search for


Etiology of Borderline Intellectual Functioning
J Korean Acad Child Adolesc Psychiatry 2024; 35(3): 188-191
Published online July 1, 2024
© 2024 Korean Academy of Child and Adolescent Psychiatry.

Hyo-Won Kim

Department of Psychiatry, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
Correspondence to: Hyo-Won Kim, Department of Psychiatry, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea
Tel: +82-2-3010-3414, Fax: +82-2-2045-4213, E-mail:
Received April 10, 2024; Revised May 31, 2024; Accepted June 7, 2024.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Borderline intellectual functioning (BIF), characterized by intelligence quotient scores between 70 and 85, can lead to challenges in daily life. This review explored the multifaceted nature of BIF by examining the interplay between genetic predisposition, prenatal/perinatal factors, environmental influences, and underlying medical conditions.
Keywords : Borderline intellectual functioning; Etiology; Genetics

Individuals with borderline intellectual functioning (BIF) have cognitive abilities that range between average intellectual functioning and intellectual disability (ID) and correspond to an intelligence quotient (IQ) between 70 and 85 [1]. BIF can be differentiated from ID by examining the deficits in cognitive and adaptive functions rather than relying solely on IQ scores. The prevalence of BIF ranges from 7% to 14% [2,3].

Children with BIF often display limitations in the cognitive, motor, social, and adaptive domains of development, which can result in learning difficulties and an increased risk of developing psychiatric disorders later in life. Limitations in social and academic areas, along with learning difficulties, imply underlying cognitive impairments, particularly in attention, executive functions, gross and fine motor skills, and the development of compensatory strategies [4]. However, individuals with BIF can present with diverse clinical and cognitive profiles.

BIF is a constellation of symptoms caused by diverse etiologies rather than a single neurodevelopmental syndrome [5]. A recent study found a primary etiological cause of BIF in 245/651 cases (37.6%) [6]. The etiological causes identified in the 245 cases were pre- or perinatal causes (40.4%), genetic syndromes/chromosomal abnormalities (31.0%), neurologic condition (9.0%), maternal substance use (7.8%), cerebral dysgenesis (5.7%), brain injury (4.1%), psychosocial deprivation (1.6%), and central nervous system infection (0.4%). The number of cases in which a cause could be identified was similar in BIF and ID, which was similar to other cases of developmental delay [7-9].

The diversity in clinical and cognitive profiles indicates that a multitude of factors contribute to the condition, such as genetic predispositions, prenatal/perinatal events, and environmental factors [10].


Although the development of intelligence and various cognitive functions is influenced by genetic and environmental factors, intelligence is highly heritable and is heavily influenced by genetic factors [11]. The heritability of intelligence is caused by several genes with small effects [12]. A recent large-scale genetic association study including 269867 participants identified 205 associated genomic loci and 1016 genes that were involved in the development of the nervous system and synaptic structure [13]. The heritability of intelligence increases throughout the lifespan and the same genes can affect diverse cognitive abilities [14].

Individuals with BIF often have a positive family history of BIF, ID, or other neurodevelopmental disorders, genetic syndromes, or chromosomal abnormalities [6]. Neurological conditions are more frequent among first- or second-degree relatives than in the general population. Although the association may not be as strong as in ID cases, there may be a familial trend wherein BIF can be observed across generations.

Several case reports of clinical syndromes associated with rare variants of genetic mutations have suggested that several genes may be related to intelligence or BIF. SNAP-25 polymorphism has been linked to intelligence through the mediating role of brain morphological features among children with BIF [15]. Additionally, case reports of BIF have observed genetic mutations in loci, including 7q11.23 [16] and 15q21.2 [17], and genes such as CACNA1I [18], USP7 [19], LRFN2 [20], and MAGEL2 [21]. However, whether these genetic variants are specifically related to BIF or overall brain development is unclear and requires further research.


Intellectual development can be affected by prenatal factors, such as advanced maternal age, exposure to alcohol or drugs during pregnancy, and maternal infection during pregnancy, and perinatal factors, such as preterm birth, low birth weight (LBW), and complications during birth. Furthermore, they are significantly associated with an increased risk of ID and can contribute to BIF.

LBW increases the risk of BIF. Studies on hospital birth cohorts have shown a higher prevalence of LBW among the adult population with BIF than among the population with average intelligence [22]. Additionally, the prevalence of BIF among individuals with LBW ranges from 13% to 24% [23].

Preterm birth, defined as birth before 37 weeks of gestation, is also associated with cognitive difficulties. In general, intelligence tends to be directly proportional to the gestational age. Preterm children are more likely to experience developmental delays, have low academic performance, and low mean IQ scores than their full-term counterparts [24]. Recent meta-analyses shows that preterm children (<32 weeks of gestational age) score an average of 11.5 to 12.9 points lower on IQ tests than full-term children [25].

Prenatal exposure to drugs, alcohol, infections, or malnutrition can influence neural development and potentially lead to BIF. The negative effects of alcohol exposure during pregnancy on the child’s cognitive development have been well documented [26]. Children exposed to alcohol during pregnancy typically score in the low-average-to-borderline range on IQ tests and display impairments in visual-spatial reasoning, memory, learning, and executive functioning [27]. Maternal infections during pregnancy can have a latent effect on cognitive development and decrease the child’s IQ [28].

Children’s brain development can be affected by various prenatal and perinatal risk factors, which can further impact their cognitive development and contribute to the development of BIF. Therefore, it is crucial to monitor the cognitive development of children born with perinatal risk factors closely and provide early educational interventions.


Research has shown that children with intellectual impairment are at a greater risk of exposure to early life adversities, including low socioeconomic status (SES), maltreatment, neglect, and high levels of parental/family stress. Additionally, several neuroimaging studies investigating the impact of early life adversity have shown a link between low SES, maltreatment, and neglect experienced during childhood and abnormal brain functioning and development [29-31].

Children from low-income families may be at a higher risk of developing BIF because of factors such as malnutrition, lack of early stimulation, or exposure to environmental toxins. A very large cohort study of 14000 children showed that children from low-SES families scored an average of 6 IQ points lower at age 2 than children from high-SES families. Furthermore, this difference became more pronounced with age [32]. Low SES has also been reported to affect both learning abilities and development of brain regions critical for memory and emotion regulation, such as the hippocampus and amygdala [30].

A higher number of adults with BIF had mothers with low education level than the population with average intelligence [22]. Furthermore, Farhadifar et al. [33] reported an association between maternal illiteracy and BIF in their children, suggesting that low parental education may contribute to the development of BIF.

Family structures characterized by a lack of support, enrichment, or frequent disruptions can increase the risk of developing BIF [34]. Living with a single parent is also associated with a higher incidence of BIF [35]. Early childhood experiences of family disruption, such as maltreatment or neglect, can have a lasting impact on brain development [31,36,37]. Maltreatment reportedly reduces the volume in the hippocampus, anterior cingulate, and ventromedial and dorsomedial cortices, affects the development of key white matter tracts and appears to alter cognitive development processes [38].

A crucial aspect of environmental risk factors is that they are modifiable and amenable to interventions. Moreover, social support, including supportive parents, role models for achievement, and warm relationships, is considered to be a preventive factor against BIF [34]. Thus, interventions are required to create a supportive social infrastructure where parents can raise their children well and provide parents with comprehensive parenting education programs.


BIF is a complex condition with diverse causes and presentations. Although it is not classified as an ID, individuals with BIF can experience challenges in various aspects of life. This review highlights the interplay between genetic predisposition, prenatal/perinatal factors, and environmental factors in the development of BIF.

Enhancing our understanding of factors that contribute to BIF is crucial for early identification and intervention. Early intervention strategies combined with access to supportive environments and educational resources can significantly improve the outcomes for individuals with BIF. Future research should identify the modifiable risk factors and develop effective preventive measures to reduce the impact of BIF.

Availability of Data and Material

Data sharing not applicable to this article as no datasets were generated or analyzed during the study.

Conflicts of Interest

The author has no potential conflicts of interest to disclose.

Funding Statement




  1. Greenspan S. Borderline intellectual functioning: an update. Curr Opin Psychiatry 2017;30:113-122.
    Pubmed CrossRef
  2. Karande S, Kanchan S, Kulkarni M. Clinical and psychoeducational profile of children with borderline intellectual functioning. Indian J Pediatr 2008;75:795-800.
    Pubmed CrossRef
  3. Ninivaggi FJ. Borderline intellectual functioning in children and adolescents: reexamining an underrecognized yet prevalent clinical comorbidity. Conn Med 2001;65:7-11.
  4. Cornoldi C, Giofrè D, Orsini A, Pezzuti L. Differences in the intellectual profile of children with intellectual vs. learning disability. Res Dev Disabil 2014;35:2224-2230.
    Pubmed CrossRef
  5. Salvador-Carulla L, García-Gutiérrez JC, Ruiz Gutiérrez-Colosía M, Artigas-Pallarès J, García Ibáñez J, González Pérez J, et al. Borderline intellectual functioning: consensus and good practice guidelines. Rev Psiquiatr Salud Ment 2013;6:109-120.
    Pubmed CrossRef
  6. Sätilä H, Jolma LM, Koivu-Jolma M. Children, adolescents, and young adults with borderline intellectual functioning: etiological, neurophysiological, and MRI findings in a cohort of 651 patients. Neurol Int 2022;14:1007-1017.
    Pubmed KoreaMed CrossRef
  7. Shevell MI, Majnemer A, Rosenbaum P, Abrahamowicz M. Etiologic determination of childhood developmental delay. Brain Dev 2001;23:228-235.
    Pubmed CrossRef
  8. Srour M, Mazer B, Shevell MI. Analysis of clinical features predicting etiologic yield in the assessment of global developmental delay. Pediatrics 2006;118:139-145.
    Pubmed CrossRef
  9. López-Pisón J, García-Jiménez MC, Monge-Galindo L, Lafuente-Hidalgo M, Pérez-Delgado R, García-Oguiza A, et al. Our experience with the aetiological diagnosis of global developmental delay and intellectual disability: 2006-2010. Neurologia 2014;29:402-407.
    Pubmed CrossRef
  10. Marcus Jenkins JV, Woolley DP, Hooper SR, De Bellis MD. Direct and indirect effects of brain volume, socioeconomic status and family stress on child IQ. J Child Adolesc Behav 2013;1:1000107.
    Pubmed KoreaMed CrossRef
  11. Polderman TJ, Benyamin B, de Leeuw CA, Sullivan PF, van Bochoven A, Visscher PM, et al. Meta-analysis of the heritability of human traits based on fifty years of twin studies. Nat Genet 2015;47:702-709.
    Pubmed CrossRef
  12. Manolio TA, Collins FS, Cox NJ, Goldstein DB, Hindorff LA, Hunter DJ, et al. Finding the missing heritability of complex diseases. Nature 2009;461:747-753.
    Pubmed KoreaMed CrossRef
  13. Savage JE, Jansen PR, Stringer S, Watanabe K, Bryois J, de Leeuw CA, et al. Genome-wide association meta-analysis in 269,867 individuals identifies new genetic and functional links to intelligence. Nat Genet 2018;50:912-919.
    Pubmed KoreaMed CrossRef
  14. Templer DI, Arikawa H. Association of race and color with mean IQ across nations. Psychol Rep 2006;99:191-196.
  15. Blasi V, Bolognesi E, Ricci C, Baglio G, Zanzottera M, Canevini MP, et al. SNAP-25 single nucleotide polymorphisms, brain morphology and intelligence in children with borderline intellectual functioning: a mediation analysis. Front Neurosci 2021;15:715048.
    Pubmed KoreaMed CrossRef
  16. Velleman SL, Mervis CB. Children with 7q11.23 duplication syndrome: speech, language, cognitive, and behavioral characteristics and their implications for intervention. Perspect Lang Learn Educ 2011;18:108-116.
    Pubmed KoreaMed CrossRef
  17. Lintas C, Sacco R, Azzarà A, Cassano I, Laino L, Grammatico P, et al. Genetic dysruption of the histaminergic pathways: a novel deletion at the 15q21.2 locus associated with variable expressivity of neuropsychiatric disorders. Genes (Basel) 2022;13:1685.
    Pubmed KoreaMed CrossRef
  18. El Ghaleb Y, Schneeberger PE, Fernández-Quintero ML, Geisler SM, Pelizzari S, Polstra AM, et al. CACNA1I gain-of-function mutations differentially affect channel gating and cause neurodevelopmental disorders. Brain 2021;144:2092-2106.
    Pubmed KoreaMed CrossRef
  19. Wimmer MC, Brennenstuhl H, Hirsch S, Dötsch L, Unser S, Caro P, et al. Hao-Fountain syndrome: 32 novel patients reveal new insights into the clinical spectrum. Clin Genet 2024;105:499-509.
    Pubmed CrossRef
  20. Thevenon J, Souchay C, Seabold GK, Dygai-Cochet I, Callier P, Gay S, et al. Heterozygous deletion of the LRFN2 gene is associated with working memory deficits. Eur J Hum Genet 2016;24:911-918.
    Pubmed KoreaMed CrossRef
  21. Marbach F, Elgizouli M, Rech M, Beygo J, Erger F, Velmans C, et al. The adult phenotype of Schaaf-Yang syndrome. Orphanet J Rare Dis 2020;15:294.
    Pubmed KoreaMed CrossRef
  22. Chen CY, Lawlor JP, Duggan AK, Hardy JB, Eaton WW. Mild cognitive impairment in early life and mental health problems in adulthood. Am J Public Health 2006;96:1772-1778.
    Pubmed KoreaMed CrossRef
  23. Chaudhari S, Otiv M, Chitale A, Pandit A, Hoge M. Pune low birth weight study--cognitive abilities and educational performance at twelve years. Indian Pediatr 2004;41:121-128.
  24. Ionio C, Riboni E, Confalonieri E, Dallatomasina C, Mascheroni E, Bonanomi A, et al. Paths of cognitive and language development in healthy preterm infants. Infant Behav Dev 2016;44:199-207.
    Pubmed CrossRef
  25. Arpi E, D'Amico R, Lucaccioni L, Bedetti L, Berardi A, Ferrari F. Worse global intellectual and worse neuropsychological functioning in preterm-born children at preschool age: a meta-analysis. Acta Paediatr 2019;108:1567-1579.
    Pubmed CrossRef
  26. Waite D, Burd L. Common developmental trajectories and clinical identification of children with fetal alcohol spectrum disorders: a synthesis of the literature. Adv Drug Alcohol Res 2023;3:10877.
    Pubmed KoreaMed CrossRef
  27. Doyle LR, Mattson SN. Neurobehavioral disorder associated with prenatal alcohol exposure (ND-PAE): review of evidence and guidelines for assessment. Curr Dev Disord Rep 2015;2:175-186.
    Pubmed KoreaMed CrossRef
  28. Kwok J, Hall HA, Murray AL, Lombardo MV, Auyeung B. Maternal infections during pregnancy and child cognitive outcomes. BMC Pregnancy Childbirth 2022;22:848.
    Pubmed KoreaMed CrossRef
  29. Whittle S, Dennison M, Vijayakumar N, Simmons JG, Yücel M, Lubman DI, et al. Childhood maltreatment and psychopathology affect brain development during adolescence. J Am Acad Child Adolesc Psychiatry 2013;52:940-952.e1.
    Pubmed CrossRef
  30. Hair NL, Hanson JL, Wolfe BL, Pollak SD. Association of child poverty, brain development, and academic achievement. JAMA Pediatr 2015;169:822-829.
    Pubmed KoreaMed CrossRef
  31. Kelly PA, Viding E, Wallace GL, Schaer M, De Brito SA, Robustelli B, et al. Cortical thickness, surface area, and gyrification abnormalities in children exposed to maltreatment: neural markers of vulnerability?. Biol Psychiatry 2013;74:845-852.
    Pubmed CrossRef
  32. von Stumm S, Plomin R. Socioeconomic status and the growth of intelligence from infancy through adolescence. Intelligence 2015;48:30-36.
    Pubmed KoreaMed CrossRef
  33. Farhadifar F, Ghotbi N, Yari A, Haydarpur M, Mohammadzadeh H, Afkhamzadeh A, et al. Risk factors associated with borderline intelligence in schoolchildren: a case-control study. Pak J Med Sci 2011;27:102-106.
  34. Peltopuro M, Ahonen T, Kaartinen J, Seppälä H, Närhi V. Borderline intellectual functioning: a systematic literature review. Intellect Dev Disabil 2014;52:419-443.
    Pubmed CrossRef
  35. Hassiotis A, Brown E, Harris J, Helm D, Munir K, Salvador-Carulla L, et al. Association of borderline intellectual f unctioning and adverse childhood experience with adult psychiatric morbidity. Findings from a British birth cohort. BMC Psychiatry 2019;19:387.
    Pubmed KoreaMed CrossRef
  36. Puetz VB, Parker D, Kohn N, Dahmen B, Verma R, Konrad K. Altered brain network integrity after childhood maltreatment: a structural connectomic DTI-study. Hum Brain Mapp 2017;38:855-868.
    Pubmed KoreaMed CrossRef
  37. Baglio F, Cabinio M, Ricci C, Baglio G, Lipari S, Griffanti L, et al. Abnormal development of sensory-motor, visual temporal and parahippocampal cortex in children with learning disabilities and borderline intellectual functioning. Front Hum Neurosci 2014;8:806.
    Pubmed KoreaMed CrossRef
  38. Teicher MH, Samson JA, Anderson CM, Ohashi K. The effects of childhood maltreatment on brain structure, function and connectivity. Nat Rev Neurosci 2016;17:652-666.
    Pubmed CrossRef

July 2024, 35 (3)
Full Text(PDF) Free
PubMed Central
Google Scholar Search

Social Network Service
Close ✕

Stats or Metrics

Author ORCID Information