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. 2015 Sep;30(10):1327-34.
doi: 10.1002/mds.26265. Epub 2015 Jun 22.

Tremor in the Elderly: Essential and Aging-Related Tremor

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Free PMC article

Tremor in the Elderly: Essential and Aging-Related Tremor

Günther Deuschl et al. Mov Disord. .
Free PMC article

Abstract

Background: Isolated tremor in the elderly is commonly diagnosed as essential tremor (ET). The prevalence of tremor increases steeply with increasing age, whereas hereditary tremor is becoming less common. Moreover, late-manifesting tremor seems to be associated with dementia and earlier mortality. We hypothesize that different entities underlie tremor in the elderly.

Methods: Two thousand four hundred forty-eight subjects from the Longitudinal Study of Aging Danish Twins older than 70 y answered screening questions for ET in 2001. Two thousand fifty-six (84%) participants drew Archimedes spirals to measure their tremor severity, and classical aging phenotypes were assessed. A subgroup of 276 individuals fulfilling either screening criteria for ET or being controls were personally assessed. Medications and mortality data are available.

Results: The spiral score increased with age. The spiral score correlated with tremor severity. For the whole cohort, mortality was significantly correlated with the spiral score, and higher spiral scores were associated with lower physical and cognitive functioning. Multivariate analysis identified higher spiral scores as an independent risk factor for mortality. In contrast, the ET patients did not show an increased but rather a lower mortality rate although it was not statistically significant. Consistent with a slower than normal aging, they were also physically and cognitively better functioning than controls.

Conclusions: Because incident tremors beyond 70 y of age show worse aging parameters and mortality than controls and ET, we propose to label it 'aging-related tremor' (ART). This tremor starts later in life and is accompanied by subtle signs of aging both cognitively and physically. More detailed clinical features and pathogenesis warrant further assessment.

Keywords: Essential tremor; aging; aging-related tremor; mortality; predictors for mortality.

Conflict of interest statement

Relevant conflicts of interest/financial disclosures: Nothing to report. Full financial disclosures and author roles may be found in the online version of this article.

Figures

FIG. 1
FIG. 1
Spiral score severity and age. (A) Mean spiral scores for all subjects (men and women) with confidence limits according to age groups. The differences between all age groups are highly significant: P < 0.001). (B) Percentage of subjects with a spiral score of 4 or more, which can be considered symptomatic tremors. The percentage increases with each age group. This shows that the spiral score increases with age, and this is attributable to increasing numbers of patients with high spiral scores.
FIG. 2
FIG. 2
Kaplan-Meier curves for mortality in the whole cohort. Subjects with higher spiral scores have increased mortality. The reference population has a spiral score of 0 to 2 (n = 783 subjects). Subjects with a spiral score of 3 (n = 690), a score of 4 (n = 365), or 5–7 do have significantly worse hazard rations for mortality. All groups are significantly different at P < 0.01 from the reference population. This indicates that the survival of subjects is dependent on the tremor spiral score. The higher the tremor score is, the shorter is the life expectancy. Because this group is dominated by patients with aging-related tremor (ART), this shows that they have a shortened life expectancy. Instead of calculating the Kaplan-Meier curves, this also can be analyzed with hazard ratios for mortality. This shows the same result and is shown in Supplemental Data Table C.
FIG. 3
FIG. 3
Hypothetical model of the prevalence of tremor in the community. Essential tremor (ET) is more prevalent at younger age, and hereditary ET reaches complete penetrance in the 7th decade, but the observed tremor prevalence continuously increases. The group responsible for this growth is hypothetically assumed to represent the aging-related tremor, which increases until late life. The observed tremor prevalence was calculated based on data from Louis and Ferreira (Supplemental Data Fig. C). The prevalence of hereditary and sporadic ET is estimated from epidemiologic studies. The aging-related tremor curve is calculated by subtracting hereditary and sporadic ET cases from the observed tremor prevalence.

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