Objective:Previous studies had shown that even with normal early development, preterm children at age six still have executive function deficits, including planning, cognitive flexibility, and nonverbal working memory. The present study aims to discuss further the correlation between IQ and EF of preterm children with different birthweight in order to clarify the potential influence of birthweight.Participants and Methods:The preterm children were recruited from the Regional Cohort Network for premature infants who were admitted to neonatal intensive care units. Inclusion criteria were their scores of Bayley Scales of Infant and Toddler Development, second or third edition at 12 and 24 months, and Wechsler Preschool and Primary Scale of Intelligence, Revised Edition at 5 years old were higher than 70. Meanwhile, their FSIQ of Wechsler Intelligence Scale for Children, Fourth Edition were higher than 85 at age 6. Exclusion criteria were visual impairment, hearing impairment, and cerebral palsy. There was a total of 251 preterm children recruited in the present study. Preterm children were then divided into very low birthweight (VLBW) and extremely low birth weight (ELBW) groups. The VLBW group included 183 preterm children, whose birthweight is between 1000-1500g, and gestational age is less than 37 weeks. The ELBW group included 68 preterm children, whose birthweight is less than 1000g and gestational age is less than 37 weeks. Four types of executive function were assessed. Inhibition was assessed through Comprehensive Nonverbal Attention Test Battery (CNAT), cognitive flexibility was assessed through Wisconsin Card Sorting Test (WCST), verbal working memory was assessed through the Longest Digit Span Forward (LDSB) index of Digit Span Subtest of Wechsler Intelligence Scale for Children-IV (WISC-IV), and nonverbal working memory was assessed through Knox's Cube Test (KCT), and planning ability was assessed through Tower of London (ToL). Data were analyzed with independent T-test and Pearson Correlation.Results:In VLBW preterm group, results showed that there were significant correlations (p<.05) between FSIQ and EF indexes in five out of six indexes of WCST, LDSB of Digit Span of WISC-IV, Backward score of Knox's Cube Test, and three out of six indexes of ToL. As to the CNAT, there was no index of CNAT that was significantly correlated with FSIQ in the VLBW preterm group. In ELBW preterm group, results showed that there were significant correlations (p<.05) between FSIQ and EF indexes in one out of five indexes of CNAT, one out of six indexes of WCST, Backward score of Knox's Cube Test, and two out of six indexes of ToL. And the LDSB of Digit Span of WISC-IV was not significantly correlated with FSIQ in ELBW preterm group.Conclusions:There were fewer EF indexes significantly correlated with FSIQ in ELBW preterm children with normal early development than VLBW preterm children with normal early development, suggesting that even with an IQ higher than 85, lower the birthweight, especially lower than 1000g, higher the EF performance should be concerned. Therefore, in the clinical setting, it is very important to assess the EF independently. And birthweight may be a crucial factor in preterm children's prefrontal cortex maturity.

中文翻译：

---

9 早期发育正常的VLBW和ELBW早产儿智商与执行功能的相关性

目的：之前的研究表明，即使早期发育正常，六岁时的早产儿仍然存在执行功能缺陷，包括计划、认知灵活性和非语言工作记忆。本研究旨在进一步探讨不同出生体重的早产儿IQ和EF之间的相关性，以阐明出生体重的潜在影响。 参与者和方法：早产儿是从地区队列网络中招募的早产儿。新生儿重症监护病房。纳入标准为12个月和24个月时的贝利婴幼儿发展量表第二版或第三版以及5岁时的韦氏学前和小学智力量表修订版得分高于70分。同时，韦氏的FSIQ儿童智力量表第四版6岁时高于85。排除标准为视力障碍、听力障碍和脑瘫。本研究共招募了 251 名早产儿。然后将早产儿分为极低出生体重（VLBW）和极低出生体重（ELBW）组。VLBW组包括183名早产儿，出生体重在1000-1500g之间，胎龄小于37周。ELBW组包括68名早产儿，出生体重小于1000g，胎龄小于37周。评估了四种类型的执行功能。通过综合非语言注意力测试电池（CNAT）评估抑制，通过威斯康星卡片分类测试（WCST）评估认知灵活性，通过韦氏智力量表数字跨度子测试的最长数字跨度向前（LDSB）指数评估言语工作记忆Children-IV (WISC-IV) 和非语言工作记忆通过诺克斯立方测试 (KCT) 进行评估，规划能力通过伦敦塔 (ToL) 进行评估。数据采用独立T检验和Pearson相关分析。结果：在VLBW早产组中，结果显示WCST、LDSB的数字跨度6个指标中的5个FSIQ与EF指标之间存在显着相关性（p<.05） WISC-IV、Knox's Cube Test 的后向分数、ToL 六项指标中的三项。至于CNAT，在VLBW早产组中没有发现与FSIQ显着相关的CNAT指标。在 ELBW 早产组中，结果显示，CNAT 的 5 个指标中的 1 个、WCST 的 6 个指标中的 1 个、Knox's Cube Test 的后向评分以及 2 个指标中，FSIQ 和 EF 指标之间存在显着相关性（p<.05）。 ToL 的六项指标。ELBW早产儿WISC-IV的数字跨度LDSB与FSIQ不显着相关。结论：早期发育正常的ELBW早产儿与早期发育正常的VLBW早产儿相比，与FSIQ显着相关的EF指标较少。这表明即使智商高于85，出生体重较低，特别是低于1000克，较高的EF表现也应引起关注。因此，在临床环境中，独立评估EF非常重要。而出生体重可能是早产儿前额皮质成熟度的关键因素。