Conflict Resolution And Interference Effect In Alzheimer’s Disease And Mild Cognitive Impairment

The ability of resolving conflicts is indispensable to address daily life and tends todecrease with aging, in particular, with Alzheimer’s disease (AD) and mild cognitiveimpairment (MCI). The paper is intended to the abilities of conflict resolution atdifferent cognitive levels and which level the interference effect occurs. We alsodiscovery the changes of parameter of event related potentials reflect the changes of thefrontal lobe or not, and if the parameters can predict cognition decline. The Eriksenflanker task has been widely used to investigate processes involved in resolvingconflicts. In the present study,16normal controls,14MCI and seven AD patients wererecruited in a modified Eriksen flanker task which is composed of four conditions：target-alone condition(<or>), no interference, congruent condition(<<<<<or>>>>>),which mean no-conflict; neutral condition(++<++or++>++)， conflict existed onperceptual level; incongruent condition(<<><<or>><>>)，conflict existed on bothperceptual and response level. The perceptual interference by the difference betweenneutral stimuli and none stimuli and response interference by the difference betweenneutral stimuli and incongruent stimuli were investigated within these subjects. In thisstudy it requires participants make judgments upon the central target stimulus whileignoring beside distracts. The accuracy and reaction time were recorded, and N2andP300components of event-related potential (ERP) were investigated. Result: In allgroups, the accuracy rate of target-alone condition was greater significantly than that ofneutral (perceptual interference) and the reaction time of the incongruent was longerthan that of neutral (response interference). The magnitude of response and perceptualinference effect was larger in AD group compared to MCI and NC groups. The MCIsubjects showed less interference effects than AD patients, but the performance wasdiscounted, compared with NC. In conditions including flankers, longer N2and P300latency were found in AD group than MCI and NC groups. The MCI group showed alonger latency in P300, but not in N2, than NC. The difference of P300amplitude wasfound between NC and MCI and between NC and AD. All in all, the subjects with MCIhad stronger perceptual interference during resolving conflicts than normal control, and AD was the strongest. And AD patients appeared significant higher level interference inthe response than MCI and NC, but MCI patients were not differ from NC. Conclusion:1.With the decline of cognitive function, the abilities of conflict resolution andinterference control decrease, which showed the accuracy decreased and the responsetime prolonged;2. In this flanker task, longer N2latency and smaller N2amplitudewere found between NC and MCI and between NC and AD, which suggested theimpairment of frontal conflict resolution and interference control. The negative wave,N2, was more sensitive than positive wave, P300, in assessing conflict resolution andinterference control;3. In current experiment pattern, following the stimuli conditions,the change of P300was not concerned with the change of reaction time, but theamplitude, so P300was not a appropriate index to reflect the change and impairment offrontal conflict resolution function.4. The subjects with AD had stronger interferenceeffect in both perceptual and response levels. In contrast, MCI patients had strongerinterference effect at the level of perception. So the different level of interference effectmay be a predictor to distinguish the AD and MCI.