The Cognitive Functions Of Mild Cognitive Impairment:A Follow-up Study

Mild Cognitive Impairment(MCI)refers to the progressive decline in memory or other Cognitive functions,which does not affect the ability to live in daily life and does not meet the diagnostic criteria for dementia.It is a transitional stage from normal aging to dementia.The research results are contradictory to each other on the cognitive deficits and progression in people with mild cognitive impairment.There have been few studies to explain conflicting results from different causes of MCI.In fact,the etiology of MCI is diverse,the most important of which is the pathological invasion of alzheimer's disease and vascular dementia.Therefore,this study hypothesized that mild cognitive impairment caused by different etiologies would present different cognitive deficits and progression,which may explain the contradictory results of previous studies.In addition,a large number of studies on MCI have focused on episodic memory,while a small number of studies have involved prospective memory.Few studies have focused on implicit memory of MCI,especially conceptual implicit memory.By using the method of neuropsychological tests and psychological experiments,this study explores the cognitive deficits and risk factors of alzheimer's type of mild cognitive impairment(hereinafter referred to as the AMCI)and vascular mild cognitive impairment(hereinafter referred to as the VMCI)),including prospective memory and conceptual implicit memory,and through 6 to 36 months of follow-up,understands their change laws,providing the basis for subsequent cognitive intervention.On this basis,neuropsychological tests or test combinations with good sensitivity and specificity were selected for subsequent large-scale community screening.There are four studies in this dissertation.1.Study 1 investigated the baseline cognitive function of 411 community adults over 60 years old.The results were as follows :(1)the prevalence of mild cognitive impairment in the baseline population was 32.3%,and the overall prevalence of dementia was 1.7%;(2)there were significant differences in age,number of years of education,educational level,whether to eat fish,surf the Internet and take photos between people with mild cognitive impairment and normal people.Older age was a risk factor for individuals with mild cognitive impairment,while higher education level was a protective factor for mild cognitive impairment;(3)there were significant differences in cognitive fields such as memory,attention,executive ability,language fluency,visual-spatial ability and directional ability between people with mild cognitive impairment and healthy people;(4)the depression test scores and depression rate of people with mild cognitive impairment were higher than those of healthy people,and their daily life functions were impaired compared with those of healthy people.(5)according to the ROC curve,to screen mild cognitive impairment from the general population the most effective test is: Montreal cognitive assessment(Mo CA)score,with area under the curve(Areaundercurve,AUC),0.907(sensitivity 88.2%,specificity 78.8%),Montreal cognitive assessment combining RAVLT-Delayed recall and Activity of Daily Living can obtain higher specificity at the same time of guarantee good sensitivity;(6)attention impairment was more severe in VMCI group than in AMCI group,and immediate recall function was more severely impaired in AMCI group than in VMCI group.2.Study 2 explores the conceptual implicit memory of the subjects by using the category exemplar generation task.It was found that the conceptual implicit memory function of VMCI was intact,while that of AMCI was impaired,and the performance of VMCI in conceptual implicit memory was significantly higher than that of AMCI in the category exemplar generation task of "occupation".Conceptual implicit memory was positively correlated with verbal fluency and categorical fluency,suggesting that the prefrontal cortex was also involved in implicit memory.3.Study 3 used the event-based non-focal prospective task to study the participants' prospective memory,and found that compared with normal subjects,AMCI and VMCI had no significant impairment in prospective memory.4.A total of 232 baseline subjects were followed up in study 4,with an average followup time of 18.96+7.686 months.The results show that all kinds of progressions exist,including maintaining the baseline diagnosis,progressing to MCI or dementia,and reversing to normal.Memory and language are important areas of normal and MCI interconversion,and picture completion,memory,and abstract ability tests tend to improve during follow-up.Baseline RAVLT-immediate recall,delayed recall and classification fluency are the best predictors for normal progressing to MCI,baseline Mo CA score and abstract ability score can predict mild cognitive impairment reversed back to normal.All in all,people with mild cognitive impairment showed overall impairment of cognitive functions compared to the heathy group.Two different subtypes of mild cognitive impairment-mild cognitive impairment due to Alzheimer's disease AMCI and vascular mild cognitive impairment VMCI – have different fields of cognitive impairment.The impairment of implicit memory and prospective memory is also different.Demographic variables,such as age,education level are associated with the development of mild cognitive impairment.The research results are helpful for the accurate diagnosis of MCI due to different etiology sources.The combination of episodic memory,prospective memory and implicit memory of the same individual is helpful for a deeper and more comprehensive understanding of the individual memory system.