DÄ internationalArchive31-32/2009Risk Factors for Headache in Children

Original article

Risk Factors for Headache in Children

Dtsch Arztebl Int 2009; 106(31-32): 509-16. DOI: 10.3238/arztebl.2009.0509

Gaßmann, J; Vath, N; Gessel, H v; Kröner-Herwig, B

Background: 10% to 30% of all children worldwide suffer from headaches at least once a week, potentially constituting a serious health problem that may lead to impairment in multiple areas. Therefore, one aim of the epidemiological longitudinal study "Children, Adolescents, and Headache" (KiJuKo) is the study of potential risk factors for the development of recurrent headaches.
Methods: In the first survey (2003), questionnaires were sent to 8800 households with a child between 7 and 14 years of age. Three further surveys followed, one each year from 2004 to 2006. A number of predictors having to do with family characteristics and leisure activities were identified on the basis of the first survey and were then studied in the second survey (n = 2952) with respect to their influence on the new occurrence of headaches.
Results: The risk of developing recurrent headaches between the first and the second survey was elevated by a factor of approximately 1.8 for boys who experienced quarrels in the family more than once per week, and by a factor of 2.1 for boys who only "sometimes" had free time for themselves. The risk of developing recurrent headaches was 25% higher in girls whose parents’ behavior towards the child positively or negatively reinforced the occurrence of headaches.
Conclusions: These findings are in accordance with those of other studies showing that, for boys, the frequency of quarreling in the family and the extent of leisure time are major factors in the development of recurrent headaches. For girls, the manner in which the parents respond to the child's headache seems to be important.
Dtsch Arztebl Int 2009; 106(31–32): 509–16
DOI: 10.3238/arztebl.2009.0509
Key words: child health, headache, epidemiology, morbidity risk, leisure activities
LNSLNS The prevalence of headache in children and adolescents continues to rise. International studies have documented this trend (1, 2). In addition, it is assumed that headache symptoms persist into adulthood in a relatively high percentage of cases (about 50%) (3).

Recurrent headaches in particular are considered to come about not only as a consequence of pathophysiological mechanisms, but as a multifactorial event (4) in which psychosocial components also play a role. The study of potential risk factors for the initial appearance (incidence) and maintenance of headaches in children is, therefore, of obvious importance.

The results of the studies that have been performed to date are comparable to no more than a limited extent, because of considerable methodological differences and deficiencies. Furthermore, only a handful of longitudinal studies have been carried out on this subject in Germany until now (5, 6), often involving only a small number of cases. These reasons provided the motivation for the present longitudinal epidemiological study, called "Children, Adolescents, and Headache" (in the original German: Kinder, Jugendliche und Kopfschmerz, abbreviated KiJuKo). The primary objective of this large-scale research project is to identify the psychosocial risk factors for headache in children and adolescents.

A large number of variables were tested in the study. For the purposes of this article, the variables concerning the child's family and leisure activities were selected (Table 2), because the published literature indicates that these factors are involved in headache. Family problems are often said to provoke headache (7, 8); for example, children with frequent headaches report quarreling in the family much more frequently than healthy children of the same age (age-matched controls) (9). Parental behavior when the child complains of headache seems to play a major role as well. Positive or negative reinforcement is given, through which the child learns that illness behavior confers certain advantages or privileges (10). Learning theory implies that reinforcement of this kind leads to the more frequent appearance of headache-related behavior.

Leisure activities also seem to affect the frequency of headache. It has been shown, for example, that children who suffer from headache at least once per month tend to be more active (i.e., are more likely to participate in sports) than children in the control groups without headache (11).

The relevance of friends and social relationships to psychophysiological health has been pointed out by multiple authors. Children with weekly headaches are said to have fewer friends than children of the same age without headaches (12). Children with headaches, compared to those without, also spend more time per day watching television (9) or using a computer or game console (13).

Each one of these factors can be interpreted as a type of psychosocial stress. Waldie, in a prospective study (14), showed that intense stress during puberty—operationalized with reference to various stressful events, e.g., conflict with parents—increases the probability of migraine in early adulthood. There is thought to be a two-way interaction between stress and headache (15), in which the cause-and-effect relationship remains unclear (16). Headache itself can be experienced as a stressor (17), but a variety of potential stressors can also contribute to the causation of headache.

Research findings on the subject until now do not permit any conclusion as to whether the psychosocial factors studied promote the development of headache, are themselves a consequence of headache symptoms, or possibly both.

The purpose of this article is to study the potential causes of headache with a unidirectional analytical approach. In the long term, the findings of longitudinal studies such as this one may contribute to appropriate modifications in existing prevention programs and therapeutic measures and to the development of new ones.

Methods
This investigation is part of a large-scale, longitudinal epidemiological study (KiJuKo), in which data were obtained in each of four consecutive years (20032006) in annual "waves." In this paper, we present results and parent questionnaire responses from the first two waves (2003 and 2004).

The initial acquisition of data was performed by means of a questionnaire sent to the parents and another questionnaire sent to the child (as long as the child was at least 9 years old). A total of 8800 families with a child aged 7 to 14 years were selected at random from the population of southern Lower Saxony (the districts of Holzminden, Osterode, Göttingen, and Northeim) and the city of Hanover by the registration office and data-processing center for southern Lower Saxony. Thus, a representative sample for the local city and state population was generated. The persons who had participated in the first wave were asked to participate in the second wave in the following year.

The literature was extensively searched to identify potential risk factors, on the basis of which a total of 111 questions were asked in the wave 1 parent questionnaire, concerning the following variable domains:

- Social demography
- Psychosocial factors
- Leisure-time activities
- Health
- Family
- School
- Parental health
- Life events.

Previously tested measuring instruments were incorporated into the question pool as far as this was possible (Table 2). The use of complete questionnaires to operationalize the risk factors was not possible, in view of the need for conciseness and practicality. Instead, items were chosen on the basis of statistical evaluative criteria for each risk factor. It was realized that this procedure would limit the validity and reliability of the results to some extent.

The questionnaires were developed in three pretest phases, according to the procedure recommended by Dillmann (18) for questionnaire implementation (19) (Supplement 1). The first two waves had a total of n = 4159 participants (47.3% of persons initially contacted) (e-Figure 1 gif ppt). At the time of the second wave (2004), the participating children were, on average, 11.25 years old (standard deviation, 2.28 years; range, 8–15 years).

In each of the four waves, the frequency of headaches in the past six months was assigned to one of four categories, on the basis of the parents' responses to the questionnaire:

- no headaches,
- less than one episode of headache per month,
- at least one headache episode per month,
- at least one headache episode per week.

In order to make it possible to derive an effective means of predicting whether headaches would develop after one year of follow-up, children were included in the analysis only if they had no headaches in wave 1 (i.e., no headaches or less than one episode of headache per month in the past six months), but reported having headaches one year later in wave 2 (defined as at least one headache episode per month) (Table 1 gif ppt, e-Figure 2 gif ppt).

The criterion (dependent variable) in wave 2 was membership in the group "recurrent headaches: yes" (i.e., at least one headache episode per month), versus "recurrent headaches: no" (i.e., less than one headache episode per month) (Table 1, e-Figure 2).

A further important characteristic of this longitudinal study was the consideration of symptoms that arose even before headaches did. The predictors consisted of various items in the first wave of the parent questionnaire (Table 2 gif ppt), along with age and sex, and were assigned to the categories "Family" and "Leisure Activities."

In the first step of the binary logistic regression analyses, each risk factor was studied individually for its predictive value with respect to the development of headaches occurring at least once per month (20). In preliminary analyses, sex was found to have a significant effect on the new development of headaches (p = 0.000; odds ratio = 1.54; 95% confidence interval [CI] 1.24–1.92). Therefore, subsequent evaluations were performed separately for boys and girls.

After this univariate analysis, the variables whose p-values were less than 0.25 were fed into the multiple regression model (20). As the internal consistency values (Cronbach's alpha) were satisfactory (Table 2), an overall score (average item value) was created from the subitems in five-level rating scales. High values represented unfavorable situations. A number of categories were combined because of their content and to achieve adequate case numbers (Table 3 gif ppt).

The odds ratios (OR) given in the Results section are the multiplicative factors that quantify the increased risk of developing headaches if the predictor in question is present (i.e., present to a high degree) as compared to the reference group (in which the predictor is present only to a low degree). For continuous predictors, the OR indicates the increase in the probability of developing headaches when the variable in question changes by one unit. All statistical evaluations were preformed with the SPSS 14 program package.

Results
In the second wave (2004), according to the parents' responses to the questionnaire,

- 49.5% (n = 1908) of children had no headaches,
- 26.7% (n = 1029) had only rare headaches,
- 17.1% (n = 659) had headaches at least once per month,
- 6.8% (n = 261) had headaches at least once per week.

Boys and girls differed in the frequency of headache (c2 = 51.79, df = 3, p<0.001). The prevalence of symptoms occurring weekly was twice as high in girls (Figure 1 gif ppt). The prevalence of monthly and weekly headaches rises with age (Figure 2 gif ppt).

In the binary logistic regression analyses for the evaluation of the potential effect of the individual risk factors (bivariate analyses) on the incidence of recurrent headaches, the significant factors for boys were found to be the family environment, the frequency of quarreling, and the amount of free time (Table 4 gif ppt). Each model controlled for the effect of age, which was found to be irrelevant (p > 0.05) in all cases.

The results of the overall model for boys indicate the importance of frequent quarreling in the family and of the child's free time as relevant influential factors. Boys who experienced a family quarrel more than once per week were 1.8 times as likely to have headaches than those who experienced a family quarrel only once per week or less (Table 4). Free time seems to play an even more important role: Boys who only sometimes had time for themselves were 2.1 times as likely to develop headaches (Table 4). Age was found to have no significant effect in the multivariate model as well (p = 0.211; OR = 1.05; 95% CI = 0.97–1.13).

In the bivariate analyses, the only significant factors for the development of headaches in girls were parental behavior when the child complained of headache and the number of friends. For girls, unlike boys, age was found to be an influential factor, although the odds ratios for the effect of age were in a very low range (1.030 to 1.091). Age thus seems to have no more than a weak effect on the development of headaches.

When both variables were considered together in a multivariate model, it turned out that, in fact, only parental behavior had an effect on the development of headaches in girls. Girls whose parents behaved unfavorably (i.e., with positive or negative reinforcement) when they complained of headache had 1.3 times the risk of developing headaches at one year (Table 4). Age was not found to be a relevant influential factor in the multivariate model (p = 0.471; OR = 1.03; 95% CI = 0.95–1.13).

Discussion
In line with previous research findings, a number of the variables mentioned were found to be risk factors for the new development of headaches in children (depending on sex) one year after the initial survey. For boys, the frequency of quarreling in the family and the amount of free time available were significant factors for the development of recurrent headaches; for girls, the significant factor was parental behavior tending to reinforce their daughters' headache symptoms.

These results can be considered in the context of other research findings on the subject, as follows:

This study, like other studies, revealed no association between physical activity and headache (17).

Larsson and Sund (21) showed that a reduction of leisure-time activities is associated with frequent headaches. The present study shows that, for boys, the amount of free time indeed has an effect on the development of headaches. Adequate free time thus seems to be a protective factor against headache.

Even though friends have often been described as having a relevant (protective) effect on the development of headaches (12), the present study found an effect only in girls, and only in the bivariate analyses; in the overall model, this factor loses its predictive value. This finding is in accordance with that of Gordon et al. (17). Even though children with headaches spend more time each day watching television than children without headaches (9), our analysis found this behavior to have a significant effect only in boys, and only when considered individually. When it was considered together with other variables, its effect was no longer significant. In a study of younger children, Aromaa et al. (22) found that the frequency of television-watching at age 5 was not predictive for the development of headaches by age 6. The findings of the present study are consistent with this.

In contrast to the findings of Oksanen et al. (13), we did not find the daily use of a personal computer or game console to have a significant effect on the development of headaches in children.

Overview
As a cautiously drawn conclusion from the findings reported above, it seems reasonable to advise parents to make sure that their children have adequate time for themselves. The deleterious effect of an overfilled agenda on children's psychophysiological health (and that of adults as well) is well known from many studies. Furthermore, frequent family quarrels also seem to promote the development of headaches in boys.

Girls seem to react more sensitively than boys to their parents' behavior when they complain of headache. Unfavorable parental reactions to their daughters' headaches may lead to the daughters reporting headaches more frequently, if they can thereby obtain certain privileges (e.g., staying home rather than going to school, a type of negative reinforcement) or more parental attention (positive reinforcement). These parental reactions should be precisely observed and analyzed so that they can be taken into account by the treating physician or psychologist.

A particular positive feature of the "KiJuKo" study is the longitudinal acquisition and evaluation of data. Currently available data from cross-sectional analyses show an association of headaches in children with headaches in their parents, as well as with other bodily symptoms in the children (23); influential factors of these types deserve to be further studied in longitudinal analyses. It should also be borne in mind that the present report concerns the findings of follow-up at 1 year. It may be assumed that some variables will manifest a significant effect only after longer latencies.

As mentioned at the beginning of this article, a causal relationship in the opposite direction would have been both conceivable and explicable. From a psychosomatic perspective, for example, it might be argued that unexpressed emotions in the family and the resulting chronic tension ought to lead to headaches in children, so that quarreling might have a cathartic effect and actually reduce the child's risk of developing headaches. Such possibilities will need to be considered in further, bidirectional analyses. When interpreting the results of the present study, one must bear in mind that the questionnaire response rates were not very satisfactory, which lessens the general applicability of the findings.

The present study did not distinguish among different types of headache (migraine, tension-type headache). Some authors have criticized the procedure in which responses to a questionnaire are used to draw conclusions about a diagnosis, and have insisted that interviews ought to be conducted (24). Furthermore, different types of headache frequently have overlapping symptoms and are, therefore, thought to share a common pathogenesis, so that the drawing of distinctions among types of headache might be questionable in any case (25). For these reasons, the present study focused on the frequency of headache. Other researchers argue for additional consideration of pain intensity or of the degree of impairment resulting from headache, matters which this article does not address.

Acknowledgement
This research project is a component project of the Research Association of the German Headache Konsortium under the direction of Professor Dr. med. H.C. Diener, Essen, and is supported by the German Federal Ministry of Education and Research (BMBF), grant number 01EM0521.
Conflict of interest statement
The authors declare that they have no conflict of interest as defined by the guidelines of the International Committee of Medical Journal Editors.

Manuscript received on 26 November 2008; revised version accepted on 2 March 2009.


Corresponding author
Jennifer Gaßmann, Dipl.-Psych., Psychologische Psychotherapeutin
Georg-Elias-Müller-Institut für Psychologie
Abteilung Klinische Psychologie und Psychotherapie
Georg-August-Universität Göttingen
Goßlerstr. 14
37073 Göttingen, Germany
jgassma2@uni-goettingen.de
1.
Anttila P, Metsähonkala L, Sillanpää M: Long-term trends in the incidence of headache in Finnish schoolchildren. Pediatrics 2006; 117: 1197–201. MEDLINE
2.
Laurell K, Larsson B, Eeg-Olofsson O: Prevalence of headache in Swedish schoolchildren, with a focus on tension-type headache. Cephalalgia 2004; 24: 380–8. MEDLINE
3.
Kienbacher C, Wöber C, Zesch HE et al.: Clinical features, classification and prognosis of migraine and tension-type headache in children and adolescents: a long-term follow-up study. Cephalalgia 2006; 26: 820–30. MEDLINE
4.
Connelly M: Recurrent pediatric headache: A comprehensive review. Children's Health Care 2003; 32: 153–89.
5.
Schmidt MH, Blanz B, Esser G: Häufigkeit und Bedeutung des Kopfschmerzes im Kindes- und Jugendalter. Kindheit und Entwicklung 1992; 1: 31–5.
6.
Ostkirchen GG, Andler F, Hammer F et al.: Prevalences of primary headache symptoms at school-entry: a population-based epidemiological survey of preschool children in Germany. J Headache Pain 2006; 7: 331–40. MEDLINE
7.
Luka-Krausgrill U, Reinhold B: Kopfschmerzen bei Kindern: Auftretensrate und Zusammenhang mit Streß, Streßbewältigung, Depressivität und sozialer Unterstützung. Zeitschrift für Gesundheitspsychologie 1996; 4: 137–51.
8.
Kaynak Key F, Donmez S, Tuzun U: Epidemiological and clinical characteristics with psychosocial aspects of tension-type headache in Turkish college students. Cephalalgia 2004; 24: 669–74. MEDLINE
9.
Aromaa M, Sillanpää M, Rautava P, Helenius H: Pain experience of children with headache and their families: A controlled study. Pediatrics 2000; 106: 270–5. MEDLINE
10.
Bijttebier P, Vertommen H: Antecedents, concomitants, and consequences of pediatric headache: Confirmatory construct validation of two parent-report scales. Journal of Behavioral Medicine 1999; 22: 437–56. MEDLINE
11.
Carlsson J, Larsson B, Mark A: Psychosocial functioning in schoolchildren with recurrent headaches. Headache 1996; 36: 77–82. MEDLINE
12.
Larsson B, Sund AM: Emotional/behavioural, social correlates and one-year predictors of frequent pains among early adolescents: Influences of pain characteristics. European Journal of Pain 2007; 11: 57–65. MEDLINE
13.
Oksanen A, Metsähonkala L, Anttila P et al.: Leisure activities in adolescents with headache. Acta Paediatrica 2005; 94: 609–15. MEDLINE
14.
Waldie KE: Childhood headache, stress in adolescence, and primary headache in young adulthood: A longitudinal cohort study. Headache 2001; 41: 1–10. MEDLINE
15.
Nash JM, Thebarge RW: Understanding psychological stress, its biological processes, and impact on primary headache. Headache 2006; 46: 1377–86. MEDLINE
16.
Saile H, Scalla P: Chronische Kopfschmerzen und Stress bei Kindern. Zeitschrift für Klinische Psychologie und Psychotherapie 2006; 35: 188–95.
17.
Gordon KE, Dooley JM, Wood E: Self-reported headache frequency and features associated with frequent headaches in Canadian young adolescents. Headache: The Journal of Head and Face Pain 2004; 44: 555–61. MEDLINE
18.
Dillman DA: Mail and internet surveys. The tailored design method. 2nd ed. New York, NY: John Wiley & Sons 2000; 464.
19.
Kröner-Herwig B, Heinrich M, Morris L: Headache in German children and adolescents: A population-based epidemiological study. Cephalalgia 2007; 27: 519–27. MEDLINE
20.
Muche R, Ring C, Ziegler C: Entwicklung und Validierung von Prognosemodellen auf Basis der logistischen Regression. Aachen: Shaker 2005; 1–221.
21.
Larsson B, Sund AM: One-year incidence, course, and outcome predictors of frequent headaches among early adolescents. Headache 2005; 45: 684–91. MEDLINE
22.
Aromaa M, Rautava P, Helenius H, Sillanpää M: Factors of early life as predictors of headache in children at school entry. Headache 1998; 38: 23–30. MEDLINE
23.
Kröner-Herwig B, Morris L, Heinrich M: Biopsychosocial correlates of headache: What predicts pediatric headache occurrence? Headache 2008; 48: 529–44. MEDLINE
24.
Rasmussen BK, Jensen R, Olesen J: Questionnaire versus clinical interview in the diagnosis of headache. Headache 1991; 31: 290–95. MEDLINE
25.
Turkdogan D, Cagirici S, Soylemez D, Sur H, Bilge C, Turk U: Characteristic and overlapping features of migraine and tension-type headache. Headache 2006; 46: 461–68. MEDLINE
e1.
Virtanen R, Aromaa M, Rautava P, Metsähonkala L, Anttila P, Helenius H et al.: Changes in headache prevalence between pre-school and pre-pubertal ages. Cephalalgia 2002; 22: 179–85. MEDLINE
e2.
Laurell K, Larsson B, Eeg-Olofsson O: Prevalence of headache in Swedish schoolchildren, with a focus on tension-type headache. Cephalalgia 2004; 24: 380–8. MEDLINE
e3.
Zencir M, Ergin H, Sahiner T, Kilic I, Alkis E, Ozdel L et al: Epidemiology and symptomatology of migraine among school children: Denizli urban area in Turkey. Headache 2004; 44: 780–5. MEDLINE
e4.
Fendrich K, Vennemann M, Pfaffenrath V, Evers S, May A, Berger K, Hoffmann W: Headache prevalence among adolescents—the German DMKG headache study. Cephalalgia 2007; 27: 347–54. MEDLINE
e5.
Hurrelmann K, Klocke A, Melzer W, Ravens-Sieberer U: WHO-Jugendgesundheitssurvey. Konzept und ausgewählte Ergebnisse für die Bundesrepublik Deutschland. Erziehungswissenschaft 2003; 27: 79–108.
e6.
Roth-Isigkeit A, Thyen U, Raspe HH, Stoven H, Schmucker P: Reports of pain among German children and adolescents: An epidemiological study. Acta Paediatrica 2004; 93: 258–63. MEDLINE
e7.
Walker LS, Zemann JL: Parental response to child illness behavior. Journal of Pediatric Psychology 1992; 17: 49–71. MEDLINE
e8.
Esser G, Blanz B, Geisel B, Laucht M: Mannheimer Elterninterview (MEI): Strukturiertes Interview zur Erfassung von kinderpsychiatrichen Auffälligkeiten. Weinheim: Beltz 1989.
e9.
Prochaska JJ, Salllis JF, Griffith B, Douglas J: Physical activity levels of Barbadian youth and comparison to a U.S. Sample. International Journal of Behavioral Medicine 2002; 9: 360–72. MEDLINE
e10.
Lampert T, Sygusch R, Schlack R: Nutzung elektronischer Medien im Jugendalter – Ergebnisse der KiGGS-Studie. Bundesgesundheitsblatt. Ergebnisse des Kinder- und Jugendgesundheitssurveys 2007; 50: 643–52. MEDLINE
e11.
Gaßmann J, Morris L, Heinrich M, Kröner-Herwig B: One-year course of paediatric headache in children and adolescents aged 8-15 years. Cephalalgia 2008; 28: 1154–62. MEDLINE
Abteilung Klinische Psychologie und Psychotherapie, Georg-Elias-Müller-Institut für Psychologie der Georg-August-Universität Göttingen:
Dipl.-Psych. Gaßmann, Dipl.-Psych. Dr. rer. nat. Vath, van Gessel, MSc, Dipl.-Psych. Prof. Dr. phil. Kröner-Herwig
1. Anttila P, Metsähonkala L, Sillanpää M: Long-term trends in the incidence of headache in Finnish schoolchildren. Pediatrics 2006; 117: 1197–201. MEDLINE
2. Laurell K, Larsson B, Eeg-Olofsson O: Prevalence of headache in Swedish schoolchildren, with a focus on tension-type headache. Cephalalgia 2004; 24: 380–8. MEDLINE
3. Kienbacher C, Wöber C, Zesch HE et al.: Clinical features, classification and prognosis of migraine and tension-type headache in children and adolescents: a long-term follow-up study. Cephalalgia 2006; 26: 820–30. MEDLINE
4. Connelly M: Recurrent pediatric headache: A comprehensive review. Children's Health Care 2003; 32: 153–89.
5. Schmidt MH, Blanz B, Esser G: Häufigkeit und Bedeutung des Kopfschmerzes im Kindes- und Jugendalter. Kindheit und Entwicklung 1992; 1: 31–5.
6. Ostkirchen GG, Andler F, Hammer F et al.: Prevalences of primary headache symptoms at school-entry: a population-based epidemiological survey of preschool children in Germany. J Headache Pain 2006; 7: 331–40. MEDLINE
7. Luka-Krausgrill U, Reinhold B: Kopfschmerzen bei Kindern: Auftretensrate und Zusammenhang mit Streß, Streßbewältigung, Depressivität und sozialer Unterstützung. Zeitschrift für Gesundheitspsychologie 1996; 4: 137–51.
8. Kaynak Key F, Donmez S, Tuzun U: Epidemiological and clinical characteristics with psychosocial aspects of tension-type headache in Turkish college students. Cephalalgia 2004; 24: 669–74. MEDLINE
9. Aromaa M, Sillanpää M, Rautava P, Helenius H: Pain experience of children with headache and their families: A controlled study. Pediatrics 2000; 106: 270–5. MEDLINE
10. Bijttebier P, Vertommen H: Antecedents, concomitants, and consequences of pediatric headache: Confirmatory construct validation of two parent-report scales. Journal of Behavioral Medicine 1999; 22: 437–56. MEDLINE
11. Carlsson J, Larsson B, Mark A: Psychosocial functioning in schoolchildren with recurrent headaches. Headache 1996; 36: 77–82. MEDLINE
12. Larsson B, Sund AM: Emotional/behavioural, social correlates and one-year predictors of frequent pains among early adolescents: Influences of pain characteristics. European Journal of Pain 2007; 11: 57–65. MEDLINE
13. Oksanen A, Metsähonkala L, Anttila P et al.: Leisure activities in adolescents with headache. Acta Paediatrica 2005; 94: 609–15. MEDLINE
14. Waldie KE: Childhood headache, stress in adolescence, and primary headache in young adulthood: A longitudinal cohort study. Headache 2001; 41: 1–10. MEDLINE
15. Nash JM, Thebarge RW: Understanding psychological stress, its biological processes, and impact on primary headache. Headache 2006; 46: 1377–86. MEDLINE
16. Saile H, Scalla P: Chronische Kopfschmerzen und Stress bei Kindern. Zeitschrift für Klinische Psychologie und Psychotherapie 2006; 35: 188–95.
17. Gordon KE, Dooley JM, Wood E: Self-reported headache frequency and features associated with frequent headaches in Canadian young adolescents. Headache: The Journal of Head and Face Pain 2004; 44: 555–61. MEDLINE
18. Dillman DA: Mail and internet surveys. The tailored design method. 2nd ed. New York, NY: John Wiley & Sons 2000; 464.
19. Kröner-Herwig B, Heinrich M, Morris L: Headache in German children and adolescents: A population-based epidemiological study. Cephalalgia 2007; 27: 519–27. MEDLINE
20. Muche R, Ring C, Ziegler C: Entwicklung und Validierung von Prognosemodellen auf Basis der logistischen Regression. Aachen: Shaker 2005; 1–221.
21. Larsson B, Sund AM: One-year incidence, course, and outcome predictors of frequent headaches among early adolescents. Headache 2005; 45: 684–91. MEDLINE
22. Aromaa M, Rautava P, Helenius H, Sillanpää M: Factors of early life as predictors of headache in children at school entry. Headache 1998; 38: 23–30. MEDLINE
23. Kröner-Herwig B, Morris L, Heinrich M: Biopsychosocial correlates of headache: What predicts pediatric headache occurrence? Headache 2008; 48: 529–44. MEDLINE
24. Rasmussen BK, Jensen R, Olesen J: Questionnaire versus clinical interview in the diagnosis of headache. Headache 1991; 31: 290–95. MEDLINE
25. Turkdogan D, Cagirici S, Soylemez D, Sur H, Bilge C, Turk U: Characteristic and overlapping features of migraine and tension-type headache. Headache 2006; 46: 461–68. MEDLINE
e1. Virtanen R, Aromaa M, Rautava P, Metsähonkala L, Anttila P, Helenius H et al.: Changes in headache prevalence between pre-school and pre-pubertal ages. Cephalalgia 2002; 22: 179–85. MEDLINE
e2. Laurell K, Larsson B, Eeg-Olofsson O: Prevalence of headache in Swedish schoolchildren, with a focus on tension-type headache. Cephalalgia 2004; 24: 380–8. MEDLINE
e3. Zencir M, Ergin H, Sahiner T, Kilic I, Alkis E, Ozdel L et al: Epidemiology and symptomatology of migraine among school children: Denizli urban area in Turkey. Headache 2004; 44: 780–5. MEDLINE
e4. Fendrich K, Vennemann M, Pfaffenrath V, Evers S, May A, Berger K, Hoffmann W: Headache prevalence among adolescents—the German DMKG headache study. Cephalalgia 2007; 27: 347–54. MEDLINE
e5. Hurrelmann K, Klocke A, Melzer W, Ravens-Sieberer U: WHO-Jugendgesundheitssurvey. Konzept und ausgewählte Ergebnisse für die Bundesrepublik Deutschland. Erziehungswissenschaft 2003; 27: 79–108.
e6. Roth-Isigkeit A, Thyen U, Raspe HH, Stoven H, Schmucker P: Reports of pain among German children and adolescents: An epidemiological study. Acta Paediatrica 2004; 93: 258–63. MEDLINE
e7. Walker LS, Zemann JL: Parental response to child illness behavior. Journal of Pediatric Psychology 1992; 17: 49–71. MEDLINE
e8. Esser G, Blanz B, Geisel B, Laucht M: Mannheimer Elterninterview (MEI): Strukturiertes Interview zur Erfassung von kinderpsychiatrichen Auffälligkeiten. Weinheim: Beltz 1989.
e9. Prochaska JJ, Salllis JF, Griffith B, Douglas J: Physical activity levels of Barbadian youth and comparison to a U.S. Sample. International Journal of Behavioral Medicine 2002; 9: 360–72. MEDLINE
e10. Lampert T, Sygusch R, Schlack R: Nutzung elektronischer Medien im Jugendalter – Ergebnisse der KiGGS-Studie. Bundesgesundheitsblatt. Ergebnisse des Kinder- und Jugendgesundheitssurveys 2007; 50: 643–52. MEDLINE
e11. Gaßmann J, Morris L, Heinrich M, Kröner-Herwig B: One-year course of paediatric headache in children and adolescents aged 8-15 years. Cephalalgia 2008; 28: 1154–62. MEDLINE