首发抑郁症患者心理旋转任务的事件相关电位研究

Event-related potentials during mental rotation tasks in patients with first-episode depression

背景抑郁症患者的心理旋转意象能力受损,但与此相关联的异常脑电生理机制仍不清楚。 目的比较抑郁症患者与健康对照完成心理旋转任务时的事件相关电位（event-related potertials，ERPs）的差异。方法对32例住院或门诊首发抑郁症患行和29名对照进行心理旋转任务的ERP测定，给予不同旋转角度的测试刺激。测定4个脑区的ERPs（PZ、CZ、P3和P4）。测量指标包括错误数、反应时以及P500潜伏则和波峰值。结果与对照组相比，患者组完成心理旋转任务的反应时显著延长[689（98）ms比569（55hm：t=4．36，p〈0．0001],错误率显著升高[30．2％01．4％）比20．3％（7．2％）：1=3．61．p=0．015]，且原所有4个旋转角度均有差异。完成心理旋转任务时的事件相关电位测定发现，抑郁症患者在4个脑区总P500潜伏期有所增加，但无统计学意义．而P500波峰值显著降低。患者组与对照组错误率、反应时、P500潜伏期及波峰值均随着旋转角度（0°～180°）的递增而呈逐渐增加对照组平均ERP波形在700ms处出现一个正波峰，而在患者组未见。结论本研究证实了既往研究利用心理旋转任务评定抑郁症患者认知功能缺陷的有效。本研究发现心理旋转任务诱发的事件相关电位的电生理指标，特别是P500及P700波峰值，可能是抑郁症的潜行在生物学标记。需要前瞻性研究测定上述指标在抑郁症病程中的变化，以证交其有效性。

Background： The ability to mentally rotate images is impaired in depressed patients but the electrophysiological abnormalities in the brain related to this impairment remain unclear. Aim： To compare the event-related potentials （ERPs） of depressed patients and control subjects during the completion of a mental rotation （MR） task. Methods： Thirty-two inpatients and outpatients with first-episode depression and twenty-nine control subjects were administered an MR task that presented test stimuli at different angles of orientation. During the test ERPs were measured in four regions of the brain （PZ, CZ, P3 and P4）. Outcome variables included the error rate, reaction time, P500 latency and maximum P500 amplitude. Results： Compared to control subjects, patients with depression completing the MR test had a significantly longer mean （sd） reaction time （689 [98] ms vs. 569 [55] ms; t=4.36, p〈0.001） and a significantly higher mean percent error rate （30.2% [11.4%] vs. 20.3% [7.2%]; t=3.61, p=0.015）; these differences were also significant at each of the four orientation angles assessed. The ERP assessment during the MR test found that patients had a non-significant increase in the overall P500 latency and a significant reduction in the mean maximum P500 amplitude at each of the four brain regions assessed. For both patients and controls the error rate, reaction time, P500 latency and P500 amplitude increased significantly in a stepwise fashion as the angle of orientation of the presented stimulus increased from 0 °to 180°. In the control group there was a positive peak in the averaged ERP waveforms at about 700 ms that was not present in the patient group. Conclusion： Our study confirms previous work on the usefulness of MR tests to assess the cognitive deficits in depression. We find that the electrophysiological measures provided by ERP assessments during MR tasks, particularly maximum P500 amplitude and maximum P700 amplitude, are potential biological markers for depression. Prospective studies that assess changes in these measures over the course of a depressive illness will be needed to confirm their usefulness.