Eur J Pediatr (1992) 151 : 522-525
European Journal of
Pediatrics
9 Springer-Verlag1992
Psychological and social findings in adolescents with phenylketonuria J. Weglage 1, B. Fiinders 1, B. Wilken 1, D. Schubert 1, E. Schmidt 2, P. Burgard 2, and K. Ullrich 1 ~Department of Paediatrics, University of Manster, Albert-Schweitzer-Strasse 33, W-4400 Mtinster, Federal Republic of Germany 2Department of Paediatrics, University of Heidelberg, W-6900 Heidelberg, Federal Republic of Germany Received October 8, 1991 / Accepted after revision December 12, t991
Abstract. In a retrospective study, 34 early treated, normally intelligent adolescents with phenylketonuria (PKU) and their parents were tested with several psychometric personality inventories and self-developed questionaires concerning their psychosocial situation and their diseaseand diet-specific knowledge. Results show that the patients are characterized by less autonomy, a m o r e negative evaluation of their scholastic ability, less achievement motivation, low frustration tolerance, m o r e negative self description, less extraversion and impulsiveness, a feeling of not being quite healthy, more grave and a higher level of dependency from their families. The patients saw their whole social situation as being destinctly restricted. Their knowledge concerning disease and diet was alarmingly p o o r and the majority had great difficulties in managing the diet satisfactorily without parental help. Up to the age of 15 years the serum phenylalanine levels were persistently above the desired range. Key words: Adolescent phenylketonuria - Psychological characteristics - Social findings - Dietary control
Introduction Since patients with phenylketonuria (PKU) caused by phenylalanine hydroxylase deficiency are subjected to a diet low in phenylalanine (Phe) soon after birth, most studies have reported m e a n intelligence quotients (IQ) within the normal range and have come to optimistic conclusions concerning the response to treatment [5, 8]. Nevertheless several studies have shown that a discontinuation of diet led to an irreversible decline in I Q even in adolescence [13, 20]. In both young and adult patients, reversible neuropsychological deficits such as concentration problems, restlessness, slower reaction times and reduced information processing abilities linked with a Offprint requests to: J. Weglage Abbreviations: IQ =intelligence quotient; Phe=phenylalanine;
PKU = phenylketonuria
drop of I Q and problems in school are reported consequences of acute high serum Phe concentrations [4, 16]. A few studies have reported that patients with P K U also have an increased incidence of psychopathological problems such as aggressiveness, anxiety, hyperactivity, low frustration tolerance and p o o r interpersonal behaviour [11, 12, 15]. Consequently, length of time during which patients with P K U should stay on a rigid diet has been continually increased in recent years. In this retrospective study we attempted to identify psychological and social characteristics of the patients including their disease- and diet-specific knowledge and that of their relatives.
Patients and methods Thirty-four patients with classical PKU [3], their mothers and 15 of their fathers participated in the study. All patients started diet before the end of the 6th week of life. Five mothers and three fathers were not tested for IQ. Of the patients, 16 were girls and 18 boys. They were 14.6 • 2.0 years old (range: 11 to 18 years). Their physical development was normal [17]. With the help of the variables family income, degree of father and job of father, the socio-economic status of the family (SES) was defined. The families were classified into five categories: high, 9%; middle-high, 15%; middle, 47%; middle-low, 20% ; and low, 9%. The study was carried out separately for the patients and their relatives. The battery of tests and questionaires are shown in Table 1. The Grundintelligenztest Skala 2 CFT 20 [18] is the German adaptation of the Culture Fair Intelligence Test - Scale 2 by R. B. Cattell for the diagnosis of the general mental capacity. The Mannheimer Biographisches Inventar describes the environmental situation as experienced by the patients [9]. The PersOnlichkeitsfragebogen ffir Kinder, a personality inventory, measures behavioural patterns, motives and self-image and was completed by patients up to the age of 15.6 years [14]. The Freiburger Pers6nlichkeits-Inventar consists of 12 scales for the description of personality characteristics and was completed by patients older than 15.7 years and their parents [6]. Annual medians were computed from the serum Phe concentrations, which were regularly registered from birth. They were only calculated, if there were at least ten Phe checks in the years 1-5, eight Phe checks in the years 6-10 and after that four Phe checks annually. The mean of the annual medians was taken as an index of dietary control.
523 Table 2. Mannheimer Biographic Iventory (MBI)
Table 1. Test battery
Patients (n=34)
Mothers (n=34)
Fathers (n=15)
1. IQ-test: Scale 2 CFT 20 34 29 2. Mannheimer Biographic Inventory (MBI) 34 3. Personality Questionaire for Children (PFK 9-14) 18a 4. Freiburger Personality Inventory (FPI-R) 16 5. Self developed questionaires: a) Knowledge concerning disease and diet 34 b) Psychosocial situation 34 6. SerumPhe concentrations 34 a One of the 18 questionaires could not be evaluated
12 1. Support of family 2. Autonomy 3. Interpersonal behaviour 4. Situation in school 5. Working discipline 6. Creativity 7. Assertiveness 8. Achievement motivation 9. Frustration tolerance 10. Self image 11. Health Total: Social situation
PKU group (n = 34)
Control group (n = 2832)
Mean SD
Mean SD
7.5 4.0 4.7 2.7 4.8 4.5 5.0 4.0 3.0 4.1 3.0 3.3
5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0
2.1 4.0 4.0 2.1 2.7 2.8 2.9 2.9 2.3 3.1 1.5 2.7
2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
P*
0.001 0.05 NS 0.001 NS NS NS 0.05 0.001 0.05 0.001 0.001
* One-sided-t-test NS, Not significant
mg/dl 20-
15
T 10-
4-
i
i 5
. . . .
1,0
. . . .
' 15
'
'
iJ8
years
Fig. 1. Serum-phenylalanine-concentration: average of annual me-
dians with SD (
= real level; . . . . .
desired levels)
Results
The patients' average yearly medians of the serum Phe concentrations increased continuously with age and remained up to their 15th year above the limits recommended for different age groups by the G e r m a n Paediatric Society in 1989 (Fig. 1) [7]. With an IQ of 93.6 + 12.6 the patients reached a normal mean intellectual performance (85-115) but this is significantly (P < 0.05) below the IQ of the general population (100 + 15), the IQ of their mothers (98.2 + 11.3) and of their fathers (105.4 + 11.9). With the help of the Mannheimer Biographisches Inventar the patients described their social situation as specified in Table 2. With regard to the social context the P K U group was significantly different from the norm. The patients reported: more support by their family, less autonomy,
lower evaluation of their situation in school, less achievement motivation, less frustration tolerance, more negative self descriptions and less health. No significant differences regarding the scales interpersonal behavior, working discipline, creativity and assertiveness were found. The patients saw their social situation as being distinctly restricted. There were no significant differences between girls and boys. According to the results of the Pers6nlichkeitsfragebogen ft~r Kinder which are shown in Table 3, the patients showed a significantly less desire for autonomy, less masculinity of attitudes and less carefreeness and impulsiveness (Table 3). Girls and boys did not show any significant difference. With the help fo the Freiburger Pers6nlichkeits-Inventar the patients described their personality. Compared to the norm the PKU patients reported that they were significantly less satisfied with life, less social orientated, less orientated towards success, less open, less extravert and less emotional; they also experienced increased physical complaints (Table 4). There were no significant differences between girls and boys. The majority of patients (77%) found it very difficult to stay on the diet. Most of them (94%) wisted to stop the diet immediately. About 80% of the patients stated that they adhered sometimes or always to a stricter diet before the serum Phe concentrations were checked. Despite regular consultations by doctors and dietary assistants the disease- and diet-specific knowledge of patients and mothers was poor. Tables 5 and 6 report patients and mothers beliefs concerning the aetiology of P K U and reasons for high serum Phe concentrations. Older ( > 15.0 years) and younger ( < 15.0 years) patients did not differ significantly in their knowledge. On their own admission, 59% of patients were unable to manage the diet without help of their mothers. Referring to the dietary competence, there were no significant differences between older ( > 15.0 years) and younger ( < 15.0 years)
524 Table 3. Personality questionaire for children (PFK 9-14)
Behavioural patterns: 1. Emotionalsensitivity 2. Lack of will control 3. Extravert temperament 4. Interpersonalbehaviour Needs and motives: 1. Aggressive need for selfpresentation 2. Need for autonomy and self-sufficiency 3. Scholastic ambition 4. Socialcommitment 5. Dependency on adults 6. Masculinity of attitudes Self-image: 1. Generalanxiety 2. Self-confidence 3. Impulsiveness/Carefreeness 4. Self-deception 5. Feelings of inferiority
PKU group (n = 17)
Control group (n = 1237)
Mean SD
Mean SD
Table 5. Answers to the question "aetiology of PKU" p*
41.7 47.2 48.7 49.2
10.7 9.2 10.5 9.8
50.0 50.0 50.0 50.0
10.0 10.0 10.0 10.0
NS NS NS NS
48.1
10.8
50.0
10.0
NS
46.5 50.9 48.2 50.8 41.4
10.7 9.5 9.7 9.0 9.5
50.0 50.0 50.0 50.0 50.0
10.0 10.0 10.0 10.0 10.0
0.05 NS NS NS 0.01
47.6 47.6
9.7 7.7
50.0 50.0
10.0 10.0
NS NS
46.9 52.9 48.1
7.7 5.3 11.1
50.0 50.0 50.0
10.0 10.0 10.0
NS NS NS
* One-sided-t-test
Table 4. Freiburger Personality Iventory (FBI-R) PKU group (n = 16)
Control group
P*
1. Heredity 2. I don't know 3. Too much protein during pregnancy 4. Damage during pregnancy 5, Pure chance 6. Other reasons
PKU patients (n = 34) (%)
Mothers (n = 34) (%)
41.3 32.3 17.6 14.5 5,9 5.9
88.2 8.8 52.9 55.7 5.9 0.0
Table 6. Answers to the question "reasons of high blood Phe levels"
1. Too much protein 2. Too little amino acid mixture 3. Too much amino acid mixture 4. I don't know 5. Illness 6. Stress
PKU patients (n = 34) (%)
Mothers (n = 34) (%)
67.8 29.4 26.5 17.6 8.8 2.9
94.1 11.8 29.4 0.0 29.4 47.0
social and emotional problems such as less a u t o n o m y and m o r e d e p e n d e n c y on adults, low frustration tolerance, less carefreeness, less extraversion and less satisfaction with life as well as greater emotional excitability (r = 0.33-0.45, P < 0.05). Boys and girls did not show any significant difference.
(,, = 343)
1. Satisfaction with life 2. Social orientation 3. Orientation towards success 4. Inhibition 5. Irritability 6. Aggressivity 7. Stress 8. Physical complaints 9. Health worries 10. Openess 11. Extraversion 12. Emotionality
Discussion
Mean SD
Mean SD
4.8 5.0
1.6 1.9
6.4 6.4
3.1 2.6
0.05 0.05
3.1 6.0 5.1 5.3 4.9 4.4 4.7 5.0 3.5 4.9
1.5 1.5 2.1 1.3 1.7 2.0 1.9 1.8 1.6 1.8
6.5 5.0 5.6 4.9 5.2 2.8 3.9 7.3 8.1 6.2
2.7 3.0 3.1 3.1 3.3 2.2 2.6 2.7 3.3 3.1
0.001 NS NS NS NS 0.05 NS 0.01 0.001 0.05
* One-sided-t-test
patients. O f the mothers, 68% characterized the upbringing of their children with P K U as overprotective, especially carefully and restrictive. T h e data show the following relationships: low socio-economic status and low I Q of m o t h e r s were significantly correlated with higher average serum Phe concentrations of the patients r = - 0 . 4 5 , P < 0.05). Patients with p o o r dietetic control had m o r e
C o n c e r n i n g the quality of dietary compliance and intellectual o u t c o m e , our data confirm the results of the N o r t h A m e r i c a n and G e r m a n Collaborative P K U Studies [1, 8, 19]. The average serum Phe concentrations of m o s t patients rose continuously with age and they were above the desired levels up to the age of 15 years. T h e m e a n I Q of the patients was within the n o r m a l range but below that of their parents and that of the n o r m a l p o p u lation. Using the M a n n h e i m e r Biographic I n v e n t o r y , the Personality Questionaire for Children and the Freiburger Personality I n v e n t o r y the adolescent patients with P K U described their social life and their emotional dev e l o p m e n t as being distinctly restricted. O u r data support the assumption that the strictness or flexibility of dietary practice had a p r o f o u n d effect on the children's personality d e v e l o p m e n t [2, 15]. O u r patients were less impulsive, less extravert, less emotional, less carefree, less i n d e p e n d e n t and less satisfied with life. In agreem e n t with other authors these characteristics m a y be reg a r d e d as consequences of an insufficient coping with the diet and the chronic illness in general as well as a direct result of the metabolic disorder [2, 15]. L a c k of social c o m p e t e n c e and i n d e p e n d e n c e as well as a feeling of
525 insufficiency and a negative self-image of the patients are possible consequences of an overprotective and restrictive upbringing of the children, as reported by the majority of the mothers in our study. The fact that most patients maintained a m o r e stricter diet before serum Phe checking also indicates an insufficient coping strategy as does the fact that 94% wished to end the diet immediately because maintenance a p p e a r e d too difficult. Many of the personality characteristics and coping strategies indicated here in respect of P K U are likewise described in the literature on chronic diseases of children and adolescents [2, 10]. The question of how P K U patients develop specific to their disease could possibly be answered by comparative studies of patients with other chronic diseases. A n alarmingly p o o r disease- and diet-specific knowledge and a low practical dietary competence of most patients contribute to their dependence on their parents and to their negative attitude towards the diet. Feelings towards P K U as an uncomfortable, uncontrollable, frustrating and aversive threat were stabilized by patients' ignorance concerning disease and diet as well as by persistently high serum Phe levels. Beyond this, high serum Phe levels and a lower m e a n I Q than expected for the general population have b e e n shown to be risk factors for behavioural and emotional disturbances [15]. W h a t are conditions for a m o r e sufficient coping with P K U ? A basic condition is a profound disease- and dietspecific knowledge associated with practical dietary competence. Training p r o g r a m m e s in attractive group settings or supervision of dietary practice at h o m e by dietitians or help of young patients and their families by experienced families may probably be successful methods. Patients should learn as soon as possible to accept their own responsibility for the diet. Beyond dietary competence, effective coping with P K U requires an independant, responsible and creative m a n a g e m e n t of the disease. This is particular true for adolescents. Therefore an overprotective and restrictive upbringing of the patients and a rigid dietary regime caused by anxiety and insufficient coping strategies of parents and patients - are contraproductive [2]. Social counselling programmes and psychotherapy should in special cases be offered to parents and patients continually from soon after birth. Ideal metabolic levels as achieved by strict parenteral supervision m a y interfere with a balanced development of the children [2]. In order to find a compromise between a good attitude to the b u r d e n s o m e diet and a normal personality development, we have to accept optimal serum Phe levels for each patient which in the individual case m a y not be ideal from the medical standpoint.
Acknowledgement. We thank Maizena GmbH, Heilbronn, Germany for generous financial support.
References 1. Acosta PB, Trahms C, Wellmann NS, Williamson N (1983) Phenylalanine intakes of 1- to 6-years old children with phenylketonuria undergoing therapy. Am J Clin Nutr 38 : 694-700 2. Awiszus D, Unger I (1990) Coping with PKU: results of narrative interviews with parents. Eur J Pediatr 149 [Suppl 1] : 45-51 3. Blascovis ME, Scheffler GE, Hack S (1974) Phenylalaninemia. Differential diagnosis. Arch Dis Child 49 : 835-843 4. Brunner R, Berry H (1987) Phenylketonuria and sustained attention: The continous performance test. Int J Clin Neuropsych 9 : 68-70 5. Dobson JC, Williamson ML, Azen C, Koch R (1977) Intellectual assessment of 111 four year old children with phenylketonuria. J Pediatr 5 : 53-56 6. Fahrenberg J, Hampel R, Selg H (1983) Das Freiburger Pers6nlichkeitsinventar (FPI-R), Verlag far Psychologie Dr CH Hogrefe, G6ttingen 7. German Paediatric Society (1990) Limits in serum phenylalanine concentrations of different ages. Convention of the "Deutsche Arbeitsgemeinschaft ft~r Pfidiatrische Stoffwechselerkrankungen". Monatschr Kinderheilk 138 : 636 8. Holtzman N, Richard M, Kornmal A (1986) Effect of age at loss of dietary control on intellectual performance and behavior of children with phenylketonuria. N Engl J Med 314: 593-598 9. J~iger R, Berbig E, Geisel B, Gosslar H, Hagen J, Liebich W, Schafheutle R (1973) Mannheimer Biographisches Inventar (MBI), Verlag far Psychologie, Dr. H.J. Hogrefe, GOttingen 10. Petermann F, Noeker M, Bode U (1987) Psychologie chronischer Krankheiten im Kindes- und Jugendalter. Psychologie Verlags-Union, Mtinchen-Weinheim 11. Realmuto G, Garfinkel BD, Tuchmann M, Tsai MT, Chang PN, Fisch RO, Sharpio S (1986) Psychiatric diagnosis and behavioral characteristics of phenylketonurie children. J Nerv Ment Dis 174 : 536-540 12. Reber M, Kazak AE, Himmelberg P (1987) Phenylalanine control and family functoning in early treated phenylketonuria. Dev Behav Pediatr 8 : 311-317 13. Schmidt H, Mahle M, Michel U, Pietz J (1987) Continuation vs discontinuation of low-phenylalanine diet in PKU adolescents. Eur J Pediatr 146 [Suppl 1] : A12-A16 14. Seitz W, Rausche A (1976) Pers6nlichkeitsfragebogen far Kinder (PFK 9-14). Westermann-Verlag Braunschweig 15. Smith I, Beasly MG, Wolff OH, Ades AE (1988) Behaviour disturbances in 8-year-old children with early treated phenylketonuria. J Pediatr 112: 408 16. Sonneville LMJ de, Schmidt E, Michel U, Batzler U (1990) Preliminary neuropsychological test results. Eur J Pediatr 149 [Suppl 1] : A39-A44 17. Tanner JM (1962) Wachstum und Reifung des Menschen. Thieme-Verlag, Stuttgart 18. Weir3 RH (1987) Grundintelligenztest Skala 2 CFT 20. Verlag ftir Psychologie, DR CJ Hogrefe G6ttingen 19. Wendel U, Ullrich K, Schmidt H, Batzler U (1990) Six-year follow up of phenylalanine intakes and plasma phenylalanine concentrations. Eur J Pediatr 149 [Suppl 1] : 13-16 20. Zwiauer K, Widhalm S, Scheibenreiter S, Knoll E (1990) Longterm intellectual development in 86 children with phenylketonuria (PKU) Pediatr Res 28 : 74
European Journal of
Pediatrics
9 Springer-Verlag1992
Psychological and social findings in adolescents with phenylketonuria J. Weglage 1, B. Fiinders 1, B. Wilken 1, D. Schubert 1, E. Schmidt 2, P. Burgard 2, and K. Ullrich 1 ~Department of Paediatrics, University of Manster, Albert-Schweitzer-Strasse 33, W-4400 Mtinster, Federal Republic of Germany 2Department of Paediatrics, University of Heidelberg, W-6900 Heidelberg, Federal Republic of Germany Received October 8, 1991 / Accepted after revision December 12, t991
Abstract. In a retrospective study, 34 early treated, normally intelligent adolescents with phenylketonuria (PKU) and their parents were tested with several psychometric personality inventories and self-developed questionaires concerning their psychosocial situation and their diseaseand diet-specific knowledge. Results show that the patients are characterized by less autonomy, a m o r e negative evaluation of their scholastic ability, less achievement motivation, low frustration tolerance, m o r e negative self description, less extraversion and impulsiveness, a feeling of not being quite healthy, more grave and a higher level of dependency from their families. The patients saw their whole social situation as being destinctly restricted. Their knowledge concerning disease and diet was alarmingly p o o r and the majority had great difficulties in managing the diet satisfactorily without parental help. Up to the age of 15 years the serum phenylalanine levels were persistently above the desired range. Key words: Adolescent phenylketonuria - Psychological characteristics - Social findings - Dietary control
Introduction Since patients with phenylketonuria (PKU) caused by phenylalanine hydroxylase deficiency are subjected to a diet low in phenylalanine (Phe) soon after birth, most studies have reported m e a n intelligence quotients (IQ) within the normal range and have come to optimistic conclusions concerning the response to treatment [5, 8]. Nevertheless several studies have shown that a discontinuation of diet led to an irreversible decline in I Q even in adolescence [13, 20]. In both young and adult patients, reversible neuropsychological deficits such as concentration problems, restlessness, slower reaction times and reduced information processing abilities linked with a Offprint requests to: J. Weglage Abbreviations: IQ =intelligence quotient; Phe=phenylalanine;
PKU = phenylketonuria
drop of I Q and problems in school are reported consequences of acute high serum Phe concentrations [4, 16]. A few studies have reported that patients with P K U also have an increased incidence of psychopathological problems such as aggressiveness, anxiety, hyperactivity, low frustration tolerance and p o o r interpersonal behaviour [11, 12, 15]. Consequently, length of time during which patients with P K U should stay on a rigid diet has been continually increased in recent years. In this retrospective study we attempted to identify psychological and social characteristics of the patients including their disease- and diet-specific knowledge and that of their relatives.
Patients and methods Thirty-four patients with classical PKU [3], their mothers and 15 of their fathers participated in the study. All patients started diet before the end of the 6th week of life. Five mothers and three fathers were not tested for IQ. Of the patients, 16 were girls and 18 boys. They were 14.6 • 2.0 years old (range: 11 to 18 years). Their physical development was normal [17]. With the help of the variables family income, degree of father and job of father, the socio-economic status of the family (SES) was defined. The families were classified into five categories: high, 9%; middle-high, 15%; middle, 47%; middle-low, 20% ; and low, 9%. The study was carried out separately for the patients and their relatives. The battery of tests and questionaires are shown in Table 1. The Grundintelligenztest Skala 2 CFT 20 [18] is the German adaptation of the Culture Fair Intelligence Test - Scale 2 by R. B. Cattell for the diagnosis of the general mental capacity. The Mannheimer Biographisches Inventar describes the environmental situation as experienced by the patients [9]. The PersOnlichkeitsfragebogen ffir Kinder, a personality inventory, measures behavioural patterns, motives and self-image and was completed by patients up to the age of 15.6 years [14]. The Freiburger Pers6nlichkeits-Inventar consists of 12 scales for the description of personality characteristics and was completed by patients older than 15.7 years and their parents [6]. Annual medians were computed from the serum Phe concentrations, which were regularly registered from birth. They were only calculated, if there were at least ten Phe checks in the years 1-5, eight Phe checks in the years 6-10 and after that four Phe checks annually. The mean of the annual medians was taken as an index of dietary control.
523 Table 2. Mannheimer Biographic Iventory (MBI)
Table 1. Test battery
Patients (n=34)
Mothers (n=34)
Fathers (n=15)
1. IQ-test: Scale 2 CFT 20 34 29 2. Mannheimer Biographic Inventory (MBI) 34 3. Personality Questionaire for Children (PFK 9-14) 18a 4. Freiburger Personality Inventory (FPI-R) 16 5. Self developed questionaires: a) Knowledge concerning disease and diet 34 b) Psychosocial situation 34 6. SerumPhe concentrations 34 a One of the 18 questionaires could not be evaluated
12 1. Support of family 2. Autonomy 3. Interpersonal behaviour 4. Situation in school 5. Working discipline 6. Creativity 7. Assertiveness 8. Achievement motivation 9. Frustration tolerance 10. Self image 11. Health Total: Social situation
PKU group (n = 34)
Control group (n = 2832)
Mean SD
Mean SD
7.5 4.0 4.7 2.7 4.8 4.5 5.0 4.0 3.0 4.1 3.0 3.3
5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0
2.1 4.0 4.0 2.1 2.7 2.8 2.9 2.9 2.3 3.1 1.5 2.7
2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
P*
0.001 0.05 NS 0.001 NS NS NS 0.05 0.001 0.05 0.001 0.001
* One-sided-t-test NS, Not significant
mg/dl 20-
15
T 10-
4-
i
i 5
. . . .
1,0
. . . .
' 15
'
'
iJ8
years
Fig. 1. Serum-phenylalanine-concentration: average of annual me-
dians with SD (
= real level; . . . . .
desired levels)
Results
The patients' average yearly medians of the serum Phe concentrations increased continuously with age and remained up to their 15th year above the limits recommended for different age groups by the G e r m a n Paediatric Society in 1989 (Fig. 1) [7]. With an IQ of 93.6 + 12.6 the patients reached a normal mean intellectual performance (85-115) but this is significantly (P < 0.05) below the IQ of the general population (100 + 15), the IQ of their mothers (98.2 + 11.3) and of their fathers (105.4 + 11.9). With the help of the Mannheimer Biographisches Inventar the patients described their social situation as specified in Table 2. With regard to the social context the P K U group was significantly different from the norm. The patients reported: more support by their family, less autonomy,
lower evaluation of their situation in school, less achievement motivation, less frustration tolerance, more negative self descriptions and less health. No significant differences regarding the scales interpersonal behavior, working discipline, creativity and assertiveness were found. The patients saw their social situation as being distinctly restricted. There were no significant differences between girls and boys. According to the results of the Pers6nlichkeitsfragebogen ft~r Kinder which are shown in Table 3, the patients showed a significantly less desire for autonomy, less masculinity of attitudes and less carefreeness and impulsiveness (Table 3). Girls and boys did not show any significant difference. With the help fo the Freiburger Pers6nlichkeits-Inventar the patients described their personality. Compared to the norm the PKU patients reported that they were significantly less satisfied with life, less social orientated, less orientated towards success, less open, less extravert and less emotional; they also experienced increased physical complaints (Table 4). There were no significant differences between girls and boys. The majority of patients (77%) found it very difficult to stay on the diet. Most of them (94%) wisted to stop the diet immediately. About 80% of the patients stated that they adhered sometimes or always to a stricter diet before the serum Phe concentrations were checked. Despite regular consultations by doctors and dietary assistants the disease- and diet-specific knowledge of patients and mothers was poor. Tables 5 and 6 report patients and mothers beliefs concerning the aetiology of P K U and reasons for high serum Phe concentrations. Older ( > 15.0 years) and younger ( < 15.0 years) patients did not differ significantly in their knowledge. On their own admission, 59% of patients were unable to manage the diet without help of their mothers. Referring to the dietary competence, there were no significant differences between older ( > 15.0 years) and younger ( < 15.0 years)
524 Table 3. Personality questionaire for children (PFK 9-14)
Behavioural patterns: 1. Emotionalsensitivity 2. Lack of will control 3. Extravert temperament 4. Interpersonalbehaviour Needs and motives: 1. Aggressive need for selfpresentation 2. Need for autonomy and self-sufficiency 3. Scholastic ambition 4. Socialcommitment 5. Dependency on adults 6. Masculinity of attitudes Self-image: 1. Generalanxiety 2. Self-confidence 3. Impulsiveness/Carefreeness 4. Self-deception 5. Feelings of inferiority
PKU group (n = 17)
Control group (n = 1237)
Mean SD
Mean SD
Table 5. Answers to the question "aetiology of PKU" p*
41.7 47.2 48.7 49.2
10.7 9.2 10.5 9.8
50.0 50.0 50.0 50.0
10.0 10.0 10.0 10.0
NS NS NS NS
48.1
10.8
50.0
10.0
NS
46.5 50.9 48.2 50.8 41.4
10.7 9.5 9.7 9.0 9.5
50.0 50.0 50.0 50.0 50.0
10.0 10.0 10.0 10.0 10.0
0.05 NS NS NS 0.01
47.6 47.6
9.7 7.7
50.0 50.0
10.0 10.0
NS NS
46.9 52.9 48.1
7.7 5.3 11.1
50.0 50.0 50.0
10.0 10.0 10.0
NS NS NS
* One-sided-t-test
Table 4. Freiburger Personality Iventory (FBI-R) PKU group (n = 16)
Control group
P*
1. Heredity 2. I don't know 3. Too much protein during pregnancy 4. Damage during pregnancy 5, Pure chance 6. Other reasons
PKU patients (n = 34) (%)
Mothers (n = 34) (%)
41.3 32.3 17.6 14.5 5,9 5.9
88.2 8.8 52.9 55.7 5.9 0.0
Table 6. Answers to the question "reasons of high blood Phe levels"
1. Too much protein 2. Too little amino acid mixture 3. Too much amino acid mixture 4. I don't know 5. Illness 6. Stress
PKU patients (n = 34) (%)
Mothers (n = 34) (%)
67.8 29.4 26.5 17.6 8.8 2.9
94.1 11.8 29.4 0.0 29.4 47.0
social and emotional problems such as less a u t o n o m y and m o r e d e p e n d e n c y on adults, low frustration tolerance, less carefreeness, less extraversion and less satisfaction with life as well as greater emotional excitability (r = 0.33-0.45, P < 0.05). Boys and girls did not show any significant difference.
(,, = 343)
1. Satisfaction with life 2. Social orientation 3. Orientation towards success 4. Inhibition 5. Irritability 6. Aggressivity 7. Stress 8. Physical complaints 9. Health worries 10. Openess 11. Extraversion 12. Emotionality
Discussion
Mean SD
Mean SD
4.8 5.0
1.6 1.9
6.4 6.4
3.1 2.6
0.05 0.05
3.1 6.0 5.1 5.3 4.9 4.4 4.7 5.0 3.5 4.9
1.5 1.5 2.1 1.3 1.7 2.0 1.9 1.8 1.6 1.8
6.5 5.0 5.6 4.9 5.2 2.8 3.9 7.3 8.1 6.2
2.7 3.0 3.1 3.1 3.3 2.2 2.6 2.7 3.3 3.1
0.001 NS NS NS NS 0.05 NS 0.01 0.001 0.05
* One-sided-t-test
patients. O f the mothers, 68% characterized the upbringing of their children with P K U as overprotective, especially carefully and restrictive. T h e data show the following relationships: low socio-economic status and low I Q of m o t h e r s were significantly correlated with higher average serum Phe concentrations of the patients r = - 0 . 4 5 , P < 0.05). Patients with p o o r dietetic control had m o r e
C o n c e r n i n g the quality of dietary compliance and intellectual o u t c o m e , our data confirm the results of the N o r t h A m e r i c a n and G e r m a n Collaborative P K U Studies [1, 8, 19]. The average serum Phe concentrations of m o s t patients rose continuously with age and they were above the desired levels up to the age of 15 years. T h e m e a n I Q of the patients was within the n o r m a l range but below that of their parents and that of the n o r m a l p o p u lation. Using the M a n n h e i m e r Biographic I n v e n t o r y , the Personality Questionaire for Children and the Freiburger Personality I n v e n t o r y the adolescent patients with P K U described their social life and their emotional dev e l o p m e n t as being distinctly restricted. O u r data support the assumption that the strictness or flexibility of dietary practice had a p r o f o u n d effect on the children's personality d e v e l o p m e n t [2, 15]. O u r patients were less impulsive, less extravert, less emotional, less carefree, less i n d e p e n d e n t and less satisfied with life. In agreem e n t with other authors these characteristics m a y be reg a r d e d as consequences of an insufficient coping with the diet and the chronic illness in general as well as a direct result of the metabolic disorder [2, 15]. L a c k of social c o m p e t e n c e and i n d e p e n d e n c e as well as a feeling of
525 insufficiency and a negative self-image of the patients are possible consequences of an overprotective and restrictive upbringing of the children, as reported by the majority of the mothers in our study. The fact that most patients maintained a m o r e stricter diet before serum Phe checking also indicates an insufficient coping strategy as does the fact that 94% wished to end the diet immediately because maintenance a p p e a r e d too difficult. Many of the personality characteristics and coping strategies indicated here in respect of P K U are likewise described in the literature on chronic diseases of children and adolescents [2, 10]. The question of how P K U patients develop specific to their disease could possibly be answered by comparative studies of patients with other chronic diseases. A n alarmingly p o o r disease- and diet-specific knowledge and a low practical dietary competence of most patients contribute to their dependence on their parents and to their negative attitude towards the diet. Feelings towards P K U as an uncomfortable, uncontrollable, frustrating and aversive threat were stabilized by patients' ignorance concerning disease and diet as well as by persistently high serum Phe levels. Beyond this, high serum Phe levels and a lower m e a n I Q than expected for the general population have b e e n shown to be risk factors for behavioural and emotional disturbances [15]. W h a t are conditions for a m o r e sufficient coping with P K U ? A basic condition is a profound disease- and dietspecific knowledge associated with practical dietary competence. Training p r o g r a m m e s in attractive group settings or supervision of dietary practice at h o m e by dietitians or help of young patients and their families by experienced families may probably be successful methods. Patients should learn as soon as possible to accept their own responsibility for the diet. Beyond dietary competence, effective coping with P K U requires an independant, responsible and creative m a n a g e m e n t of the disease. This is particular true for adolescents. Therefore an overprotective and restrictive upbringing of the patients and a rigid dietary regime caused by anxiety and insufficient coping strategies of parents and patients - are contraproductive [2]. Social counselling programmes and psychotherapy should in special cases be offered to parents and patients continually from soon after birth. Ideal metabolic levels as achieved by strict parenteral supervision m a y interfere with a balanced development of the children [2]. In order to find a compromise between a good attitude to the b u r d e n s o m e diet and a normal personality development, we have to accept optimal serum Phe levels for each patient which in the individual case m a y not be ideal from the medical standpoint.
Acknowledgement. We thank Maizena GmbH, Heilbronn, Germany for generous financial support.
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