Increased sensitivity to proactive and retroactive interference in amnestic mild cognitive impairment: New insights

BackgroundIncreased sensitivity to proactive (PI) and retroactive (RI) interference has been observed in amnestic mild cognitive impairment (aMCI). PI and RI are often explained as being the result of a response competition mechanism. However, patients with aMCI are supposed to suffer mostly from encoding deficits. We hypothesized that in aMCI interference may occur at encoding and not only at the retrieval stage.Material and methodsWe developed an original paradigm enabling PI and RI to be tested with and without response competitors. Eighteen young controls (YC), 16 elderly controls (EC) and 15 aMCI participated in the study.ResultsThe YC and EC groups presented interference effects only in conditions that included a direct response competitor. In contrast, aMCI had interference effects in all conditions including the one without response competitor.ConclusionIncreased sensitivity to interference in aMCI appears to occur at the encoding/consolidation stage and not only at the retrieval stage, as is the case in healthy subjects. This result is discussed in the context of the associative encoding deficits characterizing aMCI.

► Controls only suffer from interference in the presence of response competitors.
► aMCI also suffer from interference in the absence of response competitors.
► This may be due to encoding deficits in amnestic mild cognitive impairment (aMCI).