Social Cognition In Patients With Amnestic Mild Cognitive Impairment And Alzheimer's Disease

Objective Social cognition refers to who can process and analysis social information and then understand other people's intentions,beliefs;meanwhile guiding the behavior of the self,it is an essential skill to cope with various interpersonal communication,previous studies showed that both the amnestic mild cognitive impairment and Alzheimer's disease patients had the deficiency in some social cognitive domain,such as face basic emotion recognition,eye emotion recognition,risk decision and so on,the aim of this paper is further to investigate whether the musical emotion recognition and biological motion perception is damaged in in patients with amnestic mild cognitive impairment and Alzheimer's disease.Methods Experiment 1: 17 a MCI patients and 16 healthy subjects were submitted to duration discrimination paradigm,which involved global and local biological motion sequences and inanimate motion sequences(the inverted biological motion sequences),all participants were required to make a two-alternative forced choice to accurately indicate which interval(the first or the second)appeared longer,and then recorded the point of subjective equality.Experiment 2: Patients with amnestic mild cognitive impairment(n=19),Alzheimer's disease(n=16)and healthy control participants(n=16)were required to choose an appropriate emotional label from four choices to match the music that they heard,which induced happy,sad,and peaceful and fearful musical emotions.Results In experiment 1,In the global biological motion condition,one sample t-test revealed that the PSEs of healthy control group were significantly different from zero(t=3.95;P=0.01),and the PSEs of a MCI patients is positive value(0.08±0.41),whilst an independent samples t-test revealed that the PSE of both groups were significantly different(t=3.60;P=0.001);In the local biological motion condition,the PSEs of healthy control group and a MCI patients were both negative values(a MCI patients,-0.10±0.35;NC,-0.20±0.31),there were no significantly statistical difference between them(t=0.86,P=0.40)and also were not different from zero(a MCI,t=1.18,P=0.26;NC,t= 2.52,P=0.24).In experiment 2,Comparing to the normal subjects,both of the patient groups showed deficits in the recognition of fearful musical emotions(NC,7.88±1.36;a MCI,5.05±2.34;AD,3.69±2.02),and one-way ANOVA confirmed a significant main effect of the group(F=18.70,p<0.001),however there was no difference between the AD and a MCI groups(p =0.115),and there were a significant correlation between MMSE scores and correct scores in verifying fearful emotions(r=0.578;p < 0.001).No significant statistical differences were present among the three groups for the happy,sad and peaceful musical expressions scores(all p>0.05).Conclusion The experiment one indicated that a MCI patients had deficits in perceiving biological motion signals,they could obtain a certain number of local information(eg,the speed and track of moving stimulus)for the moving living entities,yet the ability to integrate the local information to a intact figure is decreasing,it may be a potential fact for declining social communication.According to visual processing theory,it inferred us that the function of visual ventral stream was impaired in the a MCI stage.The result of experiment two suggested us that the three canonical emotions(happiness,sadness,peacefulness)were preserved,however,decreased ability to distinguish fearful emotions occurred not only in patients with Alzheimer's disease but also in subjects mild cognitive impairment,it might have some correlation with diminished cognitive function and abnormal function or early decreasing volume of amygdala.