Objective: Investigate neuropsychological differences between Parkinson’s disease (PD) and essential tremor (ET) patients presenting for evaluation for Deep Brain Stimulation (DBS) surgery.

Background: Although patients with PD and ET have been shown to have a range of cognitive difficulties on formal neuropsychological tests, few studies have directly compared these two groups on the same battery of tests.

Method: Thirty-eight patients with PD who were considering DBS surgery were compared to 9 patients with ET who were also considering this surgery on a standard battery of neuropsychological tests.

Results: There were no statistical differences between the groups in terms of age, education, sex, and race. ET patients performed significantly worse than the PD patients on a global measure of cognition (Dementia Rating Scale – 2 Total, p = 0.03). Patients will ET also performed worse than patients with PD on tests of processing speed (Trails A, p = 0.02), language (Token Test, p = 0.03), phonemic fluency (COWAT, p = 0.04), verbal reasoning (WAIS-IV Similarities, p = 0.01), judgment (NAB Judgment, p < 0.001), and motor functioning (Grooved Pegboard and Finger Tapping Test, ps < 0.01). The two groups were not different in depressive symptoms (p = 0.7).

Conclusion: Despite small sample sizes, the current study points towards the notable cognitive difficulties in patients with ET considering deep brain stimulation, which were comparable or worse than patients with PD.  Although a neuropsychological evaluation is not generally considered a necessary step in the selection of ET DBS candidates, clinically these data suggest that cognitive screening is important in these individuals. Moreover, further investigation may be warranted in this patient population, taking into account the differences between ET and PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neuropsychological-differences-between-patients-with-parkinsons-disease-and-essential-tremor/