Stimulated by Dave Kerby's great post on the topic, I did a PubMed search. The bottom line seems to be that "diet for life" is the current recommendation. As the diet is severe and hard on those who have to live with it, relaxation at some point would be welcome. But although the data in support of life-long continuation are meagre, it looks as though no one wants to take a chance on the potential harm that would result from recommending otherwise. Early dietary treatment only started in 1957, so the very oldest of those receiving intervention would now only be 42 years old. So there has hardly been enough time to answer questions about the effects of discontinuing diet in early adulthood. In the meantime, progress is being made in developing gene therapy for PKU. If successful, this would treat the root cause of PKU, allow them to metabolize phenylalanine, and eliminate the need for a special diet entirely. Simonoff (1996) discusses this, and gives references. I've appended the results of my Medline search after the reference for Simonoff, which is an excellent review paper, and one that I've found very useful. -Stephen Simonoff, E., et al (1996). Mental retardation: genetic findings, clinical implications and research agenda. Journal of child psychology and psychiatry, 37, 259-280. PubMed (Medline) recent abstracts: Eur J Pediatr 1999 Jan;158(1):46-54 Rationale for the German recommendations for phenylalanine level control in phenylketonuria 1997. Burgard P, Bremer HJ, Buhrdel P, Clemens PC, Monch E, Przyrembel H, Trefz FK, Ullrich K Fachrichtung Psychologie, Universitat des Saarlandes, Im Stadtwald, Saarbrucken, Germany. [EMAIL PROTECTED] Treatment of hyperphenylalaninaemias due to phenylalanine hydroxylase deficiency with a low phenylalanine (Phe) diet is highly successful in preventing neurological impairment and mental retardation. There is consensus that, for an optimal outcome, treatment should start as early as possible, and that strict blood Phe level control is of primary importance during the first years of life, but for adolescent and adult patients international treatment recommendations show a great variability. A working party of the German Working Group for Metabolic Diseases has evaluated research results on IQ data, speech development, behavioural problems, educational progress, neuropsychological results, electroencephalography, magnetic resonance imaging, and clinical neurology. Based on the actual knowledge, recommendations were formulated with regard to indication of treatment, differential diagnosis, and Phe level control during different age periods. The development of the early-and-strictly-treated patient in middle and late adulthood still remains to be investigated. Therefore, the recommendations should be regarded as provisional and subject to future research. Efficient treatment of phenylketonuria has to go beyond recommendations for blood Phe level control and must include adequate dietary training, medical as well as psychological counselling of the patient and his family, and a protocol for monitoring outcome. CONCLUSIONS: Early-and-strictly-treated patients with phenylketonuria show an almost normal development. During the first 10 years treatment should aim at blood Phenylalanine levels between 40 and 240 micromol/L. After the age of 10, blood phenylalanine level control can be gradually relaxed. For reasons of possible unknown late sequelae, all patients should be followed up life-long. PMID: 9950308, UI: 99133807 J Am Coll Nutr 1997 Apr;16(2):147-51 Phenylketonuria: current dietary treatment practices in the United States and Canada. Fisch RO, Matalon R, Weisberg S, Michals K Department of Pediatrics, University of Minnesota, Minneapolis-St. Paul, USA. OBJECTIVE: A survey of treatment centers for phenylketonuria (PKU) in the United States and Canada was undertaken regarding current practices of dietary treatment of PKU. METHODS: A total of 111 centers, who follow more than 6,950 patients with PKU responded to the survey. RESULTS: The majority of the centers, 87%, favor life-long dietary control of phenylalanine intake. The survey found lack of uniformity regarding acceptable range of blood phenylalanine levels. The frequency of clinic visits varied and became less frequent as patients got older. Although most of the clinics recommend diet for life, only one-third of the clinics follow patients beyond the age of 18 years, therefore, it is unclear who manages these patients beyond that age. The survey also showed a high number of families with children who were reported for medical neglect (3.0% compared to < 0.06% in the general population). Because of dietary noncompliance, 1% of the children were removed from the home. DISCUSSION: The survey points to the common treatment goal of diet for life for patients with PKU and underscores the need for uniform guidelines for achieving this goal. PMID: 9100215, UI: 97254805 Acta Paediatr Suppl 1994 Dec;407:92-7 PKU in adolescents: rationale and psychosocial factors in diet continuation. Levy HL, Waisbren SE Biochemical Genetics Unit of the Division of Genetics, Children's Hospital, Boston, MA 02115, USA. Follow-up of early-treated children with PKU has shown that diet discontinuation in childhood presents risks of cognitive and emotional dysfunction in a substantial number of adolescents and young adults. This dysfunction includes IQ loss, mental processing abnormalities, learning difficulties, anxiety and personality disorders. In addition, neurologic deterioration has been reported in several such individuals. As a consequence of this current understanding of PKU, diet continuation, at least through adolescence and in the young adult years, is now recommended. Many centers are extending this to a policy of "diet for life". This represents a major challenge to adolescents and their families. Metabolic control using the criteria applied during childhood is virtually impossible to achieve past 12 years of age. Time constraints, social pressures, financial limitations and growing independence from the family combine to interfere with dietary control. Added to these difficulties are the biological changes during teenage years which reduce phenylalanine tolerance. To meet these challenges, we have identified a number of psychosocial factors that interfere with adherence to medical recommendations. The factors most highly related to metabolic control were social support for the diet and positive perceptions of treatment. This information has led to the development of support programs for adolescents and young adults with PKU ------------------------------------------------------------------------ Stephen Black, Ph.D. tel: (819) 822-9600 ext 2470 Department of Psychology fax: (819) 822-9661 Bishop's University e-mail: [EMAIL PROTECTED] Lennoxville, QC J1M 1Z7 Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy ------------------------------------------------------------------------
