A - 96 Cognitive Profiles of Patients with Essential Tremor and Parkinson’s Disease: a Comparative Study

Abstract Objective Essential tremor (ET) is traditionally thought of as a pure motor condition1 defined by isolated action tremor. However, research suggests cognitive decline is more prevalent in ET than originally proposed2. Movement Disorder Society guidelines recommend patients with ET and cognitive decline be classified “ET-Plus3”. ET-related cognitive decline may occur through breakdown of prefrontal integrity via frontocerebellar networks. This is similar to frontosubcortical dysfunction in PD, which may result in similar cognitive changes. The present study compared cognitive profiles of patients with ET to PD and healthy controls (HC). Method Data was obtained through Baylor College of Medicine’s Neuropsychology Repository. 51 ET patients were compared to 190 PD patients and 189 age-matched HC. Group differences were assessed with one-way ANOVAs and post-hoc t-tests. Results ET performed worse than HC on multiple cognitive measures including executive functioning, processing speed, and memory. Largest effects were observed on Trailmaking B (p < 0.001, d = 0.93) and Stroop Word Reading (p < 0.001, d = 1.15). ET performed similarly to PD across most measures, although PD performed worse on Logical Memory I & II (p < 0.001, d = 0.57), and Clock Drawing (p = 0.001, d = 0.49). Rates of mild cognitive impairment were similar in ET (45%) and PD (44%). Conclusion(s) Findings suggest cognitive deficits in ET occur in a similar pattern and at a similar rate as in PD. The findings are consistent with research exploring the phenotypic heterogeneity of ET and provide evidence against the prevailing belief that ET is monosymptomatic.