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Intellectual Development in 12-Year-Old Children Treated for Phenylketonuria

Intellectual Development in 12-Year-Old Children Treated for Phenylketonuria Abstract • Intelligence and achievement test scores were evaluated for 95 12-year-old children with phenylketonuria who had begun dietary therapy during the neonatal period. Dietary control of blood phenylalanine below 900 μmol/L was maintained beyond age 10 years in 23 children; 72 others had blood phenylalanine persistently above that level at ages ranging from 18 months to 10 years. Test scores at age 12 years were negatively correlated with the age at initiation of diet and with blood phenylalanine levels from ages 4 to 10 years, and positively correlated with parent IQ scores and the age at loss of dietary control. Children who maintained phenylalanine levels below 900 μmol/L beyond age 10 years showed no deficits in test scores, except for arithmetic, the scores of which declined between ages 6 and 12 years in 90% of the children in this study. These data strongly support a recommendation that dietary restriction of phenylalanine should be maintained through adolescence. (AJDC. 1991;145:35-39) References 1. Cabalska B, Duczynska N, Borzymowska J, Zorska, K, Koslacz-Folga A, Bozkowa K. Termination of dietary treatment in phenylketonuria . Eur J Pediatr . 1977;126:253-262.Crossref 2. Smith I, Lobascher ME, Stevenson JE, et al. Effect of stopping low-phenylalanine diet on intellectual progress of children with phenylketonuria . BMJ . 1978;2:723-726.Crossref 3. Waisbren SE, Schnell RR, Levy HL. Diet termination in children with phenylketonuria: a review of psychological assessments used to determine outcome . J Inherited Metab Dis . 1980;3:149-153.Crossref 4. Holtzman NA, Kronmal RA, van Doorninck W, Azen C, Koch R. Effect of age at loss of dietary control on intellectual performance and behavior of children with phenylketonuria . N Engl J Med . 1986;314:593-598.Crossref 5. Fishler K, Azen C, Henderson R, Friedman EG, Koch R. Psychoeducational findings among children treated for phenylketonuria . Am J Ment Defic . 1987;92:65-73. 6. Schmidt H, Mahle M, Michel U, et al. Continuation vs discontinuation of low-phenylalanine diet in PKU adolescents . Eur J Pediatr . 1987;146 ( (suppl) ):17-19.Crossref 7. Naughten ER, Kiely B, Saul I, Murphy D. Phenylketonuria: outcome and problems in a "diet-for-life" clinic . Eur J Pediatr . 1987;146( (suppl) ):23-24.Crossref 8. Waisbren SE, Mahon BE, Schnell RR, Levy HL. Predictors of intelligence quotient and intelligence quotient change in persons treated for phenylketonuria early in life . Pediatrics . 1987;79:351-355. 9. Saudubray JM, Rey F, Ogier H, et al. Intellectual and school performance in early-treated classical PKU patients: the French collaborative study . Eur J Pediatr . 1987;146( (suppl) ):20-22.Crossref 10. Koch R, Azen C, Hurst N, Friedman EG, Fishler K. The effects of diet discontinuation in children with phenylketonuria . Eur J Pediatr . 1987;146( (suppl) ):12-16.Crossref 11. Williamson ML, Dobson JC, Koch R. Collaborative study of children treated for phenylketonuria: study design . Pediatrics . 1977;60:815-821. 12. Williamson ML, Koch R, Azen C, Chang C. Correlates of intelligence test results in treated phenylketonuric children . Pediatrics . 1981;68:161-167. 13. Koch R, Azen CG, Friedman EG, Williamson ML. Preliminary report on the effects of diet discontinuation in PKU . J Pediatr . 1982;100:870-875.Crossref 14. Koch R, Azen C, Friedman EG, Williamson ML. Paired comparisons between early treated PKU children and their matched sibling controls on intelligence and school achievement test results at eight years of age . J Inherited Metab Dis . 1984;7:86-90.Crossref 15. Wechsler D. Wechsler Intelligence Scale for Children-Revised . New York, NY: Psychological Corp; 1974. 16. Jastak J. Wide Range Achievement Test . Wilmington, Del: Story Press; 1946. 17. Thorndike RL. Stanford-Binet Intelligence Scale 1972 Norms, Tables, Form LM . Boston, Mass: Houghton Mifflin Co; 1972. 18. Wechsler D. Wechsler Adult Intelligence Scale . New York, NY: Psychological Corp; 1955. 19. SAS Institute Inc. SAS User's Guide: Statistics . Version 5 ed. Cary, NC: SAS Institute Inc; 1985. 20. Dixon WJ, Brown MB, Engelman L, Jennrich RI, eds. BMDP Statistical Software 1985 Printing . Berkeley, Calif: University of California Press; 1985. 21. Flynn JR. Wechsler intelligence tests: do we really have a criterion for mental retardation? Am J Ment Defic . 1985;90:236-244. 22. Pennington BF, van Doorninck WJ, McCabe LL, McCabe ERB. Neuropsychologic deficits in early treated phenylketonuric children . Am J Ment Defic . 1985;89:467-474. 23. Krause W, Halminski M, McDonald L, et al. Biochemical and neuropsychological effects of elevated plasma phenylalanine in patients with treated phenylketonuria . J Clin Invest . 1985;75:40-48.Crossref 24. Lou HC, Güttler F, Lykkelund C, Bruhn P, Niederwieser A. Decreased vigilance and neurotransmitter synthesis after discontinuation of dietary treatment for phenylketonuria in adolescents . Eur J Pediatr . 1985; 144:17-20.Crossref 25. Lenke RR, Levy HL. Maternal phenylketonuria and hyperphenylalaninemia: an international survey of the outcome of untreated and treated pregnancies . N Engl J Med . 1980;303:1202-1208.Crossref 26. Kirkman NH. Projections of a rebound in frequency of mental retardation from phenylketonuria . Appl Res Ment Retard . 1982;3:319-328.Crossref 27. Koch R, Friedman EG, Wenz E, Jew K, Crowley C, Donnell GN. Maternal phenylketonuria . J Inherited Metab Dis . 1986;9( (suppl) ):159-168.Crossref 28. Michals K, Dominik M, Schuett V, Brown E, Matalon R. Return to diet therapy in patients with phenylketonuria . J Pediatr . 1985;106:933-936.Crossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png American Journal of Diseases of Children American Medical Association

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References (30)

Publisher
American Medical Association
Copyright
Copyright © 1991 American Medical Association. All Rights Reserved.
ISSN
0002-922X
DOI
10.1001/archpedi.1991.02160010037012
Publisher site
See Article on Publisher Site

Abstract

Abstract • Intelligence and achievement test scores were evaluated for 95 12-year-old children with phenylketonuria who had begun dietary therapy during the neonatal period. Dietary control of blood phenylalanine below 900 μmol/L was maintained beyond age 10 years in 23 children; 72 others had blood phenylalanine persistently above that level at ages ranging from 18 months to 10 years. Test scores at age 12 years were negatively correlated with the age at initiation of diet and with blood phenylalanine levels from ages 4 to 10 years, and positively correlated with parent IQ scores and the age at loss of dietary control. Children who maintained phenylalanine levels below 900 μmol/L beyond age 10 years showed no deficits in test scores, except for arithmetic, the scores of which declined between ages 6 and 12 years in 90% of the children in this study. These data strongly support a recommendation that dietary restriction of phenylalanine should be maintained through adolescence. (AJDC. 1991;145:35-39) References 1. Cabalska B, Duczynska N, Borzymowska J, Zorska, K, Koslacz-Folga A, Bozkowa K. Termination of dietary treatment in phenylketonuria . Eur J Pediatr . 1977;126:253-262.Crossref 2. Smith I, Lobascher ME, Stevenson JE, et al. Effect of stopping low-phenylalanine diet on intellectual progress of children with phenylketonuria . BMJ . 1978;2:723-726.Crossref 3. Waisbren SE, Schnell RR, Levy HL. Diet termination in children with phenylketonuria: a review of psychological assessments used to determine outcome . J Inherited Metab Dis . 1980;3:149-153.Crossref 4. Holtzman NA, Kronmal RA, van Doorninck W, Azen C, Koch R. Effect of age at loss of dietary control on intellectual performance and behavior of children with phenylketonuria . N Engl J Med . 1986;314:593-598.Crossref 5. Fishler K, Azen C, Henderson R, Friedman EG, Koch R. Psychoeducational findings among children treated for phenylketonuria . Am J Ment Defic . 1987;92:65-73. 6. Schmidt H, Mahle M, Michel U, et al. Continuation vs discontinuation of low-phenylalanine diet in PKU adolescents . Eur J Pediatr . 1987;146 ( (suppl) ):17-19.Crossref 7. Naughten ER, Kiely B, Saul I, Murphy D. Phenylketonuria: outcome and problems in a "diet-for-life" clinic . Eur J Pediatr . 1987;146( (suppl) ):23-24.Crossref 8. Waisbren SE, Mahon BE, Schnell RR, Levy HL. Predictors of intelligence quotient and intelligence quotient change in persons treated for phenylketonuria early in life . Pediatrics . 1987;79:351-355. 9. Saudubray JM, Rey F, Ogier H, et al. Intellectual and school performance in early-treated classical PKU patients: the French collaborative study . Eur J Pediatr . 1987;146( (suppl) ):20-22.Crossref 10. Koch R, Azen C, Hurst N, Friedman EG, Fishler K. The effects of diet discontinuation in children with phenylketonuria . Eur J Pediatr . 1987;146( (suppl) ):12-16.Crossref 11. Williamson ML, Dobson JC, Koch R. Collaborative study of children treated for phenylketonuria: study design . Pediatrics . 1977;60:815-821. 12. Williamson ML, Koch R, Azen C, Chang C. Correlates of intelligence test results in treated phenylketonuric children . Pediatrics . 1981;68:161-167. 13. Koch R, Azen CG, Friedman EG, Williamson ML. Preliminary report on the effects of diet discontinuation in PKU . J Pediatr . 1982;100:870-875.Crossref 14. Koch R, Azen C, Friedman EG, Williamson ML. Paired comparisons between early treated PKU children and their matched sibling controls on intelligence and school achievement test results at eight years of age . J Inherited Metab Dis . 1984;7:86-90.Crossref 15. Wechsler D. Wechsler Intelligence Scale for Children-Revised . New York, NY: Psychological Corp; 1974. 16. Jastak J. Wide Range Achievement Test . Wilmington, Del: Story Press; 1946. 17. Thorndike RL. Stanford-Binet Intelligence Scale 1972 Norms, Tables, Form LM . Boston, Mass: Houghton Mifflin Co; 1972. 18. Wechsler D. Wechsler Adult Intelligence Scale . New York, NY: Psychological Corp; 1955. 19. SAS Institute Inc. SAS User's Guide: Statistics . Version 5 ed. Cary, NC: SAS Institute Inc; 1985. 20. Dixon WJ, Brown MB, Engelman L, Jennrich RI, eds. BMDP Statistical Software 1985 Printing . Berkeley, Calif: University of California Press; 1985. 21. Flynn JR. Wechsler intelligence tests: do we really have a criterion for mental retardation? Am J Ment Defic . 1985;90:236-244. 22. Pennington BF, van Doorninck WJ, McCabe LL, McCabe ERB. Neuropsychologic deficits in early treated phenylketonuric children . Am J Ment Defic . 1985;89:467-474. 23. Krause W, Halminski M, McDonald L, et al. Biochemical and neuropsychological effects of elevated plasma phenylalanine in patients with treated phenylketonuria . J Clin Invest . 1985;75:40-48.Crossref 24. Lou HC, Güttler F, Lykkelund C, Bruhn P, Niederwieser A. Decreased vigilance and neurotransmitter synthesis after discontinuation of dietary treatment for phenylketonuria in adolescents . Eur J Pediatr . 1985; 144:17-20.Crossref 25. Lenke RR, Levy HL. Maternal phenylketonuria and hyperphenylalaninemia: an international survey of the outcome of untreated and treated pregnancies . N Engl J Med . 1980;303:1202-1208.Crossref 26. Kirkman NH. Projections of a rebound in frequency of mental retardation from phenylketonuria . Appl Res Ment Retard . 1982;3:319-328.Crossref 27. Koch R, Friedman EG, Wenz E, Jew K, Crowley C, Donnell GN. Maternal phenylketonuria . J Inherited Metab Dis . 1986;9( (suppl) ):159-168.Crossref 28. Michals K, Dominik M, Schuett V, Brown E, Matalon R. Return to diet therapy in patients with phenylketonuria . J Pediatr . 1985;106:933-936.Crossref

Journal

American Journal of Diseases of ChildrenAmerican Medical Association

Published: Jan 1, 1991

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