Ludy C. Shih

Background: Higher step width variability while walking is associated with poor physical function and falls. Sleep is an established modifiable risk factor for both gait and physical function impairments, but it remains to be examined whether sleep is also related to step width variability. Objective: This study aimed to evaluate the cross-sectional associations between objectively measured sleep quality, using cardiopulmonary coupling spectrograms, and step width variability during a preferred walking condition among middle-aged and older adults. Methods: This study included 72 adults (mean age 71, SD 8.3 y; n=37, 51% female; n=65, 90% non-Hispanic White) who had ≥2 nights of objectively measured sleep (cardiopulmonary coupling via SleepImage ring) and completed a 10-m walk at preferred speed while wearing inertial sensors (APDM Mobility Lab). Sleep measures included sleep duration, efficiency, fragmentation, stability, apnea-hypopnea index, percentage of time oxygen saturation level <90%, oxygen desaturation index, and respiratory disturbance index. Additional derived sleep variables were explored using least absolute shrinkage and selection operator models. Step width variability was defined by the asymmetry of lateral step variability and categorized as medial (≤−7.5 cm), minimal (within ±7.5 cm; reference), or lateral displacement (≥7.5 cm). Multinomial logistic regression models adjusted for age, sex, race, education, BMI, and usual gait speed evaluated cross-sectional associations between sleep and step width variability categories. Results: We found that a 1% higher sleep fragmentation was associated with a 6% higher probability of step width variability ≥7.5 cm (95% CI 1.01‐1.11), while a 1% higher sleep stability was associated with a 5% lower probability of variability ≥7.5 cm (95% CI 0.91‐0.99), compared to minimal variability. From the least absolute shrinkage and selection operator models, we found that a 1% higher sleep quality index, a 1% higher rapid eye movement sleep, a 1-second shorter apnea duration, and a 1-beat per minute slower mean heart rate were also associated with a lower probability of lateral compared to minimal displacement. Conclusions: Poor sleep quality was associated with higher step width variability among middle-aged and older adults. This suggests that sleep may be a modifiable risk factor for maintaining postural stability while walking among middle-aged and older adults. Future studies are needed to examine whether intervening in these sleep measures also lowers the risk of falls.

Limited information exists on incident dementia in individuals with Parkinson's disease (PD) in US community‐based samples. We examined cognitive statuses and PD diagnoses of 183 individuals in the Framingham Heart Study (FHS) to establish incident dementia, mortality rates, associations with sex, age at PD onset, and education level. Annual incidence rates of dementia (5.0%, 95% CI [3.7%–6.4%]) and mortality (10.5%, 95% CI [8.7%–12.3%]), did not differ by sex or education level. Increased age at PD diagnosis was a significant risk factor for incident dementia and mortality. Sex may not be a significant risk factor for community‐based PD dementia.

BACKGROUND Higher step width variability while walking is associated with poor physical function and falls. Sleep is an established modifiable risk factor for both gait and physical function impairments, but it has yet to be examined whether sleep is also related to step width variability. OBJECTIVE This study aimed to evaluate the cross-sectional associations between objectively measured sleep quality, using cardiopulmonary coupling (CPC) spectrograms, and step width variability during a preferred walking condition among middle aged and older adults. METHODS This study included 72 adults (mean age: 71 years, 51% female, 90% non-Hispanic White) who had ≥ 2 nights of objectively measured sleep (CPC via SleepImage ring) and completed a 10-meter walk while at preferred speed wearing inertial sensors (APDM Mobility Lab). Sleep measures included: sleep duration, efficiency, fragmentation, stability, apnea hypopnea index, time SpO2 levels < 90%, oxygen desaturation index, and respiratory disturbance index. Additional derived sleep variables were explored using LASSO models. Step width variability was defined by asymmetry of lateral step variability and categorized as medial (≤ -7.5 cm), minimal (within ± 7.5 cm; reference), or lateral displacement (≥ 7.5 cm). Multinomial logistic regression models adjusted for age, sex, race, education, and body mass index evaluated cross-sectional associations between sleep and step width variability categories. RESULTS We found that 1% higher sleep fragmentation was associated with 6% higher probability of step width variability ≥ 7.5 cm (95% CI: 1.01-1.11), while 1% higher sleep stability was associated with 5% lower probability of variability ≥ 7.5 cm (95% CI: 0.91-0.99), compared to minimal variability. From the LASSO models, we found that 1% higher sleep quality index, 1% higher REM sleep, 1-second shorter apnea duration, and 1-beat/minute slower mean heart rate were also associated with lower probability of lateral compared to minimal displacement. CONCLUSIONS Poor sleep quality was associated with higher step width variability among middle aged and older adults. This suggests that sleep may be a modifiable risk factor for maintaining postural stability while walking among middle aged and older adults. Future studies are needed to examine whether intervening on these sleep measures also lowers risk of falls.

Background: Essential tremor (ET) is a common movement disorder that affects the upper limbs in vital activities of daily living. Few studies have examined the impact of tremor severity on caregiving intensity. Methods: Clinic-based data were collected in the United States (US) from March 2021 to August 2021 through the Adelphi ET Disease Specific Programme (DSP). Linked data between physician and care partner/patient pairs were used to evaluate care partner-reported weekly hours of patient care. Tremor severity was assessed with the Essential Tremor Rating Assessment Scale (TETRAS) Performance and Activities of Daily Living subscales. Pearson chi-square, correlation and multivariate regression analyses were conducted to examine the relationships between tremor severity and hours of care partner assistance. Results: A quarter of 960 individuals with ET required care partners. Most care partners were spouses (61%), but other family members or friends also served as care partners. About 23% of care partners reported giving constant care, defined as 112 hours per week or more, while the remainder of care partners reported caregiving time averaging 24.5 hours per week. The probability of needing a care partner was significantly associated with tremor severity, and the association between care partner need and tremor severity was moderate (bivariate r = 0.32–0.37) and not substantially impacted by the inclusion of additional covariates (age, sex, race, comorbidity, relationship with patient, and living with patient). Discussion: Roughly 25% of patients with ET have care partner needs, and the number of care partner hours provided is correlated with tremor severity. Therefore, treatments that ameliorate tremor severity have the potential to reduce caregiving intensity in ET.

Background: Essential tremor (ET) affects nearly 7 million people in the United States and consists of upper limb tremor that can affect activities of daily living, including activities related to work. Research examining the effect of ET on work productivity is limited and there are no studies using validated work productivity instruments. Methods: Clinic-based data were collected between March 2021 and August 2021 from US physicians participating in the Adelphi ET Disease Specific Programme (DSP). Patients were evaluated with the Essential Tremor Rating Assessment Scale (TETRAS), Quality of Life in Essential Tremor (QUEST) questionnaire, and the Work Productivity and Activity Impairment (WPAI) questionnaire. Statistical associations between tremor severity and work productivity were examined. Results: A total of 1,003 ET patients were identified, and 420 patients completed the WPAI questionnaire and were included in this study. Activity impairment was independently associated with tremor severity, adjusting for age, full-time vs. part-time employment, household income, depression, and anxiety. Of those who were employed (n = 165), 133 (80.6%) were employed full-time, and 141 (85.5%) had some level of work impairment. Work impairment was also independently associated with tremor severity, adjusting for the same covariates. Among those patients for whom QUEST responses were available, 47% (64/135) of patients with ET working full-time and 88% (36/41) of those working part-time reported that tremor interfered with work. Discussion: Work impairment is significantly correlated with tremor severity. Although a minority of patients in this clinic-based cohort were identified as employed, nearly all reported a negative impact on work performance.

Deep brain stimulation (DBS) for essential tremor is remarkably effective, leading to over 80% reduction in standardized tremor ratings. However, for certain types of tremor, such as those accompanied by ataxia or dystonia, conventional DBS targets have shown poor efficacy. Various rationales for using cerebellar DBS stimulation to treat tremor have been advanced, but the varied approaches leave many questions unanswered: which anatomic target, stimulation settings, and indications seem most promising for this emerging approach. This article reviews the clinical experience published to date and explores some of the pre-clinical and human physiology data that might support a role for further systematic investigation of cerebellar DBS for clinical use. Four tremor disorders to date have been targeted with cerebellar DBS in humans: essential tremor, post-stroke tremor, dystonic tremor, and tremor associated with degenerative cerebellar ataxias, like spinocerebellar ataxia type 3. The dentate nucleus is the most frequently chosen target, but key stereotactic and imaging details are missing from many of the case reports. Interestingly, consensus on laterality has not been definitively established as there are conflicting models of the hypothesized mechanism of action of DBS of the dentate nuclei, and conflicting reports of benefit on the tremor ipsilateral to and contralateral toto the affected limb. Several points are highlighted, including the prediction from in vivo preclinical physiology studies and interventional studies, the remaining uncertainty regarding the preferred laterality of targets, and the lack of clear prioritization of tremor etiologies to be targeted in future rigorously designed interventional studies (e.g., preferably repeated n-of-1 or sham-controlled studies involving more than one patient).