Fay Horak

Fay Horak
Oregon Health & Science University | OHSU · Department of Neurology

About

572
Publications
245,138
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49,356
Citations
Additional affiliations
January 2014 - present
Portland VA Medical Center
Position
  • Senior Researcher

Publications

Publications (572)
Article
Importance: There is unclear evidence on when to initiate physical therapy after mild traumatic brain injury (mTBI) in non-athlete, adult population. Objective: The objective of this study was to investigate physical therapy timing after mTBI through changes in patient-reported and clinically-assessed tools and objective and mechanism measuremen...
Preprint
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Background. Spinocerebellar ataxia (SCA) is a degenerative cerebellar disease, causing progressive impairment of gait and balance in adults. To identify the ideal subjects for disease-modifying therapies it is critical to identify biomarkers for the earliest stages of SCA. Objective. We investigated whether prefrontal cortex activity is increased d...
Article
Background Evidence has suggested that cognitive decline may be a risk factor for freezing of gait (FOG) in Parkinson’s disease (PD). Complex and challenging exercises have been suggested as potential rehabilitation strategies to decrease FOG severity and improve cognition; however, it is unknown whether improvement in cognition would explain decre...
Article
Full-text available
PURPOSE Chemotherapy-induced peripheral neuropathy (CIPN) and falls can be persistent side effects of cancer treatment. Standing postural sway and gait tests with body-worn, inertial sensors provide objective digital balance and gait measures that represent several different domains controlling mobility. Specific domains of balance and gait that re...
Article
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Although supervised and real-time telerehabilitation by videoconferencing is now becoming common for people with Parkinson’s disease (PD), its efficacy for balance and gait is still unclear. This paper uses a scoping approach to review the current evidence on the effects of telerehabilitation by videoconferencing on balance and gait for patients wi...
Article
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Older adults, as well as those with certain neurological disorders, may compensate for poor neural control of postural stability by widening their base of foot support while walking. However, the extent to which this wide-based gait improves postural stability or affects postural control strategies has not been explored. People with idiopathic Park...
Preprint
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Background Androgen deprivation therapy (ADT) increases the risk of frailty, falls, and, poor physical functioning in prostate cancer survivors. Detection of frailty is limited to self-report instruments and performance measures, so unbiased tools are needed. We investigated relationships between an unbiased measure – daily life mobility – and ADT...
Article
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Purpose To determine whether strength training or tai ji quan can reduce frailty in older, postmenopausal women treated with chemotherapy for cancer. Methods We conducted a secondary data analysis from a 3-arm, single-blind, randomized controlled trial where older (50–75 years), postmenopausal women cancer survivors were randomized to supervised g...
Article
Background Progressive loss of standing balance is a feature of Friedreich's ataxia (FRDA). Objectives This study aimed to identify standing balance conditions and digital postural sway measures that best discriminate between FRDA and healthy controls (HC). We assessed test–retest reliability and correlations between sway measures and clinical sco...
Article
Background Maintaining balance is crucial for independence and quality of life. Loss of balance is a hallmark of spinocerebellar ataxia (SCA). Objective The aim of this study was to identify which standing balance conditions and digital measures of body sway were most discriminative, reliable, and valid for quantifying balance in SCA. Methods Fif...
Article
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Individuals with Parkinson’s disease (PD) and freezing of gait (FOG) have a loss of presynaptic inhibition (PSI) during anticipatory postural adjustments (APAs) for step initiation. The mesencephalic locomotor region (MLR) has connections to the reticulospinal tract that mediates inhibitory interneurons responsible for modulating PSI and APAs. Here...
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This study aimed to validate a wearable device’s walking speed estimation pipeline, considering complexity, speed, and walking bout duration. The goal was to provide recommendations on the use of wearable devices for real-world mobility analysis. Participants with Parkinson’s Disease, Multiple Sclerosis, Proximal Femoral Fracture, Chronic Obstructi...
Preprint
Full-text available
Individuals with Parkinson’s disease (PD) and freezing of gait (FOG) have a loss of presynaptic inhibition (PSI) during anticipatory postural adjustments (APAs) for step initiation. The mesencephalic locomotor region (MRL) has connections to the reticulospinal tract that mediates inhibitory interneurons responsible for modulating PSI and APAs. Here...
Article
Full-text available
Smartphone sensors are used increasingly in the assessment of ataxias. To date, there is no specific consensus guidance regarding a priority set of smartphone sensor measurements, or standard assessment criteria that are appropriate for clinical trials. As part of the Ataxia Global Initiative Digital-Motor Biomarkers Working Group (AGI WG4), aimed...
Article
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With disease-modifying drugs on the horizon for degenerative ataxias, ecologically valid, finely granulated, digital health measures are highly warranted to augment clinical and patient-reported outcome measures. Gait and balance disturbances most often present as the first signs of degenerative cerebellar ataxia and are the most reported disabling...
Article
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Background Chemotherapy-induced peripheral neuropathy (CIPN) is a debilitating and dose-limiting side effect of systemic cancer therapy. In many cancer survivors, CIPN persists after treatment ends and is associated with functional impairments, abnormal gait patterns, falls, and diminished quality of life. However, little is known regarding which p...
Article
Full-text available
Objective Investigate the brain functional networks associated with motor impairment in people with Parkinson’s disease (PD). Background PD is primarily characterized by motor dysfunction. Resting-state functional connectivity (RsFC) offers a unique opportunity to non-invasively characterize brain function. In this study, we hypothesized that the...
Article
Full-text available
Background Gait and balance impairments are among the main causes of falls in older adults. The feasibility and effectiveness of adding sensor-based feedback to physical therapy (PT) in an outpatient PT setting is unknown. We evaluated the feasibility and effectiveness of PT intervention combined with a therapist-assisted visual feedback system, ca...
Article
Full-text available
Background Balance impairments, that lead to falls, are one of the main symptoms of Parkinson’s disease (PD). Telerehabilitation is becoming more common for people with PD; however, balance is particularly challenging to assess and treat virtually. The feasibility and efficacy of virtual assessment and virtual treatment of balance in people with PD...
Preprint
Full-text available
Purpose: To determine whether strength training or tai ji quan can reduce frailty in older, postmenopausal women treated with chemotherapy for cancer. Methods: We conducted a secondary data analysis from a 3-arm, single-blind, randomized controlled trial where older (50+ years), postmenopausal women cancer survivors were randomized to supervised gr...
Article
Full-text available
Objective To analyze the effect of combined training (CT) in postural control and gait parameters in postmenopausal women. Methods A parallel-group, randomized, control study was conducted with 16 weeks of combined training ( n = 16) versus a non-training control group ( n = 12) in postmenopausal women (aged 59.3 ± 8.0). Pre and postintervention as...
Article
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Background The simultaneous completion of multiple tasks (dual-tasking, DT) often leads to poorer task performance (DT cost, DTC). People with Parkinson’s disease (PwPD) exhibit difficulty with DT, and DTC may be particularly pronounced in PwPD with freezing of gait (FOG). Objective This study assessed the relationship between FOG status and DTC d...
Article
Introduction: The relationship between mobility and cognition has been studied in the aging population and associations have been also reported in people with Parkinson's disease (PD). Objective: To compare different aspects of gait and balance between individuals with PD who have normal cognition and those with impaired cognition, using both cl...
Article
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Background: Methods for modulating the cerebellum with transcranial magnetic stimulation (TMS) are well established, and preliminary data from our group and others has shown evidence of transient improvements in balance after cerebellar repetitive transcranial magnetic stimulation (rTMS) in progressive suprancuclear palsy (PSP). This study examine...
Article
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Background The use of objective gait and balance metrics is rapidly expanding for evaluation of atypical parkinsonism, and these measures add to clinical observations. Evidence for rehabilitation interventions to improve objective measures of balance and gait in atypical parkinsonism is needed. Aim Our aim is to review, with a narrative approach,...
Article
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Over the course of the disease, freezing of gait (FoG) will gradually impact over 80% of people with Parkinson’s disease (PD). Clinical decision-making and research design are often based on classification of patients as ‘freezers’ or ‘non-freezers’. We derived an objective measure of FoG severity from inertial sensors on the legs to examine the co...
Article
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Background: Gait and balance impairments are among the most troublesome and heterogeneous in Parkinson's disease (PD). This heterogeneity may, in part, reflect genetic variation. The apolipoprotein E (APOE) gene has three major allelic variants (ε2, ε3 and ε4). Previous work has demonstrated that older adult (OA) APOE ε4 carriers demonstrate gait...
Article
Background and Aim: Standing postural sway and gait tests with body-worn inertial sensors provide a multitude of objective, digital balance, and gait measures that represent several different domains controlling mobility. However, it is not clear which domains of balance or gait best reflect the impact of treatment-induced peripheral neuropathy on...
Article
Purpose: To compare the efficacy of tai ji quan versus strength training to prevent falls after chemotherapy in older, postmenopaual women. Methods: We conducted a three-arm, single-blind, randomized controlled trial where older (50+ years), postmenopausal women cancer survivors participated in one of three supervised group exercise programs (ta...
Article
Full-text available
Objectives To investigate if digital measures of gait (walking and turning) collected passively over a week of daily activities in people with Parkinson's disease (PD) increases the discriminative ability to predict future falls compared to fall history alone. Methods We recruited 34 individuals with PD (17 with history of falls and 17 non-fallers...
Article
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Physical activity and sleep monitoring in daily life provide vital information to track health status and physical fitness. The aim of this study was to establish concurrent validity for the new Opal Actigraphy solution in relation to the widely used ActiGraph GT9X for measuring physical activity from accelerometry epic counts (sedentary to vigorou...
Article
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We tested the feasibility of one session of treadmill training using a novel physical therapist assisted system (Mobility Rehab) using wearable sensors on the upper and lower limbs of 10 people with Parkinson’s disease (PD). Participants performed a 2-min walk overground before and after 15 min of treadmill training with Mobility Rehab, which inclu...
Article
Individuals with Parkinson’s disease (PD) and freezing of gait (FOG) have difficulty initiating and maintaining a healthy gait pattern; however, the relationship among FOG severity, gait initiation, and gait automaticity, in addition to the neural substrate of this relationship has not been investigated. This study investigated the association amon...
Article
Background Although much is known about the multifactorial nature of falls in Parkinson's disease (PD), optimal classification of fallers remains unclear. Objective To identify clinical (demographic, motor, cognitive and patient-reported) and objective mobility (balance and gait) measures that best discriminate fallers from non-fallers in PD. Met...
Article
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Background People with Parkinson’s disease (PD) have a high fall rate and many falls are associated with turns. Despite this, there is minimal research on effects of rehabilitation on the quality of turns. Further, quantifying turns in the home may have broader implications since rehabilitation of turns would ideally improve turning in real world m...
Article
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Dopaminergic activity decreases in older adults (OAs) with normal aging and is further reduced in Parkinson’s disease (PD), affecting cortical motor and sensorimotor pathways. Levodopa is the prevailing therapy to counter dopamine loss in PD, though not all PD motor signs improve with levodopa. The purpose of this preliminary study was to explore t...
Article
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We previously showed that both open-loop (beat of a metronome) and closed-loop (phase-dependent tactile feedback) cueing may be similarly effective in reducing Freezing of Gait (FoG), assessed with a quantitative FoG Index, while turning in place in the laboratory in a group of people with Parkinson’s disease (PD). Despite the similar changes on th...
Article
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Objective measures of balance and gait have the potential to improve prediction of future fallers because balance and gait impairments are common precursors. We used the Instrumented Stand and Walk Test (ISAW) with wearable, inertial sensors to maximize the domains of balance and gait evaluated in a short test. We hypothesized that ISAW objective m...
Article
Background: It is unknown whether medication status (off and on levodopa) or laboratory versus home settings plays a role in discriminating fallers and non-fallers in people with Parkinson's disease (PD). Objectives: To investigate which specific digital gait and turning measures, obtained with body-worn sensors, best discriminated fallers from...
Article
Background Although many studies have shown abnormalities in brain structure and function in people with Parkinson’s disease (PD), we still have a poor understanding of how brain structure and function relates to freezing of gait (FOG). Graph theory analysis of electroencephalography (EEG) can explore the relationship between brain network structur...
Article
Full-text available
Background To date, no medication has slowed the progression of Parkinson’s disease (PD). Preclinical, epidemiological, and experimental data on humans all support many benefits of endurance exercise among persons with PD. The key question is whether there is a definitive additional benefit of exercising at high intensity, in terms of slowing disea...
Poster
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A single dose of L-dopa does not affect cortical sensorimotor inhibition or mobility in OAs. However, sensorimotor inhibition of the cortex is related to postural control in both gait and quiet stance in OAs, and the relationships are affected by dopamine. Since dopamine replacement therapy in people with PD impairs sensorimotor inhibition and post...
Research
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BACKGROUND AND AIM: Cortical dopaminergic activity decreases in normal aging, with an exacerbated decrease observed in Parkinson's disease (PD). Levodopa (L-dopa), a dopamine replacement medication, is the prevailing therapy to treat PD. Although the pace of gait improves with L-dopa, postural sway may not improve or may worsen. Additionally, corti...
Article
Background and Aim Individuals with Parkinson’s disease (PD) with and without freezing of Gait (FoG) may respond differently to exercise interventions for several reasons, including disease duration. This study aimed to determine whether both people with and without FoG benefit from the Agility Boot Camp with Cognitive Challenges (ABC-C) program....
Article
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This study investigates the potential of passive monitoring of gait and turning in daily life in people with multiple sclerosis (PwMS) to identify those at future risk of falls. Seven days of passive monitoring of gait and turning were carried out in a pilot study of 26 PwMS in home settings using wearable inertial sensors. The retrospective fall h...
Article
Background Parkinson’s disease (PD) is a neurodegenerative disorder causing postural control impairments. Postural control involves multiple domains, such as control of postural sway in stance, automatic postural responses (APRs) and anticipatory postural adjustments (APAs). We hypothesize that impairments in each postural domain is associated with...
Article
Full-text available
The extent to which the heterogeneity of gait and balance problems in PD may be explained by genetic variation is unknown. Variants in the glucocerebrosidase (GBA) gene are the strongest known genetic risk factor for PD and are associated with greater motor and cognitive severity. However, the impact of GBA variants on comprehensive measures of gai...
Preprint
BACKGROUND Patients with hematologic malignancies undergo induction chemotherapy potentially impairing mobility and worsening symptoms prior to autologous hematopoietic stem cell transplant (autoHSCT). Wearable sensors may identify patients with altered mobility from chemotherapy-related symptoms before additional treatment who can benefit from ear...
Article
Full-text available
Background Wearable sensors could be a simple way to quantify and characterize mobility in patients with hematologic cancer scheduled to receive autologous hematopoietic stem cell transplant (autoHSCT) and how they may be related to common treatment-related symptoms and side effects of induction chemotherapy. Objective We aimed to conduct a cross-s...
Article
TPS193 Background: Many prostate cancer survivors are treated with androgen deprivation therapy (ADT), but these therapies may increase frailty, worsen physical functioning, and increase fall risk. While exercise may counter functional declines associated with ADT, no studies have tested whether and which type of exercise may reduce falls and frail...
Article
81 Background: Androgen deprivation therapy (ADT) for prostate cancer may result in accelerated aging that increases the risk for falls. Falls are higher in men with a history of ADT use, even if treatment is discontinued, compared to men never on ADT. Less is known, however, about the specific patient characteristics that might be associated with...
Article
Full-text available
The “total distance walked” obtained during a standardized walking test is an integral com- ponent of physical fitness and health status tracking in a range of consumer and clinical applications. Wearable inertial sensors offer the advantages of providing accurate, objective, and reliable measures of gait while streamlining walk test administration...
Article
Full-text available
Background Instrumented measures of balance and gait measure more specific balance and gait impairments than clinical rating scales. No prior studies have used objective balance/gait measures to examine associations with ventricular and brain volumes in people with Parkinson’s disease (PD). Objective To test the hypothesis that larger ventricular...
Article
Full-text available
Background Many prostate cancer survivors are treated with androgen deprivation therapy (ADT), but these therapies may increase frailty, worsen physical functioning, and increase fall risk. While exercise may counter functional declines associated with ADT, no studies have tested whether and which type of exercise may reduce falls and frailty. The...
Article
Background Telemedicine has the advantage of expanding access to care for patients with Parkinson’s Disease (PD). However, rigidity and postural instability in PD are difficult to measure remotely, and are important measures of functional impairment and fall risk. Research Question: Can measures from wearable sensors be used as future surrogates fo...