The Pattern of Cognitive-Functional Decline in Elderly Essential Tremor Patients: An Exploratory-Comparative Study With Parkinson's and Alzheimer's Disease Patients

Objective: Essential tremor (ET) is a neurological disorder that produces motor, cognitive, and functional disability. However, there has been no investigation linking cognitive impairment with functional disability in ET. Therefore, we examine the similarities and differences between ET, Alzheimer's disease (AD), and Parkinson's disease (PD) in terms of the linkage between cognitive and functional impairment. Design: Thirty-four ET, 26 PD, and 31 AD subjects were tested for cognition (Mini-Mental State Examination [MMSE]), motor disability (United Parkinson's Disease Rating Scale part III [UPDRS-III]), and functional disability (Minimum Data Set-Activities of Daily Living Section [MDS-ADL]). Results: As expected, in PD and AD subjects, MDS-ADL scores significantly correlated with UPDRS-III and MMSE scores. The ET subjects showed a different pattern of functional disability with MDS-ADL scores significantly correlating only with MMSE scores, and with the orientation MMSE modalities. Conclusions: Our findings highlight the need to be more cognizant of the nonmotor aspects of ET, which in some patients may be more functionally disabling than the motor features themselves.