Home → Publications → Reports → Research and public policy series → 67 → Chapter 5: Temporal order of substance use and crime (in: Alcohol, drugs and crime : a study of juveniles in detention)
Alcohol, drugs and crime : a study of juveniles in detention
Jeremy Prichard and Jason Payne
ISBN 0 642 53891 3 ; ISSN 1326-6004
Canberra: Australian Institute of Criminology: 2005
(Research and public policy series, no. 67)
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Chapter 5: Temporal order of substance use and crime
This chapter continues to explore the link between substance use and juvenile crime by examining the overall life-course of offenders. Does regular substance use precede regular offending, or vice versa? Or do adolescents begin substance use and crime in the same period of their life? Answers to these questions can inform intervention strategies for juveniles that focus on substance abuse and crime prevention.
A difficulty with interpreting some of the results presented in this chapter relates to the age of the juvenile DUCO cohort. The average age of the male DUCO sample was about 30 years, and the adult female DUCO sample about 33 years. This means that most adult participants were reporting events in their criminal and drug-taking careers over a period of multiple decades. In contrast, the average age of the DUCO juveniles was 15.8, with the youngest being 11 and the oldest 17. Consequently, reported ages for the onset of offending, for example, are far more condensed. Time differences between events tend to be measured in months rather than years, as was often the case in the adult DUCO studies.
Are small time differences significant for adolescents? On one hand, significant physical and cognitive changes occur during adolescence that are unmatched in the adult years (Crain 1992; Piaget 1965). For example, one year for a youth may encompass marked developmental changes, while one year for an adult may be relatively uneventful. On the other hand, events occurring a few months apart could arguably be considered to be concurrent in the context of the life-course of a juvenile.
Onset and persistence of substance use and crime
As with the adult DUCO studies, it is useful to compare the mean age of first and regular substance use, and the mean age of first and regular offending. Logically, if substance use begins at an earlier age than criminal behaviour then it may have contributed to that behaviour. If substance use begins after the onset of offending but before the development of regular offending, then substance use may have contributed to the persistence of offending behaviour (Johnson 2004: 59).
Table 5.1 presents the mean age of onset for all offenders and types of substance users. The results indicate that regular offenders began committing offences at a younger age than those who did not progress to regular offending. This same pattern was observed in the adult DUCO studies (Makkai & Payne 2003; Johnson 2004). Further aspects of Table 5.1 suggest that:
- the onset of offending for all youths occurred in a critical two to three year period, from ages 11 to 14;
- stealing was the offence youths began at the earliest age. The mean age of onset for those who later became regular offenders was 11.3, and for all offenders the mean age was 11.7;
- stealing is followed by vandalism, then burglary and assault;
- youths who became regular violent offenders began committing violent crimes more than 12 months before those who did not progress to regular violent offending;
- juveniles began buying drugs before selling;
- for all types of crime, regular offending developed within 18 months of the first offence; and
- selling drugs became a regular activity in under three months.
With the exception of inhalants, the age of onset for substance use was earlier for juveniles who progressed to become regular users:
- the first substances to be used on average were cannabis (11.8 years) and alcohol (12.1 years);
- while the onset of stealing occurred prior to cannabis or alcohol use, generally the first use of these substances took place at about the same time as the onset of vandalism, assault and burglary;
- first use of inhalants, ecstasy and amphetamines occurred later than the first use of alcohol and cannabis; however
- regular use of inhalants, ecstasy and amphetamines developed in the space of several months, far quicker than the rate of progression to regular cannabis or alcohol use.
The rate at which the youths progressed to regular use of alcohol and cannabis are comparable to the escalation rates reported by the adult DUCO participants (Johnson 2004; Makkai & Payne 2003). However, a particular concern is the rapid onset of regular use of amphetamine, inhalants and ecstasy amongst the youths. Even the most chronic substance users in the DUCO adult male study reported, on average, taking one year to progress from their first use of amphetamines to regular use (Makkai & Payne 2003). For most incarcerated adults, two years passed before regular amphetamines use began (Johnson 2004; Makkai & Payne 2003).
Differences between the ages of first substance use also appear within the juvenile sample by offender type. On average, regular violent offenders reported first using all substances at a younger age than regular property offenders, and non-regular offenders began using substances later still (Table 5.2). The greatest mean age differences appeared in the onset of alcohol and cannabis use. While regular violent offenders began using alcohol and cannabis at the age of 11, regular property offenders did so at the age of 12 and non-regular offenders at 13. The earliest age of initiation reported for alcohol and cannabis was two years of age.
Further analysis revealed that:
- 10 per cent of all youths had tried alcohol, cannabis and/or inhalants when they were nine years old;
- by the age of 11, almost one in three had used alcohol and/or cannabis and one in five had tried inhalants; and
- one in 10 juveniles used amphetamines by the time they were 12 years old.
School systems in Australian jurisdictions differ in terms of the age brackets used for each grade, and whether high school begins in grade seven or eight. On average, Australian youths make the transition to high school at about age 12 (SCRGSP, 2005; MCEETYA, 2002). In total, 176 juveniles first used drugs by the age of 11, that is, before reaching high school. A statistically significant difference (p<0.01) appeared between the offender types in terms of whether they first used any substance before high school (Figure 5.1). Regular offenders (violent or property) were twice as likely as non-regular offenders to have first used any substance before high school age.
Figure 5.1: The onset of substance use in the pre-high school years, by offender type
Source: Australian Institute of Criminology, DUCO Juvenile Survey, 2005 [computer file].
As discussed in Chapter 4, two thirds of the youths (n=249) used one or more substances on a daily basis in the six months prior to being arrested for their current offence. The chapter highlighted that daily users displayed more serious offending patterns than those who used substances less frequently. Table 5.3 suggests, however, that daily users do not start criminal behaviour at a much younger age than non-daily users.
Daily users started offending before non-daily users, but the age difference was less than six months for most types of crime. There was no age difference in respect to the onset of burglary. These findings indicate that, on average, the age at which detainees begin offending does not influence whether they later become daily substance users later on.
Temporal order of drug use and crime
Debates over the causal relationship between drugs and crime have relied heavily on the examination of the temporal order in which they occur. This may be done simply by comparing the percentages of youths who: used substances before they began offending; began substance use and offending at the same time (i.e. within the same year); and began substance use after their criminal behaviour started. These percentages are shown in Figure 5.2 for each offender type. This pattern is similar to that of the adult DUCO adult males (Makkai & Payne 2003). Generally, crime began before substance use for half of the youths. A quarter of youths began using substances within the same year that their criminal behaviour began while the remaining youths used drugs prior to offending. Clearly, the patterns between the offender types are very similar. The differences between the regular property offenders and the other two groups did not approach statistical significance. This suggests that the ordering of the onset of substance use and criminal behaviour does not influence whether juveniles will progress to either regular violent or property offending.
Figure 5.2: Temporal order of substance use and crime
Source: Australian Institute of Criminology, DUCO Juvenile Survey, 2005 [computer file].
Pathways models are commonly used to explore the temporal order of onset between specific offence types, drug types, or both. Previous DUCO studies (see Makkai and Payne 2003; Johnson 2004) illustrated that the pathways into drug use and crime varied for different offender typologies, and more serious offenders are more likely to have commenced drug use and offending at younger ages. Similar pathways analysis is not feasible in the present study of juveniles because not all youths had reached an age when specific events (such as violent offending) were most likely to occur. Instead, we use longitudinal methodologies to examine 'periods of risk'. These methods allow us to account for the fact that the juveniles in this study were of varying ages at the time of interview.
Figure 5.3 shows the preliminary findings of the risk analysis for first property and violent offence and first cannabis and amphetamine use. It demonstrates unique risk experienced by the juvenile detainees at each age as estimated in discrete time survival analysis. The risk that a juvenile will commit their first property offence begins to increase from five years of age. Between the ages of 13 and 16, the probability of committing a property offence is maximised (an approximate 60 per cent chance). Note that the risk for cannabis use, although not reaching as high as first property offence, follows a similar trajectory. Interestingly, the risk of using cannabis is maximised at 13 years of age, but subsequently declines by more than half to age 16 years. This illustrates that should a juvenile not use cannabis on or before 14 years, the risk of doing so subsequently declines.
The risk of violent offending and amphetamine use do not peak as high as first property offence or cannabis use, and the increase in risk is delayed (increases at a later time period). This preliminary analysis will be the subject of further detailed exploration.
Figure 5.3: Risk curves for offending and drug use
Source: Australian Institute of Criminology, DUCO Juvenile Survey, 2005 [computer file].
Summary
The juvenile detainees mainly reported beginning substance use and all types of crime between the ages of 10 and 13. Their onset for the use of cannabis and amphetamines were markedly lower than reported by incarcerated adults. Further, juveniles tended to progress to regular substance use very quickly in comparison with the adult prisoners, particularly in relation to amphetamines, inhalants and ecstasy. A large number of youths began substance use in primary school or earlier. Early substance use seems to be interrelated with regular offending; regular offenders were twice as likely as non-regular offenders to have begun using substances before reaching high school. These worrying trends suggest that alcohol and drug interventions should consider targeting primary school children. It may also be appropriate for existing parenting programs to canvass the dangers of very early substance use.
No clear evidence arose of a causal stepping stone from substance use to crime with most juveniles reporting their first offence at least one year prior to their first use of illegal substances. In terms of when events occurred, regular violent offenders tended to begin using substances earlier than regular property offenders. The latter group, in turn, began substance use before non-regular offenders. It is important to note that regular violent offenders also began violent behaviour an average of two years before other types of offenders. The extent to which these behaviours are related to the environment and background of the youths is the focus of the next chapter.
- Next section: Chapter 6: Risk factors for substance use and offending
- Previous section: Chapter 4: Linking drugs and crime
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