Could you be more specific? Intra-individual inconsistency variables derived from different tasks demonstrate...

Objective Inconsistency, or intra-individual variability in performance across time (IIV-I), is a possible marker of subtle cognitive weakness. Little neuropsychological research on IIV-I has occurred, and its neurocognitive underpinnings remain unclear. Some hypothesize IIV-I is a unique construct that taps into specific neuroanatomic/cognitive processes, regardless of the task from which IIV-I was derived. However, IIV-I could also be a novel approach to measuring the same constructs being measured by the tasks from which IIV-I was derived. The present study sought to investigate IIV-I's (a) construct validity (i.e., its relationships with standard clinical measures of cognition) and (b) incremental utility beyond mean performance on the same task to help elucidate the clinical utility of IIV-I variables. Method A sample of 72 community-dwelling older adults completed clinical measures and computerized tasks used to derive IIV-I that tapped into processing speed, inhibition, and working memory (i.e., domains that have demonstrated associations with IIV-I). Results In multiple linear regressions, IIV-I variables demonstrated associations with clinical measures with shared neurocognitive underpinnings as the task from which the IIV-I variable was derived. Additionally, in hierarchical regressions, one IIV-I variable demonstrated potential for incremental utility beyond mean performance. Conclusions The present findings suggest that IIV-I may not be an independent construct that shows consistent associations with particular cognitive processes, regardless of how it is measured. Rather, IIV-I variables may tap into the cognitive constructs being measured by the task from which they are derived. Additionally, the incremental utility of IIV-I must continue to be established.