (NMAs). Non-pharmacological therapies include psychological interventions and non-invasive brain stimulation techniques, while excluding drug administration. In the general population experiencing PSD, SSRIs (sertraline in particular) are the most prescribed, whereas the combination of antidepressants and psychotherapy is underused. Furthermore, about one-third of patients do not receive treatment for PSD. In regard to older adults with PSD, the possibility of more adverse effects or contraindications to antidepressant prescription due to comorbidities may limit the therapeutic window. Although drugs such as citalopram, escitalopram, sertraline, venlafaxine, and vortioxetine are usually well tolerated by older patients with PSD, the few randomized controlled trials (RCTs) specifically considering older adults with PSD have been conducted with fluoxetine, fluvoxamine, reboxetine, citalopram and nortriptyline, often with very small patient samples. Furthermore, data regarding the results of non-pharmacological therapies are scarce. High-quality RCTs recruiting large samples of older adults are needed in order to better manage PSD in this population. In addition, adequate screening and diagnosis instruments, with reliable timing of evaluation, should be applied.

Research progress on post-stroke depression

Stroke is a highly prevalent and widely detrimental cardiovascular disease, frequently resulting in impairments of both motor function and neural psychological capabilities, such as post-stroke depression (PSD). PSD is the most prevalent neuropsychological disorder among stroke patients, characterized by persistent emotional lowness and diminished interest as its primary features. This article summarizes the mechanism research, animal models and related treatments of PSD. Further improvements are needed in the screening of research subjects and the construction of animal models in the study of PSD. At the same time, in the study of the mechanism of PSD, we need to consider the interaction between multiple systems. The treatment of PSD requires more careful consideration. This can help us to find something new in the study of the mechanism of complex PSD, which provides a new direction for us to develop new treatment delivery.

Longitudinal relationships between depressive symptoms and cognitive function after stroke: A cross-lagged panel design

OBJECTIVE

Stroke is a leading cause of mortality and disability. This study aimed to investigate the temporal and directional relationships between post-stroke depressive symptoms and cognitive impairment using a cross-lagged panel design. Depressive symptoms and cognitive impairment are two common post-stroke complications. However, the precise underlying mechanism remains unclear despite their close relationship. Therefore, elucidating the causal relationship between these two issues is of great clinical significance for improving the poor prognosis of stroke.

METHODS

This study employed a hospital-based multicenter prospective cohort design. A total of 610 patients with ischemic stroke were eligible. Depressive symptoms (measured using the seventeen-item Hamilton Rating Scale for Depression) and cognitive function (measured using the Montreal Cognitive Assessment) were assessed at baseline and the 12-month follow-up. Spearman's correlation was used to examine the correlation between cognitive function and depressive symptoms. Additionally, a cross-lagged panel analysis was employed to elucidate the causal relationship between these factors after adjusting for potential covariates.

RESULTS

The results of a four-iteration cross-lagged panel analysis substantiated a bidirectional relationship between post-stroke depressive symptoms and cognitive function over time. Specifically, higher scores for early depressive symptoms were associated with lower scores for later cognitive function; additionally, higher baseline cognitive function scores were associated with lower depressive symptom scores at a later point.

CONCLUSION

This study establishes a reciprocally causal long-term relationship between depressive symptoms and cognitive function after an ischemic stroke. Therefore, interventions aimed at improving cognitive function and ameliorating depressive symptoms may positively affect both cognition and mood.

TRIAL REGISTRATION

ChiCTR-ROC-17013993.

Reward network dysfunction is associated with cognitive impairment after stroke

Stroke survivors not only suffer from severe motor, speech and neurocognitive deficits, but in many cases also from a "lack of pleasure" and a reduced motivational level. Especially apathy and anhedonic symptoms can be linked to a dysfunction of the reward system. Rewards are considered as important co-factor for learning, so the question arises as to why and how this affects the rehabilitation of stroke patients. We investigated reward behaviour, learning ability and brain network connectivity in acute (3-7d) mild to moderate stroke patients (n = 28) and age-matched healthy controls (n = 26). Reward system activity was assessed using the Monetary Incentive Delay task (MID) during magnetoencephalography (MEG). Coherence analyses were used to demonstrate reward effects on brain functional network connectivity. The MID-task showed that stroke survivors had lower reward sensitivity and required greater monetary incentives to improve performance and showed deficits in learning improvement. MEG-analyses showed a reduced network connectivity in frontal and temporoparietal regions. All three effects (reduced reward sensitivity, reduced learning ability and altered cerebral connectivity) were found to be closely related and differed strongly from the healthy group. Our results reinforce the notion that acute stroke induces reward network dysfunction, leading to functional impairment of behavioural systems. These findings are representative of a general pattern in mild strokes and are independent of the specific lesion localisation. For stroke rehabilitation, these results represent an important point to identify the reduced learning capacity after stroke and to implement individualised recovery exercises accordingly.

A Large-Scale Prospective Study on Functional Ability and Mortality Following Stroke Based on HRS Data Set: Implications for Rehabilitation

According to the WHO, 15 million people worldwide suffer a stroke annually. Of these, 5 million die and another 5 million are left permanently disabled. Patients endure the impacts of strokes during their rehabilitation and afterward, placing economical and emotional burdens on family and community. Using data from the Health and Retirement Study (HRS) of the USA, the research performed a large-scale prospective analysis to examine how demographics, socioeconomic factors, cognition, emotion, and physical activity predict functional impairment and mortality. Multiple regression was employed to identify statistically significant variables that predict longitudinal Activities of Daily Life (ADLs). The least absolute shrinkage and selection operator (LASSO) logistic regression, a supervised machine learning approach, was deliberately chosen to obtain the subset of predictors that provide the best possible classification for the dependent variable. The LASSO regression produced a model with a fair mean Area Under the Curve (AUC) of 0.75 in predicting the risk of the patient's mortality. My findings also uncovered the important roles of BMI, mobility, muscle strength, memory, mental status, and socioeconomic status play in the long-term ADLs and survival of patients with stroke.

Improving Depressive Symptoms of Post-stroke Depression Using the Shugan Jieyu Capsule: A Resting-State Functional Magnetic Resonance Imaging Study

Regional homogeneity (ReHo) and fractional amplitude of low-frequency fluctuation (fALFF) were used to detect the neuroimaging mechanism of Shugan Jieyu Capsule (SG) in ameliorating depression of post-stroke depression (PSD) patients. Fifteen PSD patients took SG for 8 weeks, completed the 24-item Hamilton Depression Scale (HAMD) assessment at the baseline and 8 weeks later, and underwent functional magnetic resonance imaging (fMRI) scanning. Twenty-one healthy controls (HCs) underwent these assessments at the baseline. We found that SG improved depression of PSD patients, in which ReHo values decreased in the left calcarine sulcus (CAL.L) and increased in the left superior frontal gyrus (SFG.L) of PSD patients at the baseline. The fALFF values of the left inferior parietal cortex (IPL.L) decreased in PSD patients at the baseline. Abnormal functional activities in the brain regions were reversed to normal levels after the administration of SG for 8 weeks. Receiver operating characteristic (ROC) analysis found that the changes in three altered brain regions could be used to differentiate PSD patients at the baseline and HCs. Average signal values of altered regions were related to depression in all subjects at the baseline. Our results suggest that SG may ameliorate depression of PSD patients by affecting brain region activity and local synchronization.

Effects of Optimized Acupuncture and Moxibustion Treatment on Depressive Symptoms and Executive Functions in Patients With Post-Stroke Depression: Study Protocol for a Randomized Controlled Trial

Background

Post-stroke depression (PSD), a common neuropsychiatric comorbidity after stroke, has a negative impact on the functional recovery and quality of life of survivors. It lacks effective therapeutic drugs with good curative effects and few adverse reactions. Preliminary experiments have shown that the optimized acupuncture and moxibustion treatment (OAMT), including acupuncture, moxibustion, and auricular intradermal acupuncture, improved depressive symptoms and neurological deficits in patients with PSD. However, the evidence for its effectiveness is still insufficient. Hence, we designed this study to evaluate the efficacy and safety of the OAMT in the treatment of PSD and to explore its possible mechanism from the perspective of executive functions.

Methods/Design

This is a randomized controlled trial, which comprises a total of 134 patients with PSD. Participants are randomized into intervention group and control group at a 1:1 ratio. All treatments are given five times per week for 4 weeks. The primary outcome is the severity of depression, which is evaluated by the Hamilton Depression Scale-17 (HAMD-17) and the Beck Depression Rating Scale (BDI). Secondary outcomes are executive abilities, which are measured by several neuropsychological tests, including the Stroop Color and Word Test (SCWT), the Trial Making Test (TMT), the Digit Symbol Substitution Test (DSST), and the Matrix Reasoning Test (MRT). All outcomes have been evaluated at baseline and weeks 4, 8, 12, and 20. At the same time, functional MRI (fMRI) is used to measure the functional connectivity in the cognitive control network (CCN) at baseline and 4 weeks after intervention.

Discussion

This study aims to provide high-quality evidence for the efficacy and safety of the OAMT for treating PSD. In addition, this trial is the first trial to explore if the improvement condition of depression in the OAMT group is related to the improvement of executive functions and the favorable changes in the structure.

Clinical Trial Registration

Chinese Clinical Trial Registry, identifier: ChiCTR2100048431.

A meta-analysis on neural changes of cognitive training for mental disorders in executive function tasks: increase or decrease brain activation?

BACKGROUND

Cognitive impairment is often found in patients with psychiatric disorders, and cognitive training (CT) has been shown to help these patients. To better understand the mechanisms of CT, many neuroimaging studies have investigated the neural changes associated with it. However, the results of those studies have been inconsistent, making it difficult to draw conclusions from the literature. Therefore, the objective of this meta-analysis was to identify consistent patterns in the literature of neural changes associated with CT for psychiatric disorders.

METHODS

We searched for cognitive training imaging studies in PubMed, Cochrane library, Scopus, and ProQuest electronic databases. We conducted an activation likelihood estimation (ALE) for coordinate-based meta-analysis of neuroimaging studies, conduct behavioral analysis of brain regions identified by ALE analysis, conduct behavioral analysis of brain regions identified by ALE analysis, and then created a functional meta-analytic connectivity model (fMACM) of the resulting regions.

RESULTS

Results showed that CT studies consistently reported increased activation in the left inferior frontal gyrus (IFG) and decreased activation in the left precuneus and cuneus from pre- to post- CT.

CONCLUSION

CT improves cognitive function by supporting language and memory function, and reducing neuronal resources associated with basic visual processing.

Poststroke Cognitive Impairment Research Progress on Application of Brain-Computer Interface

Brain-computer interfaces (BCIs), a new type of rehabilitation technology, pick up nerve cell signals, identify and classify their activities, and convert them into computer-recognized instructions. This technique has been widely used in the rehabilitation of stroke patients in recent years and appears to promote motor function recovery after stroke. At present, the application of BCI in poststroke cognitive impairment is increasing, which is a common complication that also affects the rehabilitation process. This paper reviews the promise and potential drawbacks of using BCI to treat poststroke cognitive impairment, providing a solid theoretical basis for the application of BCI in this area.

Application of neuropsychology and imaging to brain injury and use of the integrative cognitive rehabilitation psychotherapy model

BACKGROUND

An early approach to cognitive rehabilitation therapy (CRT) was developed based on A. R. Luria's theory of brain function. Expanding upon this approach, the Integrative Cognitive Rehabilitation Psychotherapy model (ICRP) was advanced.

OBJECTIVE

To describe the ICRP approach to treatment of clients post brain injury and provide a comprehensive list of evaluation tools to determine the client's abilities and needs. Finally, to provide a link between CRT and functional imaging studies designed to improve rehabilitation efforts.

METHODS

History of cognitive rehabilitation and neuropsychological testing is reviewed and description of cognitive, academic, psychiatric, and substance abuse tools are provided. Cognitive and emotional treatment techniques are fully described. Additionally, a method of determining the client's stage of recovery and pertinent functional imaging studies is detailed.

RESULTS

Authors have been able to provide a set of tools and techniques to use in comprehensive treatment of clients with brain injury.

CONCLUSIONS

Inclusive treatment which is outlined in the ICRP model is optimal for the client's recovery and return to a full and satisfying life post brain injury. The model provides a framework for neuropsychologists to integrate issues that tend to co-occur in clients living with brain injury into a unified treatment plan.

Brain-based mechanisms of late-life depression: Implications for novel interventions

Late-life depression (LLD) is a particularly debilitating illness. Older adults suffering from depression commonly experience poor outcomes in response to antidepressant treatments, medical comorbidities, and declines in daily functioning. This review aims to further our understanding of the brain network dysfunctions underlying LLD that contribute to disrupted cognitive and affective processes and corresponding clinical manifestations. We provide an overview of a network model of LLD that integrates the salience network, the default mode network (DMN) and the executive control network (ECN). We discuss the brain-based structural and functional mechanisms of LLD with an emphasis on their link to clinical subtypes that often fail to respond to available treatments. Understanding the brain networks that underlie these disrupted processes can inform the development of targeted interventions for LLD. We propose behavioral, cognitive, or computational approaches to identifying novel, personalized interventions that may more effectively target the key cognitive and affective symptoms of LLD.

Distinct functional and structural connections predict crystallised and fluid cognition in healthy adults

White matter pathways between neurons facilitate neuronal coactivation patterns in the brain. Insight into how these structural and functional connections underlie complex cognitive functions provides an important foundation with which to delineate disease‐related changes in cognitive functioning. Here, we integrate neuroimaging, connectomics, and machine learning approaches to explore how functional and structural brain connectivity relate to cognition. Specifically, we evaluate the extent to which functional and structural connectivity predict individual crystallised and fluid cognitive abilities in 415 unrelated healthy young adults (202 females) from the Human Connectome Project. We report three main findings. First, we demonstrate functional connectivity is more predictive of cognitive scores than structural connectivity, and, furthermore, integrating the two modalities does not increase explained variance. Second, we show the quality of cognitive prediction from connectome measures is influenced by the choice of grey matter parcellation, and, possibly, how that parcellation is derived. Third, we find that distinct functional and structural connections predict crystallised and fluid abilities. Taken together, our results suggest that functional and structural connectivity have unique relationships with crystallised and fluid cognition and, furthermore, studying both modalities provides a more comprehensive insight into the neural correlates of cognition.