Essential tremor and cognitive impairment: who, how, and why

Background and aims Recent years have witnessed the switch from considering essential tremor (ET) a monosymptomatic disorder to consider it as part of a spectrum, including other neurological signs, such as mild cognitive impairment and dementia, thus defining it as ET plus. There are few data on cognitive impairment in ET patients. The aim of this review is to analyze the clinical characteristics of ET patients developing cognitive impairment, their neuropsychological profile, the underpinning mechanisms, and the possible biomarkers. Methods The authors performed a narrative review on cognitive decline in essential tremor, including articles written in English since the year 2000. Discussion The most recent pathogenetic theories of cognitive impairment in ET rely on the cerebellar dysfunction, being part of the Cerebellar Cognitive Affective Syndrome spectrum. Cognitive impairment in ET patients could be assessed through many tests that demonstrate the involvement of different domains, such as attention, executive functions, and language. There are some clinical characteristics of ET that may indicate a greater risk of developing cognitive impairment, namely, cerebellar symptoms, falls, age at onset, and family history. However, there are no established clinical, neurophysiological, neuropathological, and fluid biomarkers of cognitive impairment in ET. Conclusions Increasing data are showing in ET the presence of cerebellar symptoms and cognitive impairment. Further studies are needed to better understand cognition in ET patients, and to define the boundary between ET and ET plus, since deeper phenotyping might have important clinical and therapeutic implications.

Automated summary

This review discusses the clinical characteristics, neuropsychological profile, mechanisms, and possible biomarkers of cognitive impairment in essential tremor (ET) patients. The most recent theories suggest cerebellar dysfunction as a potential underlying mechanism. Various tests can be used to assess cognitive impairment in ET patients, but there are no established biomarkers. Further research is needed to better understand cognition in ET patients and define the boundary between ET and ET plus.