Mortality in People with Action Tremor: Findings from Three Population‐Based Cohort Studies

BACKGROUND: Action tremor is common in adults and increases with age. Although essential tremor (ET) is a major subgroup, action tremor comprises heterogeneous phenotypes, and its prognostic implications remain uncertain. OBJECTIVES: Our aim was to examine the association between action tremor and all-cause mortality using complementary population-based cohorts. METHODS: We triangulated data from three Danish cohorts: a nationwide register-based cohort of 3487 individuals with outpatient hospital-diagnosed ET, each matched to 10 controls; the Longitudinal Study of Aging Danish Twins (LSADT), including spiral-based tremor assessment on 2029 individuals and a neurologist-examined subgroup; and the Danish Symptom Cohort, including 2472 individuals with self-reported tremor, each matched to four controls. Mortality follow-up was obtained through nationwide registers. Cox regression models were applied with age as the time variable. RESULTS: In the outpatient cohort, hospital-diagnosed ET was associated with increased mortality (hazard ratio [HR], 1.37, 95% confidence interval, 1.27-1.46). In LSADT, subjects with high Archimedes scores indicating symptomatic action tremor (scores 5-7 vs. 0-2) yielded HR, 1.67 (1.42-1.97). Additionally, higher spiral scores were associated with progressively lower survival. In the Danish Symptom Cohort, even self-reported tremor was associated with increased mortality (HR, 1.56, 1.38-1.75), robust to adjustment for alcohol use. CONCLUSIONS: In three population-based cohorts, action tremor was consistently associated with increased mortality. We showed that our clinically diagnosed ET-cohort, a cohort with spiral score validated action tremor, and a cohort with self-diagnosed symptomatic action tremor, all showed increased mortality. Action tremor may represent a marker of underlying health vulnerability rather than a benign motor sign.