Age as a Predictor of Cannabis Use

C H A P T E R

4 Age as a Predictor of Cannabis Use D. Bergen-Cico*, R.D. Cico** *Department of Public Health, Addiction Studies, Syracuse University, Syracuse, NY, United States **Columbia University, New York, NY, United States

goods and chocolates. Extraction of resin from the Cannabis plant may be used to produce hashish (hash), typically a brown sticky oil or solid form that can be smoked or prepared into specialty foods. Most cannabis is psychoactive and produces a mild sense of euphoria and relaxation, at moderate doses.

SUMMARY POINTS • This chapter examines the prevalence of cannabis use among people across all age groups. • The largest percentage of cannabis users are people under the age of 20. • People are most likely to first use cannabis prior to age 20; however, the number of people over the age of 30 who first initiate cannabis use has steadily increased over the past decade. • Cannabis use spans the full life course. • Although people are most likely to first use cannabis during their youth, their use may decline during early adulthood, and intermittently resurface in mid-to-late adulthood. • Cannabis use among older adults may be becoming normative with the increasing prevalence of cannabis using peer cohorts who came of age during and following the 1960s. • Cannabis use among adults over the age of 50 may reflect recreational and medicinal use.

Key Facts of Measuring Cannabis Use The measurement of recreational drug use, including cannabis, is quantified with standard questions that ask respondents’ to report if they have: (1) ever used cannabis (this indicates lifetime prevalence); (2) used cannabis in the past year (this indicates recent use); and (3) used cannabis in the past 30 days (this indicates current use). These recall and reporting measures are consistently used across most countries for national longitudinal trend tracking and cross-national comparison. Cannabis use or users are characterized in one of seven categories: (1) abstainers, (2) adolescent only users, (3) persistent users, (4) early adulthood decliners, (5) episodic users, and (6) late starters (Geller, Loftis & Brink, 2004; Juon et al., 2011; Patrick et al., 2011).

Key Facts of the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA)

KEY FA C T S

The EMCDDA was established in 1993 to provide the European Union and its member states with regular monitoring data of drug use problems and trends in European countries. The mission of the EMCDDA is to provide practitioners, public health officials, and policymakers with objective data to support informed drug laws and strategies. The EMCDDA scientifically monitors and routinely collects country-based data using consistent methodology to enable reliable comparative data across nations and over time.

Key Facts of Cannabis Cannabis is a genus of flowering plants (Cannabis indica, Cannabis ruderalis, C. sativa) and psychoactive preparations derived from C. sativa that are commonly known as cannabis, hash, hashish, marihuana, or marijuana. Cannabis may be used in several forms. It is most commonly used in dried leaf form that can be smoked, vaporized, and eaten when prepared in food products such as specialty baked Handbook of Cannabis and Related Pathologies. http://dx.doi.org/10.1016/B978-0-12-800756-3.00005-3 Copyright © 2017 Elsevier Inc. All rights reserved.

33

34

4.  Age as a Predictor of Cannabis Use

Key Facts of Medical Cannabis Medical cannabis, also known as medical marijuana, refers to the use of cannabis for the treatment, or symptom reduction, of a range of illnesses and conditions. It is recognized as a treatment for glaucoma, wasting disease, nausea, some forms of pain, and some seizure disorders. Medicinal cannabis may be used in several forms, and the method of ingestion depends on the condition being treated, and the preference of the use. It may be extracted into an oil or tincture that can be consumed directly, orally or mixed into beverages or foods. It can also be consumed in dried whole leaf form, which may be smoked, vaporized, and eaten when prepared in specialty food products, such as baked goods and chocolates. Most forms of medicinal cannabis produce some psychoactive effects. As such, some specialty forms of cannabis are cultivated to have very low levels of psychoactive compounds.

LIST OF ABBREVIATIONS Canadian Centre on Substance Abuse Cannabis use disorder European Monitoring Center on Drugs and Drug Addiction NSDUH National Survey on Drug Use and Health SAMHSA Substance Abuse Mental Health Services Administration THC Tetrahydrocannabinol UNODC United Nations Office for Drugs and Crime CCSA CUD EMCDDA

INTRODUCTION This chapter examines cannabis (marijuana, hashish) use by age group, across the lifespan with an emphasis on current (past 30 days) and recent (past year) cannabis use in Europe and the United States. We have focused on these countries where cannabis use is more prevalent, and reliable data is routinely collected to track trends over time. Data from Australia, Canada, and New Zealand is included where available. Lifetime cannabis use is virtually nonexistent in Asian countries, whereas it is most prevalent in the Czech Republic, Denmark, France, New Zealand, Spain, and the United States (EMCDDA, 2012; Degenhardt et al., 2008). Moreover, there is no singular pattern or trajectory of cannabis use initiation or continuation within these countries. Although there are some differences in survey methodology between countries, there are well-established standard cannabis use questions that enable comparative analysis. Specifically, such questions that ask if

the respondent has ever used cannabis (indicates lifetime prevalence), used cannabis in the past year ­(recent use), and/or has used cannabis in the past 30 days (current use). Furthermore, cannabis use is generally characterized within one of seven categories: abstainers, adolescent only users, persistent users, early adulthood decliners, episodic users, and late starters (Geller, Loftis, & Brink, 2004; Juon, Fothergill, Green, Doherty, & Ensminger, 2011; Patrick, Schulenberg, O’Malley, Johnston, & Bachman, 2011). Although this chapter examines age as a predictor of cannabis use among people in countries in Europe and North America, within the age groups and populations in each country there are unique patterns of use, particularly when further analyzed by gender and race/ethnicity. Case in point, examination of cannabis use among youth in the United States shows that black youths consistently use cannabis at lower rates than their white peers ( Johnston, O’Malley, Bachman, & Schulenberg, 2010; Wallace, 1999); however, rates of cannabis use among black adults are equal to or higher than usage rates among white adults (age matched peers), indicating a “crossover effect” (Juon et al., 2011). What this means for the data presented here is that, although there are distinct patterns of use within age groups in each country, age alone does not indicate likelihood of cannabis use. Furthermore, there are notable differences in the prevalence of cannabis use by age group from one country to the next.

Initiation of Cannabis Use Individuals begin using psychoactive substances for reasons that reflect individual history, as well as social, familial, environmental, and educational influences (Bachman et al., 2008; Eaton et al., 2010). Therefore, it is necessary to examine current and historical usage patterns of cannabis among people of all age groups. Much of the literature and monitoring data on cannabis use has focused on new initiates (age of first use) and use among youth and emerging adults because use has been highest among these age groups, in recent history. Moreover, the age of first alcohol intake has significant relevance to rates of initiation for cannabis use in many cultures (Arria, Dohey, Mezzich, Bukstein, & Van Thiel, 1995; Bergen-Cico and Lape, 2013; Eaton et al., 2010; Johnston et al., 2010; Kokkevi et al., 2006). Although there is no set age that marks the development or establishment of a cannabis use disorder (CUD), the younger a person is when they begin using, the greater the maturational deviation and psychological dysregulation, thereby increasing the risk of early age onset for CUDs (Kosterman, Hawkins, Guo, Catalano, & Abbott, 2000). It is noteworthy that initiation of cannabis use increases rapidly during adolescence, through age 18–20, with sharp declines after the age of 20 (SAMHSA, 2013; Schulenberg et al.,

I.  Setting the scene, botanical, general and international aspects



Introduction

2005). Research has shown an association between delaying the onset of first use until age 20 or later with a lower risk of cannabis abuse and dependence (Behrendt, Wittchen, Höfler, Lieb, & Beesdo, 2009; Winters & Lee, 2008). Although cannabis has relatively low addiction potential, compared to stimulant and depressant drugs, people who use cannabis frequently, particularly cannabis with increasingly high THC levels, can develop cannabis dependence (Inaba & Cohen, 2014). Research has also found that persistent regular use of cannabis is associated with higher rates of mental health problems among susceptible persons (Fergusson, Horwood, & Swain-Campbell, 2002). Historically, research has shown that people who began using cannabis at an early age were less likely to graduate high school and go to college (Grunbaum et al., 2004); however, more recent studies have found cannabis use among college students to be on a par with peers not attending college (Bergen-Cico & Lape, 2013; Johnston et al., 2010). Despite early and continued use of cannabis, a substantial percentage of youths who use cannabis are capable of graduating from high school and gaining entry to college; however, the frequency and intensity of cannabis (and other drug) use is a significant determinant of academic retention and success in college (Bergen-Cico, 2000; Bergen-Cico, Urtz, & Baretto, 2004; Horwood et al., 2010). Age of first use is related to cannabis use disorder risk, whereby the younger the age of first use, the higher the risk of cannabis abuse and dependence (Behrendt et al., 2009; Bergen-Cico & Lape, 2013; Chen, O’Brien, & Anthony, 2005; Lopez-Quintero et al., 2011; Winters & Lee, 2008). Early age of first use for cannabis follows similar patterns for the development of substance dependence for alcohol (Dawson, Goldstein, Chou, Ruan, & Grant 2008; DeWit, Adlaf, Offord, & Ogborne, 2000) and nicotine (Behrendt et al., 2009), with some evidence of temporal ordering whereby early onset of alcohol use may be associated with subsequent development of cannabis abuse (Bergen-Cico & Lape, 2013; Kirisci et al., 2013). Moreover, research has found a significant relationship between the age of first cannabis use and drinking alcohol by oneself (Bergen-Cico & Lape, 2013). This is of concern because use of alcohol or cannabis when alone (solitary use) is not an indicator of social use, but rather a marker of social isolation and potential indicator of dependency. However, as noted in the chapter How Age Leads to Cannabis Use Disorders, Dr Behrendt notes there is limited documentation of higher risk of escalating cannabis use among people who begin using at younger ages, which produces a void in important data that may pertain to the progression from early age of fist cannabis use to the development of CUDs later in life (Behrendt, 2015). Moreover, delaying cannabis use until after age 20 does not in and of itself inoculate

35

people from associated mental health problems. A study by Washburn and Capaldi (2014) found that patterns of cannabis use among men during their 20s was associated with diagnoses of cannabis disorders in their mid20s, and predicted antisocial behavior and deviant peer association in their mid-30s, thus concluding that differential patterns of marijuana use in early adulthood may be associated with psychopathology toward midlife ­(Washburn & Capaldi, 2014).

Trends in Cannabis Use Across the Lifespan Fig. 4.1 illustrates the percentage of past year and past month cannabis use across all age groups (age 12 and older) among people in the United States, based on national monitoring data collected in 2012 (SAMHSA, 2013). The major graph lines illustrate the higher prevalence of use through about age 20. The trend lines show a general decrease in usage as people get older, with a moderate convergence between past year and past month use, as age increases. This figure illustrates a mountainous peak around age 20, with substantial use following this peak in a gradual downward slope through age 25, followed by sharp declines. Thus, it indicates that use generally decreases as people age, and their responsibilities (work, family) increase (Fig. 4.2) (Tables 4.1 and 4.2). A 30-year longitudinal study of cannabis use among adolescents in the United States found that social norms and attitudes regarding cannabis use vary and cluster within birth cohorts. This clustering directly affects cannabis use among teens, even after controlling for individual attitudes and perceptions of norms (Keyes et al. 2011). This proclivity and peer social influence may also pertain to use among adults, as evidenced by the increasing rates of current cannabis use among older populations, most notably people over the age of 50 (Fig. 4.3). People in birth cohorts that are disapproving of cannabis use are less likely to use, independent of their personal attitudes toward cannabis use, and vice versa. Age alone does not predict cannabis use, social norms, attributes of low self-control, sensation seeking, and externalizing behavior have strong long-term predictive power with regard to distinct trajectories of marijuana use over time (Brook, Zhang & Brook, 2011). Initiation of cannabis use continues well beyond adolescence, and people begin using across their lifespan. The data in Table 4.3 illustrate the mean age of first use for US adults aged 26–49 who began using during the corresponding phase of adulthood. Over the 10-year time period covered in this table, the mean age increases from 31.2 to 33.1, while the numbers of new users in this age group concomitantly increased more than 50% from 90,000 in 2002, to 139,000 in 2012. Moreover, people may initiate cannabis use during their teens or early adulthood, and then discontinue use in midadulthood

I.  Setting the scene, botanical, general and international aspects

36

4.  Age as a Predictor of Cannabis Use

FIGURE 4.1  Cannabis use across age groups. This graph shows the percentage of past year and past month cannabis use across ages and age groups (age 12 and older) among people in the United States, based on national monitoring data collected in 2012 by the US Substance Abuse Mental Health Services Administration (SAMHSA, 2013). The blue and red graph lines illustrate the higher prevalence of use peaking through ∼age 20. The black trend lines show a general decrease in usage as people get older, with a moderate convergence between past year and past month use as age increases (55 + ).

FIGURE 4.2  Percentage of past year cannabis use by age group and country. European data is from the European Monitoring Center on Drugs and Drug Addiction (EMCDDA, 2012), US data is from NSDUH (SAMHSA, 2013). Past year use is highest among 15–24 year olds across all countries. The highest prevalence of use among people in the 45–54 and 55–64 age group is in the United States.

I.  Setting the scene, botanical, general and international aspects



37

Introduction

TABLE 4.1 Percentage of Current Age Cohorts and Corresponding Age of First Use for Cannabis Age of first use

Current age cohort (years) 12–17

18–25

26–34

35–49

50 ≥

≤ 13

6.5

7.8

7.9

7.2

1.9

14–15.

7.3

12.4

12.6

9.9

4.7

16–17

3.1

15.4

15.4

14

8.2

18–20

0

13.7

12.1

10.8

10.7

21–24

0

2.9

5.3

4.4

5

25 ≥

0

0

1.8

3.6

6.2

US NSDUH 2012 (SAMHSA, 2013). Note: bold data indicates highest prevalence for age of first use by current age cohort. The data in this table show that regardless of the current age group and cohort, people are most likely to first use cannabis by the age of 20.

TABLE 4.2 Cannabis Use by Age Group in US (Percentage) Cannabis Use

12–17 (years)

18–25 (years)

26–34 (years)

35–49 (years)

50≥ (years)

Ever use cannabis

17

52.2

Used past year

13.5

Past 30 day use

7.3

1–5 days use past year

3.8

6–10 days use past year

0.9

11–25 days use past year 26–100 days use past year Over 100 days of use past year

45.2

50

36.7

a

19.5

10

4.6

a

31.4 18.5

11.5

5.7

3

a

4.5

2.6

1.2

a

1

0.5

0.2

a

7.4 1.6

1.9

3.4

1.7

1.1

0.5

2.8

a

2.8

1.8

0.8

8.6

4

1.9

4

5

a

14

US NSDUH 2012 (SAMHSA, 2013). Note: bold data indicates highest prevalence for use by current age cohort, when excluding lifetime use (ever used). Past year use is most prevalent. a Indicates age group with greatest prevalence by usage frequency. 18–25 year olds have the highest rate of chronic use.

FIGURE 4.3  Past month cannabis use by age group and country. European data is from the European Monitoring Center on Drugs and Drug Addiction (EMCDDA, 2012), US data is from NSDUH (SAMHSA, 2013). Past month use is highest among 15–24 year olds across all countries, except Belgium, where it is greater among 25–34 year olds. The highest prevalence of use among people in the 45–54 age group is in the United States. I.  Setting the scene, botanical, general and international aspects

38

4.  Age as a Predictor of Cannabis Use

TABLE 4.3 Past Year Initiates Cannabis Use among US Adults Aged 26–49, 2002–2012 Mean age at first cannabis use among past year initiates in the United States, aged 26–49 Age

31.2

29.6

29.5

30.4

29.1

32.4

32.6

32.2

36.3

29.5

33.1

Numbers

90,000

56,000

127,000

122,000

126,000

121,000

155,000

49,000

210,000

138,000

139,000

Year

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

SAMHSA (2013); US NSUDH, 2002–2012.

as responsibilities (work, family) increase, and return to using again later in life (Kotarba, 2012). The mean age of first use of cannabis in Australia for persons aged 12 and older was 18.5 in 2010, indicating that youth are delaying their age of first use and/or there is an increase in older populations initiating cannabis use (AIHW, 2011).

Cannabis Use, Social Norms, and Legal Status Over the past decade, many countries have reduced the severity of penalties for simple cannabis use or possession (Bergen-Cico, 2013; EMCDDA, 2014). European emphasis on cannabis control has focused on targeting drug supply and trafficking, rather than personal use and minor possession, and yet the number of offences related to cannabis personal possession and use have steadily increased over the past decade (EMCDDA, 2014). The legalization of cannabis in Uruguay, Colorado State and Washington State, where recreational cannabis use has been legalized with oversight and control, have been accompanied by increasing support for decriminalization and legalization of cannabis across the United States, Mexico, Central and South America, and many European countries (Uruguay, 2014; State of Washington, 2011; Amendment 64 Use and Regulation of Marijuana, 2012). Portugal and Netherlands have decriminalized cannabis use, and Switzerland is experimenting with legal recreational use. The United States reported a major decrease (∼77%) in cannabis cultivation site eradication from 2011 to 2012, in conjunction with declining law enforcement efforts and increasing licit cultivation in the states of Colorado and Washington. What the change in licit supply will mean for usage across age groups is not yet known, as legal recreational use has been in place for less than a year, as of the writing of this chapter. The states of Washington and Colorado have established 21 as the minimum legal age for purchasing cannabis; how this may affect usage rates across age groups, notably people who were previously deterred by the illicit status of cannabis, has yet to be measured. With the change in legal status comes a need to revisit the ways in which we have traditionally assessed consequences of cannabis use, and how legal consequences have delineated CUDs. Legal status aside, there is a need to examine potential risks associated with cannabis use across age groups, in the context of current use, frequency

of use, and well-being. Decreases in legal consequences and increasing legal access to cannabis are reportedly part of the reason for increasing usage among older populations. Furthermore, cannabis use among older adults may be becoming normative, with increasing prevalence of cannabis using peer cohorts, as discussed in the latter part of this chapter.

Global Use In 2012, between 125 million and 227 million people were estimated to have used cannabis, corresponding to about 3–5% of the global population aged 15–64 years (UNODC, 2014). According to the United Nations Office of Drugs and Crime (UNODC), the regions with the highest prevalence rates are West and Central Africa, Western and Central Europe, North America, and Oceania. Current cannabis usage epidemiological data is not available from Asia although the World Drug Report suggests use is increasing in Asia. Among European nations, past year usage rate is estimated at 18.1 million, or 5.3% of the population aged 15–64 years. Whereas the past year usage rate for the United States was 7.3% of the population aged 12 and older, in 2012, this represents a notable increase from a rate of 6.2% in the United States in 2002. A closer look at this data within age groups provides some divergent trends. For example, among people aged 12–17 in the United States, the usage rates for cannabis dropped to 7.2% in 2012, from 8.2% in 2002. In fact, over this 10 year period, cannabis usage actually decreased among all age groups, for people under the age of 18 in the United States, while it increased among 18–25 year olds: from 17.3 in 2002 to 18.3% in 2012; from 7.7 to 11.3% among 26–34 year olds; and from 3.1 to 3.9% among those over the age of 35 (NCHS, 2014). Table 4.4 presents data on current cannabis use by age group for 30 countries, and Table 4.5 includes data for 28 countries. The data illustrates the percentage of the population who currently use cannabis, where current use is defined in Table 4.4 as past year, and in Table 4.5 covers data on use in the past month. There are notable variations in the prevalence of use reported by country and by age group. It is important to note such variation because when we examine age as a predictor of use, use is contextual to the country, as well as age group. Variations

I.  Setting the scene, botanical, general and international aspects



39

Introduction

TABLE 4.4 Past Year Cannabis Use by Age Group: Europe, Canada, and the United States Age groups

15–24

25–34

35–44

45–54

55–64

Austria

10.6

2.8

1.8

2.4

0.4

Belgium

11.9

10.5

3.5

0.7

1.0

Bulgaria

11.2

6.0

1.3

0.0

0.1

a

Canada

20.3

8.4

Croatia

12.6

8.4

2.5

0.7

0.5

Cyprus

4.3

4.0

1.0

0.2

0.7

Czech Republic

23.3

14.6

6.2

2.9

0.7

Denmark

23.9

10.4

3.6

2.3

1.2

Estonia

19.4

7.6

1.1

0.0

0.0

Finland

11.8

10.7

1.2

0.4

0.0

France

20.8

14.3

5.1

2.4

0.8

Germany

14.7

8.7

2.9

1.7

0.2

Greece

3.6

2.8

1.1

0.1

0.2

Hungary

10.1

2.9

0.4

0.4

0.0

Ireland

12.9

8.5

3.7

2.6

0.9

Italy

12.1

5.7

1.5

N.A.

N.A.

Latvia

10.0

4.6

3.7

0.3

0.1

Lithuania

6.1

4.0

0.7

0.1

0.1

Netherlands

16.1

11.3

4.9

N.A.

N.A.

Norway

11.7

4.0

0.7

1.5

0.3

Poland

11.0

5.7

1.4

0.3

0.4

Portugal

5.8

4.6

2.3

1.0

0.2

Romania

0.9

0.4

0.0

0.3

0.0

Slovakia

11.2

4.1

1.5

0.5

0.3

Slovenia

15.0

6.9

1.7

0.8

0.2

Spain

20.7

14.6

8.5

4.3

1.3

Sweden

9.7

4.3

1.2

0.4

0.3

Turkey

0.5

0.3

0.2

0.1

0.5

United Kingdom

13.5

7.9

4.4

2.6

1.7

12–25

26–34

35–49

50–54

55–64

22.7

19.5

10

8

5.9c

Age Groups b

United States

Note: some US age groups differ between EMCDDA, Canada and the United States. N.A., data not available. a CCSA (2014). b SAMHSA (2013). c Estimate from NSDUH 2012 data. EMCDDA 2008–2012 unless noted.

between the 15–24 years age group and the 25–34 age group for past year cannabis use are quite notable for some countries, such as, Austria (10.6 and 2.8, respectively) and Hungary (10.1 and 2.9, respectively), yet negligible for others, such as, Belgium (11.9 vs 10.5 respectively) and Finland (11.8 vs 10.7 respectively) (EMCDDA, 2012).

Cannabis Use Among Older Adults Until recently, cannabis use and CUD among older individuals was considered rare (Compton, Grant, Colliver, Glantz, & Stinson, 2004). However, as the generation who came of age in the 1960s began to reach age 50, we have

I.  Setting the scene, botanical, general and international aspects

40

4.  Age as a Predictor of Cannabis Use

TABLE 4.5 Past Month Cannabis Use by Age Group, Europe and the United States Age groups

15–24

25–34

35–44

45–54

55–64

Austria

5.3

1.4

1.4

0.3

0.0

Belgium

6.6

7.1

1.9

0.6

0.6

Bulgaria

6.6

3.2

0.8

0.0

0.0

Croatia

7.3

4.8

1.5

0.5

0.5

Cyprus

2.0

2.0

0.4

0.2

0.4

Czech Republic

11.0

7.3

3.4

1.1

0.2

Denmark

8.5

4.0

1.6

1.2

0.6

Estonia

5.3

1.0

0.4

0.0

0.0

Finland

3.3

3.3

0.6

0.0

0.0

France

11.8

7.9

2.8

1.0

0.2

Germany

6.8

4.3

1.5

1.1

0.0

Greece

1.2

1.8

0.8

0.0

0.2

Hungary

4.6

1.5

0.4

0.2

0.0

Ireland

5.4

4.0

1.9

1.7

0.3

Italy

5.7

2.5

0.5

N.A.

N.A.

Latvia

3.4

1.9

1.8

0.1

0.0

Lithuania

1.8

1.5

0.1

0.0

0.0

Netherlands

8.2

7.1

3.5

N.A.

N.A.

Norway

5.1

1.6

0.2

0.9

0.0

Poland

5.3

2.8

0.5

0.0

0.0

Portugal

3.4

2.8

1.4

1.0

0.1

Romania

0.5

0.2

0.0

0.0

0.0

Slovakia

3.7

2.0

0.7

0.1

0.0

Slovenia

7.5

3.7

1.0

0.4

0.1

Spain

14.7

11.0

6.3

2.7

1.1

Sweden

3.0

1.1

0.4

0.1

0.1

Turkey

0.2

0.1

0.2

0.1

N.A.

12–25

26–34

35–49

50+

13

11.5

5.7

3

Age Groups a

United States

N.A.

Note: Some US age groups differ between EMCDDA. N.A., data not available. a (SAMHSA, 2013) EMCDDA 2008–2012 unless noted.

seen an increase in current cannabis users among older people (Blazer & Wu, 2009; Han et al., 2009a,b). This generational shift in drug use is evident in the US National Survey on Drug Use and Health (NSDUH) data that shows increasing rates of current recreational drug use among persons aged 50–64 (SAMHSA, 2013). The current 50–64 year old cohort, comprised of baby boomers born after 1950, had higher rates of recreational drug use among youth, as compared to previous generations. By 2014, the 50–64 year old cohort consisted entirely of baby

boomers who now account for the increase in cannabis use among older adults. A decade ago, researchers predicted that, by 2020, there would be a threefold increase in substance abuse problems among adults aged 50 and older (Gfroerer, Penne, Pemberton, & F ­olsom, 2003; Gfroerer, Wu, & Penne, 2002). In 2012, the percentage of persons in the age groups 50–54, 55–59, and 60–64 who reported using marijuana in the past year increased significantly over the prior decade (since 2002). In the United States, in 2012, 8% of those aged 50–54 said they had used

I.  Setting the scene, botanical, general and international aspects



41

Mini-dictionary

FIGURE 4.4  Percentage of older adults in United States using cannabis in the past year. These graphs show strong and steady upward trends in the percentage of older adults who recently used cannabis. The data represent people who came of age during and following the 1960s and, therefore, belong to a peer cohort in which cannabis use has been more normative than previous generations. Source: NSDUH 2002, 2007, and 2012 (SAMHSA, 2013).

marijuana in the past year, nearly double the percentage from 2002. Users aged 55–59 more than quadrupled, from 1.6% in 2002 to 7.4% in 2012. Among Americans aged 60–64, use nearly doubled, from 2.4 to 4.4% in the same period. Fig. 4.4 shows the rates of marijuana use in the previous year, by 5-year age groups (45–49; 50–54; 55–59; 60–64) for the years 2002, 2007, and 2012. Use among the older adults and the elderly varies from country to country and, upon further analysis, there are notable differences within age groups in a given country. For example, in England, current cannabis use among older adults varies widely between those in the 50–64  age group (1.8% past year use) and those over 65 (0.4%), and people over 50 living in London use cannabis at a rate 4 times higher than England (Fahmy, Hatch, Hotopf, & Stewart, 2012). Survey data alone does not provide much context regarding current cannabis use among older adults, although they increasingly report using cannabis medically for nausea and pain (Sacco & Kuerbis, 2013). In addition to recreational use of cannabis, there is increasing use of cannabis for medical purposes. Medical use of cannabis is legal and controlled in Canada, the Netherlands, Switzerland, and several states in the United States. Cannabis abuse or dependence is reported by very few older adults, with only 0.004% of US adults aged 50–64 reporting cannabis abuse or possible dependence in the current year. This suggests that current cannabis

use among older populations may not be problematic, provided the individuals have the ability to cope with stressors, and self-regulate their emotions in the absence of cannabis and other psychoactive substances. The extent to which their use may be problematic depends on factors, such as, emotional coping strategies in the absence of cannabis use, interpersonal and social skills, and the extent to which they have been able to be active contributing members of society, regardless of their use.

MINI-DICTIONARY Age of first use; age of initiation; age of onset  These terms may be used interchangeably. The term refers to the age at which a person first used a drug. In this chapter, the drug is cannabis. Cannabis  A drug derived from certain plants in the Cannabaceae/hemp family. Cannabis is also commonly known as Cannabis indica, Cannabis sativa, hash, hashish, marihuana, or marijuana. Cannabis may be used in several forms, but is most commonly used in dried leaf form that can be smoked, vaporized, and eaten when prepared in food products such as specialty baked goods and chocolates. Current use  This term refers to use of a drug within the past 30 days and indicates a person who currently uses that drug. In this chapter, the drug refers to cannabis. Lifetime use Reported use of cannabis in the 30 days or past month preceding the survey or similar means of data collection. Medicinal cannabis  Medical cannabis, also known as medical marijuana, refers to the use of cannabis for the treatment, or symptom reduction, of a range of illnesses and conditions. It is

I.  Setting the scene, botanical, general and international aspects

42

4.  Age as a Predictor of Cannabis Use

recognized as a treatment for glaucoma, wasting disease, nausea, some forms of pain, and some seizure disorders. Past 30-day use Reported use of cannabis in the 30 days or past month preceding the survey or similar means of data collection. Past year use Reported use of cannabis in the 12 months preceding the survey or similar means of data collection. Prevalence  The proportion (usually expressed as a percentage) of a defined group (eg, age group, gender, race) or population reporting a specified behavior or outcome. In this chapter, the behavior is cannabis use. Recent use  This term refers to use of a drug at a recent point in time in a person’s life, defined here as within the previous year. In this chapter, the drug refers to cannabis. THC  is the acronym for tetrahydrocannabinol, the psychoactive ingredient in cannabis. The higher the level of THC the more potent the cannabis is. Chronic use of high potency THC increases likelihood of CUD and dependency. Levels of THC vary from across types of cannabis.

References Amendment 64 Use and Regulation of Marijuana, Constitution of the State of Colorado. Article XVIII, Available from: http://www.fcgov.com/mmj/pdf/amendment64.pdf Arria, A. M., Dohey, M. A., Mezzich, A. C., Bukstein, O. G., & Van Thiel, D. H. (1995). Self-reported health problems and physical symptomatology in adolescent alcohol abusers. Journal of Adolescent Health, 16(3), 226–231. Australian Institute of Health and Welfare (AIHW) (2011) National Drug Strategy Household Survey 2010.;1; Drug Statistics Series No. 25. Cat. no. PHE 145. Canberra: AIHW. Bachman, J. G., O’Malley, P. M., Schulenberg, J. E., Johnston, L. D., Freedman-Doan, P., & Messersmith, E. E. (2008). The education-drug use connection: How successes and failures in school relate to adolescent smoking, drinking, drug use, and delinquency. New York: Francis Taylor. Bergen-Cico, D. (2000). Substance abuse and attrition among first-year college students. Journal of the First-Year Experience & Students in Transition, 12(1), 61–76. Bergen-Cico, D. (2013). Perspectives of US drug policy: observations and advice from drug policy administrators in emerging democracies in Central and Eastern Europe. World Medical & Health Policy, 5(4), 362–389. Bergen-Cico, D., & Lape, M. (2013). Age of first use as a predictor of current alcohol and marijuana use among college-bound adolescents. Journal of Child and Adolescent Substance Abuse, 22, 235–253. Bergen-Cico, D., Urtz, A., & Barretto, C. (2004). Longitudinal assessment of the effectiveness of environmental management and enforcement strategies on college student substance abuse behaviors. Journal of Student Affairs Research and Practice, 41(2), 235–262. Behrendt, S. (2015). How age leads to cannabis use disorders. In Victor Preedy (Ed.), The comprehensive handbook of cannabis related pathology. Biology, diagnosis, treatment, and pharmacology. Philadelphia: Academic Press. Behrendt, S., Wittchen, H. -U., Höfler, M., Lieb, R., & Beesdo, K. (2009). Transitions from first substance use to substance use disorders in adolescence: is early onset associated with a rapid escalation? Drug and Alcohol Dependence, 99(1), 68–78. Blazer, D. G., & Wu, L. T. (2009). The epidemiology of substance use and disorders among middle aged and elderly community adults: national survey on drug use and health. American Journal of Geriatric Psychiatry, 17(3), 237–245. Brook, J. S., Zhang, C., & Brook, D. W. (2011). Developmental trajectories of marijuana use from adolescence to adulthood: personal predictors. Archives of Pediatrics & Adolescent Medicine, 165(1), 55–60.

Canadian Centre on Substance Abuse (CCSA). (2014). Canadian drug summary: cannabis ISBN 9781771781244. Chen, C. Y., O’Brien, M. S., & Anthony, J. C. (2005). Who becomes cannabis dependent soon after onset of use? Epidemiological evidence from the United States: 2000-2001. Drug and Alcohol Dependence, 79, 11–22. Compton, W. M., Grant, B. F., Colliver, J. D., Glantz, M. D., & Stinson, F. S. (2004). Prevalence of marihuana use disorders in the United States. 1991–1992 and 2001–2002. Journal of the American Medical Association, 291(17), 2114–2121. Dawson, D. A., Goldstein, R. B., Chou, S. P., Ruan, W. J., & Grant, B. F. (2008). Age at first drink and the first incidence of adult-onset DSM-IV alcohol use disorders. Alcoholism: Clinical and Experimental Research, 32(12), 1–12. Degenhardt, L., Chiu, W. T., Sampson, N., Kessler, R. C., Anthony, J. C., Angermeyer, M., & Wells, J. E. (2008). Toward a global view of alcohol, tobacco, cannabis, and cocaine use: findings from the WHO World Mental Health Surveys. PLoS Medicine, 5(7), e141. DeWit, D. J., Adlaf, E. M., Offord, D. R., & Ogborne, A. C. (2000). Age at first alcohol use: a risk factor for the development of alcohol disorders. American Journal of Psychiatry, 157(5), 745–750. Eaton, D. K., Kann, L., Kinchen, S., Shanklin, S., Ross, J., Hawkins, J., … & Wechseler, H. (2010). Youth risk behavior surveillance—United States, 2009. MMWR Surveillance Summaries, 59(SS-5), 1–148. European Monitoring Centre for Drugs and Drug Addiction (EMCDDA). (2012). Annual report [2010:] the state of the drugs problem in Europe. Luxembourg: Publications Office of the European Union. European Monitoring Centre for Drugs and Drug Addiction (EMCDDA). (2014). European drug report 2014 trends and developments. Lisbon Portugal. Luxembourg: Publications Office of the European Union. Fahmy, V., Hatch, S. L., Hotopf, M., & Stewart, R. (2012). Prevalences of illicit drug use in people aged 50 years and over from two surveys. Age and Ageing, 41(4), 553–556. Fergusson, D. M., Horwood, L. J., & Swain-Campbell, N. R. (2002). Cannabis use and psychosocial adjustment in adolescence and young adulthood. Addiction, 97(9), 1123–1135. Geller, T., Loftis, L., & Brink, D. S. (2004). Cerebellar infarction in adolescent males associated with acute marijuana use. Pediatrics, 113(4), e365–e370. Gfroerer, J., Penne, M., Pemberton, M., & Folsom, R. (2003). Substance abuse treatment need among older adults in 2020: the impact of the aging baby-boom cohort. Drug and Alcohol Dependence, 69(2), 127–135. Gfroerer, J.C., Wu, L.-T., & Penne, M.A. (2002). Initiation of marijuana use: trends, patterns, and implications (Analytic Series: A-17, DHHS Publication No. SMA 02-3711). Rockville, MD: Substance Abuse and Mental Health Services Administration (SAMHSA), Office of Applied Studies. Grunbaum, J. A., Kann, L., Kinchen, S., Ross, J., Hawkins, J., Lowry, R., … & Collins, J. (2004). Youth risk behavior surveillance--United States, 2003. MMWR. Surveillance Summaries. 53(2), 1–96. Han, B., Gfroerer, J. C., Colliver, J. D., & Penne, M. A. (2009a). Substance use disorder among older adults in the United States in 2020. Addiction, 104(1), 88–96. Han, K. H., Lim, S., Ryu, J., Lee, C. W., Kim, Y., Kang, J. H., Kang, S. S., Ahn, Y.K., Park, C.S. & Kim, J. J. (2009b). CB1 and CB2 cannabinoid receptors differentially regulate the production of reactive oxygen species by macrophages. Cardiovascular Research, cvp240. Horwood, L. J., Fergusson, D. M., Hayatbakhsh, M. R., Najman, J. M., Coffey, C., Patton, G. C., & Hutchinson, D. M. (2010). Cannabis use and educational achievement: findings from three Australasian cohort studies. Drug and Alcohol Dependence, 110(3), 247–253. Inaba, D., & Cohen, W. E. (2014). Uppers, downers, all rounders: Physical & mental effects of psychoactive drugs (7th ed.). Medford, OR: CNS Productions.

I.  Setting the scene, botanical, general and international aspects



REFERENCES

Johnston, L.D., O’Malley, P.M., Bachman, J.G., & Schulenberg, J.E. (2010). Monitoring the Future: National Survey Results on Drug Use, 19752009. Volume II: College Students and Adults Ages 19–50. NIH Publication No. 10-7585. National Institute on Drug Abuse.(NIDA). Juon, H. S., Fothergill, K. E., Green, K. M., Doherty, E. E., & Ensminger, M. E. (2011). Antecedents and consequences of marijuana use trajectories over the life course in an African American population. Drug and Alcohol Dependence, 118(2), 216–223. Keyes, K. M., Schulenberg, J. E., O’Malley, P. M., Johnston, L. D., Bachman, J. G., Li, G., & Hasin, D. (2011). The social norms of birth cohorts and adolescent marijuana use in the United States, 1976–2007. Addiction, 106(10), 1790–1800. Kirisci, L., Tarter, R., Ridenour, T., Zhai, Z. W., Fishbein, D., Reynolds, M., & Vanyukov, M. (2013). Age of alcohol and cannabis use onset mediates the association of transmissible risk in childhood and development of alcohol and cannabis disorders: evidence for common liability. Experimental and Clinical Psychopharmacology, 21(1), 38–45. Kokkevi, A., Gabhainn, S. N., & Spyropoulou, M. (2006). Early initiation of Cannabis use: a cross-national European perspective. Journal of Adolescent Health, 39(5), 712–719. Kosterman, R., Hawkins, D., Guo, J., Catalano, R. E., & Abbott, R. D. (2000). The dynamics of alcohol and marijuana initiation: patterns and predictors of first use in adolescence. American Journal of Public Health, 90(3), 360–366. Kotarba, J. A. (2012). Baby boomer rock‘n’roll fans: the music never ends. Lanham, MD: Scarecrow Press. Lopez-Quintero, C., Perez de los Cobos, J., Hasin, D. S., Okuda, M., Wang, S., Grant, B. F., & Blanco, C. (2011). Probability and predictors of transition from first use to dependence on nicotine, alcohol, cannabis, and cocaine: results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug and Alcohol Dependence, 115(1), 120–130. National Center for Health Statistics (NCHS) (2014) Health, United States, 2013: Special feature on prescription drugs. Hyattsville, MD.

43

Patrick, M. E., Schulenberg, J. E., O’Malley, P. M., Johnston, L. D., & Bachman, J. G. (2011). Adolescents’ reported reasons for alcohol and marijuana use as predictors of substance use and problems in adulthood. Journal of Studies on Alcohol and Drugs, 72(1), 106–116. Sacco, P., & Kuerbis, A. (2013). Older adults. In M. G. Vaughn, & B. E. Perron (Eds.), Social work practice in the addictions, contemporary social work practice (pp. 213–227). New York: Springer. Schulenberg, J. E., Merline, A. C., Johnston, L. D., O’Malley, P. M., Bachman, J. G., & Laetz, V. B. (2005). Trajectories of marijuana use during the transition to adulthood: the big picture based on national panel data. Journal of Drug Issues, 35(2), 255–280. Substance Abuse and Mental Health Services Administration (SAMHSA), (2013) Results from the 2012 National Survey on Drug Use and Health (NSDUH): Summary of National Findings, NSDUH Series H-46, HHS Publication No. (SMA) 13-4795. Rockville, MD: Substance Abuse and Mental Health Services Administration. State of Washington. (2011). Initiative Measure No. 502. Accessed at http://lcb.wa.gov/publications/Marijuana/I-502/i502.pdf United Nations Office on Drugs and Crime (UNODC). (2014). World Drug Report 2014. Vienna, Austria. Uruguay. (2014). Law No. 19.172. Wallace, J. M., Forman, T. A., Guthrie, B. J., Bachman, J. G., O’Malley, P. M., & Johnston, L. D. (1999). The epidemiology of alcohol, tobacco and other drug use among black youth. Journal of Studies on Alcohol, 60(6), 800–809. Washburn, I. J., & Capaldi, D. M. (2014). Heterogeneity in men’s marijuana use in the 20s: adolescent antecedents and consequences in the 30s. Development and Psychopathology, 1–13. Winters, K. C., & Lee, C. -Y. S. (2008). Likelihood of developing an alcohol and-cannabis use-disorder during youth: association with recent use and age. Drug and Alcohol Dependence, 92(1–3), 239–247.

I.  Setting the scene, botanical, general and international aspects