OUP user menu

Use of dietary supplements and anabolic-androgenic steroids among Finnish adolescents in 1991–2005

Ville M. Mattila , Jari Parkkari , Lauri Laakso , Harri Pihlajamäki , Arja Rimpelä
DOI: http://dx.doi.org/10.1093/eurpub/ckp124 306-311 First published online: 26 August 2009

Abstract

Background: The aim of the study was to describe the prevalence, trends and associated factors of dietary supplements (DS) and anabolic-androgenic steroids (AAS) use among Finnish adolescents. Methods: The sample comprised 30 511 adolescents aged 12–18 years, of which 22 519 (74%) answered a questionnaire. We also studied associations between 14 socioeconomic, health and health behavioural variables and DS and AAS use by logistic regression. Results: The proportion of respondents using DS was 45% during the past year and it increased linearly by age. Vitamins (37%) and herbal products (13%) were the most common DSs. In 1991, 9% of the boys aged 16–18 years reported protein use, while the frequency in 2005 was 17% (P < 0.001). AAS use was uncommon; only 53 boys (0.5%) and 20 girls (0.2%) reported AAS use. The strongest factors associated with DS use in multivariate model were physical exercise outside sports clubs (OR 1.9; 95% CI: 1.6–2.2), and in sports clubs (OR 1.7; 95% CI: 1.5–1.9). Recurrent drunkenness (OR 5.8; 95% CI: 1.5–21.6) and peer drug use in boys (OR 2.1; 95% CI: 1.2–3.7) were the risk factors for AAS use, whereas physical exercise outside sports clubs (OR 0.3; 95% CI: 0.1–0.5) was a protecting factor. Conclusions: Although the overall use of DS remained at the same level during the study period, there was a slight trend towards increasing use of vitamin and protein supplements. DS use is associated with frequent sports participation and poorer than average health, while AAS use is associated with health-compromising behaviours.

  • adolescents
  • anabolic-androgenic steroids
  • dietary supplements
  • health behaviour
  • risk indicators
  • epidemiology

Introduction

The availability and usage of dietary supplements (DSs) have been increasing dramatically among adolescents in the USA in the past decade,1–3 while in European countries knowledge on use is insufficient. Although it has been emphasized that diet is the best source of nutrition for healthy children and adolescents,4 the use of DS is popular and prevalence figures ranging from one-third to half have been reported.3,5 DS use is even more common among athletes,6 which has been explained by the fact that they are thought to improve physical performance.7

The most common DS among adolescents are vitamins, iron, protein supplements and herbal products.2,8,9 In addition, adolescents have also used anabolic-androgenic steroids (AASs) to increase the peak physical performance and muscle mass. The non-competing use of AAS has been reported since 1980s and despite largely studied adverse effects, such as myocardial hypertrophy, hypogonadism, negative changes in serum lipid profile and psychiatric disorders,10,11 the use of AAS has seemed to increase.12 At the same time, pursuit of muscularity and low-body fat has become more popular.13 Nowadays, in addition to improve results in sports, the motive for DS use and especially AAS use is self-image improvement13 by increasing muscle mass and by decreasing body fat. In Finland, as in many other countries, importing and selling of AAS has been criminalized, but there is no law to ban the use.

The prevalence of AAS use among adolescents has been mainly studied in the USA,12 and occurrence figures had varied from 3% to 11%.12 A recent study from the USA showed an increasing trend in AAS use in the 1990s, while the latest figures showed a decline in AAS use.12 In 2007, 3.9% of participants had used AAS.14 Information on the prevalence of DS and AAS use outside the USA is scarce. A study comparing AAS use in six developed countries in Europe (France, Germany, Greece, Italy, Israel and Finland) showed that the occurrence of lifetime use of AAS was 2.6%.15 Steroid use was more common among males and no significant variation between the countries included was found.15 A survey study from Sweden revealed that the lifetime prevalence of adolescent males aged 16–17 years using AAS was 3%.16

In addition to sports activities,15,17 it has been suggested that DS and AAS use in adolescents is related to health-compromising behaviours.18,19 Increased frequency of smoking,18 alcohol consumption15 and drug use20 have shown to be related to AAS use.

Given the fact that the recent trends and prevalence of DS and AAS use are poorly known in Europe, the aim of the present study was to describe the prevalence of DS and AAS use during the past year as well as socioeconomic, health and health behavioural associative factors among Finnish adolescents.

Methods

The biennial Adolescent Health and Lifestyle Survey (AHLS) (Finland) is a nationwide monitoring system of health and health-related lifestyle conducted since 1977.21 Two re-inquiries were sent to non-respondents after 3 and 7 weeks. The materials with respect to sampling, research methods, questions and time of inquiry were maintained as similar as possible for each year. The sample of 12-, 14-, 16- and 18-year olds was drawn from the National Population Register Centre through selection of all Finns born on certain days in June, July or August. The mean ages of the respondents were 12.6, 14.6, 16.6 and 18.6 years. Adolescents were asked about their performance-enhancing substance use in 1991, 1995 and 2005.22 The numbers of respondents and response rates were: 1991 (n = 7634, 77%), 1995 (n = 8382, 79%) and 2005 (n = 6503, 66%). The total number of respondents was 22 519 and the response rate was 74%. The questionnaires have always been anonymous, and thus, without any information about identification.

The main outcome variables in our study were self-reported lifetime DS and AAS use. They were elicited with the question ‘Have you used the followings during the past year in order to enhance your performance?’ The following alternatives were: ‘vitamins, protein supplements, iron supplements, herbal products, AASs, other’. In the present study, vitamins, proteins and iron supplements, herbal products and others were combined and they are referred to as DSs.

Background variables

Altogether, 14 categorical variables from the Adolescent Health and Lifestyle Survey were used to explore association between them and in relation to self-reported use of DSs (vitamins, protein supplement, iron and other) and AASs. All of these were self-reported, with the exception of age, sex and urbanization level of residence, which were derived from the sample information (Population Register Centre). The repeatability of the background variables has been previously tested and shown to be good.23 Those who did not respond to the questionnaire and single questions that remained unanswered from the analyses were excluded. Sociodemographic background was investigated by three variables. Social position of the adolescent's family was measured by father's or other guardian's education, which was classified as low (≤9 years of education), middle (9–12 years) and high (>12 years). The structure of the respondent's family indicated whether the respondent was living with his own parents or not. Urbanization level of residence was determined by the population density: capital area (Helsinki and the adjoining towns), large town (population over 100 000), small town, village (densely populated areas in rural municipalities) or sparsely populated rural municipality (isolated homesteads in rural municipalities).

Adolescents’ health was monitored in terms of their perceived health status, chronic disease or disability restricting daily activities. A summary index of eight stress symptoms (stomach aches, tension, irritability, sleep difficulties, headache, trembling of hands, feeling tired or weak, feeling dizzy) perceived weekly was calculated. Body mass index (BMI) was calculated by dividing weight (kg) with the square of height (m). The cut-off points of overweight were set according to Cole and colleagues,24 being 21.56 and 22.14 kg/m2 in 12-year-old boys and girls, 22.96 and 23.66 kg/m2 in 14-year-old boys and girls, 24.19 and 24.54 kg/m2 in 16-year-old boys and girls and 25 kg/m2 in 18-year olds.

Adolescents’ health-compromising behaviours were described by daily use of tobacco and drinking style (abstinence, occasional drinking, recurrent drinking and recurrent drunkenness). Health-enhancing behaviours were described by the frequency of participation in organized sports, and other leisure time physical exercise by combining activities done alone, with friends or with family members. In addition, adolescents were asked about peer drug use.

In statistical analysis, age-, sex- and survey year-adjusted logistic regression models were used and association between each background variable and both outcome variables (DS use and AAS use) were tested separately (table 1). Odd ratios (OR) were calculated with 95% confidence intervals (95% CI). We also analysed the risk factors of specific supplement use inside the DS category (vitamins, protein and iron supplements, herbal products and others) separately, but since significant difference was not seen, they were analysed as a group (DS). The moderating effects of gender were tested in logistic regression analysis by creating an interaction term (gender*background variable). For all variables with a significant moderating effect (P < 0.1) between variable and gender, the analysis was performed separately for males and females. For those variables for which the moderating effect of gender was significant, a new variable was created taking into account gender and specific background variables (daily smoking and frequency of drunkenness) and these were used in multivariate analysis.

View this table:
Table 1

Age, sex and survey year-adjusted odds ratios by adolescent background variables for DS and AAS usea

Background variableOR (95% CI) for DS useOR (95% CI) for AAS use
Urbanization level of residence
    Capital area (Helsinki and the adjoining towns11
    Large town (population over 100 000)1.0 (0.9–1.1)0.8 (0.3–2.1)
    Small town1.0 (0.9–1.1)1.0 (0.5–2.3)
    Village1.0 (0.9–1.1)1.6 (0.5–3.0)
    Sparsely populated rural municipality0.8 (0.70.9)0.8 (0.3–2.0)
Family composition
    Own biological parents11
    Other1 (1.0–1.2)1.3 (0.8–2.2)
Father's or other guardian's education
    High11
    Middle1.1 (1.0–1.2)1.7 (0.8–3.3)
    Low1.0 (0.9–1.1)1.8 (0.8–4.1)
Perceived health status
    Excellent11
    Good1.6 (1.51.8)0.5 (0.30.9)
    Poor1.1 (1.0–1.1)1.4 (0.8–2.5)
Chronic disease or disability
    No11
    Yes1.4 (1.21.5)1.7 (0.9–3.3)
Number of health complaints weekly
    011
    11.2 (1.11.3)1.2 (0.6–2.2)
    21.3 (1.21.4)0.5 (0.2–1.4)
    3+1.7 (1.61.9)2.4 (1.44.2)
Overweight
    No11
    Yes0.9 (0.80.9)1.7 (1.0–3.0)
Smokingb
    Boys not daily11
        daily0.9 (0.8–1.0)3.3 (1.85.9)
    Girls not daily11
        daily1.1 (1.0–1.2)2.8 (1.0–7.5)
Peer drug use
    No11
    Yes1.4 (1.31.5)2.5 (1.54.1)
Drinking styleb
    Boys abstinence11
        Occasional drinking1.6 (1.51.8)1.7 (0.5–6.5)
        Recurrent drinking1.7 (1.51.9)3.3 (0.9–11.7)
        Recurring drunkenness1.9 (1.62.1)10.2 (3.034.6)
    Girls abstinence11
        Occasional drinking1.5 (1.31.6)1.5 (0.4–5.1)
        Recurrent drinking1.7 (1.51.9)1.0 (0.3–4.2)
        Recurring drunkenness1.9 (1.62.1)1.5 (0.3–6.8)
Frequency of participation in sports clubs
    Never11
    Two to three times a week or less1.2 (1.21.3)0.8 (0.5–1.4)
    Four to five times a week or more1.7 (1.51.8)1.7 (0.9–3.1)
Frequency of other physical exercise
    Never11
    Two to three times a week or less1.5 (1.3–1.7)0.2 (0.1–0.4)
    Four to five times a week or more1.8 (1.6–2.1)0.4 (0.2–0.7)
  • Significant variables are shown in bold

  • a: Bivariate logistic regression models

  • b: For those variables (smoking and drinking style) for which the moderating effect of gender was significant (P < 0.1), boys and girls were analysed separately

Finally, all significantly associated background variables were entered into the same age-, sex- and survey year-adjusted multivariate logistic regression models for both outcome variables (DS and AAS use) (table 2). To test for possible time effects, the data were divided into three data sets based on the survey year, and separate logistic regression models were calculated for each year. However, since no time effect was seen (data not shown), a pooled analysis of all data was performed including the study year in the analysis.

View this table:
Table 2

Multivariate logistic regression model for DS and AAS usea

Background variableOR (95% CI) for DS useOR (95% CI) for AAS use
Urbanization level of residence
    Capital area (Helsinki and the adjoining)1NI
    Towns1.0 (0.9–1.1)
    Large town (population over 100 000)1.0 (0.9–1.1)
    Small town1.0 (0.9–1.1)
    Village0.9 (0.8–1.2)
    Sparsely populated rural municipality
Perceived health status
    Excellent11
    Good1.0 (0.9–1.1)0.4 (0.20.8)
    Poor1.0 (0.9–1.1)0.7 (0.4–1.4)
Chronic disease or disability
    No1NI
    Yes1.3 (1.21.5)
Number of health complaints weekly
    011
    11.2 (1.11.3)1.2 (0.6–2.4)
    21.2 (1.11.3)0.5 (0.2–1.4)
    3+1.6 (1.51.7)1.6 (0.8–3.2)
Overweight
    No1NI
    Yes1.0 (0.9–1.1)
Smokingb
    Boys not dailyNI1
        daily2.0 (0.9–4.0)
    Girls not daily0.1 (0.0–0.7)
        daily0.2 (0.0–2.0)
Peer drug use
    No11
    Yes1.2 (1.11.3)2.1 (1.23.7)
Drinking styleb
    Boys abstinence11
        Occasional drinking1.4 (1.21.6)1.2 (0.3–5.2)
        Recurrent drinking1.4 (1.21.4)2.4 (0.6–8.9)
        Recurring drunkenness1.3 (1.11.6)5.8 (1.521.6)
    Girls abstinence0.7 (0.6–0.9)2.1 (0.4–12.5)
        Occasional drinking0.9 (0.8–1.0)2.7 (0.6–12.0)
        Recurrent drinking0.8 (0.7–1.0)1.2 (0.3–5.3)
        Recurring drunkenness1.0 (0.9–1.1)1.8 (0.3–7.2)
Frequency of participation in sports clubs
    Never1NI
    Two to three times a week or less1.2 (1.21.3)
    Four to five times a week or more1.7 (1.51.9)
Frequency of other physical exercise
    Never11
    Two to three times a week or less1.5 (1.31.7)0.3 (0.10.5)
    Four to five times a week or more1.9 (1.62.2)0.5 (0.2–1.1)
  • NI = not included

  • Significant variables are shown in bold

  • Nagelkerke's R2 for DS model was 0.063 and for AAS model 0.113

  • a: Models included all significant variables from the age, sex and survey year-adjusted models

  • b: For those variables for which the moderating effect of gender was significant (drinking style and gender, P = 0.035, smoking and gender P = 0.042), a new variable was created taking into account gender and specific background variables (daily smoking, frequency of drunkenness)

The logistic regression analyses were performed only on those respondents who had provided answers to every question and, thus, persons with incomplete answers were excluded. The frequency of missing values in the explanatory variables varied from 1% to 4% and in multivariate models from 4% to 7%.

Results

The overall proportion of respondents with the use of DS for performance-enhancing purpose during past year was 45% (n = 10 107). Girls (49%) reported DS use more often than boys (40%) (P < 0.001). The proportion of DS use increased linearly by age; among 12-year olds, 36% of the boys and 40% of the girls had used DS, while the corresponding figures among 18-year olds were 44 and 57%. Supplementary table S1 shows the distribution of substances by sex. Vitamins (n = 8429, 37%) and herbal products (n = 2804, 13%) were the most common DS. Boys (n = 722, 7%) reported protein use significantly more often than girls (n = 160, 1%) (P < 0.001). The overall use of DS remained at the same level during the study period between 1991 and 2005. The use of herbal products among 16- to 18-year-old girls decreased from 21% in 1991 to 12% in 2005 (P < 0.001), while the use in other age and sex groups remained at the same level (figure 1). An increasing trend in protein use among 16- to 18-year-old boys was seen (figure 2). In 1991, 9% of boys aged 16–18 years reported protein use, while the corresponding figure in 2005 was 17% (P < 0.001). The use of vitamin products remained at the same level during the study period. Iron supplementation use showed a slightly decreasing trend, 15% of girls aged 16–18 years reported iron use in 1991, while 11% of the girls in the same age group reported iron use in 2005 (P < 0.001). The use of other dietary supplementation increased during the study period between 1991 and 2005, but remained at low level (Supplementary table S1).

Figure 1

Percentage of users of herbal products by age, sex and survey year

Figure 2

Percentage of users of protein supplement by age, sex and survey year

AAS use was uncommon among Finnish adolescents between 1991 and 2005. Only 53 boys (0.5%) and 20 girls (0.2%) reported AAS use (P < 0.001). No clear difference in AAS use by age was seen (Supplementary table S1). The proportion of adolescents reporting AAS use did not vary during the study period.

When factors associated with DS and AAS use were studied, it was seen that boys reported 3.1 (95% CI: 1.9–5.2) times higher AAS use prevalence than girls. In the age-, sex- and study year-adjusted logistic regression models, the strongest risk factors of DS use were recurrent drunkenness as drinking style (OR 1.9; 95% CI 1.6–2.1 in girls and 1.9; 95% CI: 1.6–2.1 in boys), participation in other physical exercise four to five times or more weekly (OR 1.8; 95% CI: 1.6–2.1) and more than three health complaints weekly (OR 1.7; 95% CI: 1.6–1.9). The strongest risk factors of AAS use were recurrent drunkenness as drinking style (OR 10.2; 95% CI: 3.0–34.6) and daily smoking in boys (OR 3.3; 95% CI 1.8–5.9). The age-, sex- and study year-adjusted logistic regression models are shown in table 1.

When all significant variables from the age-, sex- and survey year-adjusted models were entered to the same multivariate logistic regression model (table 2), the strongest factors associated with DS use for the whole cohort were frequent participation in other sports (OR 1.9; 95% CI: 1.6–2.2), frequent participation in sports clubs (OR 1.7; 95% CI: 1.5–1.9) and reporting more than two health complaints weekly (OR 1.6; 95% CI: 1.5–1.7). In the multivariate logistic regression model for AAS use, the strongest associated factors were peer drug use (OR 2.1; 95% CI: 1.2–3.7). Participation in sports outside sports clubs two to three times or less per week seemed to decrease the risk of AAS use (OR 0.3; 95% CI: 0.1–0.5). Also good self-reported health status decreased the risk of AAS use (OR 0.4; 95% CI: 0.2–0.8) compared with those reporting excellent health status. For those variables for which the moderating effect of gender was significant (smoking and drinking style), boys and girls were analysed separately. Boys reporting recurrent drunkenness had 5.8 times (95% CI: 1.5–21.6) higher rates of AAS use in multivariate models than boys reporting abstinence.

Discussion

The aim of this study was to get a reliable insight into the DS and AAS use in Finnish adolescents in 1991–2005. Almost half of the 22 519 respondents reported DS use during the past year, girls were more than boys. The overall use of DS remained at the same level during the study period between 1991 and 2005. Vitamins and herbal products were the most common substances. Use of protein supplements almost doubled among boys aged 16–18 years. AAS use seems to be rare in Finnish adolescents; only 0.3% of the respondents reported AAS use. Several factors associated with DS and AAS use were found. DS use was associated not only with frequent participation in sports but also with poorer health than average. AAS use was associated with peer drug use. Frequent sport participation outside sport clubs was associated with decreased AAS use.

In the present study, the proportion of adolescents reporting DS use during past year was 45%, which is a somewhat lower figure than that reported in the USA.2,3,25 Picciano and coworkers found that ∼30% of adolescents aged 12–18 years had used dietary supplementation during the past month. Also somewhat higher figures than ours were presented in the study of Hoffman and colleagues,26 in which 71% of the adolescent respondents had used at least one DS. A recent study among high-performance Canadian athletes aged 20 years showed that 88% of respondents had used DS during past 6 months.6 Taking current recommendations for adolescent nutrition into account, in which DSs are recommended only in specific situations, such as in nutritional deficiencies,4 the prevalence of 45–88% reported among adolescents can be considered high. Also adverse effects of DS may be more common as previously thought.27 Taking these facts into account, health care professionals should ask their patients about DS use; and adolescents and their parents should be reminded that DSs are not substitutes for a healthy and sufficient diet.

Multivitamins and minerals were the most common used DS among Finnish adolescents, which is in accordance with the previous studies.3,9,26 The trend of DS use did not vary significantly during the 15-year study period. This finding is similar to the previous studies from the USA.3 However, we found that overall use of vitamin products increased somewhat from 37% to 40% and use of protein supplements from 3% to 6%. The increase in protein use was most visible in boys aged 16–18 years. The reason for this is not known, but the increase in protein use may be related to pursuit of muscularity, which has become more popular.28 In addition, weight training at gym has increased.

The proportion of respondents reporting AAS use in our sample was only 0.3%. This is a significantly lower figure than previously reported. In an international report describing AAS use in several European countries, the frequency of AAS use in Finnish University students was 3.9%.15 However, a third of this sample consisted of individuals from the faculty of sports science, including a large number of competing athletes. In addition, study subjects were markedly older (19- to 25-year olds) than persons in the current sample (12- to 18-year olds). Most of the studies describing AAS use among adolescents have been performed in the USA,12 where the prevalence of AAS use has varied from 3% to 11%.12 The Youth Risk Behavior Survey of 2007 (9th to 12th graders) showed that 3.9% of the participants had used AAS.14 Accordingly, it appears that AAS use is substantially more common in the USA than in Finland. However, a Swedish survey reported, surprisingly, high figures of AAS use in an age group corresponding with that of ours; the prevalence of AAS use among Swedish males aged 16–17 years was 3.9%.16 The reason for this difference is not known.

In the present study, DS use was associated with sports in and outside sports clubs, several health complaints weekly and drunkenness as drinking style. These background variables maintained their significance even when other confounding variables were taken into account. Adolescent athletes are known to use DS more often than average adolescents,1,3,6 which is at least partly explained by the fact that they are thought to support the development of physical performance. On the other hand, the use of DS can be thought to be part of wellness-oriented lifestyle.1 However, DS use was also associated with health complaints in our study. This finding is contradictory to a previous study showing that those reporting poor health status use DS less frequently.25 However, the association between poorer health and DS use may be explained by the idea of adolescents trying to treat their symptoms with DS.

The risk factors of AAS use were related to health-compromising behaviours, such as peer drug use and frequent drunkenness in boys. Previously, the use of AAS has shown to be strongly related to weight training at fitness centres.19,29 Unfortunately, we had no questions concerning weight training at gym, but interestingly, sports participation outside sports clubs seemed to decrease AAS use in our sample. It seems that those adolescents engaging in health-promoting behaviours, such as sports, rarely use AAS. In addition, it is possible that persons using other substances, such as alcohol, tobacco and drugs, may have a lower threshold to use AAS too. Previous studies have shown the association between AAS use and drinking until drunkenness.15,19

It should be noted that our study had some limitations. Although the response rates were at a good level (from 58% to 86%, depending on the age, sex and survey year), we naturally had to take non-response bias into account. It is possible that especially AAS use may be more common among the non-respondents, and thus, the results may somewhat underestimate the true prevalence of AAS use. In addition, it was not studied how reliably adolescents reported their DS and AAS use. However, the anonymous survey is the method of choice when describing DS and AAS use in population level. In addition, a possible bias may result from the fact that we asked DS and AAS use for performance-enhancing purpose. This may have caused a slight underestimation of the true prevalence, especially in vitamins, herbal products and iron if the respondents have thought that they use DS for other cause than performance-enhancing purpose. On the other hand, the time period covered was 1 year. Taking a single tablet of a multivitamin product once a year, classified a respondent as a DS user and thus, the prevalence of DS use reported in this study may overestimate the real, daily use of DS. The strengths of our study included the largest sample ever reported (n = 22 519), accurate and well-documented study setting22,23 with identical questions during the study period between 1991 and 2005. We also had the opportunity to use a large scale of background variables, whose reliability have previously shown to be good.23 We may, thus, conclude that our results are well generalizable to the adolescent population.

To sum up, almost half of the adolescent respondents reported DS use during past year. Girls used DSs more frequently than boys, and vitamins and herbal products were the most commonly used substances. Although the overall use of DSs remained at the same level during the study period, there was a slight trend towards increasing use of vitamin and protein supplements. AAS use seems to be rare in Finnish adolescents; only 0.3% of the respondents reported AAS use. Several factors associated with DS and AAS use were found. DS use was associated with frequent participation in sports but also with poorer than average health. Frequent sport participation outside sport clubs was associated with decreased AAS use. Health care professionals and coaches of young athletes are recommended to remind adolescents and their parents that DSs are not substitutes for a healthful and sufficient diet.

Funding

Academy of Finland (grant 119537); the Ministry of Social Affairs and Health (§27 Appropriation of the Tobacco Act); Competitive Research Fund of Pirkanmaa Hospital District, Tampere University Hospital.

Conflicts of interest: None declared.

Key points

  • From the 22 519 adolescent respondents, 45% reported DS use during the past year.

  • The overall use of DS remained at the same level during the study period between 1991 and 2005. However, the use of protein supplements almost doubled among boys aged 16–18 years.

  • DS use was more common in girls and it increased linearly along with age.

  • The strongest factors associated with DS use in multivariate model were leisure time physical activity and participation in organized sports.

  • AAS use was uncommon among Finnish adolescents between 1991 and 2005. Only 0.2% of the girls and 0.5% of the boys reported AAS use.

  • Recurrent drunkenness in boys and peer drug use were risk factors for AAS use, while physical exercise outside sports clubs was a protecting factor.

Acknowledgement

We thank Anne Kopperoinen for language editing.

References

View Abstract