Faculty Bibliography

Background Vascular function is compromised in Alzheimer disease (AD) years before amyloid and tau pathology are detected and a substantial body of work shows abnormal platelet activation states in patients with AD. The aim of our study was to investigate whether platelet function in middle age is independently associated with future risk of AD. Methods and Results We examined associations of baseline platelet function with incident dementia risk in the community-based FHS (Framingham Heart Study) longitudinal cohorts. The association between platelet function and risk of dementia was evaluated using the cumulative incidence function and inverse probability weighted Cox proportional cause-specific hazards regression models, with adjustment for demographic and clinical covariates. Platelet aggregation response was measured by light transmission aggregometry. The final study sample included 1847 FHS participants (average age, 53.0 years; 57.5% women). During follow-up (median, 20.5 years), we observed 154 cases of incident dementia, of which 121 were AD cases. Results from weighted models indicated that platelet aggregation response to adenosine diphosphate 1.0 µmol/L was independently and positively associated with dementia risk, and it was preceded in importance only by age and hypertension. Sensitivity analyses showed associations with the same directionality for participants defined as adenosine diphosphate hyper-responders, as well as the platelet response to 0.1 µmol/L epinephrine. Conclusions Our study shows individuals free of antiplatelet therapy with a higher platelet response are at higher risk of dementia in late life during a 20-year follow-up, reinforcing the role of platelet function in AD risk. This suggests that platelet phenotypes may be associated with the rate of dementia and potentially have prognostic value.

While the COVID-19 pandemic has catalyzed the expansion of telemedicine into nearly every specialty of medicine, few articles have summarized current practices and recommendations for integrating virtual care in the practice of neuro-oncology. This article identifies current telemedicine practice, provides practical guidance for conducting telemedicine visits, and generates recommendations for integrating virtual care into neuro-oncology practice. Practical aspects of telemedicine are summarized including when to use and not use telemedicine, how to conduct a virtual visit, who to include in the virtual encounter, unique aspects of telehealth in neuro-oncology, and emerging innovations.

OBJECTIVE:Carotid stenosis is currently treated by carotid endarterectomy (CEA), carotid artery stenting (CAS), or transcarotid artery revascularization (TCAR). This study sought to add to the literature by providing real-world data comparing the safety and effectiveness associated with the performance of these carotid revascularization techniques by dual-trained neurosurgeons. METHODS:The authors performed a retrospective review of carotid stenosis databases at two US centers. Patients treated by CEA, transfemoral CAS, or TCAR for atherosclerotic carotid artery disease were included. Clinical outcomes were compared at 30 days after the procedure. RESULTS:Seven hundred eighty patients were included (583 with CAS, 165 with CEA, and 32 with TCAR). Overall, 486 patients (62.3%) were men, and 393 (50.4%) had left-sided carotid stenosis. Most patients (n = 617, 79.1%) had symptomatic disease. Among the three treatment groups, there were no statistically significant differences with respect to 30-day ischemic events (CAS 3.8%, CEA 1.8%, TCAR 6.3%; p = 0.267) or 30-day mortality rates (CAS 3.6%, CEA 2.4%, TCAR 3.1%; p = 0.857). Male sex had significantly lower odds of 30-day transient ischemic attack (TIA) or stroke in both univariable (p = 0.024) and multivariable (p = 0.023) regression models. Increasing age had significantly higher odds of 30-day mortality on univariable (p = 0.006) and multivariable (p = 0.003) regression. Patients with the occurrence of 30-day TIA or stroke also had significantly higher odds of 30-day mortality on univariable (p < 0.001) and multivariable (p < 0.001) regression. CONCLUSIONS:This real-world experience reflects the current practice of hybrid neurosurgery at two high-volume tertiary care centers and suggests that all three treatment modalities have comparable safety and effectiveness if patients are properly selected.

BACKGROUND:Preclinical studies suggest body temperature (Tb) and consequently brain temperature has the potential to bidirectionally interact with tau pathology in Alzheimer's Disease (AD). Tau phosphorylation is substantially increased by small (<1 °C) decreases in temperature within the human physiological range, and thermoregulatory nuclei are affected by tau pathology early in the AD continuum. In this study we evaluated whether Tb (as a proxy for brain temperature) is cross-sectionally associated with clinically utilized markers of tau pathology in cognitively normal older adults. METHODS:Tb was continuously measured with ingestible telemetry sensors for 48-h. This period also included two nights of nocturnal polysomnography to delineate whether Tb during waking vs sleep is differentially associated with tau pathology. Tau phosphorylation was assessed with plasma and cerebrospinal fluid (CSF) tau phosphorylated at threonine 181 (P-tau), sampled the day following Tb measurement. In addition, neurofibrillary tangle (NFT) burden in early Braak stage regions was imaged with PET-MR using the [18F]MK-6240 radiotracer on average one month later. RESULTS:Lower Tb was associated with increased NFT burden, as well as increased plasma and CSF P-tau levels (p < 0.05). NFT burden was associated with lower Tb during waking (p < 0.05) but not during sleep intervals. Plasma and CSF Ptau levels were highly correlated with each other (p < 0.05), and both variables were correlated with tau tangle radiotracer uptake (p < 0.05). CONCLUSIONS:These results, the first available for human, suggest that lower Tb in older adults may be associated with increased soluble and aggregated tau pathology. Our findings add to the substantial preclinical literature associating lower body and brain temperature with tau hyperphosphorylation. CLINICAL TRIAL NUMBER/BACKGROUND:NCT03053908.

BACKGROUND:Alzheimer's disease (AD) is the most prevalent form of dementia worldwide and is characterized by progressive memory loss and cognitive impairment. Our understanding of AD pathogenesis is limited and no effective disease-modifying treatment is available. Mitochondria are cytoplasmic organelles critical to the homeostatic regulation of glucose and energy in the cell. METHODS:Mitochondrial abnormalities are found early in the course of AD and dysfunctional mitochondria are involved in AD progression. The resulting respiratory chain impairment, neuronal apoptosis, and generation of reactive oxygen species are highly damaging to neurons. Restoration of mitochondrial function may provide a novel therapeutic strategy for AD. RESULTS:This review discusses the specifics of mitochondrial fragmentation, imbalances in fission and fusion, and DNA damage seen in AD and the contribution of compromised mitochondrial activity to AD etiopathogenesis. It explores how an understanding of the processes underlying mitochondrial failure may lead to urgently needed treatment innovations. It considers individual mitochondrial proteins that have emerged as promising drug targets and evaluates neuroprotective agents that could improve the functional state of mitochondria in the setting of AD. CONCLUSIONS:There is great promise in exploring original approaches to preserving mitochondrial viability as a means to achieve breakthroughs in treating AD.

PURPOSE/OBJECTIVE:Resting heart rate variability (HRV) is an important biomarker linking mental health to cardiovascular outcomes. However, resting HRV is also impaired in autonomic neuropathy, a common and underdiagnosed complication of common medical conditions which is detected by testing autonomic reflexes. We sought to describe the relationship between autonomic reflex abnormalities and resting HRV, taking into consideration medical comorbidities and demographic variables. METHODS:Participants (n = 209) underwent a standardized autonomic reflex screen which was summarized as the Composite Autonomic Severity Score (CASS) and included measures of reflexive HRV, e.g., heart rate with deep breathing (HRDB). Resting HRV measures were: pNN50 (percentage of NN intervals that differ by > 50 ms) and cvRMSSD (adjusted root mean square of successive differences). RESULTS:In univariate analyses, lower resting HRV was associated with: older age, higher CASS, neuropathy on examination, hypertension, diabetes, chronic obstructive pulmonary disease, chronic kidney disease, and psychiatric disease. Adaptive regression spline analysis revealed that HRDB explained 27% of the variability in resting HRV for participants with values of HRDB in the normal range. Outside this range, there was no linear relationship because: (1) when HRDB was low (indicating autonomic neuropathy), resting HRV was also low with low variance; and (2) when HRDB was high, the variance in resting HRV was high. In multivariate models, only HRDB was significantly independently associated with cvRMSSD and pNN50. CONCLUSION/CONCLUSIONS:Subclinical autonomic neuropathy, as evidenced by low HRDB and other autonomic reflexes, should be considered as a potential confounder of resting HRV in research involving medically and demographically diverse populations.

BACKGROUND:Homebound individuals with advanced Parkinson's Disease (PD) require intensive caregiving, the majority of which is provided by informal, family caregivers. PD caregiver strain is an independent risk factor for institutionalization. There are currently no effective interventions to support advanced PD caregivers. Studies in other neurologic disorders, however, have demonstrated the potential for peer mentoring interventions to improve caregiver outcomes. In the context of an ongoing trial of interdisciplinary home visits, we designed and piloted a nested trial of caregiver peer mentoring for informal caregivers of individuals with advanced PD. OBJECTIVE:To test the feasibility of peer mentoring for caregivers of homebound individuals with advanced PD and to evaluate its effects on anxiety, depression, and caregiver strain. METHODS:Single-center pilot study of 16 weeks of caregiver peer mentoring nested within a yearlong controlled trial of interdisciplinary home visits. We recruited 34 experienced former or current family caregivers who completed structured mentor training. Caregivers enrolled in the larger interdisciplinary home visit trial consented to receive 16 weeks of weekly, one-to-one peer mentoring calls with a trained peer mentor. Weekly calls were guided by a curriculum on advanced PD management and caregiver support. Fidelity to and satisfaction with the intervention were gathered via biweekly study diaries. Anxiety, depression, and caregiver strain were measured pre- and post-mentoring intervention at Home Visits 2 and 3. RESULTS:Enrollment and peer mentor training began in 2018, and 65 caregivers enrolled in the overarching trial. The majority of mentors and mentees were white, female spouses or partners of individuals with PD, and mentors had a mean of 8.7 years of caregiving experience (SD 6.4). Thirty-three mentors were matched with at least one mentee. CONCLUSIONS:This is the first study of caregiver peer mentoring in PD and may establish an adaptable and sustainable model for disease-specific caregiver interventions in PD and other neurodegenerative diseases. CLINICALTRIAL/BACKGROUND:ClinicalTrials.gov NCT03189459; http://clinicaltrials.gov/ct2/show/ NCT03189459.

BACKGROUND:Delayed-onset of headache seems a specific feature of cerebrovascular events after COVID-19 vaccines. METHODS:All consecutive events reported to the United States Vaccine Adverse Reporting System following COVID-19 vaccines (1 January to 24 June 2021), were assessed. The timing of headache onset post-vaccination in subjects with and without concomitant cerebrovascular events, including cerebral venous thrombosis, ischemic stroke, and intracranial haemorrhage was analysed. The diagnostic accuracy in predicting concurrent cerebrovascular events of the guideline- proposed threshold of three-days from vaccination to headache onset was evaluated. RESULTS:There were 314,610 events following 306,907,697 COVID-19 vaccine doses, including 41,700 headaches, and 178/41,700 (0.4%) cerebrovascular events. The median time between the vaccination and the headache onset was shorter in isolated headache (1 day vs. 4 (in cerebral venous thrombosis), 3 (in ischemic stroke), or 10 (in intracranial hemorrhage) days, all P < 0.001). Delayed onset of headache had an area under the curve of 0.83 (95% CI: 0.75-0.97) for cerebral venous thrombosis, 0.70 (95% CI: 0.63-76) for ischemic stroke and 0.76 (95% CI: 0.67-84) for intracranial hemorrhage, and >99% negative predictive value. CONCLUSION/CONCLUSIONS:Headache following COVID-19 vaccination occurs within 1 day and is rarely associated with cerebrovascular events. Delayed onset of headache 3 days post-vaccination was an accurate diagnostic biomarker for the occurrence of a concomitant cerebrovascular events.