doi 10.17992/lbl.2026.01.873

Aldis Eyja Axelsdottir¹ Anna Gudmundsdottir² Ingibjorg Thorsteinsdottir2 Ingolfur Einarsson³

Kristin Leifsdottir²

¹Faculty of Medicine, University of Iceland, ²Pediatric Department, Landspitali University Hospital,

³Consulting and analysis center

Correspondence: Correspondence Aldis Eyja Axelsdottir, aldisea@landspitali.is

Key words: Premature, Neurodevelopment, Disorders, Neonatalogy

 

Introduction: Survival among extremely preterm infants has increased markedly due to advances in neonatal care. These children remain at elevated risk for neuropsychological difficulties, particularly ADHD, autism spectrum disorder (ASD), and executive function deficits, which impacts learning, behavior, and emotional regulation. This study aimed to assess the prevalence of such difficulties at 6–7 years of age and the proportion referred to The Councelling and Diagnostic Center (CDC).

Methods: This was a retrospective cohort study. Data from neuropsychological assessments by the Children’s Hospital follow-up care for preterm infants and CDC evaluations were analyzed using RStudio 4.3.3.

Results: The cohort included 60 children born before 28 weeks of gestation and/or with birthweight below 1000g. 18 (30.0%) were followed at the CDC and 45 underwent neuropsychological assessment at the Children’s Hospital. Attention difficulties were present in 53.3%, executive function deficits in 46.7%, hyperactivity in 28.6%, and signs of ASD in 13.3%. Full-scale IQ could not be determined in 64.4% of the children due to significant discrepancies between subtest scores, making it an unreliable measure of cognitive ability. Significant differences were found in executive function deficits by sex (p = 0.038) and in the ability to obtain a full-scale IQ score (p = 0.01). No significant associations were observed with ADHD or ASD.

Conclusion: Neurodevelopmental disorders are common among extremely preterm infants, and the findings suggest that a large proportion of them need to undergo further diagnostic evaluation. The results also indicate that many will require support within the educational and healthcare systems. 

Table I. Results of the WISC-IV intelligence test and mean index scores by Full Scale I

IQ measured	Verbal Comprehension (mean)	Perceptual Reasoning (mean)	Working Memory (mean)	Processing Speed (mean)
Yes (N=16)	101.1 ±10.4	103.6 ±9.4	95.7 ±7.8	96.8 ±8.3
No (N=29)	104.0 ±22.5	104.6 ±14.8	90.0 ±11.7	96.8 ±15.8

Table II. Screening for ADHD symptoms, stratified by sex

	Inattention		Hyperactivity
	Boys (N=20)	Girls (N=25)	Boys (N=20)	Girls (N=25)
Above cutoff	11 (55.0%)	13 (52.0%)	7 (35.0%)	6 (24.0%)
Below cutoff	7 (35.0%)	12 (48.0%)	11 (55.0%)	19 (76.0%)
Missing data	2 (10.0%)	0 (0%)	2 (10.0%)	0 (0%)

Table III. Screening for autism spectrum symptoms, stratified by sex

	Boys (N=20)	Girls (N=25)
Total score > 20	2 (10.0%)	4 (16.0%)
Total score < 20	16 (80.0%)	21 (84.0%)
Missing data	2 (10.0%)	0 (0%)

Table IV. Mean scores on the 5–15 questionnaire, stratified by sex

Variable	Mean (boys)	Standardized 90th percentile (boys)	Mean (girls)	Standardized 90th percentile (girls)
Executive Functions	0.93 ±0.53	0.76	0.56 ±0.51	0.58
Attention and Concentration	1.10 ±0.59	0.88	0.72 ±0.63	0.67
Overactivity and Impulsivity	0.77 ±0.58	0.86	0.43 ±0.51	0.67
Passivity and Inactivity	0.83 ±0.58	0.69	0.51 ±0.47	0.52
Planning and Organizing	1.02 ±0.64	0.92	0.60 ±0.60	0.75