Early-onset familial essential tremor is associated with nucleotide expansions of spinocerebellar ataxia in China

BACKGROUND

Essential tremor (ET) is a neurological disease characterized by action tremor in upper arms. Although its high heritability and prevalence worldwide, its etiology and association with other diseases are still unknown.

METHOD

We investigated 10 common spinocerebellar ataxias (SCAs), including SCA1, SCA2, SCA3, SCA6, SCA7, SCA8, SCA12, SCA17, SCA36, dentatorubral-pallidoluysian atrophy (DRPLA) in 92 early-onset familial ET pedigrees in China collected from 2016 to 2022.

RESULT

We found one SCA12 proband carried 51 CAG repeats within PPP2R2B gene and one SCA3 proband with intermediate CAG repeats (55) with ATXN3 gene. The other 90 ET probands all had normal repeat expansions.

CONCLUSION

Tremor can be the initial phenotype of certain SCA. For early-onset, familial ET patients, careful physical examinations are needed before genetic SCA screening.

Treatment patterns in essential tremor: Real-world evidence from a United Kingdom and France primary care database

BACKGROUND AND PURPOSE

Essential tremor (ET) is one of the most common neurological disorders, but information on treatment pattern is still scant. The aim of this study was to describe the demographic and clinical characteristics, treatment patterns, and determinants of drug use in patients with newly diagnosed ET in France and the United Kingdom.

METHODS

Incident cases of ET diagnosed between January 1, 2015 and December 31, 2018 with 2 years of follow-up were identified by using The Health Improvement Network (THIN®) general practice database. During the follow-up, we assessed the daily prevalence of use and potential switches from first-line to second-line treatment or other lines of treatment. Logistic regression models were conducted to assess the effect of demographic and clinical characteristics on the likelihood of receiving ET treatment.

RESULTS

A total of 2957 and 3249 patients were selected in the United Kingdom and France, respectively. Among ET patients, drug use increased from 12 months to 1 month prior the date of index diagnosis (ID). After ID, nearly 40% of patients received at least one ET treatment, but during follow-up drug use decreased and at the end of the follow-up approximately 20% of patients were still on treatment. Among treated patients, ≤10% maintained the same treatment throughout the entire follow-up, nearly 20% switched, and 40%-75% interrupted any treatment. Results from the multivariate analysis revealed that, both in France and the United Kingdom, patients receiving multiple concomitant therapies and affected by psychiatric conditions were more likely to receive an ET medication.

CONCLUSION

This study shows that ET is an undertreated disease with a lower-than-expected number of patients receiving and maintaining pharmacological treatment. Misclassification of ET diagnosis should be acknowledged; thus, results require cautious interpretation.

The Spectrum of Non-Parkinsonian Tremor: A Registry at a Tertiary Care Teaching Institute

Background

Tremors other than those associated with Parkinson's disease (non-parkinsonian tremor) are commonly observed in clinical settings. However, their frequency and clinical characteristics have rarely been reported.

Objectives

To classify non-parkinsonian tremors based on the consensus statement on the classification of tremors, from the task force of the International Parkinson and Movement Disorder Society published in 2018.

Methods

A prospective registry at a tertiary care teaching institute.

Results

A total of 475 patients with non-parkinsonian tremors were recruited for the study. 67.57% (n = 321) of our patients were male and a family history of tremor was present in 20.84% (n = 99) of patients. Dystonic tremor (DT) was the most common non-parkinsonian tremor (33.26%). 27.78% of patients fulfilled the new classification criteria for essential tremor, with 13.47% classified as pure ET (ET) and 14.31% exhibiting neurological soft signs, leading to the classification of ET plus (ETP). Patients with ETP had more family history (57.35%) [vs DT (26.48%, p = 0.00004) and ET (10.93%, p = 0.00003], longer duration of disease [mean ± standard deviation (SD) = 9.53 ± 8.64 years] [vs DT (5.60 ± 5.93, p = 0.0003) and ET (6.38 ± 5.97, p = 0.01) years], and more severe tremor as measured by the essential tremor rating assessment scale total score [mean ± SD = 27.42 ± 11.70] [vs DT (23.50 ± 8.62, p = 0.007) and ET (22.12 ± 8.19, p = 0.007)] compared with patients with DT and ET.

Conclusions

DT was the most common cause of non-parkinsonian tremor in our registry followed by essential tremor syndrome. ETP was more common than ET.

A prospective cohort study of familial versus sporadic essential tremor cases: Do clinical features evolve differently across time?

BACKGROUND

Although essential tremor (ET) is often divided into familial and sporadic cases, few data compare the evolution of clinical features in these groups over time. Leveraging data from a prospective, longitudinal study, we present analyses of the evolution of a broad range of cognitive, motor (i.e., tremor, tandem gait) and other features (e.g., disability) of ET.

METHODS

Sixty-six familial and 23 sporadic ET cases completed in-home evaluations at baseline and 18, 36, and 54-month follow-ups. Assessments included detailed neuropsychological testing and videotaped neurological examinations. Analyses compared the longitudinal course of 16 clinical features in familial and sporadic cases.

RESULTS

Baseline mean age was 75.2 ± 8.8 years and mean observation period was 4.7 ± 0.3 years. Tremor onset age was lower and childhood onset more common in familial than sporadic cases (p's = 0.02). Longitudinal analyses revealed no significant differences between clinical features displayed by familial and sporadic cases, or differences between the patterns of change in clinical features observed in these groups across time. Sporadic cases' daily activity skills declined significantly, whereas familial cases' did not, p's = 0.04 and 0.34, respectively; however, this finding was non-significant when controlling for false discovery rate. Several additional non-significant trends were noted.

CONCLUSION

Familial and sporadic ET cases differed in onset age, and in the prevalence of childhood tremor onset. Although a number of interesting trends were observed, no significant differences in the evolution of clinical features over time in patients with and without a family history of ET were revealed.

Odds of Medical Comorbidities in Essential Tremor: Retrospective Analysis of a Large Claims Database in the United States

INTRODUCTION

Essential tremor (ET) is the most common tremor disorder, estimated to affect 7 million individuals in the USA. There is little empirical evidence on comorbidities among this population beyond higher prevalence of brain-related and stress-related disorders. This study aims to examine differences in the prevalence of the 31 Elixhauser comorbidities among ET patients compared to statistically similar control patients.

METHODS

An extract from Optum's de-identified Clinformatics® Data Mart Database (CDM) from 2018 to 2019 of adults aged 40-80 years with at least one claim with an ET diagnosis was propensity score matched to controls. Logistic regression was used to generate doubly robust adjusted odds ratios for each of the 31 Elixhauser comorbidities.

RESULTS

In these analyses, ET patients had significantly greater adjusted odds of depression, alcohol abuse, and other neurological disorders, as well as chronic pulmonary disease, renal failure, hyperthyroidism, and cardiac arrhythmias relative to controls. They also had lower odds of uncomplicated diabetes, congestive heart failure, metastatic cancer, paralysis, peripheral vascular disease, and fluid and electrolyte disorders.

CONCLUSION

A number of recent studies, including our own, suggest that psychiatric, neurologic, and stress-related disorders may be more prevalent among ET patients than controls. Additional differences in the prevalence of a range of medical comorbidities have also been variably reported across studies, suggesting that some combination of these might be more prevalent. Further studies would be of value in sorting through these associations.

Lack of Familial Aggregation of the "Essential Tremor-Plus" Phenotype in Familial Essential Tremor

BACKGROUND

Essential tremor (ET) is a highly prevalent neurological disease that frequently runs in families. A recent and controversial proposal is to separate ET patients into two distinct groups - ET versus ET-plus. If this were a valid construct, one would expect in familial aggregation studies to observe that ET-plus would cluster in some families yet be absent in others, rather than being randomly distributed across families. We examined whether there is evidence of familial aggregation of ET-plus.

METHODS

Probands (n = 84 [56 ET-plus and 28 ET]) and their first- and second-degree relatives (n = 182 and 48) enrolled in a genetics study. χ2 and generalized estimating equations (GEE) tested associations between probands' ET-plus status and the ET-plus status of their relatives.

RESULTS

χ2 analyses revealed that ET-plus was no more prevalent in relatives of probands diagnosed with ET-plus than in relatives of probands diagnosed with ET, p > 0.05. Restricting relatives to first-degree relatives similarly did not detect a significant association (p = 0.88). GEE yielded similar results (respective p's = 0.39 and 0.81).

CONCLUSION

The data demonstrate that ET-plus does not seem to aggregate in families. As such, they do not lend support to the notion that ET-plus is a valid biological construct.

Sex and gender differences in movement disorders: Parkinson's disease, essential tremor, dystonia and chorea

Sex and gender-based differences in epidemiology, clinical features and therapeutical responses are emerging in several movement disorders, even though they are still not widely recognized. In this chapter, we summarize the most relevant evidence concerning these differences in Parkinson's disease, essential tremor, dystonia and chorea. Indeed, both sex-related biological (hormonal levels fluctuations) and gender-related variables (socio-cultural and environmental factors) may differently impact symptoms manifestation and severity, phenotype and disease progression of movement disorders on men and women. Moreover, sex differences in treatment responses should be taken into account in any therapeutical planning. Physicians need to be aware of these major differences between men and women that will eventually have a major impact on better tailoring prevention, treatment, or even delaying progression of the most common movement disorders.

Does essential tremor increase the risk of dementia? No

Essential tremor (ET) is the most common neurological cause of tremor affecting adult humans affecting about 6% of those over age 65 years. In the United States, dementia has a prevalence of 15% in those age 68 and older. Overlap of the two conditions is therefore not surprising. Several studies report mild subclinical cognitive dysfunction in non-demented people with ET, likely related to overactivity of fronto-cerebellar circuitry involved in tremor pathophysiology. Frontal/executive dysfunction is often though not exclusively noted, and some studies have even shown areas of cognitive strengths. Mild cognitive impairment (MCI) is impairment which a person is aware of but does not interfere significantly with daily activities. While MCI has been considered to presage dementia this is not necessarily the case, as some persons with MCI revert to normal cognition in follow-up. Dementia is a clinical syndrome with cognitive impairment interfering with daily activities. Population-based and clinic-based studies have shown mixed results regarding rates of MCI in ET. A handful of studies have looked at development of dementia in ET with differing results. Brain pathology studies in ET and dementia or investigating Alzheimer-type pathology have thus far been unrevealing. There is evidence by some investigators supporting a greater risk of dementia for those having older onset tremor, while those having ET at a younger age faring at least as well as controls regarding risk of cognitive impairment and dementia. At present the evidence is inconclusive that ET as a group are at a greater risk of developing dementia.

The Hidden Burden of Disease and Treatment Experiences of Patients with Essential Tremor: A Retrospective Claims Data Analysis

INTRODUCTION

Essential tremor (ET) affects approximately 7 million people in the USA, yet public recognition of the disease and its impact remain low.

METHODS

A retrospective observational study examined US claims data from 2015 to 2019 using the Compile database. ET diagnoses were captured using longitudinal data from 2015 to 2019 and for the year 2019, with diagnosis estimates extrapolated to the general US population. Confirmed ET was identified by an ET diagnosis code with at least two relevant prescriptions or by two diagnosis codes for ET and unspecified tremor at least 90 days apart. Comorbidity and treatment use data were extracted, and medication compliance and 2-year treatment persistence were assessed as measures of treatment adherence.

RESULTS

A total of 1,336,183 patients with ET diagnoses codes were identified from 2015 through 2019, corresponding to 2,226,971 projected US diagnoses. In 2019, 128,263 patients had a confirmed ET diagnosis, corresponding to 213,772 projected US confirmed diagnoses. Of these, 96% had at least one comorbidity, and 64% received at least one pharmacologic treatment. Propranolol (24%) and primidone (20%) comprised the most common ET prescriptions. Two-year medication discontinuation rates were approximately 40%.

CONCLUSION

Our findings revealed that 1 million people were diagnosed and sought treatment for ET in the USA from 2015 to 2019. Projected population estimates of approximately 2 million people diagnosed suggest a further 1 million remain untreated. Our findings highlight the complexity of patient care in ET, complicated by delayed diagnoses, multiple comorbidities, and lack of effective and tolerable therapies that can mitigate treatment adherence limitations.

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.

Orthostatic Hypotension in Elderly Patients with Essential Tremor

PURPOSE

Essential tremor (ET) is the most common movement disorder in which dysautonomia symptoms can be present. We aimed to evaluate the presence of orthostatic hypotension (OH) and its relationship with the clinical features.

PATIENTS AND METHODS

Forty-four elderly patients with ET and 118 healthy elderly controls were included. OH was assessed via the head-up tilt table test and defined, according to the change in position, as a drop of at least 20 mmHg in systolic blood pressure and/or 10 mmHg in diastolic blood pressure. Tremor severity was evaluated using the Fahn-Tolosa-Marin Tremor Rating (FTMTR) Scale. All patients underwent geriatric comprehensive assessment.

RESULTS

There were no differences between the controls and patients with ET regarding age and gender. The mean age was 72.8±6.1, the mean disease duration 19.1±13.5 years and the mean FTMTR score was 30.9±17.1 in patients with ET. The frequency of OH at the 1st minute in patients with ET was higher than in controls (31.8% vs 17.8%, p=0.046). Furthermore, the frequency of jaw tremor in patients with OH was higher than in those without OH (35.7% vs 6.7%, p=0.025). About 28.6% of ET patients with OH had orthostatic symptoms.

CONCLUSION

We demonstrated that ET patients, particularly those with jaw tremors, had OH and that most of them were asymptomatic. Therefore, in order to protect patients from complications related to OH, it would be appropriate to evaluate OH in the follow-up and treatment of elderly patients with ET.

Meat Consumption and Meat Cooking Practices in Essential Tremor: A Population-Based Study in the Faroe Islands

Background

Elevated tissue levels of the tremor-producing neurotoxin, harmane, have been detected in patients with essential tremor (ET) in the USA and Spain. Recently, a study in the Faroe Islands similarly noted an elevation in blood harmane concentrations in probable and definite ET cases. The underlying mechanism is not understood. Possible mechanisms include increased dietary consumption (esp. through cooked meats), impaired metabolism, or increased endogenous production of harmane. To investigate this issue further, we conducted a population-based study in the Faroe Islands to examine meat consumption and meat cooking practices in ET cases and controls.

Methods

1,328 Faroese adults were screened for tremor and 27 ET cases were identified. Meat consumption and meat cooking practices were compared to 200 controls. Detailed data were collected via questionnaires regarding current meat consumption for 14 meat types and meat cooking doneness for 8 meat types. Data were also available on blood harmane concentrations.

Results

Current meat consumption was similar in ET cases and controls in 12 out of 14 meat types, with no differences observed after a Bonferroni correction in any meat type; no difference was observed when stratified by gender. No difference was observed in meat doneness between ET cases and controls. Blood harmane concentrations were not correlated with dietary data.

Discussion

This is the first population-based study of harmane-linked dietary factors in ET. The study suggests the observed difference in blood harmane in ET is not driven by dietary differences and is likely due to other mechanisms (e.g., impaired metabolism).

Tremor Distribution and the Variable Clinical Presentation of Essential Tremor

In addition to having postural and kinetic tremor of the upper limbs, some patients with essential tremor (ET) may have head tremor as well as cognitive and psychiatric disorders. We aimed to investigate whether the variable clinical presentation in ET patients, including motor and non-motor symptoms, differs in patients with and without head tremor. We consecutively enrolled 70 patients with a diagnosis of ET. Tremor severity was assessed by means of clinical rating scales. Patients also underwent kinematic recordings of postural and kinetic tremor of the upper limbs based on an optoelectronic system. Several neuropsychological tests were also administered. Finally, we adopted the structured interviews for DSM-IV, SCID-I, and SCID-II to investigate psychiatric and personality disorders. ET patients with upper limb tremor plus head tremor exhibited more severe kinetic tremor of the upper limbs and a higher occurrence of axis I psychiatric disorders than ET patients with upper limb tremor only. Cognitive and other motor and psychiatric features did not differ significantly with respect to tremor distribution. The study findings support the hypothesis that body tremor distribution, i.e., the presence of head tremor, influences the variable clinical presentation of ET. The study results support the notion that cases with head tremor may represent a distinct ET subtype, characterized by a prominent cerebellar involvement, and that psychiatric disorders should be considered as a specific manifestation of ET.

Isolated Voice Tremor: A Clinical Variant of Essential Tremor or a Distinct Clinical Phenotype?

Background

The consensus statement by the Task Force on Tremor of the International Parkinson and Movement Disorder Society excludes individuals with "isolated voice tremor" as a clinical variant of essential tremor (ET). This clinical viewpoint presents a rationale for reconsideration of "isolated voice tremor" as a clinical variant of ET.

Methods

Evidence from the literature was extracted to characterize the clinical phenotype of "isolated voice tremor," or essential vocal tremor (EVT). Clinical features were extracted from relevant literature available at pubmed.gov using the terms "EVT," "essential voice tremor," "primary voice tremor," and "organic voice tremor."

Results

The average age of onset in those with EVT was older than 60 years (range 19-84 years), with 75-93% being female. The typical duration of vocal tremor ranged from 1 to 13 years (average 6 years). The distribution of structures exhibiting tremor included the larynx, soft palate, pharynx, and base of tongue in the majority of patients, with some exhibiting tremor of the head and respiratory musculature. The condition of tremor occurred during speech and quiet respiration in 74% of individuals. Rate of tremor ranged from 4 to 10 Hz. Nearly 70% reported onset of vocal tremor prior to upper limb involvement. Family history of tremor was reported in 38-42% of individuals.

Discussion

Those previously classified with EVT demonstrate a similar familial history, rate, tremor classification, and body distribution of ET. EVT is proposed as a clinical variant of ET in the pattern of onset and progression of body distribution from the midline cranial to spinal neural pathways.

The Prevalence and Clinical Characteristics of Essential Tremor in Elderly Chineses: A Population-Based Study

OBJECTIVES

To investigate the prevalence and the clinical feature of essential tremor (ET) in a community cohort in Beijing.

METHODS

Using a door-to-door, two-phase approach, we investigated 2,835 residents aged ≥55 years old from rural, urban, and mountain areas.

RESULTS

The prevalence rate of ET was 4.29%, 2.85%, and 2.29% in rural, urban, and mountain areas, respectively. The overall age- and sex-adjusted prevalence was 3.29%. Among those aged ≥75 years, the prevalence rate in the urban area was higher than those in the rural and mountain areas. The prevalence rate increased with age, and the prevalence was higher among men (6.0%) than among women (3.6%). There was a correlation of ET prevalence with age, sex, and habitation area, but not with alcohol, tea drinking, and occupation. Women (25%) with ET were more likely to have head tremor than men (16.9%).

CONCLUSIONS

The ET prevalence in the elderly of Beijing was 3.29% which is higher in the urban area and in men.

Essential tremor: diagnosis and management

Essential tremor is one of the most common movement disorders in adults and can affect both children and adults. An updated consensus statement in 2018 redefined essential tremor as an isolated action tremor present in bilateral upper extremities for at least three years. Tremor may also be present in other locations, commonly the neck or the vocal cords. Patients with additional neurologic symptoms are now categorized as "essential tremor plus." Additional clinical features associated with the condition include but are not limited to cognitive impairment, psychiatric disorders, and hearing loss. When treatment is needed, propranolol and primidone are considered first line treatments. Patients who are severely affected are often offered deep brain stimulation. Although the ventral intermediate nucleus of the thalamus is the traditional surgical target, the caudal zona incerta is also being studied as a possible superior alternative. Magnetic resonance imaging guided high intensity focused ultrasound is a newer surgical alternative that may be ideal for patients with substantial medical comorbidities. Current research explores novel oral treatments, chemodenervation, and noninvasive neuromodulation for treatment of essential tremor.

Essential Tremor and Parkinson's Disease: Exploring the Relationship

Background

There is longstanding controversy surrounding the possible link between essential tremor (ET) and Parkinson's disease (PD). Inconsistent and unreliable diagnostic criteria may in part account for some of the difficulties in defining the relationship between these two common movement disorders.

Methods

References for this systematic review were identified using PubMed with the search terms "essential tremor" AND "Parkinson's disease" with articles published in English between 1960 and September 2018 included.

Results

In this review we provide evidence that some patients diagnosed with ET have an increased risk of developing PD years or decades after onset of action tremor. There are several still unresolved questions about the link between the two disorders including lack of verifiable diagnostic criteria for the two disorders and marked overlap in phenomenology. Here we review clinical, epidemiologic, imaging, pathologic, and genetic studies that address the ET-PD relationship. Several lines of evidence support the association between ET and PD, including overlapping motor and non-motor features, relatively high prevalence of rapid eye movement sleep behavior disorder (26-43%) in ET patients, increased prevalence of PD in patients with longstanding antecedent ET, increased prevalence of ET in family members of patients with PD, and the presence of Lewy bodies in the brains of some ET patients (15-24%).

Discussion

There is a substantial body of evidence supporting the association between ET and PD within at least a subset of patients, although the nature and possible pathogenic mechanisms of the relationship are not well understood.

Clinical, electrophysiological, and imaging study in essential tremor-Parkinson's disease syndrome

INTRODUCTION

Essential tremor-Parkinson's disease (ET-PD) syndrome is a clinical condition in which individuals with a long-lasting history of Essential tremor (ET) eventually develop Parkinson's disease (PD). The aim of the study was to investigate the accuracy performances of clinical, neurophysiological, and imaging biomarkers in differentiating patients affected by ET-PD syndrome from patients with ET or PD.

METHODS

Nineteen patients affected by ET-PD syndrome, 48 ET patients, and 37 tremor-dominant PD (t-PD) patients were included. Electrophysiological studies, including blink-reflex recovery cycle and tremor parameters analyses, were performed in all groups. Nigro-striatal and cardiac sympathetic denervation were also investigated. Sensitivity, specificity and accuracy of clinical, electrophysiological, and radiological features in differentiating ET-PD syndrome from ET and PD were calculated.

RESULTS

ET-PD patients had significantly lower rigidity (p = 0.007) and higher postural/kinetic tremor (p = 0.007) scores, in comparison to t-PD patients. ET-PD patients, differently from PD patients, had a synchronous pattern of resting tremor and, differently from ET patients, had abnormal blink-reflex recovery cycle. ET-PD patients also showed reduced nigro-striatal and cardiac sympathetic uptakes, albeit to a lesser extent than in PD patients. The highest accuracy values were found for the synchronous pattern of resting tremor (97.1%) in distinguishing ET-PD from PD, and for presence of abnormal blink-recovery cycle (100%) in distinguishing ET-PD syndrome from ET.

CONCLUSION

Our study demonstrates that some electrophysiological parameters, such as a synchronous resting tremor pattern and the abnormal blink-recovery cycle were the most accurate biomarkers in distinguishing patient with ET-PD syndrome from those with ET or those with PD.

Early- and late-onset essential tremor patients represent clinically distinct subgroups

OBJECTIVE

Essential tremor is a very common disease defined by sparse clinical criteria. It is unlikely that essential tremor is an etiologically homogeneous disease. Stratifying broadly defined diseases using clinical characteristics has often aided the etiopathological understanding. Most studies of essential tremor show 2 distinct age at onset peaks: early and late. This study investigates phenotypical differences between early- and late-onset essential tremor patients.

METHODS

We studied a sample of 1137 tremor patients. Of these patients, 978 suffered from definite or probable essential tremor. All of the patients underwent the same standardized examination encompassing, among other items, drawing of the Archimedes spiral and assessment of the Fahn-Tolosa-Marin scale.

RESULTS

Two subgroups of early-onset (≤ 24 years of age, n = 317) and late-onset (≥ 46 years of age, n = 356) patients were selected based on the visual and mathematical analysis of the age-at-onset distribution. Tremor severity in both groups was comparable. Tremor progression measured as Archimedes spiral score and the Fahn-Tolosa-Marin subscales divided by the disease duration in 10-year bins was significantly faster in late-onset patients when compared with early-onset patients. Early-onset patients more frequently reported a positive family history and alcohol sensitivity of the tremor.

CONCLUSIONS

The age-at-onset distribution suggests a distinction between early- and late-onset tremor. Early-onset and late-onset essential tremor differ in the progression rates and the frequencies of a positive family history and history of a positive effect of alcohol on tremor. © 2016 International Parkinson and Movement Disorder Society.

Essential tremor-Parkinson's disease: A double whammy

BACKGROUND

Surprisingly little has been written about the combined clinical entity, essential tremor-Parkinson's disease (ET-PD), which is the result of a double disease hit. We carefully quantified tremor burden using a wide range of measures (tremor severity, tremor-related disability, tremor-related quality of life) and furthermore, studied additional motor and non-motor features in ET-PD.

METHODS

In this prospective, clinical-epidemiological study, we performed a standardized, structured clinical evaluation of 27 ET-PD patients, comparing them to age-matched samples of 35 PD and 109 ET patients.

RESULTS

The number of hours/day shaking was lowest in PD (median=3.0), intermediate in ET (median=10.0) and highest in ET-PD (median=14.0) (p<0.001). All measures of mobility and balance (Berg Balance test, Activities-specific Balance Confidence Scale, Timed Up and Go test) worsened across groups in a stepwise manner from ET to PD to ET-PD (p<0.05). Mini-mental state test scores worsened (p=0.002) and daytime sleepiness increased (p=0.002) across groups from ET to PD to ET-PD.

CONCLUSIONS

The ET-PD patient seems to be more than just a PD patient with a little more kinetic tremor. Aside from a significantly greater tremor burden, ET-PD patients exhibited more cognitive and sleep problems and more mobility and balance problems than patients with isolated PD.

Utility of the hand-drawn spiral as a tool in clinical-epidemiological research on essential tremor: data from four essential tremor cohorts

BACKGROUND

In descriptive epidemiological studies, investigators must screen large numbers of individuals. How one best screens populations for essential tremor (ET); however, remains an open question. The collection of a standardized writing sample (e.g., a hand-drawn spiral) is a method with many practical advantages, yet there are virtually no data on the validity of this particular method.

METHODS

Four hand-drawn spirals (2 right, 2 left) were collected from 831 ET cases across four distinct study settings (population-based study, family study, environmental epidemiological study, brain repository) and, in two of these studies, from 697 controls. Spirals were rated (range 0-3) by a senior movement disorder neurologist. These 1,528 participants also underwent a detailed neurological examination, and total tremor scores (range 0-36) and ET diagnoses were assigned by the neurologist.

RESULTS

The proportion of cases with hand-drawn spiral ratings ≥1.5 in either arm ranged from 78.8-97.0%; only 4.7% of controls had spirals with tremor of that severity. The hand-drawn spiral rating was highly correlated with the total tremor score (r = 0.65-0.73, p < 0.001).

CONCLUSIONS

The hand-drawn spiral is a sensitive and specific method of screening for ET. Furthermore, it serves as a valid measure of overall tremor severity.

The prevalence of essential tremor in elderly Koreans

Essential tremor (ET) is one of the most common movement disorders. The prevalence of ET varies substantially among studies. In Korea, there is no well-designed epidemiological study of the prevalence of ET. Thus, we investigated the prevalence of ET in a community in Korea. Standardized interviews and in-person neurological examinations were performed in a random sample of the elderly aged 65 yr or older. Next, movement specialists attempted to diagnose ET clinically. People who showed equivocal parkinsonian features underwent dopamine transporter imaging using [(123)I]-FP-CIT SPECT, to differentiate ET from parkinsonism. A total of 714 subjects participated in this population-based study. Twenty six of these subjects were diagnosed as having ET. The crude prevalence of ET was 3.64 per 100 persons. Age, gender, or education period were not different between the ET patients and the non-ET subjects. The prevalence of ET was slightly lower than those reported in previous studies. Further studies including more subjects are warranted.

[Essential tremor and Parkinson's disease: are they associated?]

INTRODUCTION

There is now growing evidence that essential tremor and Parkinson's disease are related.

AIM

To present the main findings from epidemiologic, genetic, clinical, imaging and pathologic studies, contrasting evidences for and against an association between essential tremor and Parkinson's disease.

DEVELOPMENT

We include a complete update of the latest findings regarding the overlap between these two disorders. There is current evidence that a history of essential tremor may herald the onset of Parkinson's disease in a subset of patients. Furthermore, the fact that the risk of essential tremor is significantly increased in relatives of patients with Parkinson's disease suggests the possibility that both conditions are genetically related, probably sharing common hereditary predisposition. Dopaminergic deficit among essential tremor patients in functional imaging studies and recent pathological studies describing Lewy bodies in some essential tremor patients, support further evidence for an overlap between both conditions, at least in a subset of patients.

CONCLUSION

The convergence of all the reviewed data suggests the possible existence of a mixed essential tremor-Parkinson's disease phenotype in some patients. However, further studies are needed to better understand this phenotype.

Autonomic function, as self-reported on the SCOPA-autonomic questionnaire, is normal in essential tremor but not in Parkinson's disease

OBJECTIVE

To compare autonomic function of subjects with Parkinson's disease (PD) and essential tremor (ET) relative to controls.

BACKGROUND

It has been reported that patients with PD have autonomic dysfunction while no literature exists regarding autonomic function in ET.

METHODS

Subjects with PD, ET, and controls had autonomic function measured using the SCOPA-Autonomic questionnaire, with the total and domain scores transformed to a scale of 0-100 points.

RESULTS

62 subjects with PD, 84 with ET, and 291 controls were included. Women were more prevalent in control (69%) compared to PD (44%) and ET (44%) groups, and mean age was significantly younger in PD (73 yrs) and older in ET (83) compared to controls (81). The mean SCOPA-Aut Total score in PD was significantly higher than controls, with no difference in ET. No autonomic dysfunction was found in any domain in ET but in PD there were significant abnormalities in gastrointestinal, cardiovascular, urinary, and thermoregulatory domains. Individual question data revealed a significantly higher percentage of subjects with dysfunction on 11/23 questions in the PD group but only 1 question (sialorrhea) in the ET group compared with controls.

CONCLUSION

Autonomic scores, particularly gastrointestinal, cardiovascular, urinary, and thermoregulatory were increased in patients with PD, as assessed by SCOPA-Aut. Patients with ET did not exhibit autonomic dysfunction, with the exception of sialorrhea.

Non-motor features in essential tremor

INTRODUCTION

Essential tremor (ET) is increasingly recognized to have several non-motor manifestations. The aim of this study was to determine the prevalence of non-motor manifestations in ET and its impact on the quality of life (QOL).

METHODS

This was a cross-sectional case-control questionnaire-based study. The subjects were 50 patients with ET and 50 matched healthy controls. All subjects were assessed by Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Parkinson Fatigue Scale, Brief Pain Inventory, Hamilton Anxiety Rating Scale, and Hamilton Depression Rating Scale. In addition, QOL in Essential Tremor questionnaire was administered to patients with ET.

RESULTS

Patients with ET, when compared with controls, had significantly higher prevalence and higher mean scores of sleep disturbances (46% vs 8%, P < 0.001; 5.9 ± 4.6 vs 2.6 ± 2.3, P < 0.001), fatigue (30% vs 8%, P = 0.009; 5.8 ± 0.8 vs 2.5 ± 0.4, P < 0.001), anxiety (66% vs 18%, P = 0.009; 7.4 ± 9.0 vs 0.7 ± 2.6, P < 0.001), depression (44% vs 8%, P = 0.009; 7.8 ± 7.9 vs 1.7 ± 3.3, P < 0.001) as well as higher mean score of pain severity (1.9 ± 2.3 vs 0.6 ± 1.2, P = 0.001) and interference owing to pain (2.0 ± 2.9 vs 0.5 ± 1.2, P = 0.001). Following hierarchical regression analysis, depression was the only non-motor feature that affected the QOL.

CONCLUSION

There was a significantly higher prevalence and greater severity of sleep disturbances, fatigue, pain, anxiety, and depression in patients with ET and depression significantly affected the QOL.

Blood harmane (1-methyl-9H-pyrido[3,4-b]indole) concentrations in essential tremor: repeat observation in cases and controls in New York

Essential tremor (ET) is a widespread late-life neurological disease. Genetic and environmental factors are likely to play important etiological roles. Harmane (1-methyl-9H-pyrido[3,4-b]indole) is a potent tremor-producing neurotoxin. Previously, elevated blood harmane concentrations were demonstrated in ET cases compared to controls, but these observations have all been cross-sectional, assessing each subject at only one time point. Thus, no one has ever repeat-assayed blood harmane in the same subjects twice. Whether the observed case-control difference persists at a second time point, years later, is unknown. The current goal was to reassess a sample of our ET cases and controls to determine whether blood harmane concentration remained elevated in ET at a second time point. Blood harmane concentrations were quantified by a well-established high-performance liquid chromatography method in 63 ET cases and 70 controls. A mean of approximately 6 yr elapsed between the initial and this subsequent blood harmane determination. The mean log blood harmane concentration was significantly higher in cases than controls (0.30 ± 0.61 g(-10)/ml versus 0.08 ± 0.55 g(-10)/ml), and the median value in cases was double that of controls: 0.22 g(-10)/ml versus 0.11 g(-10)/ml. The log blood harmane concentration was highest in cases with a family history of ET. Blood harmane concentration was elevated in ET cases compared to controls when reassessed at a second time point several years later, indicating what seems to be a stable association between this environmental toxin and ET.

Update on essential tremor

Essential tremor (ET) is one of the most common neurological disorders among adults, and is the most common tremor disorder. ET has classically been viewed as a benign monosymptomatic condition. Yet over the past 10 years, a growing body of evidence indicates that this is a progressive condition that is clinically heterogeneous, and may be associated with a variety of different features such as gait abnormalities, parkinsonism, cognitive impairment, dementia, personality disturbances, depressive symptoms, and sensory abnormalities (e.g., mild olfactory dysfunction and hearing impairment). In addition, postmortem studies are showing a pathologically heterogeneous neurodegenerative disease. The emerging view is that ET might be a family of diseases, unified by the presence of kinetic tremor, but further characterized by etiological, clinical and pathological heterogeneity. The diagnosis of ET is clinical and made by history and physical examination. Effective pharmacological treatments for the disorder currently remain limited. Drugs are generally initiated when the tremor begins to interfere with the patient's ability to perform daily activities or when the tremor becomes embarrassing. For severe, medically refractory ET, thalamic ventralis intermedius nucleus deep brain stimulation may lessen tremor and improve function.

[Investigation on prevalence rate of essential tremor in population aged 55 years old and above in Kashkar, between 2008 and 2009]

OBJECTIVE

To investigate the prevalence and clinical feature of essential tremor (ET) in a community cohort of the elderly in Kashkar.

METHODS

By using a door-to-door, two-phase screening approach, some 2834 residents of Hans ethnicity were investigated form 2008 to 2009.

RESULTS

In this study, 184 ET patients were found. The prevalence rate of ET was 6.49%. The prevalence rate was increased with age and higher in men (8.45%) than in women (4.59%), especially in people aged above 75 years old. The prevalence rate of ET was 7.26% in illiterate people, followed by 7.27%, 5.81%, 5.58% and 9.37% in those having received primary, junior, senior high school and college. The ratio of windowed people in ET patients was 15.21%, higher to the ratio of windowed people in total number.

CONCLUSIONS

The prevalence rate of ET increased with age, but not influenced by education.

Essential tremor as a neuropsychiatric disorder

The traditional view of essential (ET) tremor is as a mono-symptomatic condition characterized by action tremor. Over the past decade, researchers have learned that this picture is an over-simplification. First, it is clear that many patients also have other motor manifestations (e.g., ataxic gait). Second, the presence of a variety of non-motor features, both cognitive and psychiatric, is now appreciated. Mild cognitive changes (esp. executive dysfunction) have been documented in several studies. More recently, two population-based studies have demonstrated an association between ET and dementia. Clinically, while most of these cases developed Alzheimer's disease, the neuropathological underpinnings of this dementia have not been fully explored. Psychiatric manifestations include specific personality traits, anxiety, social phobia, and depressive symptoms. Depression may be a primary manifestation of the illness rather than a secondary response to disability. The emerging view of ET is that it is a disease whose central feature is action tremor but in which both motor and non-motor features occur. As in other neurodegenerative conditions, ET appears to be more than a disease of the motor system. Further study of these non-motor phenomena will advance our understanding of disease mechanisms and enhance the quality of clinical interactions with patients.

Essential tremor is associated with dementia: prospective population-based study in New York

BACKGROUND

Mild cognitive deficits, mainly in frontal-executive function and memory, have been reported in patients with essential tremor (ET). Furthermore, an association between ET and dementia has been reported in a single population-based study in Spain. This has not been confirmed elsewhere.

OBJECTIVE

To determine whether baseline ET is associated with prevalent and incident dementia in an ethnically diverse, community-based sample of elders.

METHODS

Community-dwelling elders in northern Manhattan were enrolled in a prospective cohort study. Baseline ET diagnoses were assigned from handwriting samples. Dementia was diagnosed at baseline and follow-up using DSM-III-R criteria.

RESULTS

In cross-sectional analyses, 31/124 (25.0%) ET cases had prevalent dementia vs 198/2,161 (9.2%) controls (odds ratio [OR](unadjusted) = 3.31, 95% confidence interval [CI] = 2.15-5.09, p < 0.001; OR(adjusted) = 1.84, 95% CI = 1.13-2.98, p = 0.01). In prospective analyses, 17/93 (18.3%) ET cases vs 171/1,963 (8.7%) controls developed incident dementia (hazard ratio [HR](unadjusted) = 2.78, 95% CI = 1.69-4.57, p < 0.001; HR(adjusted) = 1.64, 95% CI = 0.99-2.72, p = 0.055).

CONCLUSIONS

In a second population-based study of elders, essential tremor (ET) was associated with both increased odds of prevalent dementia and increased risk of incident dementia. Presence of dementia, therefore, appeared to be greater than that expected for age (i.e., a disease-associated feature). Rather than attributing cognitive complaints in patients with ET to old age, assessment and possible treatment of dementia should be routinely incorporated into the treatment plan.

Antihypertensive agents and risk of Parkinson's disease, essential tremor and dementia: a population-based prospective study (NEDICES)

BACKGROUND

Recent interest in antihypertensive agents, especially calcium channel blockers, has been sparked by the notion that these medications may be neuroprotective. A modest literature, with mixed results, has examined whether these medications might lower the odds or risk of Parkinson's disease (PD) or dementia. There are no data for essential tremor (ET).

OBJECTIVE

To examine the association between antihypertensive use (defined broadly and by individual subclasses) and ET, PD and dementia. For each disorder, we used cross-sectional data (association with prevalent disease) and prospective data (association with incident disease).

METHODS

Prospective population-based study in Spain enrolling 5,278 participants at baseline.

RESULTS

Use of antihypertensive medications (aside from beta-blockers) was similar in prevalent ET cases and controls. Baseline use of antihypertensive agents was not associated with reduced risk of incident ET. Antihypertensive medication use was not associated with prevalent or incident PD. Calcium channel blocker use was marginally reduced in prevalent dementia cases (OR(adjusted) = 0.63, p = 0.06) but was not associated with reduced risk of incident dementia (RR(adjusted) = 1.02, p = 0.95).

CONCLUSIONS

We did not find evidence of a protective effect of antihypertensive medications in these three neurodegenerative disorders.

Population-based study of baseline ethanol consumption and risk of incident essential tremor

BACKGROUND

Recent postmortem studies have demonstrated pathological changes, including Purkinje cell loss, in the cerebellum in essential tremor (ET). Toxic exposures that compromise cerebellar tissue could lower the threshold for developing ET. Ethanol is a well-established cerebellar toxin, resulting in Purkinje cell loss.

OBJECTIVE

To test whether higher baseline ethanol consumption is a risk factor for the subsequent development of incident ET.

METHODS

Lifetime ethanol consumption was assessed at baseline (1994-1995) in a prospective, population-based study in central Spain of 3285 elderly participants, 76 of whom developed incident ET by follow-up (1997-1998).

RESULTS

In a Cox proportional hazards model adjusting for cigarette pack-years, depressive symptoms and community, the baseline number of drink-years was marginally associated with a higher risk of incident ET (relative risk, RR = 1.003, p = 0.059). In an adjusted Cox model, the highest baseline drink-year quartile doubled the risk of incident ET (RR = 2.29, p = 0.018), while other quartiles were associated with more modest elevations in risk (RR(3rd quartile) = 1.82 (p = 0.10), RR(2nd quartile) = 1.75 (p = 0.10), RR(1st quartile) = 1.43 (p = 0.34) vs non-drinkers (RR = 1.00)). With each higher drink-year quartile, the risk of incident ET increased an average of 23% (p = 0.01, test for trend).

CONCLUSIONS

Higher levels of chronic ethanol consumption increased the risk of developing ET. Ethanol is often used for symptomatic relief; studies should explore whether higher consumption levels are a continued source of underlying cerebellar neurotoxicity in patients who already manifest this disease.

Environmental epidemiology of essential tremor

BACKGROUND

Essential tremor (ET) is one of the most common neurological disorders. Despite this, the disease mechanisms and etiology are not well understood. While susceptibility genotypes undoubtedly underlie many ET cases, no ET genes have been identified thus far. As with many other progressive, degenerative neurological disorders, it is likely that environmental factors contribute to the etiology of ET. Environmental epidemiology is the study in specific populations or communities of the effect on human health of physical, biologic and chemical factors in the external environment. The purpose of this article is to review current knowledge with regards to the environmental epidemiology of ET.

RESULTS

As will be discussed, a series of preliminary case-control studies in recent years has begun to explore several candidate toxins/exposures, including harmane (1-methyl-9H-pyrido[3,4-b]indole), lead and agricultural exposures/pesticides.

CONCLUSIONS

While several initial results are promising, as will be discussed, additional studies are needed to more definitively establish whether these exposures are associated with ET and if they are of etiological importance.

Prevalence of movement disorders in an elderly nursing home population

We studied the prevalence of movement disorders in a large nursing home population (397 patients, mean age 86 years) in New York City. Patients were first evaluated by specially trained research coordinators and final clinical diagnoses were confirmed by a movement disorder specialist. A movement disorder was identified in 21% of patients (83/397). The most frequent movement disorders were essential tremor (ET) (8.8%) and parkinsonism (7.1%). Only half of those admitted with a diagnosis of parkinsonism were confirmed in their diagnosis by the movement disorder specialists. Three percent of patients exhibited drug-induced tremor, 1.3% had dystonia, 0.5% had myoclonus and 0.3% had generalized dyskinesias. Overall, our findings underline the high frequency of movement disorders in a nursing home population. The discrepancy between our findings and the prevalence rates for parkinsonism reported on the initial transfer diagnosis emphasizes the difficulty of accurate diagnosis of movement disorders and in particular parkinsonism.

Prevalence of major neurological disorders among geriatric population in the metropolitan city of Kolkata

Well-conducted neuroepidemiological studies for the geriatric population are rare in India. In view of the growing aging population, we planned to determine the prevalence of common neurological disorders among the elderly population in the city of Kolkata. This was a cross-sectional study of a stratified random sample of the city population and carried in two stages through house to house survey. Initially, trained non-medical workers screened the cases with a validated family questionnaire and then a neurologist examined all the screened positive cases. A validated neuropsychological screening test was also applied among the elderly population with cognitive complaints. Results showed prevalence rates (per 1000 elderly population--> or = 60 years) of following disorders in decreasing order: stroke--33.93, essential tremor--13.76, dementia--7.89, Parkinsonism--3.30 and epilepsy--2.57. Sex-specific prevalence showed that stroke was commoner among men and that of other disorders among women. Age-specific prevalence recorded progressive increase in the rates of all disorders among both genders, though not uniformly among women. Overall the crude prevalence of neurological disorders was 60.9 per 1000. The present study shows higher rate of stroke as compared to other neurological disorders among elderly population in India, which needs urgent attention.

Validity of family history in essential tremor

In this study, we found the sensitivity and specificity of family history data given by essential tremor (ET) patients to be 43.3% and 94.4%. Compared to relatives with less severe tremor (tremor score <24), those with more severe tremor (tremor score 24) were more likely to be identified by the ET probands (8/8 vs. 5/22, p=0.001, chi2 14.3). Our study suggests that family history information reported by ET patients was inaccurate, and poorly validated. Clinical and genetic studies in ET should take the limitation of family history data into consideration.

[Relationship between essential tremor, Parkinson's disease and dementia with Lewy bodies]

INTRODUCTION

Although essential tremor (ET), Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are considered to be distinct illnesses, there is a certain overlap between some of their clinical, pathological and genetic features.

AIM

To conduct a critical examination of the evidence for and against the association between these three pathological conditions.

DEVELOPMENT

The body of evidence supporting the notion of a relation between ET and PD is growing all the time; the same can be said of the fact that a postural tremor may appear years before the onset of other extrapyramidal symptoms, the involvement of common genes in the development of both conditions or the presence of common pathological findings. In addition, it has also been suggested that there are several aspects linking PD and DLB, and it has even been claimed that that they might be part of the clinical spectrum of the same disease. The concept of ET as a benign single-symptom disease has changed in recent years and, since it has been related to cognitive disorders and Lewy bodies in the central nervous system, it is now considered to be a neurodegenerative pathology. CONCLUSIONS. ET, PD and DLB could represent different points on the same clinical spectrum.

Risk of incident dementia in essential tremor: a population-based study

Essential tremor (ET) is a late-life neurological disease. Mild cognitive deficits as well as an association with prevalent dementia have been reported in recent case-control studies. We determined whether ET was associated with an increased risk of incident dementia. In a population-based study of older people in central Spain (NEDICES), nondemented ET cases and controls were followed prospectively. Incident dementia at follow-up was diagnosed using DSM-IV criteria and the risk of incident dementia was estimated in ET cases versus controls using Cox proportional hazards models. 3,891 participants had a mean duration of follow-up of 3.2 years. Sixteen (7.8%) of 206 ET cases developed incident dementia versus 145 (3.9%) of 3,685 controls (unadjusted relative risk [RR]=2.08, 95% CI=1.24-3.50, P=0.006 and adjusted RR=1.66, 95% CI=0.99-2.80, P=0.054). In an adjusted model, ET cases with tremor onset after age 65 years were twice as likely to develop incident dementia than were controls (RR=1.98, 95% CI=1.14-3.45, P=0.01), whereas ET cases with tremor onset<age 65 years and controls were equally to develop incident dementia (RR=0.74, 95% CI=0.19-3.20, P=0.79). Although ET is often considered a benign condition, in this prospective, population-based study, elderly-onset ET was associated with an increased risk of incident dementia. The basis for this dementia, which is not known, requires additional study.

Prevalence of essential tremor in patients with Parkinson's disease vs. Parkinson-plus syndromes

Clinical literature suggests an association between essential tremor (ET) and Parkinson's disease (PD), and recent pathological studies describe Lewy bodies in some ET patients. If some ET were an expression of Lewy body disease, one could hypothesize that ET patients who develop parkinsonism would more likely develop PD (a Lewy body disease) than non-Lewy body forms of parkinsonism. The objective was to compare the proportions of patients with PD vs. Parkinson-plus syndromes who had diagnoses of ET. Retrospective chart review at the Neurological Institute (NI) of New York. A larger proportion of the 210 PD than 210 Parkinson-plus syndrome patients had kinetic tremor on examination (119 [56.7%] vs. 70 [33.3%], P < 0.001). Patients with PD were more likely to have a prior diagnosis of ET than were patients with Parkinson-plus syndromes (7.1% vs. 2.4%, OR 3.16, 95% CI 1.13-8.85, P = 0.02) and more likely to have a diagnosis of ET assigned by an NI neurologist (5.3% vs. 0.0%, OR 12.85, 95% CI 1.66-99.8, P = 0.001). Patients with PD were three to thirteen times more likely to have diagnoses of ET than were patients with Parkinson-plus syndromes. These data further confirm the link between ET and PD, and possibly, between ET and Lewy body disease.