Essential Tremor and Mortality in Older Adults: The Role of Word Recall, a Measure of Episodic Memory, in a 23-Year Follow-Up Study.

Background

The association between essential tremor (ET) and mortality risk remains uncertain. This study investigated the impact of episodic memory performance, measured through a word recall task, on mortality risk in ET within the Neurological Disorders in Central Spain (NEDICES) cohort, a population-based study of older adults.

Methods

Participants were followed until death or 31 December 2017, and divided into four groups based on ET status and memory performance (errors in the 37-Minimental Examination's three-word recall task). Cox proportional hazards models estimated mortality hazard ratios (HRs), and the Relative Excess Risk due to Interaction (RERI) assessed additive interactions.

Results

Among 3998 participants, 3432 (85.8%) died over a median follow-up of 11.2 years. ET patients with episodic memory impairments had a higher mortality risk (HR = 1.25, 95% CI: 1.06-1.46) compared with controls with similar deficits (HR = 1.19, 95% CI: 1.09-1.28), whereas no significant increase was observed for ET patients without memory impairments (HR = 0.95, 95% CI: 0.74-1.21). RERI analysis revealed no significant additive interaction between ET and memory impairment (fully adjusted RERI: 0.11 [95% CI: -0.19-0.41]). Episodic memory impairments, regardless of ET status, were strongly associated with Alzheimer's disease as a primary cause of death.

Conclusions

These findings highlight the independent contribution of episodic memory impairment to increased mortality risk, with ET modestly amplifying this effect without significant interaction. Further research is needed to explore shared pathophysiological mechanisms between ET and neurodegenerative conditions.