Three-dimension MRI And Diffusion Tensor Imaging Study On Brain Micro-structural Changes In Patients With Major Depressive Disorder

Objective : To explore the possible pathology of brain structure and cognitiveimpairment in Chinese young and middle-aged populations, three-dimensionstructure magnetic resonance imaging (3D) and diffusion tensor imaging (DTI)technology were used, combining with related neuropsychological tests such asWisconsin Card Sorting Test (WCST).Method: 70 young and middle-aged patients with unipolar major depressivedisorders (MDDs) were enrolled, according to the CCMD-3 criteria for unipolardepression and DSM-Ⅳcriteria for major depressive disorder. 46 healthy subjectswere enrolled, each was required to match a patient in gender, age, and educationlevel. All the patients have a score of 35 or higher on the 24-item HamiltonDepression Rating Scale (HAMD24) while the control subjects less than 8 points.Both depressed patients and healthy subjects were performed with a 1.5-T GEMedical Systems. Conventional MRI, 3D and DTI were scanned, also testedcognitive function by the WCST, Fluency Test and the Stroop Test et al. Thepatients were followed up for 8~10 weeks, treated by antidepressant which the typesof medication were not interfered, patients that remission better (HAMD24 reducingrate≥75%) were reassessed. Results: A total of 70 depressed cases and 35 healthy controls completed the MRIscan and cognitive tests, 29 of these subjects achieved remission and agreed in thesecond scanned after 8-10 week treatment. Over the course of the study, some datawere exclude because of a variety of factors such as severe artifacts, non-cooperation,significant differences in the demographic between patients and healthy controls.Data would be analyzed at the end of the study including 62 cases [the first episode28 cases (male 14, female 14), 34 recurrent (18 male, 16 female)] in 3D. Prior-treatment 52 samples [the first episode 25 cases (male 14, female 11), 27 recurrent(15 male, 12 female)], 20 post treatment cases in DTI, 24 healthy controls (male 12,female 12) in DTI and 28 (male 12, female 16) in 3D. Data were mainly analyzed in3D and DTI part, some of the imaging data and cognitive data were study withcorrelation analysis. 1. Three-dimension structure MRI results 1.1 The VBManalysis showed no difference in WMC among the depressed patient group and thehealthy control group (including the male and female group). In male depressedpatients, reduced GMC were found in the left middle temporal gyrus in recurrentthan in first episode patients, while in female depressed patients, GMC in the leftsub-gyral of temporal lobe and the left lingual gyrus of occipital lobe weresignificantly lower than in first episode. 1.2 Significant gender differences were notfound both in first episode and recurrent patients. In male healthy controls, malecontrols showed significant decreased GMC in the left middle temporal gyrus than infemale (all P<0.005, voxels>10). 2. DTI results 2.1 Compared with healthy controls,MDD patients showed significantly lower FA mainly in the frontal, the temporal andthe cingulate gyrus. FA value in the left middle frontal gyrus, the left superiortemporal gyrus, the left sub-gyral of temporal lobe and the cingulate gyrus of limbiclobe in first episode patients (either male or female) lower than in healthy controls,while the recurrent patients exhibited lower FA in the right middle frontal gyrus, the right inferior frontal gyrus, the bilateral sub-gyral of frontal lobe than in healthycontrols. Furthermore, reduced FA were found in recurrent patients in the leftsuperior gyrus, the right middle frontal gyrus, the left middle temporal gyrus and theright cingulate gyrus than in male patients with first episode, in female patients, FAvalues in the left middle frontal gyrus and the right superior temporal gyrus weresignificantly lower than that in first episode (all P<0.001, voxels>10). 2.2 Femalepatients showed significant decreased FA in the left precentral gyrus of frontal andthe left middle frontal gyrus than male patients in first episode group, while inrecurrent group, the female patients'reduced FA were found in the right inferiorfrontal gyrus compared to male patients. Compared to male healthy controls, thefemale healthy controls also showed significant decreased FA in the right superiorfrontal gyrus, the bilateral middle frontal gyrus, right sub-gyral of frontal lobe andthe left sub-gyral of temporal lobe(all P<0.001, voxels>20). 2.3 The self-controlanalysis showed that the post treatment patients made significant improvement in theright inferior frontal lobe, the left cingulate gyrus of limbic lobe and the right sub-gyral of occipital, the FA of prior treatment group was lower in the left sub-gyral offrontal lobe, the right inferior frontal gyrus and the right sub-gyral of temporal lobethan healthy controls. The post treatment patients still showed reduced FA in thebilateral cingulate gyrus of limbic lobe and the inferior frontal gyrus compared withhealthy controls (all P<0.001, voxels> 20). The WCST, number range memory andSymbol results were significantly increased after treatment (P<0.05), and nodifferences were found between post treatment patients and healthy controls in bothitems.Conclusions: 1. Major depressed patients disruption of neural circuits located at thelimbic-cortical circuit but not yet involve white matter quantitative changes.Recurrent depression with longer course of disease aggravated GMC. The gender differences of brain tissue may not be one of the factors of brain pathology indepression. 2. Middle-aged depressed patient disruption of neural circuits located atthe limbic-cortical circuit, including the frontal lobe, the temporal lobe and thecingulate gyrus. Recurrent major depression with longer course of disease and moreattack times aggravated white matter integrity. The cognitive function improves inpatients after effective antidepressants (not limited in the type) while the brain whitermatter fiber recovers in some extent, but also abnormal regions compared to healthycontrols. Gender difference were found in the white matter fiber, and the femalepatients (both first and recurrent major depressive patients) exsit more damaged fiberthan male. But considered the small sample of our study, the relationship of genderdifferences in the white matter and the epidemiology of depressive patients needfurther study.