Department of Psychiatry, Fujita Health University School of Medicine, Aichi, Japan.
PLoS One. 2012;7(8):e43539. doi: 10.1371/journal.pone.0043539. Epub 2012 Aug 28.
Patients with schizophrenia frequently exhibit behavioral abnormalities associated with its pathological symptoms. Therefore, a quantitative evaluation of behavioral dynamics could contribute to objective diagnoses of schizophrenia. However, such an approach has not been fully established because of the absence of quantitative biobehavioral measures. Recently, we studied the dynamical properties of locomotor activity, specifically how resting and active periods are interwoven in daily life. We discovered universal statistical laws ("behavioral organization") and their alterations in patients with major depressive disorder. In this study, we evaluated behavioral organization of schizophrenic patients (n = 19) and healthy subjects (n = 11) using locomotor activity data, acquired by actigraphy, to investigate whether the laws could provide objective and quantitative measures for a possible diagnosis and assessment of symptoms. Specifically, we evaluated the cumulative distributions of resting and active periods, defined as the periods with physical activity counts successively below and above a predefined threshold, respectively. Here we report alterations in the laws governing resting and active periods; resting periods obeyed a power-law cumulative distribution with significantly lower parameter values (power-law scaling exponents), whereas active periods followed a stretched exponential distribution with significantly lower parameter values (stretching exponents), in patients. Our findings indicate enhanced persistency of both lower and higher locomotor activity periods in patients with schizophrenia, probably reflecting schizophrenic pathophysiology.
精神分裂症患者常表现出与其病理症状相关的行为异常。因此，对行为动态进行定量评估有助于对精神分裂症进行客观诊断。但是，由于缺乏定量的生物行为测量方法，这种方法尚未完全建立。最近，我们研究了运动活动的动力学特性，特别是静息期和活跃期如何在日常生活中交织在一起。我们发现了普遍的统计规律（“行为组织”）及其在重度抑郁症患者中的变化。在这项研究中，我们使用活动记录仪获取的运动活动数据来评估精神分裂症患者（n=19）和健康受试者（n=11）的行为组织，以研究这些规律是否可以为可能的诊断和症状评估提供客观和定量的测量方法。具体来说，我们评估了静息期和活跃期的累积分布，分别定义为身体活动计数连续低于和高于预定义阈值的时间段。我们报告了控制静息期和活跃期的规律发生变化的情况；患者的静息期遵循幂律累积分布，其参数值（幂律标度指数）明显降低，而活跃期则遵循伸展指数分布，其参数值（伸展指数）明显降低。我们的研究结果表明，精神分裂症患者的较低和较高运动活动期的持续性增强，这可能反映了精神分裂症的病理生理学。
