Oct 6, 2026·Special Population & Related Conditions
Duchenne Muscular Dystrophy and IQ: Average Scores, Verbal Memory, and Stability
Duchenne muscular dystrophy IQ averages about 80 to 85, near one standard deviation below the mean, and unlike the muscle weakness it does not decline.
Dr. Russell T. WarneChief Scientist
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Boys with Duchenne muscular dystrophy (DMD) score lower on IQ tests than the general population, with meta-analyses placing the average full-scale IQ between about 80 and 85, close to one standard deviation below the mean of 100. The range is wide and many boys score in the average range, but intellectual disability is several times more common than in the general population.
Unlike the muscle disease, the cognitive difference is present from early childhood and does not get worse with age. This page covers the typical Duchenne muscular dystrophy IQ range, the verbal working memory weakness at the center of the profile, why the location of the genetic change matters, how scores behave over time, and why motor-free testing matters as weakness progresses.
The typical IQ range in Duchenne
Duchenne and the milder Becker muscular dystrophy together affect 1 in 3,500 to 5,000 newborn boys worldwide, according to MedlinePlus Genetics. Both are caused by variants in the DMD gene, which carries the instructions for dystrophin, a protein that protects muscle fibers. In Duchenne, little or no working dystrophin is made, weakness appears in early childhood, and most boys use a wheelchair by adolescence.
The first meta-analysis of intelligence in DMD, by Cotton, Voudouris and Greenwood, pooled 32 studies published between 1960 and 1999 and reported a mean full-scale IQ of 80.2, with a verbal IQ of 80.4 and a performance IQ of 85.4. Two newer meta-analyses put the average somewhat higher. Weerkamp and colleagues pooled Wechsler scores for 1,234 males with DMD from 32 studies and found a mean full-scale IQ of 84.8, about 4.5 points above Cotton's estimate. Pascual-Morena and colleagues, pooling 51 studies, estimated 84.6. Weerkamp's group also found that males with Becker muscular dystrophy averaged 92.1.
Averages hide a wide spread. Earlier studies estimated that between about 19% and 35% of boys with DMD have a full-scale IQ below 70, as summarized by Taylor and colleagues, whose own 2010 study of 62 boys found 24%. In a European study of 130 boys, Ricotti and colleagues identified intellectual disability in 26%. Many other boys score in the average range or above. The diagnostic criteria for intellectual disability, which require deficits in adaptive functioning as well as a low score, are explained in our article on low IQ and intellectual disability.
Verbal working memory at the center of the profile
The most consistent finding in DMD is a weakness in holding and working with spoken information. Hinton and colleagues compared 41 boys with DMD with an unaffected brother of similar age. The two groups performed similarly on most measures, including general verbal ability, visuospatial skills, long-term memory and abstract reasoning. The boys with DMD scored significantly lower on digit span, story recall and auditory comprehension, and on every area of academic achievement.
A companion study of 80 boys with estimated IQs from 70 to 160 found that the same three tests were usually each boy's weakest, regardless of whether his overall ability was high or low. The profile, in other words, is not just a consequence of lower IQ. A 2024 meta-analysis by Gregg and colleagues found that children with DMD score about one standard deviation below norms on the Wechsler working memory index, as they do on full-scale, verbal and performance IQ, while receptive vocabulary scores on the Peabody Picture Vocabulary Test fell within the normal range. What working memory is and how IQ tests measure it is covered in our article on what working memory is.
Neurodevelopmental conditions are also more frequent. In Ricotti's European sample, 21% of boys assessed in depth met criteria for autism spectrum disorder, 24% showed hyperactivity and 44% showed inattention. A Toronto study of 59 boys by Banihani and colleagues found learning disability in 44%, ADHD in 32% and autism spectrum disorder in 15%. Attention problems can lower scores on working memory tasks in their own right, which is one reason a full assessment looks beyond the full-scale IQ.
Why the location of the genetic change matters
The DMD gene produces several forms of dystrophin. The full-length form is found in muscle and brain, while shorter forms, named for their size, are made from start points further along the gene. Two of them, Dp140 and Dp71, are abundant in the developing brain. Variants toward the far (3′) end of the gene knock out more of these brain forms, and IQ falls as more forms are lost:
• Taylor and colleagues (2010): Boys whose variants were located between exons 46 and 79 had a mean full-scale IQ of 74, compared with 93 for boys whose variants were located before exon 30. Unrelated boys who shared the same variant had highly correlated IQs (r = 0.83).
• Pascual-Morena and colleagues (2023): Pooled means in DMD were about 93 when Dp140 and Dp71 were spared, 82 when Dp140 was lost, and 49 when both Dp140 and Dp71 were lost.
Ricotti's European study found the same pattern for diagnoses: boys with variants at the 3′ end of the gene, affecting all dystrophin forms, had higher rates of intellectual disability. This genetic gradient helps explain why intellectual disability in DMD is concentrated in a subgroup instead of spread evenly, and why a boy's genetic report can offer clinicians an early hint about cognitive risk.
Stable scores, and why motor-free testing matters
Because the muscle disease is progressive, families often worry that thinking will decline too. The evidence says it does not. In a second meta-analysis covering 1,224 children and young adults aged 2 to 27, Cotton and colleagues found no age-related difference in full-scale or performance IQ. Verbal IQ actually increased with age, and boys aged 14 and older were less likely to show the verbal weaknesses seen in younger boys. A 2025 longitudinal study by Kenepp and colleagues followed 26 boys with DMD and 27 unaffected siblings over four years: the boys with DMD read slightly less well, but their reading progressed at the same rate as their siblings', in line with earlier work showing a stable cognitive profile.
Progressive weakness does create a measurement problem. Several Wechsler subtests require arranging blocks or marking symbols quickly, and weak hands and arms can lower these scores for reasons that have nothing to do with reasoning. Weerkamp and colleagues note that motor impairment was not accounted for in either meta-analysis, and they recommend exploring a motor-free short form of the WISC-V that estimates full-scale IQ from subtests such as Vocabulary, Similarities, Visual Puzzles, Figure Weights and Digit Span. For older boys and adults, examiners can choose tests that allow pointing or spoken answers.
Banihani's team recommended psychological testing covering both cognitive and neurobehavioral conditions for every boy with DMD. A psychologist or neuropsychologist who works with a neuromuscular clinic is best placed to pick tests that separate motor limits from cognitive ones.
Frequently asked questions
What is the average IQ of a boy with Duchenne muscular dystrophy?
Meta-analyses estimate an average full-scale IQ of about 80 to 85, close to one standard deviation below the population mean. Many boys score in the average range.
Does IQ decline as Duchenne muscular dystrophy progresses?
No. A meta-analysis of more than 1,200 children and young adults found no age-related drop in full-scale IQ, and verbal IQ tended to rise with age.
Why do some boys with Duchenne have intellectual disability and others do not?
Much of the difference depends on where the genetic change sits. Variants that also knock out the brain forms of dystrophin, Dp140 and Dp71, are linked to much lower scores.
What is the main cognitive weakness in Duchenne?
Verbal working memory: holding and using spoken information, measured by tasks such as digit span and story recall. In one sibling study, general verbal and visuospatial skills were similar to those of unaffected brothers.
Do boys with Becker muscular dystrophy have lower IQs too?
On average, slightly. One meta-analysis found a mean of about 92 in Becker muscular dystrophy, higher than the Duchenne average.
The takeaway
Duchenne muscular dystrophy IQ scores average about 80 to 85, and roughly a fifth to a third of boys score below 70, with the risk rising when the genetic change also removes the brain forms of dystrophin. The core weakness is verbal working memory, and the cognitive profile stays stable while muscle strength declines, which makes motor-free testing important as boys get older. To see how working memory and reasoning combine into a full-scale score for adults, you can try an online IQ test built by psychometricians.
References
1. MedlinePlus Genetics. (2016). Duchenne and Becker muscular dystrophy. National Library of Medicine. [medlineplus.gov](. medlineplus.gov
2. Cotton, S., Voudouris, N. J., & Greenwood, K. M. (2001). Intelligence and Duchenne muscular dystrophy: Full-scale, verbal, and performance intelligence quotients. Developmental Medicine & Child Neurology, 43(7), 497-501. [doi.org/10.1017/S0012162201000913](. doi.org
3. Weerkamp, P. M. M., Mol, E. M., Sweere, D. J. J., Schrans, D. G. M., Vermeulen, R. J., Klinkenberg, S., Hurks, P. P. M., & Hendriksen, J. G. M. (2022). Wechsler scale intelligence testing in males with dystrophinopathies: A review and meta-analysis. Brain Sciences, 12(11), 1544. [doi.org/10.3390/brainsci12111544](. doi.org
4. Pascual-Morena, C., Cavero-Redondo, I., Sequí-Domínguez, I., Rodríguez-Gutiérrez, E., Visier-Alfonso, M. E., & Martínez-Vizcaíno, V. (2023). Intelligence quotient-genotype association in dystrophinopathies: A systematic review and meta-analysis. Neuropathology and Applied Neurobiology, 49(3), e12914. [doi.org/10.1111/nan.12914](. doi.org
5. Taylor, P. J., Betts, G. A., Maroulis, S., Gilissen, C., Pedersen, R. L., Mowat, D. R., Johnston, H. M., & Buckley, M. F. (2010). Dystrophin gene mutation location and the risk of cognitive impairment in Duchenne muscular dystrophy. PLoS ONE, 5(1), e8803. [doi.org/10.1371/journal.pone.0008803](. doi.org
6. Ricotti, V., Mandy, W. P. L., Scoto, M., Pane, M., Deconinck, N., Messina, S., Mercuri, E., Skuse, D. H., & Muntoni, F. (2016). Neurodevelopmental, emotional, and behavioural problems in Duchenne muscular dystrophy in relation to underlying dystrophin gene mutations. Developmental Medicine & Child Neurology, 58(1), 77-84. [doi.org/10.1111/dmcn.12922](. doi.org
7. Hinton, V. J., De Vivo, D. C., Nereo, N. E., Goldstein, E., & Stern, Y. (2001). Selective deficits in verbal working memory associated with a known genetic etiology: The neuropsychological profile of Duchenne muscular dystrophy. Journal of the International Neuropsychological Society, 7(1), 45-54. [doi.org/10.1017/S1355617701711058](. doi.org
8. Hinton, V. J., De Vivo, D. C., Nereo, N. E., Goldstein, E., & Stern, Y. (2000). Poor verbal working memory across intellectual level in boys with Duchenne dystrophy. Neurology, 54(11), 2127-2132. [doi.org/10.1212/WNL.54.11.2127](. doi.org
9. Gregg, J., Wilson, C., Curran, D., & Hanna, D. (2024). Neurocognitive functioning among children and young people with Duchenne muscular dystrophy: A systematic review and meta-analysis. The Clinical Neuropsychologist, 38(8), 1806-1833. [doi.org/10.1080/13854046.2024.2324500](. doi.org
10. Banihani, R., Smile, S., Yoon, G., Dupuis, A., Mosleh, M., Snider, A., & McAdam, L. (2015). Cognitive and neurobehavioral profile in boys with Duchenne muscular dystrophy. Journal of Child Neurology, 30(11), 1472-1482. [doi.org/10.1177/0883073815570154](. doi.org
11. Cotton, S. M., Voudouris, N. J., & Greenwood, K. M. (2005). Association between intellectual functioning and age in children and young adults with Duchenne muscular dystrophy: Further results from a meta-analysis. Developmental Medicine & Child Neurology, 47(4), 257-265. [doi.org/10.1017/S0012162205000496](. doi.org
12. Kenepp, A., Russell-Giller, S., Seehra, S., Fee, R., & Hinton, V. J. (2025). Reading skills over time among children with Duchenne muscular dystrophy. Child Neuropsychology, 31(3), 467-486. [doi.org/10.1080/09297049.2024.2386078](. doi.org
Hero image: G. Duchenne-2, portrait of Guillaume-Benjamin Duchenne de Boulogne by Nadar, public domain. Via Wikimedia Commons.
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