Older onset essential tremor: More rapid progression and more degenerative pathology

Abstract

There are few data on rate of progression in essential tremor (ET). To quantify the rate of tremor progression in a cross-sectional sample of 348 ET cases in an epidemiological study; characterize the relationship between age of tremor onset and rate of tremor progression in that sample; and characterize the relationship between age of tremor onset, rate of tremor progression, and severity of underlying brain changes in 9 cases from a brain repository. Rate of tremor progression was defined as tremor severity / duration. The degeneration index = number of torpedoes per section / Purkinje cell linear density. In the epidemiological study, older age of tremor onset was associated with faster rate of tremor progression (P < 0.001). In the brain repository, older age of tremor onset was associated with higher degeneration index (P = 0.037), and higher degeneration index was associated with faster rate of tremor progression (P = 0.018). In a large clinical sample, older age of onset was associated with more rapid tremor progression. In a brain bank, older age of onset was associated with more degenerative pathology in the cerebellum. As in several neurodegenerative disorders, in older onset cases, it is possible that the disease advances more rapidly.