Oct 5, 2026·Special Population & Related Conditions
Neurofibromatosis Type 1 and IQ: Typical Scores, Learning Problems, and the Visuospatial Profile
Neurofibromatosis IQ scores are usually in the normal range but average close to one standard deviation below comparison groups, with weak spatial skills.
Dr. Russell T. WarneChief Scientist
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Most people with neurofibromatosis type 1 (NF1) have IQ scores in the normal range, but as a group they score lower than people without the condition: a 2022 meta-analysis found a general intelligence gap of close to one standard deviation compared with typically developing people and unaffected siblings. Intellectual disability is uncommon (about 8% in a 2026 meta-analysis), while learning difficulties, attention problems and weak visuospatial skills are much more frequent.
This page covers the typical neurofibromatosis IQ range, how often learning disability, ADHD and intellectual disability occur, the cognitive profile beneath the full-scale score, why the larger heads common in NF1 do not bring higher scores, and how scores change with age.
The typical IQ range in NF1
Neurofibromatosis type 1 affects about 1 in 3,000 to 4,000 people worldwide, according to MedlinePlus Genetics. It is caused by variants in the NF1 gene, which normally helps restrain cell growth. Almost everyone with the condition develops flat, coffee-colored skin patches called café-au-lait spots in early childhood, and most adults develop benign tumors along nerves. About half of cases are inherited from a parent, and the rest arise from new genetic changes. MedlinePlus notes that most people with NF1 have normal intelligence, while learning disabilities and attention-deficit/hyperactivity disorder occur frequently.
The best summary of the group difference is a meta-analysis by Crow and colleagues, which pooled 50 studies covering 1,522 people with NF1 between 6 months and 69 years of age. People with NF1 scored lower across almost every cognitive domain, with an overall effect size of −0.64. The largest gap was in general intelligence, at −0.95. An effect size, here Hedges' g, expresses the gap in standard deviation units, so −0.95 corresponds to roughly 14 points on the usual IQ scale. Age, sex, education and parental education did not significantly change the size of the gaps.
That gap describes averages. Because the comparison groups in these studies were typically developing children and unaffected brothers and sisters, a 14-point average shift still leaves most people with NF1 in the normal range, and many score at or above 100. A 2026 Dutch study by van Abeelen and colleagues summarizes earlier longitudinal research as showing a downward shift of about 10 points relative to the general population, with scores generally in the average range. In a population-based UK study, Lehtonen and colleagues found that children with NF1 had lower full-scale IQs and lower academic achievement than their own siblings, which makes shared family background an unlikely explanation for the gap.
Learning disabilities, ADHD and intellectual disability
The most detailed single study is Hyman, Shores and North's assessment of 81 children aged 8 to 16 with NF1, compared with 49 unaffected siblings. Eighty-one percent of the children with NF1 had moderate to severe impairment in at least one area of cognitive functioning. Half performed poorly on reading, spelling and mathematics, but only 20% met the older definition of a specific learning disability based on a gap between IQ and achievement. Sixty-three percent had difficulties with sustained attention, and 38% met diagnostic criteria for ADHD.
The low rate of learning disability by the discrepancy definition reflects a measurement quirk. When IQ itself is lowered, a child can struggle at school without showing the large gap between IQ and achievement that the old definition required. The distinction between the two kinds of diagnosis is explained in our article on the difference between intellectual disability and learning disability.
Estimates of intellectual disability in NF1 range from about 4% to 8% depending on the sample. A 2026 meta-analysis by Moreno-Charco and colleagues pooled prevalence figures from 50 studies and estimated intellectual disability in 8% of people with NF1, autism in 11% and ADHD in 33%. The small group of people whose NF1 results from a larger deletion that removes the whole gene and neighboring genes (an "NF1 microdeletion") had much higher estimates: 41% for intellectual disability, based on only two studies.
ADHD appears to account for part of the IQ gap. In a German study of 111 children aged 6 to 12, Heimgärtner and colleagues found a mean full-scale IQ of 89 in children with both NF1 and ADHD, compared with 101 in children with NF1 alone. How attention problems affect test scores more generally is covered in our article on IQ and ADHD.
The visuospatial weakness and the rest of the profile
The most characteristic weakness in NF1 is visuospatial processing, meaning the ability to judge shapes, angles and spatial relationships. A 2025 meta-analysis by Yu and colleagues pooled 70 studies with more than 3,500 people with NF1 and found visuospatial and visuomotor gaps of about −0.90 each. The gap was largest in children (−0.95) and smaller in adolescents and adults. It was also larger on the Judgment of Line Orientation, a test in which people match the angle of two lines to a fan of reference lines (−1.06), than on the visual spatial index of the Wechsler intelligence scales (−0.70). IQ, learning disorder and ADHD did not significantly change the size of the visuospatial gap.
Hyman's study found weaknesses in planning, abstract reasoning, and sustained and switching attention as well. Verbal and visual memory, by contrast, were unaffected and were generally stronger than the children's level of general intellectual ability. Language skills were impaired but appeared better preserved than visuospatial skills once IQ was taken into account.
The same pattern appears in adults. Descheemaeker and colleagues compared 20 adults with NF1 with an IQ-matched control group and concluded that visuospatial problems and weaker auditory long-term memory looked specific to NF1, while attention and executive problems were more closely tied to lower general ability.
Bigger heads, not higher scores
In the general population, people with larger brains tend to have somewhat higher IQs: a meta-analysis by Pietschnig and colleagues of more than 8,000 people found a correlation of about 0.24 between brain volume and IQ, and the authors caution against treating brain size as a stand-in for intelligence. NF1 shows why. Macrocephaly, a head circumference well above the average for age, is common in the condition: Steen and colleagues cite rates of 30% to 50% in children with NF1, and found it in 7 of 18 children (39%) in their own sample, mostly reflecting enlarged white matter.
Moore and colleagues compared 52 children with NF1 with 19 controls on brain imaging and testing. Total brain volume, especially gray matter, was larger in the NF1 group, and gray matter volume in the NF1 group was related to the degree of learning disability. A larger corpus callosum, the band of fibers that connects the two hemispheres, was associated with weaker academic, visuospatial and motor performance. The authors proposed that the macrocephaly reflects a delay in the normal developmental die-off of surplus brain cells, a hypothesis that treats the extra volume as a sign of altered development.
Change with age
Measured intelligence in NF1 is largely stable through childhood. In a 2026 Dutch natural-history study of 397 children assessed at ages 3, 6, 11 and 15, van Abeelen and colleagues found that overall intelligence stayed stable between 3 and 15. Performance IQ dipped at age 11 and appeared to recover by 15, and the gap between verbal and performance IQ narrowed over time. Neither maternal education, inheritance from a parent nor ADHD predicted these changes.
Because the cognitive effects of NF1 vary so much, a full-scale IQ alone gives an incomplete picture. A neuropsychological assessment that includes attention, visuospatial and academic measures, carried out by a neuropsychologist or psychologist working with the person's NF1 clinic, describes the profile far better than a single number.
Frequently asked questions
What is the average IQ of someone with neurofibromatosis type 1?
Reviews describe a downward shift of about 10 points from the general population average of 100, and a meta-analysis found a gap close to one standard deviation against typically developing comparison groups. Most individuals still score in the normal range.
Does neurofibromatosis cause intellectual disability?
Only in a minority. A 2026 meta-analysis estimated intellectual disability in about 8% of people with NF1, with much higher rates in the small group with an NF1 microdeletion.
Is ADHD common in NF1?
Yes. Estimates are about one-third in pooled data and 38% in one detailed cohort, and children with both NF1 and ADHD tend to score lower on IQ tests than children with NF1 alone.
Why do people with NF1 struggle with spatial tasks?
Visuospatial weakness is one of the most consistent findings in NF1 and is not fully explained by IQ, learning disorder or ADHD. The underlying brain mechanism is still being studied.
Does IQ get worse over time in NF1?
Current evidence says no. A large Dutch study found that overall intelligence stayed stable between ages 3 and 15.
The takeaway
Neurofibromatosis IQ scores usually fall in the normal range, but the group average sits close to one standard deviation below that of comparison groups. Intellectual disability affects a minority, while learning difficulties, ADHD and visuospatial weaknesses are common, and memory tends to be a relative strength. The large heads seen in many people with NF1 do not translate into higher scores, and measured intelligence is largely stable through childhood. To see how a full-scale score is put together for adults in the general population, you can take a full-length online IQ test.
References
1. MedlinePlus Genetics. (2020). Neurofibromatosis type 1. National Library of Medicine. [medlineplus.gov](. medlineplus.gov
2. Crow, A. J. D., Janssen, J. M., Marshall, C., Moffit, A., Brennan, L., Kohler, C. G., Roalf, D. R., & Moberg, P. J. (2022). A systematic review and meta-analysis of intellectual, neuropsychological, and psychoeducational functioning in neurofibromatosis type 1. American Journal of Medical Genetics Part A, 188(8), 2277-2292. [doi.org/10.1002/ajmg.a.62773](. doi.org
3. Lehtonen, A., Garg, S., Roberts, S. A., Trump, D., Evans, D. G., Green, J., & Huson, S. M. (2015). Cognition in children with neurofibromatosis type 1: Data from a population-based study. Developmental Medicine & Child Neurology, 57(7), 645-651. [doi.org/10.1111/dmcn.12734](. doi.org
4. Hyman, S. L., Shores, A., & North, K. N. (2005). The nature and frequency of cognitive deficits in children with neurofibromatosis type 1. Neurology, 65(7), 1037-1044. [doi.org/10.1212/01.wnl.0000179303.72345.ce](. doi.org
5. Moreno-Charco, E., Pascual-Morena, C., Álvarez-Bueno, C., Zuheros-Lara, B., Martínez-García, I., Martínez-Sánchez, P., Contreras-Molina, M., & Patiño-Cardona, S. (2026). Prevalence of neuropsychiatric and seizure disorders in neurofibromatosis type 1: A systematic review and meta-analysis. Journal of Neurology, 273(10), 603. [doi.org/10.1007/s00415-026-14143-y](. doi.org
6. Heimgärtner, M., Granström, S., Haas-Lude, K., Leark, R. A., Mautner, V.-F., & Lidzba, K. (2019). Attention deficit predicts intellectual functioning in children with neurofibromatosis type 1. International Journal of Pediatrics, 2019, 9493837. [doi.org/10.1155/2019/9493837](. doi.org
7. Yu, L., Liu, D., Payne, J. M., Zhang, J., Moreira, J., Mukhopadhyay, E. S., Novotney, A., Chown, M. M., Killam, J., & Hou, Y. (2025). Visuospatial and visuomotor abilities of individuals with neurofibromatosis type 1: A systematic review and meta-analysis. Neuropsychology Review. [doi.org/10.1007/s11065-025-09673-7](. doi.org
8. Descheemaeker, M. J., Plasschaert, E., Frijns, J. P., & Legius, E. (2013). Neuropsychological profile in adults with neurofibromatosis type 1 compared to a control group. Journal of Intellectual Disability Research, 57(9), 874-886. [doi.org/10.1111/j.1365-2788.2012.01648.x](. doi.org
9. Steen, R. G., Taylor, J. S., Langston, J. W., Glass, J. O., Brewer, V. R., Reddick, W. E., Mages, R., & Pivnick, E. K. (2001). Prospective evaluation of the brain in asymptomatic children with neurofibromatosis type 1: Relationship of macrocephaly to T1 relaxation changes and structural brain abnormalities. American Journal of Neuroradiology, 22(5), 810-817. [pmc.ncbi.nlm.nih.gov/articles/PMC8174959](. pmc.ncbi.nlm.nih.gov
10. Pietschnig, J., Penke, L., Wicherts, J. M., Zeiler, M., & Voracek, M. (2015). Meta-analysis of associations between human brain volume and intelligence differences: How strong are they and what do they mean? Neuroscience & Biobehavioral Reviews, 57, 411-432. [doi.org/10.1016/j.neubiorev.2015.09.017](. doi.org
11. Moore, B. D., Slopis, J. M., Jackson, E. F., De Winter, A. E., & Leeds, N. E. (2000). Brain volume in children with neurofibromatosis type 1: Relation to neuropsychological status. Neurology, 54(4), 914-920. [doi.org/10.1212/WNL.54.4.914](. doi.org
12. van Abeelen, S., Hendriksen, J. G. M., de Louw, A., de Wit, M. C. Y., de Nijs, P. F. A., Oostenbrink, R., & Rietman, A. B. (2026). Intelligence over time in children with neurofibromatosis type 1 based on a structured natural history-study. Journal of Child Neurology, 41(9), 1311-1324. [doi.org/10.1177/08830738261416621](. doi.org
Hero image: Brass Protractor, by Compo, licensed CC BY-SA 4.0 (creativecommons.org/licenses/by-sa/4.0). Via Wikimedia Commons.
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