The Cerebellar Cognitive Affective Syndrome in Essential Tremor Plus

The latest tremor classification suggested to stratify patients with Essential Tremor (ET) into pure (pET) and plus (ET-plus) forms. Cognitive dysfunction in ET might reflect the Cerebellar Cognitive Affective Syndrome (CCAS), but there is no evidence in ET-plus. We aimed to evaluate the CCAS in ET-plus, further attempting to explore possible motor-cognitive associations.Thirty-nine patients with ET-plus and 19 matched healthy controls (HC) performed the CCAS-scale (CCAS-S). Patients were also assessed using the Tremor Research Group Essential Tremor Rating Scale and the Scale for the Assessment and Rating of Ataxia. Moreover, data about their soft signs were recorded. The obtained data were further compared to a published series of pET. Patients with ET-plus had worse CCAS-S performances than HC, with 69.4% of the former having a definite CCAS. Cognitive performances did not correlate with any of the clinical data, but with the presence of slowing. While the rate of definitive CCAS was similar between pET and ET-plus, they demonstrated different cognitive profiles. Poorer CCAS-S performance had a detrimental impact on activity of daily living beyond tremor severity. Our results demonstrate a pervasive cognitive impairment in ET-plus, possibly sustained by a cerebellar dysfunction. However, the association of cognitive deficits with the presence of slowing and the qualitative differences between ET-plus and pET might suggest a more widespread pathology with the involvement of extra-cerebellar brain areas, indicating that they reflect two different entities.