目的 探讨空间N‑back任务中事件相关电位P600样成分的潜伏期作为神经电生理指标，鉴别单纯ADHD（attention deficit hyperactivity disorder, ADHD）与ADHD共患DD（developmental dyslexia, DD）儿童的临床价值。 方法 采用前瞻性设计，于2025年6—9月在中南大学湘雅二医院儿童保健科招募66例6~10岁ADHD儿童作为研究对象，其中ADHD组28例，ADHD+DD组38例。另选取同期20例健康体检儿童，仅作为脑电地形图绘制的视觉参考。采用SNAP‑Ⅳ评定量表、儿童执行功能量表、康氏儿童行为量表（Conners Child Behavior Scale）、儿童汉语阅读障碍评估量表评估行为症状。执行空间N‑back任务的同时记录脑电图，提取额区（Fz）、中央区（Cz）、顶区（Pz）电极的P600样成分。采用线性混合模型分析组别、电极点、任务负荷的交互作用。绘制受试者操作特征曲线评估各指标鉴别单纯ADHD与ADHD共患DD的效能，并采用5折交叉验证以降低过拟合风险。 结果 在1‑back任务下，ADHD+DD组Pz电极P600样成分潜伏期长于ADHD组（P<0.001）。Pz电极潜伏期区分单纯ADHD与ADHD共患DD的曲线下面积为0.804（95%CI：0.697~0.910），以688 ms为截断值，灵敏度为63.2%，特异度为96.4%。分层逐步逻辑回归分析显示，模型4（P600样成分潜伏期+N1反应时+年龄）的AUC为0.804，与模型2（模型1+P600样成分峰值+P600样成分平均幅值；AUC=0.805）相当，且交叉验证稳定性更优。 结论 N‑back任务中Pz电极P600样成分潜伏期或可作为辅助鉴别ADHD是否共患DD的神经电生理指标，以此构建的简约模型与全指标模型鉴别效能相当，且交叉验证稳定性更优。

Objective To investigate the clinical value of the latency of the P600-like event-related potential component during a spatial N-back task as a neurophysiological indicator for differentiating children with attention deficit hyperactivity disorder (ADHD) alone from those with ADHD comorbid with developmental dyslexia (DD). Methods In this prospective study, 66 ADHD children aged 6-10 years were enrolled from the Department of Child Health Care, Second Xiangya Hospital of Central South University between June and September 2025, including 28 with ADHD alone and 38 with ADHD+DD. An additional 20 healthy children were included solely as a visual reference for electroencephalogram (EEG) topographic mapping. Behavioral symptoms were assessed using the SNAP-IV, the Childhood Executive Functioning Inventory, the Conners Child Behavior Scale, and the Dyslexia Checklist for Chinese Children. EEG was recorded during a spatial N-back task, and the P600-like component was extracted from Fz, Cz, and Pz electrodes. A linear mixed model was applied to analyze the interactions among group, electrode site, and task load. Receiver operating characteristic (ROC) curves were used to evaluate discriminative performance, and 5-fold cross-validation was conducted to reduce overfitting risk. Results Under the 1-back condition, the latency of the P600-like component at Pz was significantly longer in the ADHD+DD group than in the ADHD-alone group (P<0.001). The area under the curve (AUC) for the P600-like component latency at Pz in distinguishing ADHD alone from ADHD+DD was 0.804 (95%CI: 0.697-0.910). Using a cut-off value of 688 ms, sensitivity was 63.2% and specificity 96.4%. Hierarchical logistic regression analysis showed that model 4 (P600-like component latency + N1 reaction time + age) achieved an AUC of 0.804, comparable to that of model 2 (model 1 + P600-like component peak value + P600-like component average amplitude; AUC=0.805), with superior cross-validation stability. Conclusions The latency of the P600-like component at the Pz electrode during an N-back task may serve as a neurophysiological indicator to assist in differentiating whether children with ADHD have comorbid DD. A parsimonious model incorporating this indicator has discriminative performance comparable to the full-indicator model, with superior cross-validation stability.