Microstructural abnormalities in the white matter (WM) are implicated in the pathophysiology of psychosis. In vivo magnetic resonance spectroscopy (MRS) can probe the brain’s intracellular microenvironment through the measurement of transverse relaxation and diffusion of neurometabolites and possibly provide cell-specific information. In our previous studies, we observed differential metabolite signal abnormalities in first episode and chronic stages of psychosis. In the present work, longitudinal data were presented for the first time on white matter cell-type specific abnormalities using a combination of diffusion tensor spectroscopy (DTS), T2 MRS, and diffusion tensor imaging (DTI) from a group of 25 first episode psychosis patients and nine matched controls scanned at baseline and one and two years of follow-up. We observed significantly reduced choline ADC in the year 1 of follow-up (0.194 µm2/ms) compared to baseline (0.229 µm2/ms), followed by a significant increase in NAA ADC in the year 2 follow-up (0.258 µm2/ms) from baseline (0.222 µm2/ms) and year 1 follow-up (0.217 µm2/ms). In contrast, NAA T2 relaxation, reflecting a related but different aspect of microenvironment from diffusion, was reduced at year 1 follow-up (257 ms) compared to baseline (278 ms). These abnormalities were observed in the absence of any abnormalities in water relaxation and diffusion at any timepoint. These findings indicate that abnormalities are seen in in glial-enriched (choline) signals in early stages of psychosis, followed by the subsequent emergence of neuronal-enriched (NAA) diffusion abnormalities, all in the absence of nonspecific water signal abnormalities.

中文翻译：

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首发精神病中的白质代谢物松弛和扩散异常：一项纵向研究


白质（WM）的微观结构异常与精神病的病理生理学有关。体内磁共振波谱（MRS）可以通过测量神经代谢物的横向弛豫和扩散来探测大脑的细胞内微环境，并可能提供细胞特异性信息。在我们之前的研究中，我们观察到精神病首发和慢性阶段的差异代谢信号异常。在目前的工作中，首次使用扩散张量光谱 (DTS)、T2 MRS 和扩散张量成像 (DTI) 组合从 25 名首发精神病患者中获取白质细胞类型特异性异常的纵向数据在基线以及一年和两年的随访中对患者和九名匹配的对照进行扫描。我们观察到，与基线 (0.229 µm2/ms) 相比，随访第一年胆碱 ADC 显着降低 (0.194 µm2/ms)，随后第二年随访 NAA ADC 显着增加 (0.258 µm2/ms) ）从基线（0.222 µm2/ms）和第一年随访（0.217 µm2/ms）。相比之下，NAA T2 松弛反映了扩散微环境的相关但不同的方面，与基线（278 毫秒）相比，在第 1 年随访时（257 毫秒）有所减少。在任何时间点水弛豫和扩散没有任何异常的情况下观察到这些异常。这些发现表明，在精神病早期阶段，富含神经胶质（胆碱）的信号出现异常，随后出现富含神经元（NAA）的扩散异常，所有这些都没有非特异性水信号异常。