Prevalence and clinical classification of tremor in elderly--a community-based survey in Brazil

Association between postural tremor and risk of disability in community‐dwelling older people

BACKGROUND

The prevalence of postural tremor increases with age and the tremor has been found to be associated with aging-related physiological decline. However, whether postural tremor in older adults is associated with adverse outcomes such as disability is unclear. This study investigated the association between postural tremor and the risk of disability in activities of daily living (ADL) among community-dwelling older people.

METHODS

Data were derived from a population-based study of Chinese adults aged ≥55 years. Postural tremor was assessed at baseline using a two-step method (i.e., tremor screening followed by examination of positive cases). ADL disability was determined using an 8-item questionnaire, which covered the mobility and self-care domains of ADL. Participants free of ADL disability at baseline were followed for up to 4 years.

RESULTS

The prospective analyses included 5868 participants. Participants with postural tremor were at greater risk of incident ADL disability, particularly disability in the mobility domain of ADL. After multivariate adjustment, postural tremor was not significantly associated with incident ADL disability (multivariate-adjusted relative risk [RR] = 1.05, 95% confidence interval [CI] = 0.77-1.43), and was marginally associated with incident disability in the mobility domain of ADL (multivariate-adjusted RR = 1.36, 95% CI = 0.98-1.88). The risk of mobility-related ADL disability was significantly increased among men, but not women, with postural tremor (multivariate-adjusted RR = 1.84, 95% CI = 1.11-3.05). Older age and an increased number of chronic comorbidities mainly explained the higher risk of ADL disability in older people with postural tremor.

CONCLUSIONS

Postural tremor in older adults is associated with greater incidence of ADL disability, particularly mobility-related ADL disability. The association is largely due to older age and a higher prevalence of chronic comorbidities in older people with postural tremor. Postural tremor is not a strong independent predictor of ADL disability in older people.

New horizons in late-onset essential tremor: a pre-cognitive biomarker of dementia?

Essential tremor (ET) is the most common cause of tremor in older adults. However, it is increasingly recognised that 30–50% of ET cases are misdiagnosed. Late-onset ET, when tremor begins after the age of 60, is particularly likely to be misdiagnosed and there is mounting evidence that it may be a distinct clinical entity, perhaps better termed ‘ageing-related tremor’. Compared with older adults with early-onset ET, late-onset ET is associated with weak grip strength, cognitive decline, dementia and mortality. This raises questions around whether late-onset ET is a pre-cognitive biomarker of dementia and whether modification of dementia risk factors may be particularly important in this group. On the other hand, it is possible that the clinical manifestations of late-onset ET simply reflect markers of healthy ageing, or frailty, superimposed on typical ET. These issues are important to clarify, especially in the era of specialist neurosurgical treatments for ET being increasingly offered to older adults, and these may not be suitable in people at high risk of cognitive decline. There is a pressing need for clinicians to understand late-onset ET, but this is challenging when there are so few publications specifically focussed on this subject and no specific features to guide prognosis. More rigorous clinical follow-up and precise phenotyping of the clinical manifestations of late-onset ET using accessible computer technologies may help us delineate whether late-onset ET is a separate clinical entity and aid prognostication.

The Pharmacotherapeutic Landscape for Essential Tremor: Quantifying the Level of Unmet Need From a Patient and Epidemiologic Perspective

ABSTRACT

Essential tremor (ET) is one of the most common neurological diseases. Despite this high prevalence, treatment options remain limited. Recent advances in mechanistic research have led to renewed interest in developing newer pharmacotherapeutic agents. Although this is promising, there remains surprisingly little knowledge of the magnitude of the vast ET patient population who would benefit from and/or engage with such agents. This is because the vast bulk of ET patients in the population has milder tremor and does not seek medical care for their tremor. How many of these would be interested in taking a new agent? Hence, the level of unmet need, from the patient perspective and from a public health perspective, is totally unclear. In this article, the author systematically reviews peer-reviewed data on several pertinent questions that relate to this unmet need. The questions are as follows: (1) What proportion of the population of ET cases sees a health care provider for their tremor? (2) What proportion of the ET population has a tremor that is severe enough for them to want to take a medication for their tremor? (3) How do other factors such as age, sex, education, health literacy, and locale affect the receptivity to treatment in ET? (4) What is the patient use of the current ET medications? (5) Is the unmet need greater in some groups of ET cases than others? For each of these questions, available data are carefully reviewed and analyzed, and gaps in knowledge identified for further investigation.

Essential tremor

Essential tremor (ET) is one of the most common movement disorders, with a reported >60 million affected individuals worldwide. The definition and underlying pathophysiology of ET are contentious. Patients present primarily with motor features such as postural and action tremors, but may also have other non-motor features, including cognitive impairment and neuropsychiatric symptoms. Genetics account for most of the ET risk but environmental factors may also be involved. However, the variable penetrance and challenges in validating data make gene-environment analysis difficult. Structural changes in cerebellar Purkinje cells and neighbouring neuronal populations have been observed in post-mortem studies, and other studies have found GABAergic dysfunction and dysregulation of the cerebellar-thalamic-cortical circuitry. Commonly prescribed medications include propranolol and primidone. Deep brain stimulation and ultrasound thalamotomy are surgical options in patients with medically intractable ET. Further research in post-mortem studies, and animal and cell-based models may help identify new pathophysiological clues and therapeutic targets and, together with advances in omics and machine learning, may facilitate the development of precision medicine for patients with ET.

Tremor Syndromes: An Updated Review

Tremor is the most commonly encountered movement disorder in clinical practice. A wide range of pathologies may manifest with tremor either as a presenting or predominant symptom. Considering the marked etiological and phenomenological heterogeneity, it would be desirable to develop a classification of tremors that reflects their underlying pathophysiology. The tremor task force of the International Parkinson Disease and Movement Disorders Society has worked toward this goal and proposed a new classification system. This system has remained a prime topic of scientific communications on tremor in recent times. The new classification is based on two axes: 1. based on the clinical features, history, and tremor characteristics and 2. based on the etiology of tremor. In this article, we discuss the key aspects of the new classification, review various tremor syndromes, highlight some of the controversies in the field of tremor, and share the potential future perspectives.

How Common is Essential Tremor? Update on the Worldwide Prevalence of Essential Tremor

Background

Essential tremor (ET) is among the most prevalent movement disorders. Comprehensive reviews of disease prevalence were published in 1998 and 2010 but not since then. We reviewed the prevalence of ET in population-based epidemiological studies, derived a precise summary estimate of prevalence from these studies, and examined differences in prevalence across studies. We used two methods: a descriptive-analytical approach and a meta-analysis.

Methods

A PUBMED search yielded 14 published papers since the 2010 review.

Results

There were 42 population-based prevalence studies (23 countries and 6 continents). In a meta-analysis, pooled prevalence (all ages) = 1.33%, with statistically significant heterogeneity across studies (I2 = 99.3%, p < 0.0001). In additional descriptive analyses, median crude prevalence (all ages) = 0.4% and mean = 0.67%. Prevalence increased markedly with age, and especially with advanced age. In the meta-analysis, prevalence (age ≥ 65 years) = 5.79%, and in descriptive analyses, median crude prevalence (age ≥ 60-65) = 5.9% and mean = 8.0%. In the oldest age groups, median prevalence = 9.3%, with several studies reporting values >20%. The prevalence increased by 74% for every decade increase in age (p < 0.0001). Gender did not impact the prevalence of ET (p = 0.90).

Discussion

Precise prevalence estimates are important because they form the numerical basis for public health initiatives and offer clues about underlying biological factors of mechanistic importance. The prevalence of ET among those age ≥ 65 is similar to that reported for Alzheimer's disease in elders, suggesting that ET may be the most common neurodegenerative disease.

The global prevalence of essential tremor, with emphasis on age and sex: A meta-analysis

Background

Essential tremor (ET) is one of the most common neurological disorders that impairs quality of life and leads to disability and social handicap. It was estimated that approximate 0.9% of people worldwide were affected by ET. The last decade has seen new investigations on the epidemiology of ET, enabling us to provide an up-to-date estimation of ET prevalence, with emphasis on age and sex.

Methods

We searched PubMed, Medline, Embase and Global Health for studies that reported the prevalence of ET in the general population. Potential sources of heterogeneity were examined by age-adjusted meta-regression. The age- and sex-specific prevalence of ET was constructed with a multilevel mixed-effects meta-regression.

Results

A total of 29 articles were included in our systematic review and meta-analysis. The prevalence of ET increased dramatically with advancing age, where the prevalence estimate in people aged under 20 years was 0.04% (95% confidence interval [CI] = 0.00-0.29) and that in elderly aged 80 years and above was 2.87% (95% CI = 1.07-7.49). ET was consistently more common in males than in females. In 2020, the overall prevalence of ET in the general population was 0.32% (95% CI = 0.12-0.91), and the prevalence was higher in males (0.36%, 95% CI = 0.14-1.03) than in females (0.28%, 95% CI = 0.11-0.79). In 2020, the number of people affected by ET was 24.91million (95% CI = 9.51-70.92), among whom 56% were males.

Conclusions

This study provides an up-to-date estimation of ET prevalence in the general population throughout the whole life span, with emphasis on age and sex. The adoption of an internationally acknowledged diagnostic strategy is prompted in future epidemiological investigations.

Protocol registration

PROSPERO (CRD42020203979)

A single oral dose of cannabidiol did not reduce upper limb tremor in patients with essential tremor

Essential tremor (ET) is a common clinical syndrome characterized by action tremors affecting both upper limbs that can compromise manual tasks' execution and impair functional and social performance. The primary pharmacological treatment is symptomatic, but effective medicines are somewhat limited. There is a clear need to find new effective therapies for the treatment of ET. Cannabidiol (CBD) is a modulator of CB1 receptor and CB1 agonists can reduce tremors in experimental models. We hypothesized that a single acute CBD intake would reduce tremors in ET patients. We performed a randomized, controlled, double-blind, crossover study on 19 patients with ET. They were 10 males and 9 females, had mean 63 years of age, and mean 23 years of disease duration and had insufficient control of their tremors with the usual pharmacological treatment. They ingested a single oral dose of CBD (300 mg) or placebo in two experimental sessions performed 2-weeks apart. Patients were evaluated immediately before and after oral ingestion (60 min and 210 min), using the Fahn-Tolosa-Marin clinical scale. There was no carryover effect. There were no significant differences in upper limb tremors score, specific motor task tremor scores (writing and drawing/pouring) or clinical impression of change after treatment with placebo or CBD. In conclusion, a single 300 mg oral dose of CBD had no significant effect on the severity of upper limb tremors of ET patients. Our findings did not exclude the possibility that chronic treatment with CBD could have a symptomatic effect.

Postural Tremor Is Associated with Gait and Balance Impairments in Community-Dwelling Older People

OBJECTIVES

We sought to assess associations of postural tremor with gait and balance impairments among community-dwelling older people in both cross-sectional and longitudinal analyses.

DESIGN

A prospective cohort study.

SETTING

Communities in Beijing, China.

PARTICIPANTS

This study included 7075 individuals aged 55 years or older.

MEASUREMENTS

Postural tremor was assessed using a two-step method (tremor screening followed by a confirmation examination of positive cases) at baseline. Gait and balance performances were measured with the Tinetti Mobility Test at baseline and 1 year later.

RESULTS

At baseline, 45 (24.7%) of 182 tremor cases vs 663 (9.6%) of 6893 controls had gait and balance impairments. At 1-year follow-up, 19 (21.1%) of 90 tremor cases vs 416 (9.8%) of 4262 controls experienced a rapid decline in gait and balance performance. After controlling for potential confounders, postural tremor was associated with gait and balance impairments at baseline (odds ratio [OR] = 1.77; 95% confidence interval [CI] = 1.20-2.62; p = .004) and a rapid decline in gait and balance performance at 1-year follow-up (OR = 1.99; 95% CI = 1.17-3.39; p = .01).

CONCLUSION

In this population-based cohort study, we found postural tremor was associated with gait and balance impairments among community-dwelling older people in both cross-sectional and longitudinal analyses. Our findings suggest that motor function should be routinely evaluated and monitored in older people with postural tremor. J Am Geriatr Soc 67:799-803, 2019.

[Essential tremor in endemic disease control agents exposed to pesticides: a case-control study]

Tremor is the most frequent movement disorder in the population and can be associated with pesticide exposure. The aim was to assess the odds of essential tremor in 442 endemic disease control agents in Rio de Janeiro State, Brazil, exposed to pesticides. Fifty-one cases and 204 controls were selected (1:4). All participants answered a questionnaire on socio-demographic, occupational, and toxicological items. The influence of pesticide exposure on the development of tremor was estimated by non-conditional logistic regression, adjusted for selected covariables. Mean age of the study population was 49 (SD = 7) years, and the difference between cases (mean = 50.8; SD = 6.9) and controls (mean = 48.5; SD = 6.9) was statistically significant (p = 0.03). Those with 16 to 16.9 years of pesticide use showed the highest odds of essential tremor (adjusted OR = 4.60; 95%CI: 1.29-16.41). Our results suggest that 16 to 16.9 years of pesticide exposure had a major impact on the development of essential tremor.

Voluntary-Driven Elbow Orthosis with Speed-Controlled Tremor Suppression

Robotic technology is gradually becoming commonplace in the medical sector and in the service of patients. Medical conditions that have benefited from significant technological development include stroke, for which rehabilitation with robotic devices is administered, and surgery assisted by robots. Robotic devices have also been proposed for assistance of movement disorders. Pathological tremor, among the most common movement disorders, is one such example. In practice, the dissemination and availability of tremor suppression robotic systems has been limited. Devices in the marketplace tend to either be non-ambulatory or to target specific functions, such as eating and drinking. We have developed a one degree-of-freedom (DOF) elbow orthosis that could be worn by an individual with tremor. A speed-controlled, voluntary-driven suppression approach is implemented with the orthosis. Typically tremor suppression methods estimate the tremor component of the signal and produce a canceling counterpart signal. The suggested approach instead estimates the voluntary component of the motion. A controller then actuates the orthosis based on the voluntary signal, while simultaneously rejecting the tremorous motion. In this work, we tested the suppressive orthosis using a one DOF robotic system that simulates the human arm. The suggested suppression approach does not require a model of the human arm. Moreover, the human input along with the orthosis forearm gravitational forces, of non-linear nature, are considered as part of the disturbance to the suppression system. Therefore, the suppression system can be modeled linearly. Nevertheless, the orthosis forearm gravitational forces can be compensated by the suppression system. The electromechanical design of the orthosis is presented, and data from an essential tremor patient is used as the human input. Velocity tracking results demonstrate an RMS error of 0.31 rad/s, and a power spectral density shows a reduction of the tremor signal by 99.8%, while the intentional component power was reduced by <1%.

Epidemiology characteristics of constipation for general population, pediatric population, and elderly population in china

Objective. To acquire more data about the epidemiologic characteristics of constipation in different kinds of populations in China. Methods. Using "constipation" and "China" as search terms; relevant papers were searched from January 1995 to April 2014. Data on prevalence, gender, diagnostic criteria, geographical area, educational class, age, race, and physician visit results were extracted and analyzed. Results. 36 trials were included. Prevalence rates of constipation in elderly population (18.1%) and pediatric population (18.8%) were significantly higher than that in general population (8.2%). Prevalence of constipation defined by non-Rome criteria was higher than that by Rome criteria in general population. Prevalence rates of constipation were different for different geographical area. People with less education were predisposed to constipation. In pediatric population, prevalence of constipation was the lowest in children aged 2-6 years. Prevalence of constipation in ethnic minorities was higher than that in Han people. People with constipation were predisposed to FD, haemorrhoid, and GERD. Only 22.2% patients seek medical advice in general population. Conclusions. In China, prevalence of constipation was lower compared with most of other countries. The factors including female gender, diagnostic criteria, geographical area, age, educational class, and race seemed to have major effects on prevalence of constipation.

Older age relates to worsening of fine motor skills: a population-based study of middle-aged and elderly persons

INTRODUCTION

In a population-based study of 1,912 community-dwelling persons of 45 years and older, we investigated the relation between age and fine motor skills using the Archimedes spiral-drawing test. Also, we studied the effect of brain volume on fine motor skills.

METHODS

Participants were required to trace a template of a spiral on an electronic drawing board. Clinical scores from this test were obtained by visual assessment of the drawings. Quantitative measures were objectively determined from the recorded data of the drawings. As tremor is known to occur increasingly with advancing age, we also rated drawings to assess presence of tremor.

RESULTS

We found presence of a tremor in 1.3% of the drawings. In the group without tremor, we found that older age was related to worse fine motor skills. Additionally, participants over the age of 75 showed increasing deviations from the template when drawing the spiral. Larger cerebral volume and smaller white matter lesion volume were related to better spiral-drawing performance, whereas cerebellar volume was not related to spiral-drawing performance.

CONCLUSION

Older age is related to worse fine motor skills, which can be captured by clinical scoring or quantitative measures of the Archimedes spiral-drawing test. Persons with a tremor performed worse on almost all measures of the spiral-drawing test. Furthermore, larger cerebral volume is related to better fine motor skills.

Use of efficacy probability maps for the post-operative programming of deep brain stimulation in essential tremor

INTRODUCTION

Post-operative programming of deep brain stimulation for movement disorders can be both time consuming and difficult, which can delay the optimal symptom control for the patient. Probabilistic maps of stimulation response could improve programming efficiency and optimization.

METHODS

The clinically selected contacts of patients who had undergone ventral intermediate nucleus deep brain stimulation for the treatment of essential tremor at our institution were compared against contacts selected based on a probability map of symptom reduction built by populating data from a number of patients using non-rigid image registration. A subgroup of patients whose clinical contacts did not match the map-based selections prospectively underwent a tremor rating scale evaluation to compare the symptom relief achieved by the two options. Both the patient and video reviewer were blinded to the selection.

RESULTS

54% of the map-based and clinical contacts were an exact match retrospectively and were within one contact 83% of the time. In 5 of the 8 mismatched leads that were evaluated prospectively in a double blind fashion, the map-based contact showed equivalent or better tremor improvement than the clinically active contact.

CONCLUSIONS

This study suggests that probability maps of stimulation responses can assist in selecting the clinically optimal contact and increase the efficiency of programming.

How many people in the USA have essential tremor? Deriving a population estimate based on epidemiological data

BACKGROUND

Essential tremor (ET) is often reported to be among the most prevalent movement disorders, yet the precise number of cases in the USA is not known. The goal of the current analyses was to use published data from epidemiological studies to derive an estimate of the number of people currently residing in the USA who have ET.

METHODS

A PubMed search was conducted to identify population-based prevalence studies of ET. The methodology of 34 identified studies was assessed. Then the three most methodologically rigorous studies were selected, and age-specific prevalence data were abstracted. US census data from 2012 were used to determine the population in the USA by 10-year age categories.

RESULTS

Using data from three studies, estimates of the number of ET cases (2012) ranged from 6.38 to 7.63 million (mean = 7.01 million). This corresponds to approximately 2.2% of the US population.

DISCUSSION

Knowing the number of ET cases in the USA is important in terms of estimating the medical burden on communities and society, and providing an objective metric on which to base health resource planning.

Medical treatment of essential tremor

Essential tremor (ET) is the most common pathological tremor characterized by upper limb action-postural tremor (PT)/kinetic tremor (KT). There are no specific neuropathological or biochemical abnormalities in ET. The disability is consequent to amplitude of KT, which may remain mild without handicap or may become disabling. The most effective drugs for sustained tremor control are propranolol and primidone. Symptomatic drug treatment must be individualized depending on the circumstances that provoke the tremor-related disability. Broad guidelines for treatment are discussed in this review. Patients may be treated intermittently only on stressful occasions with propranolol, clonazepam, or primidone monotherapy, or an alcoholic drink. Those with persistently disabling tremor need continued treatment.

Mini Review: linkages between essential tremor and Parkinson's disease?

Essential tremor (ET) and Parkinson’s disease (PD) are two of the most common movement disorders. Tremors are the primary symptoms of ET and of some PD patients, the two are often mistaken for each other. Especially since there are no available differentiate tests for the tremor of ET or PD, the early diagnoses mainly based on clinical assessments of medical symptoms, family and medication history, and examination by physicians. There is increasing evidence suggesting an association between ET and PD, such as a similar tremor frequency, overlapping resting tremors (a typical PD tremor), postural tremors (mainly in ET patients) in both ET and PD patients, and many ET patients develop PD later in life. Although it is difficult to make a differential diagnosis of ET and tremor-dominant PD based on clinical assessment, recent developments of objective measurements, such as brain imaging, neuropathology, and genetic analysis, has opened a helpful window for distinguishing ET from PD. In this mini review, we included literatures of ET and PD studies and discussed various advanced methods for differential diagnosis between ET and PD such as neuroimaging, genetic markers, tremor intensity and frequency, and drug-responses.