Factors influencing smoking experimentation: results of the ELSPAC study
Autoři: Hrubá Drahoslava, Okrajek Petr, Kukla Lubomír
Autoři - působiště: 1 Department of Preventive Medicine, Faculty of Medicine MU, Brno; 2 Research Institution of Preventive and Social Paediatrics, FM MU, Brno
Článek: Čas Lék čes 2012; 151: 141-148
Kategorie: Original Article
Počet zobrazení článku: 435x
The causes of children’ and adolescents‘ smoking, along with mechanisms which lead to addiction, include both genetic and environmental factors: individual, social and societal. The European Longitudinal Study of Pregnancy and Childhood (ELSPAC) collects data about the cohort of children from Brno and district Znojmo at scheduled stages from 18th week of prenatal to 19th year of age, using an international standardized questionnaire set. At the age of eleven the children first reported information on themselves. The aim of this study was to analyse different life conditions of 11-year-old children from Brno with different smoking behaviour.
Methods and Results.
Respondents filled in at home a questionnaire; according which they could be personally identified, and their answers reviewed by parents. These conditions could influence the truthfulness of statements. The cohort of 2160 children was divided into the 3 groups: never smokers (79.8%), with one single attempt (15.3%) and repeatedly smoking children (4.9%). The differences were evaluated using standard statistical tests. An important part of the reviewed population experimented with legal drugs: cigarette smoking (20%) and alcohol drinking (one third of never smoking and three quarters of smoking children); there were also sporadic experiments with other psychotropic substances. The age of 9–10 years was critical for the majority of children in relation to their first experiments with addictive drugs. Smoking children were more often exposed to passive smoking, they lived in substitute or non-harmonic families, had the worse relations to school and poorer school results, their leisure time was useless. They had more health problems and some conduct disorders.
Data obtained from 11-year-aged children from the ELSPAC study have confirmed that in the Czech Republic legal drugs are easily available for young-school aged children, and inadequate attention is addressed to realisation of some goals of the National Programme Health 21.
ELSPAC, children, age 11 years, smoking initiation, determinants, co-morbidity.
The opinion that smoking is the single most important high-risk factor and that it jeopardizes the health of both smokers and non-smokers by a wide range of damage including substantial shortening of one’s life has been universally accepted, as well as the evidence that children and adolescents are more susceptible to harmful effects of smoking than adults (1).
Despite the fact that experts continue searching for the causes of child and adolescent smoking and the mechanisms leading to the formation of addiction, they are in agreement that besides genetic influences it is also the environmental ones that play an important role. The latter may be divided into three groups of determinants: individual (knowledge and attitudes), social (parents smoking, other relatives and peers smoking, socioeconomic status of the family and of the smoker itself) and societal (legislation, advertising and promotion, presentation via mass media, tolerance of society toward self-destructive behaviour and its consequences) (2). Social and societal conditions have certain geographic and historical differences, including changes over the course of time and it is therefore important that their influences in local and national studies are analyzed repeatedly.
The European Longitudinal Study of Pregnancy and Childhood (ELSPAC), in which the Czech Republic participates since 1990, has been collecting data on a cohort of children from Brno and Znojmo districts by means of internationally standardized questionnaires. The data are being obtained in the predetermined age stages of the target population spanning the 18th week of prenatal life and the 19th year of age. Besides the descriptive depiction of incidence and prevalence of the observed indicators and their development trends the study also enables analytic evaluation of relationships between the conditions of life, way of life and health of children.
The children were eleven years old when the data was submitted for the first time also by the children themselves. It was the first phase of collecting anamnestic information on the cohort of children from ELSPAC study when data was obtained not only from parents, physicians and teachers (as in the previous phases).
This work analyses various aspects of behaviour and feelings of children who differ in their smoking behaviour. The children were asked in the questionnaire among other things whether they have already tried smoking and they were given 4 variants of answers to choose from: never so far, once only, more than once and many times.
Out of an extensive questionnaire comprising questions from 5 sections, indicators were selected which enabled to evaluate the following:
- smoking environment in the child’s family
- use of other legal (alcohol) and illegal drugs by the child
- social environment of the child in its family and school, including ways of spending its leisure time
- occurrence of selected behaviour disorders from the self-evaluating view of the child
- subjective feelings (health and happiness) in the past 6 months.
The differences were evaluated by Mantel-Haenszel, Yates and chi-square statistical tests in EPI INFO, version 6.04a and the ANOVA test.
Out of the total number of 2,179 children from Brno, who were observed at this stage of the ELSPAC study, 19 failed to answer the question on their experimentation with smoking, so that the results only relate to 2,160 children. Out of this number, the majority has not smoked yet (79.8 %), 15.3 % has a single experience with their first cigarette, 4.0 % smoked more than once and the response “I have smoked many times“ was selected by 0.9 % children. For further work with the data, the children who smoked multiple times (i.e. more than once and many times) were merged into a single group.
The children were not asked specifically about their parents’ and other household members’ smoking but they stated whether and for how long they spend time in an environment filled with smoke, in working days and in days they don’t have schooling. The children who have already tried smoking have been exposed to an environment filled with smoke at their homes significantly more often than children who have not had their first attempt yet. The time of exposition estimated by the children was one up to several hours each day, but almost 50 children out of the whole group have been exposed for most part of the day or the whole day. The number of children exposed increases significantly on non-work days (tab. 1).
Among the children with repeated and one-time smoking experience there were no significant age differences in the age when they smoked their first cigarette: most often between their 9th and 10th year of age (approx. 75 %). Prior to that - among 7th and 8th year of age – approx. 14 % of children smoked and around 6 % of children stated that they had made their first attempt at pre-school age. Only 4 % of children were attempting to smoke at the time of filling in the questionnaire, i.e. between their 11th and 12th year of age.
Children experimenting with cigarettes also stated consumption of alcoholic beverages significantly more often: 84.2 % of repeated smokers and 70.9 % of one-time smokers in comparison to 33.2 % of children with no smoking experience (p< 0.001). More than a half of repeated smokers consumed alcohol more times (up to many times); this frequency has also been stated by a third of one-time smokers and nearly 15 % of non-smoking children. The most critical period for most children (approx. 60 %) for initiation alcohol testing was also between their 9th and 10th years of age, the first contact with alcohol was stated by twice the number of children at pre-school age who stated their contact with a cigarette (approx. 10 %).
Statements on experience with other drugs were only sporadic: one repeated smoker tried other drugs, 2 one-time smokers and 2 non-smokers tasted “magic mushrooms“ (psilocybin mushrooms) and 5 children (4 non-smoking children and 1 one-time smoker) tried “sniffing“. The age when these experiments took place was again most often around 10 years of age.
Even though most children from all groups (more than 80 %) stated in agreement that their parents spent time talking with them and that they had not experienced physical harm, the smoking children were more often describing occurrence of stressogenic situation in their families: separation from their mother or father, living in a family with a surrogate parent, also frequent disagreements with their parents. Compared to non-smokers the frequency of these indicators was significantly higher in repeatedly smoking children (tab. 2).
Nearly two thirds of smoking and approx 58 % of non-smoking children receive regular pocket money, exceeding on average CZK 100 monthly (CZK 130 for regular smokers, CZK 102 for smokers with single attempt and CZK 112 for non-smokers). Differences between individual groups in the amount of average pocket money are not statistically relevant. The maximum monthly income values stated were: CZK 650 for repeated smokers, CZK 800 for children who only tried smoking once and CZK 1000 in a group of children who had never smoked. Another fourth of children in each group receives money for a certain purpose when they ask for it. Roughly 10 % of children receive money as a reward and several children (total of 109 from the whole sample) do not receive any money.
Their position among their fellow schoolmates is rated by children from all 3 groups similarly, mostly as harmonious on the whole. Even though the repeatedly smoking children did select answers that they are tolerated or refused by their schoolmates, that they are being attacked or even bullied; the differences against the frequency of responses in the group of non-smoking children were only on the border line of statistical significance (p = 0.06). The smoking children stated that they have at least one good friend significantly more often than those who had never smoked. Respondents in the smokers’ groups on the other hand answered significantly more often that they did not like school (constantly or rather often), more of them were also receiving bad marks (tab. 3).
Significantly more of the repeatedly smoking children spend their extracurricular time by wandering the streets, both in work and non-work days. They also spend more time watching TV and video, but in this regard the frequency of passive viewers has not differed statistically significantly from the group of non-smoking children (tab. 4). Majority of children from all groups (approx. 80 %) described that they engaged in sports and that they were fond of it, the remaining ones engage in sports because of their parents or friends. None of the children stated that they do not engage in sports at all. Children with various smoking experience differed significantly in their relation toward books: children who had smoking experience selected significantly less often the answer that they “are fond of reading“, on the other hand they stated more often that they were not fond of reading and that they did not read at all (tab. 4).
Statements about behaviour disorders (petty thefts, lying or making up) have appeared among the smoking children more frequently. Truancy was rather sporadic on the other hand in all of the evaluated groups: a total of 32 children out of the whole sample admitted it (tab. 5).
Smoking children, especially those who smoked repeatedly, described occurrence of hyperactivity and decreased ability to concentrate and also impaired health (headaches, stomach ache) among their subjective feelings in the last 6 months significantly more often than non-smokers. Even though majority of children selected answer to the question “how do they feel on the whole“ as ”always or nearly always good“, the frequency of these answers among smoking children was significantly lower than among those who do not have smoking experience yet (tab. 6).
Most epidemiological studies based on questionnaire surveys guarantee anonymity to their respondents or at least discretion in regards to the surveyed data. The respondents of ELSPAC study, adults and children, are on the contrary identifiable and the questionnaires filled in their homes are sent together. It may be assumed then that at least part of the children might have changed their statements relating to delicate questions on their environment and behaviour in fear of their disclosure to the parents.
The stage of data collection from eleven-year old children of the ELSPAC sample is dated into years 2002/3. In 2010, data on smoking were acquired from the sample of equally old children monitored within the interventional longitudinal study to verify the effectiveness of the primarily preventative programme “Non-smoking is normal“. Most children from this later study are also from Brno or former district towns, questionnaires are filled in anonymously at school (3). The studies show a similar number of children who tried smoking once only (15.3 % and 17.2 %). But in the sample from 2010 a threefold number of children stated that they smoked repeatedly (15.4 % vs. 4.9 % in ELSPAC) and there were fewer children who had never smoked (67.5 % vs. 79.8 %); the differences from the ELSPAC data are statistically highly significant (p < 0.001). From the available materials it cannot be inferred whether these differences are influenced by a different data collection methodology (addressed vs. anonymous surveying) or whether the situation in the field of children smoking at the age of puberty onset has aggravated over the 10-year period.
The Czech Republic regularly takes part in the international study of the World Health Organisation HBSC (Health Behaviour in School-Aged Children), monitoring among others the consumption of legal and illegal drugs on representative samples of school children at the ages of 11, 13 and 15 years. Anonymous questionnaires were completed in years 1994, 1998 and 2002 (4). Unfortunately, the criterion for assessing smoking status was a definition of a regular smoker smoking at least one cigarette a week; these constituted 2 % among eleven-year-old students of 5th grades in 2002. The report does not state the number of children who have not experimented with smoking yet, therefore both studies cannot be compared.
More detailed differentiation between smokers in an HBSC study was only conducted on teenagers, among whose 64.4 % of adolescents have not tried smoking yet, which is only a little more (not significantly) than in the sample of eleven-year-old children from 2010. This comparison would rather give evidence to the hypothesis on a growing trend of smoking experimentation at elementary schools in the past decade.
Apart from the above-mentioned doubts as to providing truthful statements on requested information regarding smoking, the results of the ELSPAC sample prove the relationship usually found between smoking and other conditions in which children are living.
Numerous studies from various parts of world as well as domestic environment describe that children who have already tried smoking have more frequently smoker parents or other household members and relatives they are in frequent contact with (e.g. 4, 5, 6, 7, 8, 9, 10, 11 and 12). In this way close relatives significantly influence attitudes toward smoking which children from smoker families consider as normal part of adult life and want to imitate (13). Cigarettes are also more easily available to children in the families of smokers (14, 15) and rules regarding smoking at home or in a car either do not exist or are very vague (16, 17). A recent study conducted in Hong Kong found that initiation of child smoking is statistically significantly contributed by the actual chronic exposition to the passive smoking itself, independently of the parents smoking (18).
ELSPAC study confirmed these conclusions; smoking children stated exposition to a smoke-filled environment of their homes significantly more often than the children who had not yet had their first attempt. The number of exposed children significantly increased on non-work days, when adult smokers stay together with their family.
ELSPAC children experimenting with smoking also stated consumption of alcoholic beverages significantly more often, which also corresponds not only with our older (19, 20 and 21) and more recent findings (4, 11 and 22) but also with numerous results of international literature (e.g. 23, 24, 25 and 26). Various local and representative studies show that consumption of alcoholic beverages in children population is a very urgent problem. Even though the legal age for sale and consumption of state-tolerated drugs (alcohol, tobacco) is 18 years, many parents and relatives of children ignore the legislative norms and not only tolerate but also offer consumption of these drugs to children. It is especially sipping of alcohol on important holidays and family celebrations that is connected to helping children to alcohol (11).
According to retrospective statements of fifteen-year-old respondents of the Czech HBSC study, most children taste their first alcohol at the age of 11-12 years (4) but by surveying eleven-year-old children in the ELSPAC sample, where data was also collected retrospectively, the critical period for majority (75 % children) was the age between 9th and 10th year. In the prospective observation of the “Non-smoking is normal” programme study 60 % of seven-year-old pupils of the 2nd grade of elementary schools admitted having tasted alcoholic beverages, a year later the frequency of positive answers in the same cohort increased by further 10 % (11). It can be concluded that retrospectively obtained data from children respondents may be burdened by considerable inaccuracies in the estimation of the age of the first experience with risky behaviour.
What is rather surprising is the information on experimentation of ELSPAC children with illegal drugs, intoxicants, substances used for sniffing and consumption of mushrooms containing psychoactive substances. These were stated not only by children with cigarette experience but also by those who had not smoked yet. These data were submitted by individuals only and it cannot be ruled out that it was just these questions where many of the children might have withheld the true facts because of fear of disclosure. The use of illegal drugs in the HBSC study was only surveyed on a sample of fifteen-year-old adolescents and with the exception of marihuana, where at least one experimental use was admitted by 31 % of boys and 23 % of girls, the other drugs surveyed were mentioned rather sporadically. Nevertheless authors of the study warn that children from secondary schools are exposed to an environment where drugs are easily accessible (4). Our results show that at the same time it could also have been children from elementary schools who could encounter these drugs.
Social status of a child in a family and the position it holds among its peers is very important for acquiring experience and the process of socialization. Family influence is asserted significantly during childhood, in the period of puberty and adolescence it weakens for the benefit of peers’ influence (27). The environment in family, school, interest groups and society has always been characterized by certain standards and rules, which children gradually become aware of. If they want to belong into a certain social group, they accept them and abide by them during the process of their socialization (28). Responsiveness toward social-environmental influences may change over the course of life, especially in relation to the influence of peers (29).
Several studies state that chronic stress and depression in children and adolescents increase their sensibility to social factors connected to smoking (30). Tobacco provides a smoker with relief and reward through nicotine, which acts on the release neurotransmitters (primarily dopamine) by activating “nicotine“ receptors, and affects the release and activation of sympatico-adrenergic axis (31). Conditions in the family or at school may act as the source of chronic stress in children.
The parents’ role lies not only in creating the behavioural model but they are also important in their controlling and supporting role. Many studies have focused on analyses of these roles according to family structure and they have identically come to conclusions that the best conditions are secured to children in a complete family with two biological parents (14), while in incomplete families or families with a surrogate parent the environment leads children and adolescents to more frequent consumption of legal or illegal drugs (4, 32, 33, 34, 35). However, these relationships were not confirmed in several studies (12, 36, 37). Also the two-way relationship between family condition and initiation of children to smoking was not confirmed in the sample of children from the “Non-smoking is normal“ programme (38). But after the inclusion of “parents education“ indicator there were significantly more eleven-year-old children with no smoking experience in complete families with two biological parents when the mother had university education (39).
The smoking children in the ELSPAC sample lived more often in surrogate families and stated separation from their mother or father and frequent disagreements with their parents more often. In comparison to non-smokers, the frequency of these indicators was significantly higher in repeatedly smoking children. In this case the ELSPAC study also confirmed the relationships between stress-invoking family environment and smoking described by authors earlier.
The position of children with various smoking behaviour among their schoolmates was judged by children from all three groups of the ELSPAC study similarly, mostly as harmonious on the whole. Smokers described that they have a good friend even more frequently, but more children from this group also provided positive statements of refusal up to bullying; but the differences between the frequencies of these data between non-smokers were not statistically significant. The seeming paradox of these statements may give evidence to the fact that smokers may understand the term “friendship“ more superficially, their parents do not fulfil the role of moderators in creating friendship relationships and of the “protectors against wrong friends“ (28).
Nevertheless for some 5th grade pupils from the ELSPAC sample, school environment represents stress, which has been demonstrated in significantly higher frequency of responses from smokers that they do not like school attendance. A very important factor contributing to the low popularity of school were certainly bad school results, which were also more frequent among the repeatedly smoking children. This is also related to a higher frequency of purposeless way of spending their free time by wandering the streets, and disliking reading which develops imagination and inspiration. Such findings are in accordance with foreign findings and are warning especially for the reason that they belong among factors significantly influencing the development from smoking experiments to regular smoking and gradual development of addiction (40, 41).
Stressful family and school environment is accompanied by psychic discomfort and may lead up to development of depressive conditions. Most of the studies that focused on finding relations between smoking habit and occurrence of depression found positive associations (42). However the question of the chronological order of these two factors has not been satisfactorily answered yet: whether it is depression that leads to the smoking habit or on the contrary, whether it is smoking that may trigger depression. Biologically acceptable explanations exist for both theories: people with feelings of anxiety and depression may start smoking because nicotine – by means of neurotransmitters – helps them to cope with unpleasant moods and psychic states. Contrariwise, in psychically healthy smokers depression may start developing slowly as a result of disregulation of the hypothalamic- pituitary -adrenergic system and hypersecretion of cortisol, which regulates biological and psychogenic responses of the organism to a stress.
The period of puberty and adolescence is critical both for the development of depressive symptoms and for the commencement of smoking. Dramatic developmental and neurobiological changes are taking place in the course of adolescence which may influence both sensibility toward effects of drugs and susceptibility to stimulations triggering depression (43). Both hypotheses were confirmed in the well-arranged and analytically elaborated studies published in the years 1990 - 2007: 12 studies made a case for primary depression, which the affected individuals could deal with at least in the beginnings by means of smoking. On the other hand, 6 other studies proved that it was the smoking as the primary factor which led to the development of depressions. In both cases the relations were statistically highly significant (44).
The results of ELSPAC sample indicate that more of eleven-year-old children living in stressogenic family or school environments experiment with smoking. That would provide evidence for the theory that repeatedly smoking children are looking for and they do find help in smoking to cope with their adverse moods. However, because children who do not describe these adverse conditions in their lives smoke as well it may not be ruled out that development of depressive psychological disorders might occur in these individuals in the horizon of the following few years. The ELSPAC study will enable research of these connections in the next phases of surveying as the data collection will be completed in the 19th year of the respondents’ life.
Data on behaviour disorders among smoking ELSPAC children (single and repeated smokers) appeared more often (lying on purpose, petty thefts, anger outburst), hyperactivity (restlessness, fidgetiness), attention disorders (fidgetiness, distractedness, inability to concentrate). Smoking children also described feelings of illness (headache, stomach-ache, fatigue) more often. On the other hand, significantly fewer smoking children stated that over the last 6 months they felt good or nearly always good, both in the health and psychic respect.
Behaviour disorders characterized by negativism, aggressiveness, low ability to concentrate and disproportionate reactions (anger outbursts) occurred in the same cohort of children already in their 7th year of age at physician’s examination with a frequency of 4.4 %. Noticeable hyperactivity, psychomotoric development, school readiness and sleeping disorders also occurred among these children significantly more often. In the next stage of surveying, at the age of 8 teachers confirmed that results of these children with behaviour disorders are worse at mathematics and reading and their social adaptability to school environment was also worse. In chain of causation, an important influence identified in relation to the behaviour disorders and other comorbidities was the smoking of mothers during pregnancy (45). However, the frequency of all observed behaviour indicators in the preceding stage of surveying has been lower when surveyed by other person (physician, teacher) than in the probands’ subjective data at the time when they reached the age of eleven years.
The many years of research into causes of antisocial behaviour disorders occurring in childhood have uncovered both genetic and societal influences (46). The forefront of experts’ interest has recently focused on the factors influencing the individual prior to its birth. It has been confirmed repeatedly that suboptimal conditions of the intrauterine development may trigger manifestations of maladaptation, including the decrease of cognitive abilities, mental retardation, antisocial behaviour or attention disorders and hyperactivity (47). It is primarily exposure to cigarette smoke that belongs among the examined factors disrupting brain development in prenatal period. At least 40 studies have confirmed that smoking in pregnancy significantly increases occurrence of various neurologic dysfunctions and antisocial behaviour in offspring which manifest themselves in childhood and adulthood (48). It is true that behaviour disorders in man are the result of the effect of a complex of many factors that make it difficult to determine whether smoking has causal influence; nevertheless connections to prenatal exposure to smoking were also proved in animal models (49).
This study did not analyze relationships between selected data obtained from children and their prenatal exposition to factors, which could negatively influence their intrauterine and postnatal development that were found in the preceding stages; this shall still be the subject of another paper.
Anamnestic investigation of Brno children in the ELSPAC study has proved that at the age of 11 a significant part of this population experiments with legal drugs – cigarette smoking and alcohol drinking, and sporadically with other psychotropic substances. The following was confirmed in smoking children: not only conditions considered as classic initiation causes of this auto-aggressive behaviour (exposure to passive smoking, family environment, dislike of school, lack of stimuli in after-school hours), but also more frequent occurrence of other problematic behaviour indicators and worse health.
In several targets of the Health 21 programme, which were also adopted by the Czech Republic national programme, emphasis has been put on the creation of conditions enabling children and adolescent youth to adopt a healthy lifestyle (50). The fulfilment of specific targets must be shared between the state and its institutions, families and each and every individual. Various studies have brought evidence that despite several partial successes, the Czech Republic has not been paying sufficient attention to these targets. The findings of the ELSPAC study contribute to these conclusions.
ELSPAC = European Longitudinal Study of Pregnancy and Childhood
Thank you note: This study was supported by a grant from Internal Grant Agency of Ministry of Health R, No. NS 9669-4/2008.
Prof. MUDr. Drahoslava Hrubá, CSc.
Department of Preventive Medicine, FM MU
625 00 Brno
Tel: (+420) 549 494 068
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