Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
FIDMAG Germanes Hospitalàries Research Foundation, Barcelona, Catalonia, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Barcelona, Catalonia, Spain.
Neuroimage Clin. 2022;36:103269. doi: 10.1016/j.nicl.2022.103269. Epub 2022 Nov 15.
Individuals with schizophrenia exhibit greater inter-patient variability in functional brain activity during neurocognitive task performance. Some studies have shown associations of age and illness duration with brain function; however, the association of these variables with variability in brain function activity is not known. In order to better understand the progressive effects of age and illness duration across disorders, we examined the relationship with individual variability in brain activity.
Neuroimaging and behavioural data were extracted from harmonized datasets collectively including 212 control participants, 107 individuals with bipolar disorder, and 232 individuals with schizophrenia (total n = 551). Functional activity in response to an N-back working memory task (2-back vs 1-back) was examined. Individual variability was quantified via the correlational distance of fMRI activity between participants; mean correlational distance of one participant in relation to all others was defined as a 'variability score'.
Greater individual variability was found in the schizophrenia group compared to the bipolar disorder and control groups (p = 1.52e-09). Individual variability was significantly associated with aging (p = 0.027), however, this relationship was not different across diagnostic groups. In contrast, in the schizophrenia sample only, a longer illness duration was associated with increased variability (p = 0.027).
An increase in variability was observed in the schizophrenia group related to illness duration, beyond the effects of normal aging, implying illness-related deterioration of cognitive networks. This has clinical implications for considering long-term trajectories in schizophrenia and progressive neural and cognitive decline which may be amiable to novel treatments.
精神分裂症患者在执行神经认知任务时，大脑功能的个体间变异性较大。一些研究表明年龄和疾病持续时间与大脑功能有关；然而，这些变量与大脑功能活动的变异性之间的关系尚不清楚。为了更好地了解跨障碍的年龄和疾病持续时间的渐进影响，我们研究了与大脑活动个体变异性的关系。
从共包括 212 名对照参与者、107 名双相情感障碍患者和 232 名精神分裂症患者的协调数据集（总 n=551）中提取神经影像学和行为数据。检查了对 N 回工作记忆任务（2 回对 1 回）的功能活动。通过参与者之间 fMRI 活动的相关距离来量化个体变异性；一个参与者与所有其他人的平均相关距离被定义为“变异性得分”。
与双相情感障碍和对照组相比，精神分裂症组的个体变异性更大（p=1.52e-09）。个体变异性与年龄显著相关（p=0.027），但这种关系在不同的诊断组之间没有差异。相比之下，仅在精神分裂症样本中，较长的疾病持续时间与变异性增加相关（p=0.027）。
在精神分裂症组中观察到变异性增加与疾病持续时间有关，超出了正常衰老的影响，暗示与疾病相关的认知网络恶化。这对考虑精神分裂症的长期轨迹和可能对新疗法敏感的进行性神经和认知衰退具有临床意义。
