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Undergraduate Men’s Use of Performance- and Appearance-Enhancing Substances: An Examination of the Gateway Hypothesis
Bryan T. Karazsia The College of Wooster
Janis H. Crowther and Rachel Galioto Kent State University
The Gateway Hypothesis was examined with respect to appearance- and performance-enhancing substance use. Various sociocultural influences on substance use were also included in the analysis to determine whether prior substance use predicts current use, even in the context of other relevant predictors. Age of first protein use (M � 16.64 years) preceded first creatine use (M � 17.19), which in turn preceded first use of Androstenedione (M � 17.90) and Anabolic Steroids (M � 20.00). A series of hierarchical logistic regression analyses revealed that the strongest predictor of current illicit substance use was previous use of legal performance-enhancing substances, although socio- cultural variables were significant predictors in each analysis. This study highlights the importance of integrating theories of sociocultural influence with the Gateway Hypothesis to identify individuals at risk of using unhealthy and illegal forms of performance and appearance enhancing substances.
Keywords: steroids, gateway hypothesis, performance enhancement, creatine, protein
Approximately 2.6 to 3.5% of adolescent males report using anabolic-androgenic steroids (AASs; Cafri, van den Berg, & Thompson, 2006; Johnston, O’Malley, & Bachman, 2002). Al- though AAS use promotes increases in lean muscle mass and muscular strength (Powers, 2005), this use is accompanied by clinically significant physical and mental health risks (e.g., Irving, Wall, Story, & Neumark-Sztainer, 2002), including stunted bone growth, cardiovascular and coronary artery dis- ease, acne, hair loss, induction of psychosis, suicidality, and mood disorders (e.g., Trenton & Currier, 2005). Use of other performance- and appearance-enhancing substances (PESs) are more common (e.g., Cafri et al., 2006; Smolak, Murnen, & Thompson, 2005) yet also are associated with maladaptive outcomes, including heart disease and depression (e.g., Cafri et al., 2005). Because of the many negative health consequences and substantial media coverage, PES use is an important and pressing public health issue. However, there is limited research regarding the progression from legal and arguably healthy be- haviors (e.g., consuming protein; Alexy, Remer, Manz, Neu, & Schoenau, 2005) to maladaptive and illegal behaviors (e.g., AAS use).
Research that identifies risk factors for PES consumption is guided by two dominant theoretical approaches: the Gateway Hypothesis (Dodge & Jaccard, 2006; Kandel, 2002) and theories of sociocultural influence (e.g., Cafri et al., 2005; Smolak et al., 2005; Parent & Moradi, 2011; Thompson, Heinberg, Altabe, & Tantleff-Dunn, 1999). However, no studies have examined these
two theoretical approaches in the context of each other. Such an analysis would have important implications for public policy, intervention and prevention strategies, and future research. Thus, the present study combined social pressures and psychological risk factors (drawn from sociocultural approaches) and licit PES use (based on the Gateway Hypothesis) as predictors of current illicit PESs.
The Gateway Hypothesis and AAS Use
The Gateway Hypothesis (Kandel, 2002) posits that a develop- mental trajectory exists whereby use of licit substances (e.g., tobacco, alcohol) precedes and increases risk of using illicit sub- stances (e.g., cocaine). Three propositions underlie the Gateway Hypothesis:
1. “. . . there is a developmental sequence of involvement with different classes or categories of drugs . . .” (Kandel & Jessor, 2002, p. 365)
According to this proposition, drug use earlier in the sequence (e.g., tobacco) precedes substance use later in the sequence (e.g., cocaine).
2. “. . . use of a drug earlier in the sequence is associated with an increased risk or likelihood of use of a drug later in the sequence . . .” (p. 366)
In other words, individuals who smoke are more likely to use marijuana than individuals who do not smoke (Kandel & Jessor, 2002).
3. “. . . the use of a drug earlier in the sequence, such as alcohol or tobacco, causes the use of a drug later in the sequence, for instance, marijuana.” (p. 366)
This article was published Online First April 30, 2012. Bryan T. Karazsia, Department of Psychology, The College of Wooster;
Janis H. Crowther and Rachel Galioto, Department of Psychology, Kent State University.
Correspondence concerning this article should be addressed to Bryan T. Karazsia, Department of Psychology, The College of Wooster, Wooster, OH 44691. E-mail: [email protected]
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Psychology of Men & Masculinity © 2012 American Psychological Association 2013, Vol. 14, No. 2, 129 –137 1524-9220/13/$12.00 DOI: 10.1037/a0027810
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As discussed at length by Kandel and colleagues (e.g., Kandel & Jessor, 2002), support for propositions one and two is quite sub- stantial with regard to a sequence of drugs beginning with tobacco and extending to marijuana, cocaine, and heroine. For example, a longitudinal study conducted in Australia revealed that individuals who used marijuana were more likely to use amphetamines later in life (Degenhardt, Coffey, Carlin, Moran, & Patton, 2007). Addi- tional support for the Gateway Hypothesis among illicit drug users comes from twin studies (e.g., Agrawal, Neale, Prescott, & Ken- dler, 1999) and research with laboratory animals that are exposed to drugs early in life and then show preferences for other sub- stances later in life (Ellgren, Spano, & Hurd, 2007). However, support for the causal proposition is limited because of the inherent difficulties in establishing causal relations; carefully controlled experimental designs of illicit drug use are virtually impossible with human samples. Thus, the vast majority of research on the Gateway Hypothesis with both human and animal populations is based on and supports propositions one and two (Kandel, 2002).
Importantly, support for the first two propositions alone is not sufficient for supporting the proposition of causality. For example, in a 10-year longitudinal study, Tarter, Vanyukov, Kirisci, Reyn- olds, and Clark (2006) identified a subgroup of males who used illicit substances before licit substances. They concluded that a similar constellation of predictors does exist across the various subgroups of substances uses (i.e., those who use licit only, licit first, and illicit first), and these predictors include individual proneness to deviant behavior. Thus, use of a licit substance is neither a necessary nor sufficient condition for illicit substance use, and some individuals may engage in illicit substance use without prior engagement with licit substances. Indeed, Kandel (2002) notes that there may be a set of variables that both underlies and explains the relationship between initial use of a legal sub- stance and use of illegal substances. Therefore, many previous examinations of the Gateway Hypothesis among recreational drug users included additional predictors to determine whether sub- stance use earlier in the sequence predicted use later in the se- quence above and beyond other explanatory variables (e.g., Labou- vie & White, 2002; Schenk, 2002).
To our knowledge, Dodge and Jaccard (2006) were the first to extend this model to PES use. Based on propositions one and two of the Gateway Hypothesis, they reasoned that individuals who use legal PESs would be more likely to progress to substances that may enhance muscularity more efficiently but that are also illegal and pose serious health risks. Dodge and Jaccard (2006) found support for this hypothesis using a nationally representative sam- ple of adolescents. Specifically, users of legal PESs were approx- imately 26 times more likely to report AAS use. In their analysis, Dodge and Jaccard (2006) operationalized legal PESs as “a legal performance-enhancing substance for athletes (such as creatine Monohydrate or Andro).”
Although Dodge and Jaccard (2006) found support for the Gateway Hypothesis, their analysis was limited in several respects. First, substance use was dichotomized into legal and illegal PESs. If the Gateway Hypothesis is true, then there should be an inter- mediate step along the continuum from licit to illicit substance use. We could find no studies that tested a more refined, step-like analysis of the Gateway Hypotheses with PESs. Second, Dodge and Jaccard (2006) included Androstenedione (Andro) as a legal substance; however, Andro was banned in the United States as part
of the Anabolic Steroid Control Act of 2004 (U.S. Drug Enforce- ment Administration, 2004). This shift in the sociopolitical envi- ronment requires a redefinition of Andro as an illegal substance. Third, although Dodge and Jaccard (2006) found that sport par- ticipation and engagement in “strength-related activities (e.g., weightlifting)” (p. 369) predicted illegal substance use in a sepa- rate analysis, their test of the Gateway Hypothesis did not include any other variables that may explain the progression of PES use beyond demographics. Clearly, inclusion of additional variables that may explain the link between legal and illegal substance use is needed (e.g., Kandel & Jessor, 2002), and decisions about what variables to include should be based on relevant theories.
Sociocultural Theories
Originally developed to explain risk factors associated with body dissatisfaction and eating pathology among women (e.g., Fredrickson & Roberts, 1997; Stice, 1994; Thompson et al., 1999), theories of sociocultural influence have received substantial sup- port regarding the role of sociocultural variables as risk factors for body dissatisfaction and maladaptive eating behaviors (e.g., Cafri et al., 2005; Stice, 2002; Thompson et al., 1999; Tylka & Hill, 2004). More recent research with men suggests that multiple sociocultural variables also play important roles in their experience of body dissatisfaction and engagement in maladaptive body change behaviors (e.g., Chen, Gao, & Jackson, 2007; Parent & Moradi, 2011; Smolak et al., 2005; van den Berg, Neumark- Sztainer, Cafri, & Wall, 2007; van den Berg, Paxton et al., 2007). Several conceptual models have been developed that encompass biological, sociocultural, and psychological influences on un- healthy body change behaviors for men (Cafri et al., 2005; Grieve, 2007; Ricciardelli & McCabe, 2004). The various models have important similarities, and they have received substantial empirical support when the constructs are assessed in a manner relevant to men (Cafri & Thompson, 2004; Karazsia & Crowther, 2010; Karazsia & Peiper, 2011; Tylka, 2011).
Most theories of sociocultural influence hypothesize that en- gagement in risky body change behaviors is influenced by multiple sources of social pressure, including parents and peers (e.g., Cafri et al., 2005; Grieve, 2007; Ricciardelli & McCabe, 2004). The influence of these pressures on body change behaviors is mediated by various psychological mechanisms, such as internalization of societal ideals, engagement in social body comparison, and body dissatisfaction. Research suggests that the extent to which individ- uals experience social pressures is associated with engagement in social body comparisons, which is one mechanism through which individuals process social information (e.g., Festinger, 1954). Young men tend to compare their bodies with peers and sports figures (Karazsia & Crowther, 2009), and this process of body comparison is related strongly to internalization of societal ideals (e.g., Karazsia & Crowther, 2008). Internalization reflects the extent to which an individual adopts societal values as guiding principles (Thompson et al., 1999; Jones, 2004). The influence of social pressures and individual psychological risk factors predicts body dissatisfaction, which in turn predicts engagement in risky body change behaviors (e.g., Karazsia & Crowther, 2010; Smolak et al., 2005; Tylka, 2011).
Substantial research supports sociocultural theories as useful heuristics for conceptualizing risk factors for maladaptive muscle
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building strategies among men. For example, the societal ideal of the male figure has grown increasingly muscular (e.g., Pope, Olivardia, Gruber, & Borowiecki, 1999), and this muscular ideal is considered a representation of masculinity (e.g., Tager, Good, & Morrison, 2006). Accordingly, many men across multiple cultures report dissatisfaction with their body (Frederick et al., 2007), and internalization of the mesomporphic ideal is associated with en- gagement in risky body change behaviors (Smolak et al., 2005). Karazsia and Crowther (2008) also reported significant cross- sectional correlations between internalization and PES use in an undergraduate sample of young males, and Wright, Grogan and Hunter (2000) reported that the social comparison process was an important influence on bodybuilders’ decision to use AASs. Among adolescents, pressures from media, parents, and peers and self-reported body dissatisfaction distinguish AAS users from non- users (Smolak et al., 2005). Using a longitudinal design with a sample of adolescent men in Australia, McCabe, Ricciardelli, and Holt (2005) reported that pressures from these social influences predicted increases in muscle building strategies, although AAS use was not assessed explicitly. van den Berg, Neumark-Sztainer, and colleagues (2007) reported that adolescent boys who have a body size that is smaller than the self-reported ideal body size (i.e., body dissatisfaction) are more likely to use AASs 5 years later. Using a large-scale, longitudinal database, Dodge and Jaccard (2006) reported that participation in a sport, which can be conceptualized as a sociocultural context (Ricciardelli, McCabe, & Ridge, 2006), was associated with an increased risk of AAS use, even after controlling for various demographic variables. Thus, research from independent research laboratories suggests that sociocultural variables (e.g., pres- sures from parents, peers) and psychological risk factors (e.g., inter- nalization, social comparison, body dissatisfaction) are associated with PES use, including illicit substances such as AAS.
The Present Study
The primary purpose of this research was to conduct a more refined analysis of the Gateway Hypothesis with respect to PESs. Toward this end, we examined three distinct types of PESs. One type was protein use, which is a legal and arguably healthy practice (e.g., Alexy et al., 2005). The next type of use assessed was creatine, a naturally occurring organic substance that supplies energy to muscle cells via increased production of Adenosine Triphosphate (Burke, Chilibeck, Parise, Candow, Mahoney, & Tarnopolsky, 2003). Crea- tine is a legal substance that is generally regarded as safe for healthy individuals, though there is a dearth of scientific examination of long-term health outcomes associated with creatine use. Case reports of maladaptive outcomes have been published (e.g., Pritchard & Kalra, 1998). Thus, while creatine is a legal substance, it may serve as a gateway between protein and illicit substances. Third, we assessed two PESs designed to increase the level of testosterone in the body: Andro and AAS. Andro is a biochemical precursor to the production of androgen testosterone, and thus consumption of Andro results in increased production of testosterone (Leder et al., 2000).
Additionally, we included sociocultural variables as predictors of current PES use, and the selection of sociocultural variables was driven by relevant theories. By relying on theory, we were able to examine the influence of legal PES on illegal PES in the context of other variables that may explain the onset as well as the progres- sion from legal to illegal PES use.
Our hypotheses were as follows:
1. Gateway Hypothesis Proposition 1: Onset of legal PES use would precede onset of illegal PES use in a step-like process. We hypothesized that males would report first use of protein supplements at an earlier age than creatine use, which in turn was expected to occur at an earlier age than use of illegal substances (Andro and AAS).
2. Gateway Hypothesis Proposition 2: Substance use earlier in the sequence would increase the likelihood of use later in the sequence. Specifically, we expected that . . .
a. Previous use of protein would predict current creatine use, such that individuals who used protein previously would be more likely to use creatine.
b. Previous use of creatine would predict current illegal PES use, such that individuals who used creatine previously would be more likely to use illicit PESs.
3. Sociocultural theories: Theory-driven sociocultural vari- ables would predict both legal and illegal PES use, such that participants who played sports, reported higher body dissat- isfaction, engagement in social comparisons, internalization, and exposure or pressure from family and peers to lift weights would be more likely to utilize both legal and illegal PESs.
4. Gateway Hypothesis Proposition 3: The increased risk of using illegal PESs after use of legal PESs would remain even after accounting for the contribution of sociocultural variables from Hypothesis 3.
Method
Participants
Data analyzed in this study were drawn from two larger studies about men’s mental and physical health (Karazsia & Crowther, 2008, 2009). There were a total of 456 male participants across the two studies, of whom 448 were included in the present analyses (eight cases were deleted because of missing anthropometric or substance use data). All participants were recruited from under- graduate psychology courses at a large, public university in the Midwest. The mean age of the sample was 19.54 years (SD � 2.21). Ethnic composition of the sample was 82.8% non-Hispanic White, 8.5% Asian, 4.0% African American, and 4.7% other ethnicities (including multiracial). Mean BMI was 25.36 (SD � 4.09; Range: 17.14 – 40.55).
Measures
As part of two larger studies on men’s mental and physical health, participants completed the following measures in addition to providing basic demographic information.
Stepping Stones Inventory (Karazsia, 2007a). The Step- ping Stones Inventory is a self-report measure that assesses use of various PESs. Participants indicate whether or not they have
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131GATEWAY HYPOTHESIS
ever used a specified substance. If history of use is positive, then participants are asked follow-up questions, including age at first consumption and whether they are currently using the substance. Sample brand names of products are listed alongside substance types as examples to facilitate participant recall and accurate reporting. For the present study, participant responses regarding four substances were included in analyses: protein, creatine, Andro, and AAS.
Family and Peer Influences on Exercise Scale (FPIS; Karaz- sia, 2007b). In its entirety, the FPIS is a 28-item self-report measure that assesses social influences (mother, father, siblings, peers) on diet and exercise behaviors. Using a five-point Likert Scale ranging from 1 (never) to 5 (always), participants indicate how much each source encourages them to diet and lift weights. In this study, three composite variables were created from 12 items to assess encouragement from peers (three items), parents (six items; three for mother and three for father), and siblings (three items). In a study of undergraduate men, the subscales of the full measure had good psychometric properties and were positively associated with other measures of appearance-related social comparison, in- ternalization, and muscularity-oriented body dissatisfaction (Karazsia & Crowther, 2009). Internal consistency for responses to items on the composite scales in the present sample exceeded .80.
Sociocultural Attitudes Toward Appearance Questionnaire-3 (SATAQ-3; Thompson, vanden Berg, Roeh- rig, Guarda, & Heinberg, 2004). The original form of the SATAQ-3 is a 30-item self-report questionnaire that assesses sociocultural influences on body image. Factor analysis of the measure yielded four subscales: Information, Pressures, Internalization-General, and Internalization-Athlete. Only the in- ternalization scales were utilized in the present study, and these scales demonstrated strong psychometric properties, including fac- tor structure, internal consistency, and convergent and discrimi- nant validity in a sample of young men (Karazsia & Crowther, 2008). Items are rated using a five-point Likert scale ranging from 1 (definitely disagree) to 5 (definitely agree), with higher scores reflecting greater internalization. Internal consistency for re- sponses to items on these scales in the present sample was .93 and .84 for the general and athletic internalization scales, respectively.
Physical Appearance Comparison Scale (PACS; Thompson, Heinberg, & Tantleff, 1991). The PACS is a five-item measure that assesses the tendency to compare one’s appearance to the physical appearance of others. Participants report the extent to which they engage in five appearance comparison behaviors using a five-point Likert scale ranging from 1 (never) to 5 (always). Higher scores indicate a greater tendency to make physical com- parisons. The scale has demonstrated adequate validity (Thompson et al., 1991), and internal consistency for responses to items on this scale in the present sample was .72.
Drive for Muscularity Scale (DMS; McCreary & Sasse, 2000). The DMS is a 15-item self-report measure on which par- ticipants indicate their endorsement of muscularity-oriented attitudes and behaviors on a six-point Likert scale ranging from 1 (always) to 6 (never). The 15 items constitute two factor analytically derived subscales: muscularity-oriented body image (DMS-Bod) and a behav- ioral dimension. Only the DMS-Bod was used in present analyses as an index of body dissatisfaction, and all items were reverse scored so that higher scores reflected a greater drive for muscularity. Previous research supports the validity of this scale (McCreary & Sasse,
2000; McCreary, Sasse, Saucier, & Dorsch, 2004), and the internal consistency for responses to items on the scale in the present sample was .88.
Muscle Appearance Satisfaction Scale (MASS; Mayville, Williamson, White, Netemeyer, & Drab, 2002). The MASS is a 19-item self-report measure designed to assess symptoms of Muscle Dysmorphia, a variant of Body Dysmorphic Disorder that involves a preoccupation with one’s muscularity (Pope, Gruber, Choi, Olivardia, & Phillips, 1997). The 19 items are rated on a five-point Likert scale ranging from 1 (almost never) to 5 (almost always). The full scale contains five factor-analytically derived subscales, of which only the Muscle Satisfaction (Mass-Sat) scale was used in this study. Higher scores on this measure indicate greater satisfaction. This subscale demonstrated acceptable test– retest reliability and construct validity in a sample of undergrad- uate males (Mayville et al., 2002). Internal consistency for re- sponses to items on the scale in the present sample was .82.
Sports participation. Participants were asked whether or not they participated in varsity athletics during high school (Yes/No).
Procedure
As part of two larger studies concerning men’s mental and physical health, and after providing informed consent, partici- pants completed the aforementioned measures in a group setting under direct supervision of an experimenter. Participants were then escorted to a private room where anthropometric assess- ments were recorded (weight, height). All participants received credit toward their research requirement in an undergraduate psychology course, and all procedures were approved by the Institutional Review Board at the associated university.
Results
Preliminary Screening
All variables used in regression analyses were screened for normality and found to be acceptable, with skewness between �2 and 2 and kurtosis between �7 and 7 (Curran, West, & Finch, 1996). Less than 1% of all data points were missing, and missing values were imputed using the expectation-maximization (EM) algorithm available in EQS 6.1 (Bentler, 2004). Of the 448 par- ticipants in this sample, endorsement of current use of each sub- stance was as follows: 30.6% protein, 10% creatine, and 2.5% testosterone supplement (either Andro or AAS). Further, 60.9% (n � 273), 36.2% (n � 162), and 5.8% (n � 26) of the sample endorsed having ever used protein, creatine, and a testosterone supplement, respectively. Correlations among all variables that were included in the following analyses are displayed in Table 1.
Hypothesis 1: Gateway Proposition 1
Paired samples t tests were used to investigate differences in the mean age at first use of each substance (Protein: Mage � 16.64, SD � 1.93; creatine: Mage � 17.19, SD � 2.15; Andro: Mage � 17.90 SD � 1.59; AAS: Mage � 20.00, SD � 2.53). A Bonferroni correction was used to control for Type I error, resulting in a threshold for significance of p � .017 for these t tests. Among participants who used respective substances, results showed a
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132 KARAZSIA, CROWTHER, AND GALIOTO
significant age progression from first use of protein to first use of creatine, t(146) � �5.45, p � .001 (Cohen’s d � .49), and from first use of creatine to first use of Andro, t(18) � �4.78, p � .001 (Cohen’s d � 1.10). However, there was no significant difference between first use of Andro and first use of AAS, t(2) � �4.00, ns. Because of this lack of age difference and biological similarity between Andro and AAS (i.e., both enhance muscularity via an increase of testosterone), endorsements of Andro and AAS were collapsed into one dichotomous variable representing use of a testosterone supplement.
Hypothesis 2: Gateway Proposition 2
Two logistic regression analyses were conducted to test the hypotheses that previous protein use would predict current creatine use (Hypothesis 2a) and that previous creatine use would predict current use of illicit PESs (Hypothesis 2b). As can be seen in Table 2, both hypotheses were supported. History of protein use pre- dicted creatine use, and history of creatine use predicted illicit PES use, �2(2) � 35.74, p � .001. Among the 26 participants who reported illicit PES use, 96.2% and 84.6% reported a history of protein and creatine use, respectively. Among participants who reported illicit PES use and protein use, age of onset was always younger for protein use, with the mean number of years between first protein use and first use of illicit PESs being 2.27 years (SD �
1.78). Among participants who reported illicit PES use and crea- tine use, age of onset was younger for creatine use in all cases except one, with the mean number of years between first creatine use and first use of illicit PESs being 1.76 years (SD � 1.70).
Hypotheses 3 and 4: Sociocultural Influence and Gateway Proposition 3
A series of three hierarchical logistic regression analyses was conducted to examine various “classes” or “types” of predictors (e.g., Bellizzi & Blank, 2006). Both class type and selection of variables that constitute a given class were driven by the socio- cultural theories (Thompson et al., 1999; “Sociocultural Variables” in Table 3) and the Gateway Hypothesis (Kandel, 2002; “Previous Substance Use” in Table 3). All analyses were examined after controlling for BMI. Variables within a given class were entered as a block at each step of the analysis. Thus, the first hierarchical logistic regression analysis examined sociocultural variables as predictors. The second analysis incorporated the same sociocul- tural variables plus previous protein use as predictors of current creatine use, while the third analysis incorporated the same socio- cultural variables plus previous protein and creatine use as predic- tors of current use of a testosterone supplement. Table 3 presents the final step of the hierarchical regression for each dependent variable. We present the final step of the hierarchical regression
Table 1 Intercorrelations of Measures (n � 448)
Variables 1 2 3 4 5 6 7 8 9 10 11 12
1. BMI — 2. Encourage-peer .09 — 3. Encourage-parent .18�� .41�� — 4. Encourage-sibling .03 .37�� .42�� — 5. Sport participation .05 .09 .01 .01 — 6. Intern-general �.01 .26�� .17�� .17�� .03 — 7. Intern-athlete .02 .22�� .09 .10 .10 .76�� — 8. Body comparison .01 .24�� .16� .13� .06 .53�� .45�� — 9. Drive for muscularity �.16� .20�� .08 .05 .10 .42�� .40�� .39�� —
10. Muscle satisfaction �.04 �.14�� �.13 �.06 .10 �.30�� �.25�� �.19�� �.56 — 11. Protein (current) .06 .10 .00 .06 .13� .15� .20�� .16� .17�� .07 — 12. Creatine (current) .09 �.02 �.04 �.02 .03 .10 .08 .07 .15�� �.06 .21�� — 13. Testosterone supplement
(current) .07 .07 �.02 .04 .08 .04 .00 .14� .10 �.03 .18�� .27��
Note. Variables representing supplement use (Protein, Creatine, Testosterone) are dichotomous variables, coded as 0 � users, 1 � non-users. Values depicting associations between two dichotomous variables are Phi coefficients. � p � .01. �� p � .001.
Table 2 Logistic Regression Analysis of the Gateway Hypothesis, Proposition 1 (n � 448)
Predictor
Creatine Testosterone supplement
B SE B eB B SE B eB
Previous substance use Protein 2.02��� .53 7.56 1.63 1.09 5.12 Creatine — — — 2.71�� .66 8.78 �2 23.04��� 35.74���
Df 1 2
� p � .05. �� p � .01. ��� p � .001.
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because there are no variables that were significant predictors in earlier steps that become nonsignificant at later steps; thus, the final step offers an adequate summary of results. (Results of from each step of the analysis are available from the first author upon request.)
As can be seen in Table 3, internalization of an athletic ideal and two indices of body dissatisfaction (Drive for Muscularity and Muscle Appearance Satisfaction) predicted current protein use. Current creatine use was predicted by muscularity-oriented body dissatisfaction and previous protein use. It is worth highlighting that the odds of currently using creatine was 6.45 times greater among previous protein users than individuals with no history of protein use. Finally, engagement in body-oriented social compar- isons predicted current use of a testosterone supplement, as did previous use of creatine. The odds of engaging in testosterone supplement usage was 8.03 times greater among previous users of creatine than creatine nonusers.
Discussion
The present study evaluated the Gateway Hypothesis with re- spect to young men’s progression of PES use from legal to illegal substances. Propositions 1 and 2 of the Gateway Hypothesis were supported in this sample, which was asked to reflect on substance use throughout adolescence and emerging adulthood. In support of Proposition 1, participants reported using substances earlier in the PES sequence at a younger age than substances later in the se- quence. Additionally, and in support of Proposition 2, use of substances earlier in the sequence increased risk of subsequent use of substances later in the sequence. The third proposition, which posits that use of substances early in the sequence causes use of substances later in the sequence, cannot be tested directly in human populations. However, Kandel and colleagues (2002, 2006) em- phasize the importance of including alternative predictors, or vari-
ables that may also explain illicit substance use, in examinations of the Gateway Hypothesis. Inclusion of such variables can assist in the evaluation of the extent to which the Gateway Hypothesis explains illegal substance use above and beyond alternative pre- dictors. In the present study, our selection of alternative predictors was based on theories of sociocultural influence. Even in the context of these variables, previous substance use was a dominant predictor of current creatine (predicted by protein use) and current anabolic substance use (predicted by creatine use). For all three classes of substances assessed, at least one sociocultural variable emerged as a significant predictor as well, lending support to the utility of the sociocultural model in predicting current substance use, even when considering previous substance use.
By integrating two conceptual paradigms, these results extend previous research on men’s engagement in risky body change behaviors. Regarding the Gateway Hypothesis, the present study extends work by Dodge and Jaccard (2006) by using three distinct classes of PES use (protein, creatine, anabolic). Importantly, whereas Dodge and Jaccard (2006) examined only licit versus illicit substances, the three classes examined in this research rep- resent a step-like progression that is consistent with the Gateway Hypothesis, ranging from substances that may be healthy to those that are illegal and harmful. Thus, the present study offers a conceptualization that posits progression from licit to illicit sub- stances through more than two stages (Kandel, 2002). To our knowledge, the present study is the first to offer such a conceptu- alization after the passage of the Anabolic Steroid Control Act.
The Gateway Hypothesis received support in that previous, licit substance use was a dominant predictor of current engagement in illicit substance use. Moreover, previous use of safer forms of licit substances (protein) predicted current use of legal substances that may carry more potential for side effects (creatine). This pattern of progression is consistent with longitudinal findings of other forms
Table 3 Summary of Logistic Regression Analysis for Variables Predicting Current Substance Use (n � 448)
Predictor
Protein Creatine Testosterone supplement
B SE B eB B SE B eB B SE B eB
Covariates BMI .06� .03 1.06 .11�� .04 1.12 .09 .06 1.09
Sociocultural variables Encourage-peer .03 .05 1.03 �.08 .07 .92 .03 .09 1.03 Encourage-parent �.03 .03 .97 �.05 .05 .95 �.06 .06 .94 Encourage-sibling .06 .06 1.06 .02 .09 1.02 .03 .11 1.03 Sport participation �.37 .30 .69 .23 .45 1.25 �.67 .79 .51 Internalization-general �.01 .02 .99 .04 .04 1.04 .00 .05 1.00 Internalization-athlete .09� .04 1.09 �.03 .06 .97 �.10 .08 .91 Body comparison .03 .04 1.03 �.02 .05 .98 .15� .07 1.16 Drive for muscularity .07��� .02 1.07 .07� .03 1.07 .01 .04 1.01 Muscle appearance .20��� .05 1.22 .02 .07 �.04 .09 .96 1.22 Previous substance use Protein — — — 1.86��� .56 6.45 1.35 1.13 3.84 Creatine — — — — — — 2.08�� .69 8.03
�2 52.23��� 38.37��� 47.56���
Df 10 11 12
Note. BMI � Body Mass Index; 70.5%, 90.0%, and 94.4% of cases were classified correctly in the equations for protein, creatine, and testosterone supplement, respectively. � p � .05. �� p � .01. ��� p � .001.
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of illicit substances (e.g., Agrawal et al., 1999; Degenhardt et al., 2007; Ellgren et al., 2007). However, within the context of the Gateway Hypothesis, it is important to emphasize that results involving recreational drugs or PESs do not necessarily provide evidence of a causal pathway along various stages in the Gateway Hypothesis.
Just as proneness to deviant behavior may increase risk for the use of illicit recreational drugs (Tarter et al., 2006), psychological variables such as internalization of the athletic ideal, frequency of social body comparisons, and muscularity-oriented body dissatis- faction may be important to our understanding of who graduates from licit to illicit substances for the purpose of increasing muscle mass. Indeed, males who report more body dissatisfaction, greater internalization of an athletic ideal, and who engage more fre- quently in social body comparisons appear to be at an increased risk of using both licit and illicit substances (e.g., Cafri et al., 2005; Smolak et al., 2005; Tylka, 2011). With respect to testosterone supplements specifically, our findings indicate that individuals who progressed to Andro or AAS could be predicted by higher levels of body comparison. Thus, our analysis suggests that, in the context of all other variables assessed (including previous sub- stance use), individuals who reported higher body comparison were more likely to report use of a testosterone supplement than other individuals in the study. An unexpected finding was that different psychological risk factors predicted current use of differ- ent substances. Namely, social body comparison was the only psychological risk factor that predicted use of a testosterone sup- plement, whereas internalization or muscle-oriented body dissat- isfaction predicted protein and creatine use. This pattern of results supports previous research regarding motivations for using AASs (Wright et al., 2000) and suggests that men’s emphasis of body concern may shift from a predominant focus on the self (e.g., body dissatisfaction) to an increasing emphasis of comparing the self with others (e.g., body comparison) as they progress through various stages of supplement use.
While the present study offers several contributions to the existing literature, the findings must be interpreted in the context of the study’s limitations. First, reports of previous use and age of onset of various substances were based on retrospective reports. Reports of testosterone supplements were slightly higher in this sample than reports of AAS use obtained in previous research with adolescents (e.g., Cafri et al., 2006; Johnston et al., 2002), though this seems appropriate, as our estimates include both Andro and AAS use, and they are based on an undergraduate sample. More- over, it is important to consider that one of the key implications of this study was that men’s first use of protein almost always precedes first use of creatine, which in turn precedes anabolic substance use. Any errors regarding retrospective reports are more likely regarding specific age of onset rather than the age progres- sion. This contention is based on research that indicates reports of event sequencing tend to be reliable and valid (e.g., Morris & Slocum, 2010). Thus, the sequence of substance use is likely valid, although interpretation of this sample’s reported ages of onset should be made with caution. Second, the study sample lacked ethnic diversity, and the sample included only 26 individuals who reported use of a testosterone supplement, so results should be generalized with caution. Third, the operational definition of sport participation was limited, particularly in light of previous research that suggests sports that emphasize muscularity and power (e.g.,
powerlifting, bodybuilding, football) may increase risk while other sports do not (e.g., Bahrke, Yesalis, Kopstein, & Stephens, 2000). Furthermore, research indicates that sport participation during adolescence is associated with many positive outcomes, including academic success and psychological adjustment (e.g., Fredricks & Eccles, 2006). Moreover, the majority of males who use PESs report doing so for aesthetic purposes, not for performance en- hancement (e.g., Blouin & Goldfield, 1995; Peters, Copeland, & Dillon, 1999). Age of onset of PES use for many males may also occur at an age older than the males in this study (Yesalis, Kennedy, Kopstein, & Bahrke, 1993), so the results of this study cannot be generalized to males of all ages.
Finally, causality regarding the progression of substances as well as the influence of sociocultural influences cannot be inferred because of a lack of experimental manipulation, random assign- ment, or ruling out of all possible alternative predictors. This limitation is particularly important in light of the fact that nearly two thirds of the sample used protein, and approximately one third of the sample used creatine, though only 5.8% of the sample reported any history of using a testosterone supplement. Although legal PES use did predict illegal PES use, it is very clear that not all males who used a legal substance progressed through the sequence to illicit substances. Importantly, this finding is consis- tent with analyses of the Gateway Hypothesis in the context of recreational drugs. Kandel, Yamaguchi, and Chen (1992) illus- trated that while use at one stage may increase risk of use at another stage, it does not make use at the next stage inevitable. Therefore, research is necessary to determine the mechanisms through which use at one stage leads to another stage (i.e., medi- ators; Baron & Kenny, 1986), and specific subpopulations of users at early stages who are more likely to progress through the drug sequence (i.e., moderators; Baron & Kenny, 1986). One risk factor for such progression in the domain of recreational use appears to be perceived social norms about the benefits and risks of substance use (e.g., Hawkins, Hill, Guo, & Battin-Pearson, 2002). In the context of PES use, such norms may be associated with an indi- vidual’s appearance orientation, or the extent to which one invests cognitively and behaviorally in body image (Brown, Cash, & Mikulka, 1990). Previous experimental research indicated that the extent to which young males respond to media depicting ideal masculine images is moderated by appearance orientation (Har- greaves & Tiggeman, 2009). It will be important for future re- search to incorporate social norms, appearance orientation, en- dorsement of masculine ideologies, as well as other potential mediators and moderators, into examinations of the Gateway Hy- pothesis with respect to PESs. While we examined social pressures and psychological variables as predictors of current substance use, this directionality cannot be inferred. It is possible that use of particular substances leads to an increase in sociocultural pressures to enhance muscularity or desensitization to potential health risks associated with illicit PES substance use.
Despite these limitations, the present study offers important insights that may be useful for future research, intervention, and public policy efforts. Future research and models that explain the progression toward illicit substance use for the purpose of perfor- mance or appearance enhancement should include variables con- sistent with both sociocultural theories as well as models of sub- stance use (e.g., the Gateway Hypothesis). Longitudinal studies that assess variables from both of these theoretical paradigms will
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be important. With respect to interventions, this study highlights variables that may be useful in the identification of individuals at-risk for illicit PES use. Importantly, variables used to select individuals for targeted interventions should include those drawn from sociocultural theories (social pressures, body dissatisfaction, internalization, and social comparison) as well as the Gateway Hypothesis (previous substance use).
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Received September 9, 2011 Revision received February 12, 2012
Accepted February 13, 2012 �
T hi
s do
cu m
en t
is co
py ri
gh te
d by
th e
A m
er ic
an P
sy ch
ol og
ic al
A ss
oc ia
ti on
or on
e of
it s
al li
ed pu
bl is
he rs
. T
hi s
ar ti
cl e
is in
te nd
ed so
le ly
fo r
th e
pe rs
on al
us e
of th
e in
di vi
du al
us er
an d
is no
t to
be di
ss em
in at
ed br
oa dl
y.
137GATEWAY HYPOTHESIS
