| Back ground:Obsessive-compulsive is a kind of neurosis, including the main syndrome such as obsessions or compulsions, and the patients clearly know that those syndromes are unreasonable and unnecessary, however, they can not control or get rid of by themselves. Accordingly, they feel anxious and painful. Many a researches discovered that the patients have different cognitive dysfunctions without indefinite mechanism.Many experts suggest that cortical-basal-thalamus-cortical neuronal circuit may play an important role in the neural pathomechanism of OCD. Recently, the developed non-invasive 1H magnetic resonance spectroscopy imaging (1H-MRS) can detect the concentration of metabolite in grey matter to reflect the functional status of them. 1H-MRS was generally applied to mental disorder, schizophrenia, depression, epilepsy for instance, but only a few studies have been fund about OCD in this respect. Therefore, we plan to scan multiple brain regions of OCD by 1H-MRS with the purpose of discovering changes of brain function in OCD, and then provide an objective basis for cortical-basal-thalamus-cortical neuronal circuit theory. This is also helping us to clarify the relationship of the abnormalities among cognitive function, severity as well as course of illness.Objective:Adopting 1H-MRS to discover the abnormalities about the function of grey matter, furthermore, to explore the relationship of these values and cognitive dysfunction, severity of disease as well as illness durations.Methods: 1H-MRS are used to examie 19 OCD patients and 19 age-, sex-, education-, handedness-, familiarity with computer-matched healthy comparison subjects. We record NAA, Cho, Cr value of multiple regions of interest areas including bilateral prefrontal, parietal, temporal, occipital lobe, anterior cingutate, hippocampus, splenium and genu of corpus callosum, head of caudate nucleus (bilaterally) as well as thalamus. A special tool was adopted to evaluate the cognitive function of subjects (including other 24 persons which did not be checked by 1H-MRS). And then, we try to explore the relationship of these values and cognitive dysfunction, severity of disease as well as illness durations.Result:The ratios of NAA/Cr in left hippocampus were higher than those in normal controls (P<0.05), but NAA/Cr ratios in genu of corpus callosum were lower (P<0.01), the Cho/Cr ratios in right caudate nucleus lobe were higher than the contrast (P<0.05); The illness durations were negatively correlated with the Cho/Cr ratios of right prefrontal lobe (P<0.05); The NAA/Cr ratios of genu of corpus callosum as well as the Cho/Cr ratios of left temporal lobe were negatively correlated with Y-BOCS score (P<0.01)Attention network task showed that there were no differences in two groups about orienting and executive control network efficiency, however, alert network efficiency was lower in OCD (P<0.01),which was positively correlated with the ratios of NAA/Cr and Cho/Cr in the right hippocampus (P<0.05); the executive control network efficiency was related with the NAA/Cr ratios in left temporal lobe and splenium of corpus callosum (P<0.05); the orienting was negatively related with the ratios of Cho/Cr in left temporal lobe (P<0.05)The Wisconsin Card Sorting Test (WCST) showed that the number of response administered (Ra), errors and non-perseverative errors (nRpe) were higher than those in control subjects (P<0.01), numbers of categories completed (Cc) were lower (P< 0.01); Ra was positively related with the ratios of Cho/Cr in left anterior cingutate and bilateral occipital lobe (P<0.01); Cc was related with the Cho/Cr ratios in left temporal and bilateral occipital lobe (P<0.05);correct trials (Rc) was positively related with both the NAA/Cr and Cho/Cr ratios in left thalamus; errors and nRpe were related with Cho/Cr of bilateral occipital lobe (P< 0.01)The Iowa Gambling Task (IGT) revealed that the value of OCD about subtracting advantageous deck selections (C+D) from disadvantages deck selections (A+B) was lower than the comparison after the second block; the value were obviously related with the NAA/Cr ratios in bilateral prefrontal and left temporal, right anterior cingutate, left hippocampus as well as the Cho/Cr ratios in bilateral occipital lobe, right thalamus, left hippocampus and caudate nucleus (P< 0.05)Mental rotation test showed that the mean response time (MRT) and MRT of mirror image,0°,60°,180°,240°were higher than those in the controls (P< 0.05), of which were also related with the NAA/Cr ratios in left temporal, parietal and hippocampus, and also were obviously related with the ratios of Cho/Cr in left anterior cingutate, left thalamus, bilateral hippocampus and splenium of corpus callosum (P<0.05)Conclusion:The study revealed that the neuronal vitality of right head of caudate nucleus and left hippocampus were increased, however, decreased neuronal vitality was found in genu of corpus callosum, which were obviously correlated to course and severity of illness. Meanwhile, we found that prefrontal, parietal, temporal, anterior cingutate, occipital lobe, left hippocampus, left head of caudate nucleus, genu of corpus callosum as well as thalamus play an important role in cognition impaired -attention, memory, execution. These results provide a new evidence for cortical-basal-thalamus-cortical neuronal circuit theory. |
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