Executive function deficits are often reported as a specific weakness in preterm children. Yet, executive function development is still not fully understood. In a prospective longitudinal study, 115 preterm born children, <= 31 weeks of gestation, were recruited at birth and subject to neuropsychological assessments at ages 5.5 and 18 years. By applying Miyake and colleagues' integrative framework of executive function to our data, two core components of executive function, working memory and cognitive flexibility, were identified through confirmatory factor analysis. Developmental stability was investigated in a serial multiple mediator structural equation model. Biological, medical, and social factors as well as mental development at 10 months were entered as predictors. Both components of executive function were highly stable from 5.5 to 18 years. Gestational age, intrauterine growth, lack of perinatal medical complications, and female sex were positively related to mental development at 10 months, which together with parental education influenced both core executive functions at 5.5 years. Working memory at 5.5 years mediated outcome in working memory at 18 years. In addition to the mediation of cognitive flexibility at 5.5 years, perinatal medical complications and restricted intrauterine growth had a continued direct negative impact on cognitive flexibility at 18 years. The application of a theoretical framework added to our understanding of executive function development in preterm born children. The study supports early identification of executive deficits among children born preterm, as deficits are unlikely to diminish with maturation.

Aim: The aim of this study was to investigate long-term cognitive outcome in a cohort of 18-year-olds born preterm and previously assessed at the age of 5.5.

Methods: We tested 134 adolescents born preterm with a very low birthweight of <1500g and 94 term-born controls with a comprehensive cognitive battery at 18years of age. The cohort was subdivided into 73 extremely preterm, 42 very preterm and 19 moderately preterm infants with gestational ages of 23-27, 28-31 and 32-36weeks, respectively. The moderately preterm group was dominated by adolescents born small for gestational age.

Results:Very preterm adolescents performed on a par with term-born controls. In contrast, extremely preterm adolescents displayed inferior results on all cognitive tests, more so if they had suffered neonatal complications. Moderately preterm adolescents scored lower than very preterm and full-term born adolescents, particularly on complex cognitive tasks.

Conclusion: Adolescents born at 28weeks of gestation or later, with appropriate birthweight and no perinatal complications, functioned like term-born peers at 18years of age. Extremely preterm birth per se posed a risk for long-term cognitive deficits, particularly executive deficits. Adolescents born moderately preterm but small for gestational age were at risk of general cognitive deficits.

Cognitive outcome after preterm birth is heterogeneous, and group level analyses may disguise individual variability in development. Using a person-oriented approach, this study investigated individual cognitive patterns and developmental trajectories from preschool age to late adolescence. As part of a prospective longitudinal study, 118 adolescents born preterm, with a birth weight <1,500 g, participated in neuropsychological assessments at age 5½ years and at 18 years. At each age, four cognitive indices, two tapping general ability and two tapping executive functions, were formed to reflect each individual’s cognitive profile. Cluster analyses were performed at each age separately, and individual movements between clusters across time were investigated. At both 5½ and 18 years, six distinct, and similar, cognitive patterns were identified. Executive functions were a weakness for some but not all subgroups, and verbal ability was a strength primarily among those whose overall performance fell within the normal range. Overall, cognitive ability at 5½ years was highly predictive of ability at age 18. Those who performed at low levels at 5½ did not catch-up, but rather deteriorated in relative performance. Over half of the individuals who performed above norm at 5½ years improved their relative performance by age 18. Among those performing around norm at 5½ years, half improved their relative performance over time, whereas the other half faced increased problems, indicating a need for further developmental monitoring. Perinatal factors were not conclusively related to outcome, stressing the need for cognitive follow-up assessment of the preterm born child before school entry.

Follow-up studies of preterm children have reported a range of cognitive deficits, particularly in executive functions, visuospatial abilities, and learning. However, few researchers have adopted a person-oriented approach, exploring individual neuropsychological profiles. The aim of this study was to identify typical neuropsychological profiles among preterm children and control children, respectively. A second aim was to investigate if neuropsychological profiles at age 51/2 might be associated with perinatal medical risk factors. As part of the longitudinal Stockholm Neonatal Project, NEPSY for 4- to 7-year-old children (Korkman, 1990), WPPSI-R, and Movement ABC were administered at age 51/2 years to 145 preterm (mean gestational age 28 weeks) and 117 control children born at term. For the present study, the NEPSY results of each child were transformed into summary z scores for each of 5 neuropsychological domains: attention, memory, sensory-motor, verbal, and visuospatial functions. Subsequently, Ward's cluster analysis was performed for the preterm and control groups separately, identifying 5 neuropsychological profiles in both groups explaining around 56% and 57% of the variance, respectively. Overall, preterm children had lower neuropsychological results but also more diverging profiles compared to controls. The variability in outcome could not be sufficiently explained by birth weight, gestational age, or medical risks. The results suggest that prematurity interacts dynamically with genetic, medical, and environmental factors in neuropsychological development.

Stockholm Neonatal Project is a longitudinal population-based study of children born prematurely in 1988-93, with a very low birth weight (<1500 g), who have been followed prospectively from birth through adolescence. A matched control group was recruited at age 5 ½ years. The overall aim was to investigate long-term developmental outcome, paying particular attention to executive functions (EF) in relation to degree of prematurity, birth weight and medical risks. Study I showed a disadvantage in visuo-motor development at 5 ½ years, especially among the preterm boys. Visuo-motor skills were highly related to IQ, and also to EF. In Study II, neuropsychological profiles typical of preterm children and term born children, respectively, were identified through cluster analysis. The general level of performance corresponded well with IQ, motor functions and parental education in both groups, but preterm children had overall lower results and exhibited greater variability across domains. Study III showed that extremely preterm birth (w. 23-27) per se poses a risk for cognitive outcome at age 18, particularly for EF, and that perinatal medical complications add to the risk. By contrast, adolescents born very preterm (w. 28-31) performed just as well as term-born controls in all cognitive domains. However, adolescents born moderately preterm (w. 32-36) and small for gestational age showed general cognitive deficits. Study IV found that cognitive development was stable over time, with parental education and EF at 5 ½ years as significant predictors for cognitive outcome at age 18. Among preterm children, perinatal medical risks and being small for gestational age had a continued negative impact on cognitive development from 5 ½ to 18 years. Study V demonstrated that neuropsychological scoring of Bender drawings, developed in study I, predicted cognitive outcome in adolescence, indicating that the method  may be useful in developmental screening around school entry.

Visual-motor development and executive functions were investigated with the Bender Test at age 51/2 years in 175 children born preterm and 125 full-term controls, within the longitudinal Stockholm Neonatal Project. Assessment also included WPPSI-R and NEPSY neuropsychological battery for ages 4-7 (Korkman, 1990). Bender protocols were scored according to Brannigan & Decker (2003), Koppitz (1963) and a complementary neuropsychological scoring system (ABC), aimed at executive functions and developed for this study. Bender results by all three scoring systems were strongly related to overall cognitive level (Performance IQ), in both groups. The preterm group displayed inferior visual-motor skills compared to controls also when controlling for IQ. The largest group differences were found on the ABC scoring, which shared unique variance with NEPSY tests of executive function. Multiple regression analyses showed that hyperactive behavior and inattention increased the risk for visual-motor deficits in children born preterm, whereas no added risk was seen among hyperactive term children. Gender differences favoring girls were strongest within the preterm group, presumably reflecting the specific vulnerability of preterm boys. The results indicate that preterm children develop a different neurobehavioral organization from children born at term, and that the Bender test with a neuropsychological scoring is a useful tool in developmental screening around school start.

Objective: The aim of this study was to investigate if the Bender test, administered to late preschoolers and evaluated with a neuropsychological scoring system ,  can identify and predict executive dysfunctions at preschool age and in late adolescence, respectively.

Participants and Methods: As part of the longitudinal Stockholm Neonatal Project, 134 adolescents born preterm with very low birth weight (< 1500g) and 94 matched controls born at term, participated in follow-up studies at ages 5 ½ and 18 years. On both occasions, the participants were assessed with an age appropriate intelligence test and tests of executive functions (EF) .  Bender Visual Motor Gestalt Test was given at age 5 ½, and scored with ABC neuropsychological system. Stepwise regression analysis was used to investigate how cognitive outcome at age 18 was predicted by the Bender ABC score and EF at age 5 ½, gender,  medical risk, birth weight ratio, and parental education. The validity of the Bender ABC neuropsychological score in screening for executive dysfunction was evaluated by Receiver Operating Characteristics-analysis (ROC).

Results: Bender ABC neuropsychological scores predicted general intelligence and EF at 18 years almost as well as a more comprehensive battery, in both groups. ROC analysis showed that the Bender ABC had good diagnostic and predictive validity for identifying executive dysfunctions, with AUC-values of .84 in both cases.

Conclusion: Bender with ABC neuropsychological scoring is a promising screening instrument for identifying executive dysfunctions before school start.

Objective: Research has shown that premature birth poses a risk for later cognitive development, particularly in the executive domain, but few studies extend beyond the early school years. Adolescence is a critical period for cognitive maturation, and this study investigated the cognitive outcome in a Swedish cohort of prematurely born 18-year olds, in relation to gestational age at birth and medical risks in the perinatal period.

Participants and Methods:  As part of Stockholm Neonatal Project, 134 adolescents born preterm with very low birth weight (< 1500g) and 94 matched controls born at term, participated in a follow-up study at age 18. General intelligence, as well as executive, memory, language and visual motor functions were measured by WISC-III, Delis-Kaplan Executive Function System, naming tests, Rey Auditory Verbal Learning test, face recognition, and Visual Motor Integration test.

Results: Extremely preterm adolescents (EPT, GA 23-27, n=74) performed worse than adolescents born either very preterm or at term, on all cognitive tasks and particularly on executive measures. 50% of the EPT group had suffered perinatal medical complications, and had more pervasive cognitive deficits than EPTs with low medical risk.  By contrast, very preterm adolescents (GA 28-31; n=36) performed consistently on a par with the controls.  Moderately preterm with very low birth weight (GA 32-36; n=25), who had experienced varying degrees of intrauterine growth retardation, tended to score lower than very preterm and control adolescents, particularly on complex cognitive measures.

Conclusions: Extremely preterm birth per se poses a risk for long-term cognitive outcome, particularly in executive functions. These risks may be exacerbated by medical complications.  Children born after 28 weeks of gestation or later, with normal birth weight and no perinatal complications, do not have an elevated risk for cognitive deficits at age 18.

Objective: To investigate the stability of development in general intelligence (IQ) and executive functions (EF), and to identify predictors of cognitive development from preschool age through adolescence, in a cohort of preterm and term-born children.

Participants and Methods:  As part of the longitudinal Stockholm Neonatal Project, 134 adolescents born preterm with very low birth weight (< 1500g) and 94 matched controls born at term, participated in follow-up studies at ages 5 ½ and 18 years. On both occasions, the participants were assessed with an age appropriate Wechsler IQ test and tests of executive functions (EF). Stability in cognitive outcome was tested with Pearson correlations. Stepwise regression analyses were used to investigate how cognitive outcome at age 18 was predicted by EF at age 5 ½, parental education, gender, medical risk, and birth weight ratio.

Results: IQ was quite stable form preschool age through adolescence (r =.78 in whole group, r = .84 in preterm and r= .61 in controls), as were EF (r =  .65 in whole group, r = .64 in preterm and r = .53 in controls).  In controls, EF at age 5 ½ and parental education predicted IQ (R² = .205) and EF at 18 years (R² = .249). In the preterm group, EF at age 5 ½, parental education, medical risks and birth weight ratio predicted IQ 18 years (R² = .508), and EF at age 5 ½ and medical risks predicted EF at18 years (R² = .432).

Conclusions: Stability in cognitive outcomes from preschool through adolescence was high, particularly in the preterm group. EF at 5 ½ strongly predicted cognitive and executive functions at 18 years, in both groups. Over the same period, parental education had a continued positive effect on cognitive development. Among preterm children, perinatal medical risks predicted a less favorable continued cognitive development, especially in EF, and a low birth-weight ratio had a negative impact on general intelligence.