Speed of processing is a fundamental cognitive ability.  Deficits in speed of processing are common to vascular cognitive impairment (VCI), which in turn adversely affect executive function. Different tasks have been used to measure speed of processing in VCI, however, reliable behavioral markers have not yet been identified.

A group of 160 VCI patients were recruited into the Ontario Neurodegenerative Disease Research Initiative (ONDRI). Eight variables were chosen as measures of speed of processing, including regular saccade reaction time and percentage of saccades at express latency from the pro-saccade task, gait velocity in preferred and fast walking tasks, the number of correct items completed on Symbol digit modalities test, time to complete the two Stroop conditions (naming color and reading word) and Trail making test A. Multiple factor analysis was applied to reveal correlations and discrepancies among the variables and the three tasks.

All eight variables loaded on the same side of component 1, indicating decline of speed of processing appears to be the greatest source of variance among the three types of behavioral tasks. Saccade variables together contributed most to component 2, whereas gait and neuropsychology variables made equally large contribution to component 1 and 3.

Our results suggest that (1) the three behavioral tasks together can be used to assess decline of speed of visual information processing in VCI, with involvement of the visual sensory systems, (2) the dorsal orienting attention systems are only involved in guiding goal-directed eye movements in the pro-saccade task, do not influence gait and neuropsychological tests.