The utility of Stroop task switching as a marker for early-stage Alzheimer's disease

Abstract

Past studies have suggested attentional control tasks such as the Stroop task and the task-switching paradigm may be sensitive for the early detection of dementia of the Alzheimer's type (DAT). The authors of the current study combined these tasks to create a Stroop switching task. Performance was compared across young adults, older adults, and individuals diagnosed with very mild dementia. Results indicated that this task strongly discriminated individuals with healthy aging from those with early-stage DAT. In a logistic regression analysis, incongruent error rates from the Stroop switching task discriminated healthy aging from DAT better than any of the other 18 cognitive tasks given in a psychometric battery.

Figure 1

Mean RT and Error Rate for Young, Old, and Very Mild DAT participants as a function of Response Cue given on the current trial (Color vs. Word) and Task Switch (NSw vs. SW) conditions. Dark squares indicate trials in which the participant was cued to name the color whereas white squares indicate trials in which the participant was cued to name the word. A switch trial is one in which the participant responded to the alternate dimension (Color vs. Word) on the previous trial. Thus, on a Switch Word trial the participant must name the word on the current trial, but named to the color on the previous trial.

Figure 2

Mean RT and Error Rate for Young, Old, and Very Mild DAT participants as a function of Response Cue (color vs. word) and Stroop Interference (incongruent vs. neutral) conditions. Dark squares indicate trials in which the participant was cued to name the color whereas white squares indicate trials in which the participant was cued to name the word.