Research On Diffusion Tensor Imaging And Early Screening Of Cognitive Impairment

Backgroud and objective:Alzheimer’s diseases (AD) is a neurodegenerative disease caused by a variety of reasons, mainly characterized by progressive cognitive dysfunction and behavioral change. The cholinergic system dysfunction is one of the most important pathophysiological change of AD. Diffusion tensor imaging (DTI) is a noninvasive imaging method developed three-dimensional display of cerebral white matter fiber tracts in vivo in recent years.This research adopts the DTI technique to detect FA and MD values of interested area on the cholinergic pathway in normal people, MCI patients and AD patients, compare changes of cerebral white matter microstructure in normal people, MCI patients and AD patients, explore the relationship between the cerebral white matter abnormalities and cognitive impairment, and clear the value of DTI in early diagnosis ofMCIandAD.Methods:DTI were obtained from 20 normal people,20 MCI patients, and 20 AD patients. The FA values and MD values of the WM in dieffrent regions, including corpus callosum genu, corpus callosum splenium, anterior and posterior parts of cigulate bundles, anterior and posterior limb of internal capsule, the temperal, frontal, parietal and occipital lobes were measured. Neuropsychological data including the MMSE, MoCA, words memory scale were assessed. The correlation analysis between DTI parameters and neuropsychological data were also analysed.Results:1. There were not statistically difference in NC group, MCI group and AD group about age, sex and education. The score of MoCA and word delayed recall had statistically difference between NC group and MCI group; The score of MoCA, word immediate recall and word delayed recall had statistically difference between NC group and AD group.2. Compared with NC group, the FA values of corpus callosum splenium and posterior cingulate in MCI group were statistically reduced, and the MD values were statistically elevated; compared with NC group, the FA values of corpus callosum splenium, posterior cingulate, the temperal, frontal, parietal lobes in AD group were statistically reduced, and the MD values were statistically elevated; compared with MCI group, the FA values of the temperal, frontal, parietal lobes in AD group were statistically reduced, and the MD values were statistically elevated.3. Pearson correlation analysis between the FA values and MD values in various brain regions and neuropsychological scores showed that:the FA values and MD values of the frontal, temperal and parietal lobes have a positive correlation with MMSE score; The FA values of posterior cingulate, the frontal, temperal and parietal lobes and the MD values of corpus callosum genu, posterior cingulate, the frontal, temperal and parietal lobes have a positive correlation with MoCA score; The FA values of the frontal and parietal lobes and the MD values of corpus callosum splenium, posterior cingulate, the frontal, temperal and parietal lobes have a positive correlation with word delayed recall score.Conclusion:DTI technology provides a more reliable technology in order to further improve the early diagnosis of AD.1. DTI can show the abnormal changes of cerebral white matter and quantitatively analysis in AD and MCI patients.2. Patients with MCI and AD selectively damage cerebral white matter microstructure. The lower FA values and higher MD values in corpus callosum splenium and posterior cingulate can be used as a more sensitive in the diagnosis indicator of MCI; The lower FA values and higher MD values in corpus callosum splenium, posterior cingulate, the temperal, frontal and parietal lobes contributed to the diagnosis of AD.3. MMSE, MoCA, word memory and word recognition score had obvious correlation with FA values and MD values in multiple cerebral white matter area, suggesting impairment of brain white matter microstructure can lead to cognitive decline.Objective:To investigate the utility of AD8 for cognitive impairment in a Chinese physical examination population.Methods:Military cadres who took routine physical examination in Chinese PLA General Hospital from Jan 1,2013 to Dec 31,2013 were subjected to AD8 scale. Individual information such as age, gender, education was also collected. All data were analyzed by SPSS 19.0.Results:1.1544 of 2109 subjects were enrolled in this study with mean age 75.4±10.6 years.2. The subjects who scored 0 to 8 of AD8 scale were 1015,269,120,60,30,14, 19,8,9, respectively. Corresponding proportion were 65.7%,17.4%,7.8%,3.9%, 2.0%,0.9%,1.2%,0.5%,0.6%, respectively. The endorsement prevalence of 8 questions were 5.6%,9.2%,6.6%,9.2%,4.8%,4.5%,8.9%,24.1%, respectively. The endorsement prevalence of question 8 was significantly higher than others (P< 0.05).3.260 subjects were scored equal to or greater than 2. The abnormal rate was 16.9%. All the participants were stratified into 9 groups by age, the prevalence of dementia was highly correlated with age (Spearman p= 0.316, P= 0.000).Conclusion:AD8 scale is a convenient and effective tool for cognitive screening in routine physical examination population.