Study Of BOLD-fMRI Of Working Memory In Type 2 Diabetes Mellitus

ObjectiveType 2 diabetes mellitus(T2DM) is well known for its adverse impacts on brain and cognition,which leads to multidimensional cognitive deficits and widely spread cerebral abnormalities,and type 2 diabetes mellitus has the risk for Alzheimer's Disease(AD).Working memory(WM) is a susceptible cognitive domain of mild cognitive impairment(MCI) and AD. Aggravated cognitive and brain functional impairment in Type 2 diabetes mellitus with a resting-state functional MRI study. Therefore, whether T2 DM mainly by itself can influence the brain remains unclear.In the study,a blood oxygenation level-dependent functional resonance imaging(BOLD-fMRI) experiment was conducted to explore the brain function in T2 DM patients during a working memory task. The digit n-back task, which requires participants to monitor a series of digits and to respond the one presented N trail back.The identification of brain activation patterns under working memory loads can potentially enhance our understanding of the mechanisms underly congnitive dysfunction in T2 DM patients.Material and methods30 patients with T2 DM and 30 demographically matched right-hand euglycemic subjects were tested using mini-mental state examination(MMSE),Trail Making Test(TMT),Digit Span Test(DST),and Imaging data were collected on a 3.0 Siemens Trio Trim MR System, including T2WI?3D-T1 WI and functional magnetic resonance imaging,which was to obtain brain activations during a working memory task,the digit n-back paradigm(0-back and 2-back). Any scan in which the head motion was larger than 2 mm was excluded from further analysis. In the present study, twelve right-handed middle-aged T2 DM patients and ten controls participated. Functional data preprocessing was performed using MATLAB 2010.then the preprocessed MRI data were analyzed intwo ways :group and individual analysis, they were conducted with independent two-sample t test using SPM8.In addition, Pearson and Spearman correlation analyses were carried out between 2-back reaction time and brain activations during a working memory task for individual participants to verify whether they were associated with each other.Then we found the left anterior cingulater cortex(ACC) as the regions of interests(ROI).To compute the measure of functional connectivity between ROI and the whole brain,we conducted with independent two-sample t test between patients with T2 DM and normal controls.Results1. Relative to controls,during the n-back task, patients with T2 DM performed badly on the 2-back condition, showed significantly slower reaction times and a little less accuratily than controls.2. During the n-back task, a common brain network, including bilateral prefrontal cortices(PFC),bilateral premotor areas(PM), the left anterior cingulater cortex(ACC),the bilateral parietal cortices(PA) and occpiatal cortex, was activated in both groups.3.Patients with T2 DM showed less activation in bilateral prefrontal cortices(PFC),bilateral premotor areas(PM) and the left anterior cingulater cortex(ACC)than the normal controls.4. Our study showed that T2 DM patients exhibited brain increased activation with bilateral parietal cortices(PA)and bilateral occpiatal cortexs,compared to normal controls.5. Diabetic particpants showed significantly stronger function connectivity than control subjects between the anterior cingulater(ACC)and the left fusiform gyrus,the right cerebellum, the right inferior frontal gyri.Conclusions1.Before T2 DM patients were associated with cognitive impairments,such as psychomotor speed,executive function,they were found with impairment of working memory probability.2. Compared to healthy controls, the T2 DM group showed less activation in bilateral prefrontal cortices(PFC),bilateral premotor areas(PM),the left anterior cingulater cortex(ACC), these findings suggested the impairments of working memory related brain in T2 DM patients.3. Our study showed that T2 DM patients exhibited brain increased activation with the bilateral parietal cortices(PA), occpiatal cortexs, compared to healthy controls,which suggested a compensatory mechanism in T2 DM patients.4.The finding of increased function connectivity(FC) in diabetic particpants between the anterior cingulater and the left fusiform gyrus,the right cerebellum, the right inferior frontal gyri suggested an interaction in working memory networks.In summary, these findings provided exploratory evidence for the impact of chronic hyperglycemia on patients' working memory network.