Understanding the comorbidity between dyslexia and attention-deficit/ hyperactivity disorder

Topics in Language Disorders

Volumn 32, Issue 3, 2012, Pages 264-284

  Boada, Richard ^a   Willcutt, Erik G ^b   Pennington, Bruce F ^c  

^a University of Colorado Denver and Children s Hospital Colorado   (United States)

^b UNIVERSITY OF COLORADO   (United States)

^c UNIVERSITY OF DENVER   (United States)

Author keywords

ADHD; attention deficit hyperactivity disorder; comorbidity; dyslexia; genetics; reading disability

Indexed keywords

EID: 84865040539     PISSN: 02718294     EISSN: None     Source Type: Journal    
DOI: 10.1097/TLD.0b013e31826203ac     Document Type: Review

References (102)

1. American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author.
2. American Psychiatric Association. (2000). Diagnostic and statistical manual ofmental disorders (4th ed.). Wash-ington, DC: Author.
3. August, G. J., & Garfinkel, B. D. (1990). Comorbidity of ADHD and reading disability among clinic-referred children. Journal of Abnormal Child Psychology, 18(1), 29-45. (Pubitemid 20165212)
4. Bach, S., Brandeis, D., Hofstetter, C., Martin, E., Richardson, U., & Brem, S. (2010). Early emergence of deviant frontal FMRI activity for phonological pro-cesses in poor beginning readers. Neuroimage, 53(2), 682-693.
5. Banich, M. T., Burgess, G. C., Depue, B. E., Ruzic, L., Bidwell, L. C., Hitt-Laustsen, S., etal. (2009). The neu-ral basis of sustained and transient attentional con-trol in young adults with ADHD. Neuropsychologia, 47(14), 3095-3104.
6. Barkley, R. A. (1997). Behavioral inhibition, sustained at-tention, and executive functions: Constructing a uni-fyingtheory of ADHD.Psychological Bulletin, 121(1), 65-94. (Pubitemid 127705285)
7. Been, P. H., van Leeuwen, T. H., van Herten, M., Massen, B., van der Leij, A., & Zwarts, F. (2008). Auditory P2 is reduced in 5-month infants with dyslexic families. In Breznitz, Z. (Ed.), Brain research in language (pp. 93-110). New York: Springer.
8. Boada, R., & Pennington, B.F. (2006). Deficient im-plicit phonological representations in children with dyslexia. Journal of Experimental Child Psychology, 95(3), 153-93. (Pubitemid 44480674)
9. Boetsch, E. A., Green, P. A., & Pennington, B. F. (1996). Psychosocial correlates of dyslexia across the life span. Development and Psychopathology, 8(3), 539-562. (Pubitemid 126450316)
10. Bosse, M. L., Tainturier, M. J., & Valdois, S. (2007). Developmental dyslexia: The visual atten-tionspandeficithypothesis. Cognition, 104(2), 198-230.
11. Brady, S. A. (1991). The role ofworking memory on read-ing disability. In Brady, S. A., & Shankweiler, D. P. (Eds.), Phonologicalprocesses in literacy. A tribute to isabelle Y. Liberman (pp. 129-151). Hillsdale, NJ: Erlbaum.
12. Buchholz, J., & Davies, A. (2007). Attentional blink deficits observed in dyslexia depend on task demands. Vision Research, 47(10), 1292-1302. (Pubitemid 46551241)
13. Bush, G., Spencer, T. J., Holmes,J., Shin, L. M., Valera, E. M., Seidman, L. J., et al. (2008). Functional magnetic resonance imaging of methylphenidate and placebo in attention-deficit/hyperactivity disorder during the multi-source interference task. Archives of General Psychiatry, 65(1), 102-114.
14. Caravolas, M. (2005). The nature and causes of dyslexia in different languages. In M. J., Snowling, &C., Hulme (Eds.), Thescience of reading: A handbook (pp. 336-355) Oxford: Blackwell Publishing.
15. Carter, J. C., Lanham, D. C., Cutting, L. E., Clements-Stephens, A. M., Chen, X., Hadzipasic, M., etal. (2009). A dual DTI approach to analyzing white matter in children with dyslexia. Psychiatry Research in Neu-roimaging, 172, 215-219.
16. Castellanos, F. X., & Tannock, R. (2002). Neuroscience of attention-deficit/hyperactivity disorder: The search for endophenotypes. Nature Reviews Neuroscience, 3, 617-628. (Pubitemid 135706670)
17. Castellanos, F. X., &Proal, E. (2012). Large-scalebrainsys-tems in ADHD: Beyond the prefrontal-striatal model. Trends in Cognitive Science, 16(1), 17-26.
18. Compton, D. L., Davis, C. J., De Fries, J. C., Gayan, J., & Olson, R. K. (2001). Genetic and environmental in-fluences on reading and ran: An overview of results from the colorado twin study. In M., Wolf (Ed.), Con-ferenceproceedings of the dyslexia researchfounda-tion conference in extraordinary brain series: Time, fluency, and developmental dyslexia (pp. 277-303). Baltimore, MD: York Press.
19. Daniel, S. S., Walsh, A. K., Goldston, D. B., Arnold, E. M., Reboussin, B. A., & Wood, F. B. (2006). Suicidality, school dropout, and reading problems among adoles-cents. Journal of Learning Disabilities, 39, 507-514. (Pubitemid 44845807)
20. De Fries, J. C. (1985). Colorado reading project. In Gray, D., & Kavanaugh, J. (Eds.), Biobehavioral measures of dyslexia (pp. 107-122). Parkton, MD: York Press.
21. De Fries, J. C. (1988). Colorado reading project: Longitu-dinal analyses. Annals of Dyslexia, 38, 120-130.
22. Demonet, J. F., Taylor, M. J., & Chaix, Y. (2004). Developmental dyslexia. Lancet, 363(9419), 1451-1460. (Pubitemid 38586723)
23. Dougherty, R. F., Ben-Shachar, M., Deutsch, G. K., Hernandez, A., Fox, G. R., & Wandell, B. A. (2007). Temporal-callosal pathway diffusivity predicts phono-logical skills in children. Proceedings of the National Academy of Sciences USA, 104(20), 8556-8561. (Pubitemid 47175526)
24. Doyle, A. E., Faraone, S. V., Seidman, L. J., Willcutt, E. G., Nigg, J. T., Waldman, I. D., et al. (2005). Are en-dophenotypes based on measures of executive func-tions useful for molecular genetic studies of ADHD? Journal of Child Psychology and Psychiatry, 46(7), 774-803. (Pubitemid 40932960)
25. Ernst, M., Kimes, A. S., &Jazbec, S. (2003). Neuroimaging and mechanisms of drug abuse: Interface ofmolecular imaging and molecular genetics. Neuroimaging Clin-ics of North America, 13(4), 833-849. (Pubitemid 37445059)
26. Faraone, S. V., Biederman, J., Weber, W., & Russell, R. L. (1998). Psychiatric, neuropsychological, and psy-chosocial features of DSM-IV subtypes of attention-deficit/hyperactivity disorder: Results from a clini-cally referred sample. Journal American Academy of Child and Adolescent Psychiatry, 37(2), 185-193. (Pubitemid 28099186)
27. Feinstein, A. (1970). The pre-therapeutic classification of co-morbidity in chronic disease. Journal of Chronic Disease, 23, 57-63.
28. Fisher, S. E., & De Fries, J. C. (2002). Developmen-tal dyslexia: Genetic dissection of a complex cogni-tive trait. Nature Reviews Neuroscience, 3(10), 767-780. (Pubitemid 135706688)
29. Fisher, S. E., Francks, C., Mc Cracken, J. T., Mc Gough, J. J., Marlow, A. J., Mac Phie, I. L., et al. (2002). A genomewide scan for loci involved in attention-deficit/hyperactivity disorder. American Journal of Human Genetics, 70(5), 1183-1196. (Pubitemid 34450569)
30. Germano, E., Gagliano, A., & Curatolo, P. (2010). Comor-bidity of ADHD and dyslexia. Developmental Neu-ropsychology, 35(5), 475-493.
31. Gizer, I. R., Ficks, C., & Waldman, I. D. (2009). Candi-date gene studies of ADHD: A meta-analytic review. Human Genetics, 126(1), 51-90.
32. Goldston, D. B., Walsh, A., Mayfield, A. E., Reboussin, B., Sergent, D. S., Erkanli, A., et al. (2007). Reading problems, psychiatric disorders, and functional im-pairment from mid to late adolescence. Journal of the American Academy of Childand Adolescent Psy-chiatry, 46, 25-32. (Pubitemid 46043278)
33. Goswami, U. (2011). A temporal sampling framework for developmental dyslexia. Trends in Cognitive Science, 15, 3-10.
34. Guttorm,T.K., Leppanen, P. H.,Tolvanen,A., &Lyytinen, H. (2003). Event-related potentials in newborns with and without familial risk for dyslexia: Principal compo-nent analysis reveals differences between the groups. Journal of Neural Transmission, 110(9), 1059-1074. (Pubitemid 37100409)
35. Hadzibeganovic, T., van den Noort, M., Bosch, P., Perc, M., van Kralingen, R., Mondt, K., et al. (2010). Cross-linguistic neuroimaging and dyslexia: A critical view. Cortex, 46(10), 1312-1316.
36. Hartman, C. A., Willcutt, E. G., Rhee, S. H., &Pennington, B. F. (2004). The relation between sluggish cogni-tive tempo and DSM-IV ADHD.Journal of Abnormal Child Psychology, 32(5), 491-503. (Pubitemid 39158508)
37. Hoeft, F., Hernandez, A., Mc Millon, G., Taylor-Hill, H., Martindale, J. L., Meyler, A., et al. (2006). Neural ba-sis of dyslexia: A comparison between dyslexic and nondyslexic children equated for reading ability.Journal of Neuroscience, 26(42), 10700-10708.
38. Hoeft, F., Meyler, A., Hernandez, A., Juel, C., Taylor-Hill, H., Martindale, J. L., et al. (2007). Functional and mor-phometric brain dissociation between dyslexia and reading ability. Proceedings of the National Academy of Science US A, 104(10), 4234-4239. (Pubitemid 47181608)
39. Johnson, E. P., Pennington, B. F., Lowenstein, J. H., & Nittrouer, S. (2011). Sensitivity to structure in the speech signal by children with speech sound disor-der and reading disability. Journal of Communica-tion Disorders, 44, 294-314.
40. Kere,J. (2011). Moleculargenetics and molecularbiology of dyslexia. Wiley Interdisciplinary Review of Cogni-tive Science, 4, 441-448.
41. Krasowicz-Kupis, G., Borkowska, A. R., & Pietras, I. (2009). Rapid automatized naming, phonology and dyslexia in polish children. Medical Science Monitor, 15(9), CR460-469.
42. Ludwig, K. U., Roeske, D., Schumacher,J., Schulte-Korne, G., Konig, I. R., Warnke, A., et al. (2008). Investiga-tion of interaction between DCDC2 and KIAA0319 in a large german dyslexia sample. Journal Neural Transmission, 115(11), 1587-1589.
43. Lyon, G. R., Shaywitz, S. E., & Shaywitz, B. A. (2003). A definition of dyslexia. Annals of Dyslexia, 53, 1-14. (Pubitemid 38148515)
44. Mackie, S., Shaw, P., Lenroot, R., Pierson, R., Greenstein, D. K., Nugent, T. F. III et al. (2007). Cerebellar de-velopment and clinical outcome in attention deficit hyperactivity disorder. American Journal of Psychi-atry, 164(4), 647-655. (Pubitemid 46650197)
45. Mc Grath, L. M., Pennington, B. F., Shanahan, M. A., Santerre-Lemmon, L. E., Barnard, H. D., Willcutt, E. G., et al. (2011). A multiple deficit model of read-ing disability and attention-deficit/hyperactivity dis-order: Searching for shared cognitive deficits. Journal of Child Psychology and Psychiatry, 52(5), 547-557.
46. Mc Grath, L. M., Smith, S. D., & Pennington, B. F. (2006). Breakthroughs in the search for dyslexia candidate genes. Trends in Molecular Medicine, 12(7), 333-341. (Pubitemid 44094293)
47. Meaburn, E. L., Harlaar, N., Craig, I. W., Schalkwyk, L. C., & Plomin, R. (2008). Quantitative trait locus associa-tion scan of early reading disability and ability using pooled DNA and 100k SNP microarrays in a sample of 5760 children.Molecular Psychiatry, 13(7), 729-740. (Pubitemid 351861530)
48. Molfese, D. L. (2000). Predicting dyslexia at 8years of age using neonatal brain responses. Brain and Language, 72(3), 238-245. (Pubitemid 30250069)
49. Mueller, K. L., & Tomblin, J. B. (2012). Examining the comorbidity of language impairment and attention-deficit/hyperactivity disorder. Topics in Language Disorders, 32(3), XXX-XXX.
50. Nagy, Z., Westerberg, H., & Klingberg, T. (2004). Maturation of white matter is associated with the development of cognitive functions during child-hood. Journal of Cognitive Neuroscience, 16(7), 1227-1233. (Pubitemid 39274449)
51. Neale, M. C., Neale, B. M., &Sullivan, P. F. (2002). Nonpa-ternity in linkage studies of extremely discordant sib pairs. American Journal of Human Genetics, 70(2), 526-529. (Pubitemid 34112304)
52. Nicolson, R.I.,& Fawcett, A. J. (2007). Procedural learn-ing difficulties: Re-uniting the developmental disor-ders? Trends in Neurosciences, 30, 135-141.
53. Nigg, J. T. (2001). Is ADHD a disinhibitory disorder? Psy-chological Bulletin, 127(5), 571-598. (Pubitemid 33614928)
54. Nittrouer, S., &Lowenstein,J. H. (inpress). Separating the effects of acoustic and phonetic factors in linguistic processing by adults and children. Applied Psycholin-guistics.
55. Odegard, T. N., Farris, E. A., Ring, J., Mc Coll, R., & Black, J. (2009). Brain connectivity in non-reading impaired children and children diagnosed with developmental dyslexia. Neuropsychologia, 47(8-9), 1972-1977.
56. Papadopoulos, T. C., Georgiou, G. K., & Kendeou, P. (2009). Investigating the double-deficit hypothesis in Greek: Findings from a longitudinal study. Journal Learning Disabilities, 42(6), 528-547.
57. Pennington, B. F. (2006). From single to multiple deficit models of developmental disorders. Cognition, 101(2), 385-413. (Pubitemid 44233557)
58. Pennington, B. F., & Olson, R. K. (2005). Genetics of dyslexia. In Snowling, M., & Hulme, C. (Eds.), The sci-ence of reading: A handbook (pp. 453-472). Oxford: Blackwell Publishing. Pennington
59. Santerre-Lemmon, L., Rosenberg, J., Mac Donald, B., Boada, R., Friend, A., et al. (2011). Individual prediction of dyslexia by single vs. multi-ple deficit models. Journal of Abnormal Psychology, 121(1), 212-224.
60. Pennington, B. F.,Willcutt, E. G., &Rhee, S. H. (2005).An-alyzing comorbidity. In Kail, R. V. (Ed.), Advances in child development and behavior (Vol. 33, pp. 263-304). Oxford: Elsevier.
61. Pennington, B. F., & Lefly, D. L. (2001). Early reading development in children at family risk for dyslexia. Child Development, 72(3), 816-833. (Pubitemid 33597405)
62. Peterson, R. L., Pennington, B. F., Shriberg, L. D., &Boada, R. (2009). What influences literacy outcome in chil-dren with speech sound disorder? Journal of Speech, Languageand Hearing Research, 52(5), 1175-1188.
63. Puolakanaho, A., Ahonen, T., Aro, M., Eklund, K., Leppanen, P. H., Poikkeus, A. M., et al. (2008). De-velopmental links of very early phonological and lan-guage skills to second grade reading outcomes: Strong to accuracy but only minor to fluency. Journal of Learning Disabilities, 41(4), 353-370.
64. Qiu, D., Tan, L. H., Zhou, K., & Khong, P. L. (2008). Diffusion tensor imaging of normal white matter mat-uration from late childhood to young adulthood: Voxel-wise evaluation of mean diffusivity, fractional anisotropy, radial and axial diffusivities, and correla-tion with reading development. Neuroimage, 41(2), 223-232.
65. Ramtekkar, U. P., Reiersen, A. M., Todorov, A. A., & Todd, R. D. (2010). Sex and age differences in attention-deficit/hyperactivity disorder symptoms and diagnoses: Implications for DSM-V and ICD-11. Journal of the American Academy of Child and Adoles-cent Psychiatry, 49(3), 217-228.e211-213.
66. Ramus, F. (2004). Neurobiology of dyslexia: A reinterpre-tation of the data. Trends in Neurosciences, 27(12), 720-726.
67. Raschle, N. M., Chang, M., & Gaab, N. (2011). Struc-tural brain alterations associated with dyslexia predate reading onset. Neuroimage, 57(3), 742-749.
68. Richlan, F., Kronbichler, M., &Wimmer, H. (2009). Func-tional abnormalities in the dyslexic brain: A quanti-tative meta-analysis of neuroimaging studies. Human Brain Mapping, 30(10), 3299-3308.
69. Rimrodt, S. L., Peterson, D. J., Denckla, M. B., Kaufmann, W. E., & Cutting, L. E. (2010). White matter mi-crostructural differences linked to left perisylvian lan-guage network in children with dyslexia. Cortex, 46(6), 739-749.
70. Rubia, K., Overmeyer, S., Taylor, E., Brammer, M., Williams, S. C., Simmons, A., et al. (1999). Hypofrontal-ity in attention deficit hyperactivity disorder dur-ing higher-order motor control: A study with func-tional MRI. American Journal of Psychiatry, 156(6), 891-896. (Pubitemid 29260344)
71. Rubia, K., Smith, A. B., Brammer, M. J., Toone, B., & Taylor, E. (2005). Abnormal brain activation during in-hibition and error detection in medication-naive ado-lescents with ADHD. American Journal of Psychia-try, 162(6), 1067-1075. (Pubitemid 40770688)
72. Rutter, M., Caspi, A., Fergusson, D. M., Horwood, L. J., & Goodman, R. (2004). Gender differences in reading difficulties: Findings from four epidemiological stud-ies. Journal of the American Medical Association, 291, 2007-2012. (Pubitemid 38544283)
73. Scarborough, H. S. (1990). Very early language deficits in dyslexic children. Child Development, 61(6), 1728-1743.
74. Schnoes, C., Reid, R., Wagner, M., &Marder, C. (2006). ADHD among students receiving special education services: A national survey. Exceptional Children, 72, 483-496. (Pubitemid 44126407)
75. Semrud-Clikeman, M., Biederman,J., Sprich-Buckminster, S., Lehman, B. K., Faraone, S. V., &Norman, D. (1992). Comorbidity between attention deficit hyperactivity disorder and learning disability: A review and report in a clinically referred sample. Journal of the American Academy of Child and Adolescent Psychiatry, 31(3), 439-448.
76. Shanahan, M. A., Pennington, B. F., Yerys, B. E., Scott, A., Boada, R., Willcutt, E. G., et al. (2006). Processing speed deficits in attention deficit/hyperactivity disor-der and reading disability. Journal of Abnormal Child Psychology, 34(5), 585-602.
77. Shaywitz, S. E., & Shaywitz, B. A. (2005). Dyslexia (spe-cific reading disability). Biological Psychiatry, 57, 1301-1319.
78. Silani, G., Frith, U., Demonet, J. F., Fazio, F., Perani, D., Price, C., et al. (2005). Brain abnormalities underlying altered activation in dyslexia: A voxel based morphom-etry study. Brain, 128(Pt 10), 2453-2461. (Pubitemid 41407983)
79. Smith, S. D., Kelley, P. M., Askew, J. W., Hoover, D. M., Deffenbacher, K. E., Gayan, J., et al. (2001). Read-ing disability and chromosome 6p21.3: Evaluation of MOG as a candidate gene. Genetics, Neuropsychol-ogy, and Learning Disorders: Special Issue, 34(6), 512-519.
80. Snowling, M. J., Gallagher, A., & Frith, U. (2003). Family risk of dyslexia is continuous: Individual differences in the precursors of reading skill. Child Development, 74(2), 358-373. (Pubitemid 37244654)
81. Sonuga-Barke, E. J. S., &Castellanos, F. X. (2007). Sponta- neous attentional fluctuations in impaired states and pathological conditions: A neurobiological hypothe-sis. Neuroscience & biobehavioral Reviews, 31(7), 977-986. (Pubitemid 47332617)
82. Specht, K., Hugdahl, K., Ofte, S., Nygard, M., Bjornerud, A., Plante, E., et al. (2009). Brain activation on pre-reading tasks reveals at-risk status for dyslexia in 6-year-old children. Scandinavian Journal of Psychol-ogy, 50(1), 79-91.
83. Steinbrink, C., Vogt, K., Kastrup, A., Muller, H. P., Juengling, F. D., Kassubek, J., et al. (2008). The con-tribution of white and gray matter differences to de-velopmental dyslexia: Insights from DTI and VBM at 3.0 t. Neuropsychologia, 46(13), 3170-3178.
84. Swanson, J., Oosterlaan, J., Murias, M., Schuck, S., Flodman, P., Spence, M. A., et al. (2000). Attention deficit/hyperactivity disorder children with a 7-repeat allele of the dopamine receptor d4 gene have ex-treme behavior but normal performance on critical neuropsychological tests of attention. Proceedings of the National Academy of Sciences USA,97(9), 4754-4759. (Pubitemid 30238630)
85. Tamm, L., Menon, V., Ringel, J., & Reiss, A. L. (2004). Event-related FMRI evidence of frontotemporal in-volvement in aberrant response inhibition and task switching in attention-deficit/hyperactivity disorder. Journal of the American Academy of Child and Ado-lescent Psychiatry, 43(11), 1430-1440. (Pubitemid 39411044)
86. Torppa, M., Lyytinen, P., Erskine, J., Eklund, K., & Lyytinen, H. (2010). Language development, literacy skills, and predictive connections to reading in Finnish children with and without familial risk for dyslexia. Journal of Learning Disabilities, 43(4), 308-321.
87. Ullebo, A. K., Posserud, M. B., Heiervang, E., Obel, C., & Gillberg, C. (2011). Prevalence of the ADHD pheno-type in 7- to 9-year-old children: Effects of informant, gender and non-participation. Society of Psychiatry and Psychiatric Epidemiology, 47(5), 763-769.
88. Vaessen, A., Gerretsen, P., & Blomert, L. (2009). Naming problems do not reflect a second independent core deficit in dyslexia: Double deficits explored. Journal of Experimental Child Psychology, 103(2), 202-221.
89. Valera, E. M., Faraone, S. V., Murray, K. E., & Seidman, L. J. (2007). Meta-analysis of structural imaging findings in attention-deficit/ hyperactivity disorder. Biological Psychiatry, 61(12), 1361-1369. (Pubitemid 46855763)
90. van der Mark, S., Bucher, K., Mauer, U., Schulz, E., Brem, S., Buckelmüller,J., etal. (2009). Childrenwith dyslexia lack multiple specializations along the visual word form (VWF) system. Neuroimage, 47, 1940-1949.
91. Willcutt, E. G. (2009). ADHD. In Yeats, K. O., Ris, G., Taylor, B., & Pennington, B. F. (Eds.) Pediatric neu-ropsychology: Research, theory, and practice (pp. 393-417). New York: Guilford Press.
92. Willcutt, E. G., Betjemann, R. S., Mc Grath, L. M., Chhabildas, N. A., Olson, R. K., De Fries, J. C., et al. (2010). Etiology and neuropsychology of comorbidity between RD and ADHD: The case for multiple-deficit models. Cortex, 46(10), 1345-1361.
93. Willcutt, E. G., Betjemann, R. S., Wadsworth, S. J., Samuelsson, S., Corley, R., De Fries, J., et al. (2007a). Preschool twin study of the relation between attention deficit/hyperactivity disorder and prereading skills. Reading and Writing: An Interdisciplinary Journal, 20, 103-125.
94. Willcutt, E. G., De Fries, J. C., Pennington, B. F., Smith, S. D., Cardon, L. R., & Olson, R. K. (2003). Genetic eti-ology of comorbid reading difficulties and attention deficit hyperactivity disorder. In Plomin, R., De Fries, J. C., Craig, I. W., & Mc Guffin, P. (Eds.), Behavioral genetics in thepostgenomic era (pp. 227-246). Wash-ington, DC: American Psychological Association.
95. Willcutt, E. G., & Pennington, B. F. (2000a). Co-morbidity of reading disability and attention-deficit/hyperactivity disorder: Differences by gender and subtype. Journal of Learning Disabilities, 33(2), 179-191.
96. Willcutt, E. G., & Pennington, B. F. (2000b). Psychiatric comorbidity in children and adolescents with reading disability. Journal of Child Psychology and Psychia-try, 41(8), 1039-1048.
97. Willcutt, E. G., Pennington, B. F., Chhabildas, N. A., Friedman, M. C., & Alexander, J. (1999). Psychi-atric comorbidity associated with DSM-IV ADHD in nonreferred sample of twins. Journal of American Academy of Child and Adolescent Psychiatry, 38, 1355-1362. (Pubitemid 29513392)
98. Willcutt, E. G., Pennington, B. F., &De Fries,J. C. (2000b). Twin study of the etiology of comorbidity between reading disability and attention-deficit/hyperactivity disorder. American Journal of Medical Genetics, 96(3), 293-301.
99. Willcutt, E. G., Pennington, B. F., Olson, R. K., & De Fries, J. C. (2007b). Understanding comorbid-ity: A twin study of reading disability and atten-tion deficit/hyperactivity disorder. American Journal of Medical Genetics (Neuropsychiatric Genetics), 144B(6), 709-714. (Pubitemid 47417197)
100. Willcutt, E. G., Sonuga-Barke, E. J. S., Nigg, J. T., & Sergeant, J. A. (2008). Developments in neuropsycho-logical models of childhood psychiatric disorders. In Banaschewski, T., & Rohde, L. A. (Eds.), Advances in biological psychiatry (Vol. 24, pp. 195-226). Basel, Switzerland: Karger.
101. Wolf, M., & Bowers, P. G. (1999). The double-deficit hy-pothesis for the developmental dyslexias. Journal of Educational Psychology, 91(3), 415-438.
102. Zang, Y. F., Jin, Z., Weng, X. C., Zhang, L., Zeng, Y. W., Yang, L., et al. (2005). Functional MRI in attention-deficit hyperactivity disorder: Evi-dence for hypofrontality. Brain Development, 27(8), 544-550. (Pubitemid 41681750)