Abstract: Objective To explore the cerebral magnetization transfer ratio (MTR) changes in young and middle-age patients with major depressive disorder (MDD) and its correlation with the disease duration. Methods Thirty MDD patients and 30 healthy controls took part in the whole study. Patients were diagnosed by experienced psychiatrists according to Diagnostic and Statistical Manual of Mental Disorders Fouth Edition (DSM- Ⅳ) criteria (American Psychiatric Association, 1994). Severity of depression was assessed by 17-item Hamilton Depression Rating Scale (HAMD) and only patients who scored 18 or higher were included. Healthy controls were individually matched with the patients for age, sex, handedness and education. Magnetization transfer imaging (MTI) was acquired by using a 3.0T Siemens magnetic resonance imaging (MRI) system. MTR map calculation, normalization, smoothing and statistical analysis were all carried out in the software Statistical Parametric Mapping (SPM). A 2?sample t ?test was used for group comparison and a Pearson correlation was used to examine the relationship between MTR and disease duration in MDD patients. Results In SPM, we set the cluster level P < 0.05 as the statistical significance threshold. Compared with normal controls, no brain regions in MDD patients with significant changed MTR were found. However, significant negative correlation was observed between the disease duration of MDD subjects and their MTR in the left prefrontal, parietal and temporal areas, and bilateral anterior cingulate gyrus. Further analysis revealed that in comparison with matched controls, MTR was significantly lower in the left middle frontal gyrus, bilateral middle cingulate cortex and right anterior lobe of cerebellum in patients with longer disease duration (> 60 weeks); and MTR was higher in the left middle frontal gyrus, tempo-occipital boundary, bilateral anterior cingulate cortex and adjacent white matter in patients with shorter disease duration (≤ 60 weeks). Conclusion MDD presents cerebral MTR changes in different pattern along with disease progression, which may implicate the needs of longitudinal imaging study for MDD, and particularly the effect of long term antidepressant treatment exerting on brain structure and function should be emphasized.

Key words: Depressive disorder, Magnetic resonance imaging, Case-control studies, Adolescent, Adult

摘要： 目的 探讨青壮年重症抑郁障碍患者磁化传递率（MTR）值的改变及其与病程的相关性。方法 根据美国精神障碍诊断与统计手册，选择临床晤谈诊断明确并且17 项汉密尔顿抑郁量表评分≥18 分的30 例重症抑郁障碍患者，以及按照年龄、性别、利手性、受教育程度相匹配原则征集的30 例正常对照者。采用3.0T MRI扫描仪采集磁化传递成像数据，统计参数图软件对所得MTR 参数图进行标准化和平滑等预处理，再行基于体素的分析。MTR 值的组间比较行双样本t 检验，与病程的相关性分析采用Pearson 相关分析。结果 在统计参数图中，以团簇水平P < 0.05 作为统计显著性阈值。与正常对照组相比，重症抑郁障碍组患者未发现MTR 值差异有统计学意义的脑区；相关分析显示，其在左侧前额叶、顶叶、颞叶部分区域，以及双侧前扣带回等脑区与病程呈显著负相关。进一步亚组分析显示，长病程（>60 周）重症抑郁障碍患者MTR 值在左侧额中回、双侧中扣带回、右侧小脑前叶低于与之相匹配的正常对照者；而短病程（≤ 60 周）患者，MTR 值则在左侧额中回、颞枕交界区、双侧前扣带回及邻近白质较正常对照者升高。结论 不同病程重症抑郁障碍患者脑MTR 值呈现不同改变模式，提示对重症抑郁障碍患者长期纵向随访的必要性，尤其是长期抗抑郁治疗对脑结构及功能的影响应作为重点研究课题。

关键词: 抑郁症, 磁共振成像, 病例对照研究, 青少年, 成年人