Hypothyroidism And Diabetes And Vision Bundled Functional Brain Imaging Study

Part 1 Brain Dysfunctions in Subclinical Hypothyroidism and Diabetes MellitusIn this part, by employing a parametric fMRI technology, we evaluated the working memory capacity and working memory related brain function in patients with subclinical hypothyroidism and in primary onset middle age patients with type II diabetes mellitus.Cognitive impairments have been found in thyroid hormone related diseases (e.g., hyperthyroidism and hypothyroidism) for a long time. However, whether and how subclinical hypothyroidism (SCH) causes any deficits in brain functions, and whether a hormone replacement treatment is necessary for SCH patients, still remain controversial subjects. In the first study, functional magnetic resonance imaging (fMRI) was used to measure brain functions by asking euthyroid subjects, hyperthyroid patients, and SCH patients to perform the widely used digit n-back working memory task. Wechsler Memory Scale-Chinese Revision (WMS-CR) was also adopted to examine whether there were any differences in other memory functions among these subject groups. Working memory capacity was also evaluated in hypothyroid with the n-back task. After having been treated with L-thyroxine for about six months, the SCH patients were asked to do the same fMRI experiment. The hypothyroid and SCH patients scored significantly lower score in the 2-back task than either the hyperthyroid patients or the euthyroid subjects. The fMRI showed that a common fronto-parietal network, including bilateral middle / inferior frontal gyri (M/IFG), bilateral dorsolateral prefrontal cortex (DLPFC), bilateral premotor areas (PreMA), the supplementary motor area / anterior cingulate cortex (SMA/ACC), and bilateral parietal areas (PA), was activated by the n-back task in all the subjects. Further quantitative analysis showed that the load effect of BOLD response appeared in all the five regions of interest (ROIs) in the euthyroid and hyperthyroid subjects. In the pre-treatment SCH patients, however, the load effect of BOLD response was only found in the PA and PreMA, but not in other frontal cortex ROIs. After an approximately six-month treatment with LT4, the SCH patients exhibited the same load effects in all the five ROIs as the euthyroid subjects did along with an improvement of performance in N-back task. No significant difference in WMS-CR score was found among the three subject groups. These results support that hypothyroidism, even subclinical, but not hyperthyroidism, lead to working memory deficits. These results also suggest that working memory is impaired in SCH patients, mainly as far as disorders of the fronto-parietal network were concerned. Both the memory performance and frontal executive functions were improved after an L-thyroxine replacement treatment.In the second study, comparing with euglycaemia subjects, we evaluated the working memory capacity and working memory related brain functional change in primary onset middle-age type II diabetes patients. The same paradigm as in the first study was applied. There were no significant differences in the behavioral results. The same cortical network as in the first study, i.e., the bilateral M/IFG, the bilateral...