Characterising vascular cognitive impairment compared to cognitively healthy ageing with respect to reaction time, the intra‐individual variability of RT, and error production, practice effects and the task used in their measurement

Abstract

AbstractBackgroundTo improve the characterisation and the understanding of VCI by examining reaction time (RT), the intra individual variability of RT (IIV), errors, practice, the effects of processing load (e.g. the influence of distracting information) and the effects of hesitancy in cognitively healthy (CH) ageing compared to patients with Subcortical Ischaemic VCI (SIVCI). In addition, the potential influence of the task used to measure these factors upon these results was investigated. The DSM5 requires a measure of brain processing speed to aid in the diagnosis of vascular dementia, but there is no indication of which test to use.MethodTasks comprised of the Trail Making Task (TMT), a clinical test used to measure RT, a visual search task, commonly used in research to measure RT, IIV, errors the effect of distracting information and practice, and an iPad based test ‘iReact’ used to measure hesitancy in response to a stimuli, in the same group of participants. Finally, for the SIVCI group, task performance was investigated with respect to the level of CT or MRI‐visible white matter disease.ResultResults were test dependent, for the TMT results revealed poor completion rates, with 75% of VCI being unable to complete, results also differed depending on analysis used. The visual search task revealed a greater range of results; RT, IIV, errors production and the effect of distracters were significantly worse for those with SVCI compared to CH adults. iReact test results revealed that SIVCI were significantly more hesitant and varied in their response than CH adults. White matter disease was also identified as a poor marker of cognitive function, possibly due to silent lesions, and that RT related function is a better indicator of brain function.ConclusionSubcortical Ischaemic Vascular Cognitive Impairment is characterised by slowed RT, Increased IIV, detrimental effect of distracting information, raised error production, lack of positive practice effects on IIV, very slow response initiation and disproportionately high IIV in response initiation.