Evidence for a selective deficit in automatic activation of positive information in patients with Alzheimer's disease in an affective priming paradigm.

Using an affective priming paradigm, we studied the automatic and unconscious activation of emotional information in long-term memory. Participants had to judge target words preceded by various primes as positive or negative. The primes were masked and the SOA between the onset of primes and the onset of targets was 50 ms. Our results showed that in patients with dementia of the Alzheimer type (DAT), the negativity bias was preserved and the emotional priming effect was perturbed with positive targets. In control participants, this priming effect was restricted to negative targets. These findings are discussed in terms of preserved automatic activation of emotional information in Alzheimer's disease (AD) and in terms of an early deficit of the left hemisphere in AD making positive information more vulnerable to disease.