The contribution of Oculomotor and Motor Deficits in The Assessment of Executive Function in Progressive Supranuclear Palsy Patients

Abstract

AbstractBackgroundProgressive supranuclear palsy (PSP) was first described in 1964 and is associated with motor, oculomotor, and cognitive deficits. Cognitive assessments often assume intact physical function. Some tests like The Trail Making Test (TMT), a measure of executive function may be impacted by oculomotor and motor impairments. Our aim was to investigate the impact of oculomotor impairments and arm dysfunction on the TMT.Method71 patients from the Rossy PSP Center that met criteria for probable PSP and underwent a neuropsychological test battery, the Toronto Cognitive Assessment (TorCA), were included. Data from the following tests and assessments were used for this study: TMT A and B time, digit forwards and backwards, verbal and animal fluency, Benson copy, and Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) delayed recall, PSP Rating Scale (PSPRS) total score and its oculomotor subscore, MDS‐Unified Parkinson’s Disease Rating Scale (MDS‐UPDRS part III) subscore of the dominant hand was used to rate the motor impairment. We performed spearman correlations and used false discovery rate test correction for multiple comparisons.ResultThe PSP patients (60.6% male, mean age 71.3+/‐6.61) had mean PSPRS score of 41.5+/‐15, PSPRS‐oculomotor subscore 8.0+/‐3, and MDS‐UPDRS III subscore dominant hand 6.5+/‐3.3. We found a positive correlation between PSPRS‐oculomotor subscore and TMT A (r = 0.43 p = 0.005) and TMT B (r = 0.35 p = 0.008). We also found negative correlations between PSPRS‐oculomotor subscore and digits backward (r = ‐0.39 p = 0.005), Benson copy (r = ‐0.39 p = 0.005), CERAD delayed recall (r = ‐0.29 p = 0.034), and animal fluency (r = ‐0.44 p = 0.004). No tests were related to MDS‐UPDRS part III subscore of the dominant hand.ConclusionOculomotor but not motor function affect TMT A and B. However, oculomotor function also relates to other executive and non‐executive tests that do not require visual scanning. Although important to factor in physical deficits when doing cognitive assessments, the TMT appears to be a reliable test for assessing cognitive function in patients with PSP who can perform the test.