Differential Cognitive Effects of Unilateral Subthalamic Nucleus Deep Brain Stimulation for Parkinson's Disease.

OBJECTIVE: The aim of this study was to investigate the cognitive effects of unilateral directional versus ring subthalamic nucleus deep brain stimulation (STN DBS) in patients with advanced Parkinson's disease. METHODS: We examined 31 participants who underwent unilateral STN DBS (left n = 17; right n = 14) as part of an National Institutes of Health (NIH)-sponsored randomized, double-blind, crossover study contrasting directional versus ring stimulation. All participants received unilateral DBS implants in the hemisphere more severely affected by motor parkinsonism. Measures of cognition included verbal fluency, auditory-verbal memory, and response inhibition. We used mixed linear models to contrast the effects of directional versus ring stimulation and implant hemisphere on longitudinal cognitive function. RESULTS: Crossover analyses showed no evidence for group-level changes in cognitive performance related to directional versus ring stimulation. Implant hemisphere, however, impacted cognition in several ways. Left STN participants had lower baseline verbal fluency than patients with right implants (t [20.66 = -2.50, p = 0.02]). Verbal fluency declined after left (p = 0.013) but increased after right STN DBS (p < 0.001), and response inhibition was faster following right STN DBS (p = 0.031). Regardless of hemisphere, delayed recall declined modestly over time versus baseline (p = 0.001), and immediate recall was unchanged. INTERPRETATION: Directional versus ring STN DBS did not differentially affect cognition. Similar to prior bilateral DBS studies, unilateral left stimulation worsened verbal fluency performance. In contrast, unilateral right STN surgery increased performance on verbal fluency and response inhibition tasks. Our findings raise the hypothesis that unilateral right STN DBS in selected patients with predominant right brain motor parkinsonism could mitigate declines in verbal fluency associated with the bilateral intervention. ANN NEUROL 2024;95:1205-1219.

Differential contribution of sensorimotor cortex and subthalamic nucleus to unimanual and bimanual hand movements.

Why does unilateral deep brain stimulation improve motor function bilaterally? To address this clinical observation, we collected parallel neural recordings from sensorimotor cortex (SMC) and the subthalamic nucleus (STN) during repetitive ipsilateral, contralateral, and bilateral hand movements in patients with Parkinson's disease. We used a cross-validated electrode-wise encoding model to map electromyography data to the neural signals. Electrodes in the STN encoded movement at a comparable level for both hands, whereas SMC electrodes displayed a strong contralateral bias. To examine representational overlap across the two hands, we trained the model with data from one condition (contralateral hand) and used the trained weights to predict neural activity for movements produced with the other hand (ipsilateral hand). Overall, between-hand generalization was poor, and this limitation was evident in both regions. A similar method was used to probe representational overlap across different task contexts (unimanual vs. bimanual). Task context was more important for the STN compared to the SMC indicating that neural activity in the STN showed greater divergence between the unimanual and bimanual conditions. These results indicate that SMC activity is strongly lateralized and relatively context-free, whereas the STN integrates contextual information with the ongoing behavior.

The State of Hepatitis C Elimination from the Front Lines: A Qualitative Study of Provider-Perceived Gaps to Treatment Initiation.

BACKGROUND: Hepatitis C (HCV) is a curable chronic infection, but lack of treatment uptake contributes to ongoing morbidity and mortality. State and national strategies for HCV elimination emphasize the pressing need for people with HCV to receive treatment. OBJECTIVE: To identify provider-perceived barriers that hinder the initiation of curative HCV treatment and elimination of HCV in the USA. APPROACH: Qualitative semi-structured interviews with 36 healthcare providers who have evaluated patients with HCV in New York City, Western/Central New York, and Alabama. Interviews, conducted between 9/2021 and 9/2022, explored providers' experiences, perceptions, and approaches to HCV treatment initiation. Transcripts were analyzed using hybrid inductive and deductive thematic analysis informed by established health services and implementation frameworks. KEY RESULTS: We revealed four major themes: (1) Providers encounter professional challenges with treatment provision, including limited experience with treatment and perceptions that it is beyond their scope, but are also motivated to learn to provide treatment; (2) providers work toward building streamlined and inclusive practice settings-leveraging partnerships with experts, optimizing efficiency through increased access, adopting inclusive cultures, and advocating for integrated care; (3) although at times overwhelmed by patients facing socioeconomic adversity, increases in public awareness and improvements in treatment policies create a favorable context for providers to treat; and (4) providers are familiar with the relative advantages of improved HCV treatments, but the reputation of past treatments continues to deter elimination. CONCLUSIONS: To address the remaining barriers and facilitators providers experience in initiating HCV treatment, strategies will need to expand educational initiatives for primary care providers, further support local infrastructures and integrated care systems, promote public awareness campaigns, remove prior authorization requirements and treatment limitations, and address the negative reputation of outdated HCV treatments. Addressing these issues should be considered priorities for HCV elimination approaches at the state and national levels.

Incorporating Anti-racist Principles Throughout the Research Lifecycle: A Position Statement from the Society of General Internal Medicine (SGIM).

Biomedical research has advanced medicine but also contributed to widening racial and ethnic health inequities. Despite a growing acknowledgment of the need to incorporate anti-racist objectives into research, there remains a need for practical guidance for recognizing and addressing the influence of ingrained practices perpetuating racial harms, particularly for general internists. Through a review of the literature, and informed by the Research Lifecycle Framework, this position statement from the Society of General Internal Medicine presents a conceptual framework suggesting multi-level systemic changes and strategies for researchers to incorporate an anti-racist perspective throughout the research lifecycle. It begins with a clear assertion that race and ethnicity are socio-political constructs that have important consequences on health and health disparities through various forms of racism. Recommendations include leveraging a comprehensive approach to integrate anti-racist principles and acknowledging that racism, not race, drives health inequities. Individual researchers must acknowledge systemic racism's impact on health, engage in self-education to mitigate biases, hire diverse teams, and include historically excluded communities in research. Institutions must provide clear guidelines on the use of race and ethnicity in research, reject stigmatizing language, and invest in systemic commitments to diversity, equity, and anti-racism. National organizations must call for race-conscious research standards and training, and create measures to ensure accountability, establishing standards for race-conscious research for research funding. This position statement emphasizes our collective responsibility to combat systemic racism in research, and urges a transformative shift toward anti-racist practices throughout the research cycle.

Statistical Outcomes Guiding Periprosthetic Joint Infection Prevention and Revision Are Fragile: A Systematic Review of Randomized Controlled Trials.

BACKGROUND: Dichotomous outcomes are frequently reported in orthopaedic research and have substantial clinical implications. This study utilizes the fragility index (FI) and fragility quotient (FQ) metrics to determine the statistical stability of outcomes reported in total joint arthroplasty randomized controlled trials (RCTs) relating to periprosthetic joint infection (PJI). METHODS: The RCTs that reported dichotomous data related to PJI published between January 1, 2010, and December 31, 2022, were evaluated. The FI and reverse FI (RFI) were defined as the number of outcome event reversals required to reverse the significance of significant and nonsignificant outcomes, respectively. The FQ was determined by dividing the FI or RFI by the respective sample size. There were 108 RCTs screened, and 17 studies included for analysis. RESULTS: A total of 58 outcome events were identified, with a median FI of 4 (interquartile range [IQR] 2 to 5) and associated FQ of 0.0417 (IQR 0.0145 to 0.0602). The 13 statistically significant outcomes had a median FI of 1 (IQR 1 to 2) and FQ of 0.00935 (IQR 0.00629 to 0.01410). The 45 nonsignificant outcomes had a median RFI of 4 (IQR 3 to 5) and FQ of 0.05 (IQR 0.0361 to 0.0723). The number of patients lost to follow-up was greater than or equal to the FI in 46.6% of outcomes. CONCLUSIONS: Statistical outcomes in RCTs analyzing PJI are fragile and may lack statistical integrity. We recommend a comprehensive fragility analysis, with the reporting of FI and FQ metrics, to aid in the interpretation of outcomes in the total joint arthroplasty literature.

Longitudinal associations of apathy and regional tau in mild cognitive impairment and dementia: Findings from the Alzheimer's Disease Neuroimaging Initiative.

Introduction: It is important to study apathy in Alzheimer's disease (AD) to better understand its underlying neurobiology and develop effective interventions. In the current study, we sought to examine the relationships between longitudinal apathy and regional tau burden in cognitively impaired older adults from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Methods: Three hundred and nineteen ADNI participants with mild cognitive impairment (MCI) or AD dementia underwent flortaucipir (FTP) tau positron emission tomography (PET) imaging and clinical assessment with the Neuropsychiatric Inventory (NPI) annually. Longitudinal NPI Apathy (NPI-A) scores were examined in relation to baseline tau PET signal in three a priori selected regions implicated in AD and AD-related apathy (supramarginal gyrus, entorhinal cortex [EC] and rostral anterior cingulate cortex [rACC]). Secondary models were adjusted for global cognition (Mini-Mental State Examination score) and cortical amyloid (florbetapir PET). Results: Higher baseline supramarginal gyrus and EC tau burden were each significantly associated with greater NPI-A over time, while rACC tau was associated with higher NPI-A but did not predict its trajectory over time. These results were retained for supramarginal and EC tau after adjusting models for global cognition and cortical amyloid. Discussion: Our findings suggest that baseline in vivo tau burden in parietal and temporal brain regions affected in AD, and less so in a medial frontal region involved in motivational control, is associated with increasing apathy over time in older adults with MCI and AD dementia. Future work studying emergent apathy in relation to not only core AD pathology but also circuit level dysfunction may provide additional insight into the neurobiology of apathy in AD and opportunities for intervention. Highlights: Tau (Flortaucipir PET) in regions implicated in AD was associated with increasing apathy over timeCortical amyloid was also found to be a robust predictor of the trajectory of apathyEvidence of synergy between regional tau and amyloid in overall higher levels of apathy.

Exploring Subfactors of Adult Cognitive Disengagement Syndrome and Impact on Neuropsychological Performance.

OBJECTIVE: This study investigated subfactors of cognitive disengagement syndrome (CDS; previously referred as sluggish cognitive tempo) among adults referred for neuropsychological evaluation of attentiondeficit/hyperactivity disorder (ADHD). METHOD: Retrospective analyses of data from 164 outpatient neuropsychological evaluations examined associations between CDS subfactors and self-reported psychological symptoms and cognitive performance. RESULTS: Factor analysis produced two distinct but positively correlated constructs: "Cognitive Complaints'' and "Lethargy." Both correlated positively with symptom reports (rs = 0.26-0.57). Cognitive Complaints correlated negatively with working memory, processing speed, and executive functioning performance (rs = -0.21 to -0.37), whereas Lethargy correlated negatively only with processing speed and executive functioning performance (rs = -0.26 to -0.42). Both predicted depression symptoms, but only Cognitive Complaints predicted inattention symptoms. Both subfactors demonstrated modest to nonsignificant associations with cognitive performance after accounting for estimated premorbid intelligence and inattention. CONCLUSION: Findings indicate a bidimensional conceptualization of CDS, with differential associations between its constituent subfactors, reported symptoms, and cognitive performance.

The Effect of Intraoperative Overdistraction on Subsidence Following Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: The purpose of this study was to evaluate the effect of overdistraction on interbody cage subsidence. BACKGROUND: Vertebral overdistraction due to the use of large intervertebral cage sizes may increase the risk of postoperative subsidence. METHODS: Patients who underwent anterior cervical discectomy and fusion between 2016 and 2021 were included. All measurements were performed using lateral cervical radiographs at 3 time points - preoperative, immediate postoperative, and final follow-up >6 months postoperatively. Anterior and posterior distraction were calculated by subtracting the preoperative disc height from the immediate postoperative disc height. Cage subsidence was calculated by subtracting the final follow-up postoperative disc height from the immediate postoperative disc height. Associations between anterior and posterior subsidence and distraction were determined using multivariable linear regression models. The analyses controlled for cage type, cervical level, sex, age, smoking status, and osteopenia. RESULTS: Sixty-eight patients and 125 fused levels were included in the study. Of the 68 fusions, 22 were single-level fusions, 35 were 2-level, and 11 were 3-level. The median final follow-up interval was 368 days (range: 181-1257 d). Anterior disc space subsidence was positively associated with anterior distraction (beta = 0.23; 95% CI: 0.08, 0.38; P = 0.004), and posterior disc space subsidence was positively associated with posterior distraction (beta = 0.29; 95% CI: 0.13, 0.45; P < 0.001). No significant associations between anterior distraction and posterior subsidence (beta = 0.07; 95% CI: -0.06, 0.20; P = 0.270) or posterior distraction and anterior subsidence (beta = 0.06; 95% CI: -0.14, 0.27; P = 0.541) were observed. CONCLUSIONS: We found that overdistraction of the disc space was associated with increased postoperative subsidence after anterior cervical discectomy and fusion. Surgeons should consider choosing a smaller cage size to avoid overdistraction and minimize postoperative subsidence.

The Impact of Adverse Childhood Experiences on Symptom and Performance Validity Tests Among a Multiracial Sample Presenting for ADHD Evaluation.

OBJECTIVE: Adverse childhood experiences (ACEs) are commonly reported in individuals presenting for attention-deficit hyperactivity disorder (ADHD) evaluation. Performance validity tests (PVTs) and symptom validity tests (SVTs) are essential to ADHD evaluations in young adults, but extant research suggests that those who report ACEs may be inaccurately classified as invalid on these measures. The current study aimed to assess the degree to which ACE exposure differentiated PVT and SVT performance and ADHD symptom reporting in a multi-racial sample of adults presenting for ADHD evaluation. METHOD: This study included 170 adults referred for outpatient neuropsychological ADHD evaluation who completed the ACE Checklist and a neurocognitive battery that included multiple PVTs and SVTs. Analysis of variance was used to examine differences in PVT and SVT performance among those with high (≥4) and low (≤3) reported ACEs. RESULTS: Main effects of the ACE group were observed, such that high ACE group reporting demonstrated higher scores on SVTs assessing ADHD symptom over-reporting and infrequent psychiatric and somatic symptoms on the Minnesota Multiphasic Personality Inventory-2-Restructured Form. Conversely, no significant differences emerged in total PVT failures across ACE groups. CONCLUSIONS: Those with high ACE exposure were more likely to have higher scores on SVTs assessing over-reporting and infrequent responses. In contrast, ACE exposure did not affect PVT performance. Thus, ACE exposure should be considered specifically when evaluating SVT performance in the context of ADHD evaluations, and more work is needed to understand factors that contribute to different patterns of symptom reporting as a function of ACE exposure.

Amyloid and tau burden relate to longitudinal changes in the performance of complex everyday activities among cognitively unimpaired older adults: results from the performance-based Harvard Automated Phone Task.

Background: Changes in everyday functioning constitute a clinically meaningful outcome, even in the early stages of Alzheimer's disease. Performance-based assessments of everyday functioning might help uncover these early changes. We aimed to investigate how changes over time in everyday functioning relate to tau and amyloid in cognitively unimpaired older adults. Methods: Seventy-six cognitively unimpaired participants (72 ± 6 years old, 61% female) completed multiple Harvard Automated Phone Task (APT) assessments over 2.0 ± 0.9 years. The Harvard APT consists of three tasks, performed through an automated phone system, in which participants refill a prescription (APT-Script), select a new primary care physician (APT-PCP), and transfer money to pay a bill (APT-Bank). Participants underwent Pittsburgh compound-B and flortaucipir positron emission tomography scans at baseline. We computed distribution volume ratios for a cortical amyloid aggregate and standardized uptake volume ratios for medial temporal and neocortical tau regions. In separate linear mixed models, baseline amyloid by time and tau by time interactions were used to predict longitudinal changes in performance on the Harvard APT tasks. Three-way amyloid by tau by time interactions were also investigated. Lastly, we examined associations between tau and change in Harvard APT scores in exploratory voxel-wise whole-brain analyses. All models were adjusted for age, sex, and education. Results: Amyloid [unstandardized partial regression coefficient estimate (ß) = -0.007, 95% confidence interval (95% CI) = (-0.013, -0.001)], and medial temporal tau [ß = -0.013, 95% CI = (-0.022, -0.004)] were associated with change over time in years on APT-PCP only, i.e., higher baseline amyloid and higher baseline tau were associated with steeper rate of decline of APT-PCP. Voxel-wise analyses showed widespread associations between tau and change in APT-PCP scores over time. Conclusion: Even among cognitively unimpaired older adults, changes over time in the performance of cognitively complex everyday activities relate to cortical amyloid and widespread cerebral tau burden at baseline. These findings support the link between Alzheimer's disease pathology and function and highlight the importance of measuring everyday functioning in preclinical disease stages.