Dissociation between implicit and explicit manifestations of awareness in early stage dementia: evidence from the emotional Stroop effect for dementia-related words

OBJECTIVE: To determine whether people with dementia (PwD), and carers of PwD, show a processing bias to dementia-related words in an emotional Stroop task, and if so, whether the presence of such a bias is related to level of explicit awareness of the condition.

METHOD: Seventy-nine people with early stage Alzheimer's disease (AD), vascular or mixed dementia, and their carers, completed an emotional Stroop task. Time taken to colour-name dementia-related and neutral words was compared within and between groups. Additionally, as a comparison, ratings of the awareness of the condition shown by PwD were made on the basis of a detailed interview with each PwD and his/her carer.

RESULTS: PwD and carers showed the same level of increase in response times to salient compared to neutral words. In the PwD this effect was unrelated to the degree of awareness that they demonstrated regarding the condition.

CONCLUSIONS: The emotional Stroop effect in response to dementia-related words in PwD indicates that preserved implicit awareness of the condition can be elicited even where there is reduced explicit awareness.