PREVALENCE OF MARIJUANA USE DISORDERS IN THE UNITED STATES

1991-1992 AND 2001-2002

[abstract]

Context Among illicit substance use disorders, marijuana use disorders
are the most prevalent in the population. Yet, information about the
prevalence of current Diagnostic and Statistical Manual of Mental
Disorders, Fourth Edition (DSM-IV) marijuana use disorders and how
prevalence has changed is lacking.

Objective To examine changes in the prevalence of marijuana use,
abuse, and dependence in the United States between 1991-1992 and 2001-2002.

Design, Setting, and Participants Face-to-face interviews were
conducted in 2 large national surveys conducted 10 years apart: the
1991-1992 National Longitudinal Alcohol Epidemiologic Survey ([NLAES]
nB862) and the 2001-2002 National Epidemiologic Survey on Alcohol
and Related Conditions ([NESARC] nC093). Main Outcome Measures Rates
of past year marijuana use, abuse, and dependence. Results Among the
adult US population, the prevalence of marijuana use remained stable
at about 4.0% over the past decade. In contrast, the prevalence of
DSM-IV marijuana abuse or dependence significantly (P=.01) increased
between 1991-1992 (1.2%) and 2001-2002 (1.5%), with the greatest
increases observed among young black men and women (P?.001) and young
Hispanic men (P = .006). Further, marijuana use disorders among
marijuana users significantly increased (P = .002) in the absence of
increased frequency and quantity of marijuana use, suggesting that the
concomitant increase in potency of delta-9-tetrahydrocannabinol (delta
9-THC) may have contributed to the rising rates.

Conclusions Despite the stability in the overall prevalence of
marijuana use, more adults in the United States had a marijuana use
disorder in 2001-2002 than in 1991-1992. Increases in the prevalence
of marijuana use disorders were most notable among young black men and
women and young Hispanic men. Although rates of marijuana abuse and
dependence did not increase among young white men and women, their
rates have remained high. The results of this study underscore the
need to develop and implement new prevention and intervention programs
targeted at youth, particularly minority youth.

[text]

MARIJUANA HAS BEEN THE most common illicit substance used in the
United States for several decades. 1,2 Understanding changes in the
use of marijuana over time is important for a number of reasons.
Marijuana use is associated with impaired educational attainment,3
reduced workplace productivity, 4 and increased risk of use of other
substances.5 Marijuana use plays a major role in motor vehicle
crashes6 and has adverse effects on the respiratory and cardiovascular
systems.7-10

Marijuana use also is a necessary, although not a sufficient,
condition for developing marijuana abuse and dependence as defined in
the Diagnostic and Statistical Manual of Mental Disorders, Fourth
Edition (DSM-IV), which are clear indicators of problems in and of
themselves.11 Marijuana abuse is defined in the DSM-IV as repeated
instances of use under hazardous conditions; repeated, clinically
meaningful impairment in social/occupational/ educational functioning,
or legal problems related to marijuana use. Marijuana dependence is
defined in the DSM-IV as increased tolerance, compulsive use, impaired
control, and continued use despite physical and psychological problems
caused or exacerbated by use. Beyond the seriousness of these
disorders in their own right, marijuana abuse and dependence increase
the risk of other serious consequences, most significantly, major
mood, anxiety, and personality psychopathology. 12-14

Despite the seriousness of DSM-IV marijuana abuse and dependence, no
long-term trend information is available about whether the prevalence
of these disorders is increasing, decreasing, or remaining stable in
the United States. Such information was recently added to the National
Household Survey on Drug Abuse, but this has only been since 2000.1
For public health efforts, accurate information on changes in
potentially vulnerable groups may highlight the need for focused
planning on both a national and local level and form the basis of
rational, scientifically based prevention and intervention programs.
The current study was designed, in part, to address this gap.

To assess changes in marijuana use, abuse, and dependence in the US
population, we compared data from the 1991- 1992 National Longitudinal
Alcohol Epidemiologic Survey ([NLAES] nB862) and the 2001-2002
National Epidemiologic Survey on Alcohol and Related Conditions
([NESARC] nC093).15,16 Both surveys were conducted by the National
Institute on Alcohol Abuse and Alcoholism (NIAAA). Because changes in
the prevalence of marijuana use may not reflect changes in the
prevalence of marijuana use disorders, rates are presented separately
for marijuana use and abuse or dependence in the total population. To
assess the risk of marijuana abuse or dependence independent of these
baseline rates, conditional rates of past-year marijuana abuse or
dependence among users also are presented.

METHODS

Samples

Both the 1991-1992 NLAES and the 2001-2002 NESARC are nationally
representative samples of the adult population of the United States
and have been described in detail elsewhere.15,16 The target
population for each survey was the civilian noninstitutionalized
population, 18 years and older, residing in the United States. The
fieldwork for both studies was conducted by the US Census Bureau,
under the direction of NIAAA staff. For the NESARC, the overall survey
response rate was 81% and for the NLAES, 90%.

The NESARC's sample consisted of 655 primary sampling units (PSUs);
however, in the final NESARC datafile, only 435 PSUs are shown because
smaller PSUs were collapsed to minimize disclosure risks. The NLAES
sample consisted of 198 PSUs. Oversampling of blacks and Hispanics in
the NESARC and of blacks in the NLAES, completed at the design phase,
increased the proportion of each of these groups in the total samples.
In the final selection phase, 1 individual was randomly selected from
a list of persons living in the household. At this stage of the
survey, young adults (ages 18-24 years in the NESARC and ages 18-29
years in the NLAES) were oversampled at a rate of 2.25:1.00.

The complex sampling design necessitated weighting the data from both
surveys to reflect the probability of the following: selection of a
PSU within stratum, selection of housing units within the sample PSU,
oversampling of young adults, and nonresponse at the household and
person levels. The NESARC data were also adjusted to reduce the
variance arising from selecting 2 PSUs to represent an entire stratum.
The weighted data for both groups were then adjusted to be
representative of the US population for a variety of socioeconomic
variables including region, age, sex, and race/ethnicity using the
Decennial Census of Population and Housing (1990 for the NLAES and
2000 for the NESARC). All potential NESARC respondents were informed
in writing about the nature of the survey, the statistical uses of the
survey data, the voluntary aspect of their participation, and the
federal laws that rigorously provided for the strict confidentiality
of the identifiable survey information. Those respondents consenting
to participate after receiving this information were interviewed. The
research protocol, including informed consent procedures, received
full ethical review and approval from the US Census Bureau and US
Office of Management and Budget.

Interviewers and Training

All interviews for both the NLAES and NESARC were conducted by
professional interviewers from the US Census Bureau. On average, the
1000 NLAES and 1800 NESARC interviewers had 5 years of survey
administration experience. All completed a 5-day self-study course
followed by a 5-day inperson training session at one of the US Census
Bureau's 12 regional offices. Quality of interviewing was ensured by
regional supervisors who recontacted a random 10% of all respondents
by telephone and reasked a set of 30 questions from different parts of
the interview to verify answers.

Diagnostic Assessment

All diagnoses in the NLAES and NESARC were made according to the
criteria of the DSM-IV using the NIAAA Alcohol Use Disorder and
Associated Disabilities Interview Schedule-DSM-IV Version
(AUDADIS-IV), a fully structured diagnostic interview designed for use
by professional interviewers who are not clinicians.17 Although the
DSM-IV classification was not published until 1994, proposed
diagnostic criteria for DSM-IV marijuana abuse and dependence were
published by the American Psychiatric Association prior to the
fieldwork for the NLAES and were incorporated into the AUDADIS-IV in
their entirety.18 What was not known at the time was which diagnostic
criteria would be assigned to the abuse or dependence categories.
However, since all proposed DSM-IV diagnostic criteria had been
incorporated into the AUDADIS-IV, computer algorithms were able to
produce diagnoses of abuse and dependence that accurately represented
the placement of the criteria within abuse and dependence categories
of the final DSM-IV revision.

The NLAES and NESARC included the same core questions to assess
marijuana abuse and dependence. One minor difference is that, in the
NLAES, duration associated with a particular criterion was assessed
separately from the criterion itself. For example, if a respondent
endorsed a particular criterion symptom for marijuana, the next
question asked whether that criterion had happened more than once with
marijuana. In the NESARC, duration associated with marijuana abuse and
dependence criteria was embedded directly into the symptom questions.
Another difference is that, in the NLAES, the AUDADIS-IV was
administered using a paper-and-pencil instrument, while in the NESARC,
the AUDADIS-IV was computerized and responses were entered directly
into laptop computers. However, in both studies, all questions were
asked by highly trained interviewers. Thus, the computerization did
not change the way respondents were exposed to the questions.

In the AUDADIS-IV, symptom questions associated with DSM-IV abuse and
dependence were asked separately for marijuana and each other
substance. Consistent with DSM-IV, past-year diagnoses of marijuana
abuse required a respondent to report at least 1 of the 4 criteria of
marijuana abuse within the 12 months prior to the interview.11 These
included recurrent marijuana use resulting in failure to fulfill major
role obligations, recurrent marijuana use in physically hazardous
situations, recurrent marijuana-related legal problems, and continued
marijuana use despite having persistent or recurrent social or
interpersonal problems caused by or exacerbated by use. The diagnosis
of marijuana dependence required that at least 3 criteria from a list
of 6 during the preceding 12 months be met: (1) need for increased
amounts of marijuana to achieve the desired effect or markedly
diminished effect with continued use of the same amount of marijuana;
(2) using marijuana in larger amounts or over a longer period than
intended; (3) persistent desire or unsuccessful efforts to cut down or
reduce marijuana use; (4) a great deal of time spent obtaining, using,
or recovering from the effects of marijuana; (5) giving up important
social, occupational, or recreational activities in favor of using
marijuana; and (6) continued marijuana use despite persistent or
recurrent physical or psychological problems caused or exacerbated by
use.

Consistent with the DSM-IV, diagnoses of marijuana abuse and
dependence were mutually exclusive. A marijuana dependence diagnosis
preempts a diagnosis of marijuana abuse. Thus, respondents classified
with marijuana abuse had marijuana abuse only, and respondents
classified as dependent included those who were dependent with and
without abuse. Because the DSM-IV does not include specific criteria
for marijuana withdrawal, no criterion for marijuana withdrawal is
included in the diagnosis and the typical list of 7 DSM-IV dependence
criteria is reduced to 6 criteria for marijuana. While a number of
studies have indicated that a withdrawal syndrome can be defined and
assessed for marijuana,19,20 this point has not yet been fully
resolved. Our method of diagnosing marijuana dependence is therefore
consistent with the DSM-IV in its current standard form.

The reliability and validity of the AUDADIS- IV are well documented in
numerous national and international psychometric studies conducted in
clinical, and particularly in general, population studies, the
population for which it was designed.21-32 The psychometric properties
of the AUDADIS-IV alcohol and drug modules also were shown to be good
in numerous countries in the World Health Organization/National
Institutes of Health Joint Project on Reliability and
Validity.22,23,28-32

Data Analysis

To account for the complex sample designs of both the NLAES and
NESARC, SUDAAN software was used to estimate standard errors of all
prevalence estimates in both studies across sex, age, and race-ethnic
subgroups of the population. 33 Prevalence estimates and standard
errors, derived separately for the NLAES and NESARC, were compared
using t tests designed for independent samples. To take into account
the sampling design, all standard errors of the prevalence estimates
were calculated using SUDAAN, a software program that uses Taylor
series linearization to make adjustments for weighted data. In all
cases, results are not displayed when standard errors are greater than
or equal to 50% of the weighted prevalence because these are too
imprecise to be reliable.

RESULTS

Past-Year Marijuana Use

Past-year marijuana use was reported by 4.0% of the respondents in the
1991- 1992 NLAES and 4.1% of the respondents in the 2001-2002 NESARC
(TABLE 1). Marijuana use did not significantly increase in the full
sample or among males or females, or among whites, blacks, or
Hispanics overall. However, some subgroups did show significant
increases and no subgroups showed significant decreases. Increased
rates of marijuana use were observed among 18- to 29-year-old black
and Hispanic women. The prevalence of marijuana use also increased
significantly over the last decade among 45- to 64-year-old men and
women overall and white men and black women in this age group.

Past-Year Marijuana Abuse and Dependence

In both the NLAES and NESARC, past year marijuana abuse was more
common than dependence. For the total population in 1991-1992 (the
NLAES), past-year prevalence of marijuana abuse was 0.9% and
dependence was 0.3%. Similarly, in 2001-2002 (the NESARC), past-year
marijuana abuse was reported by 1.1% and dependence by 0.4%. This
pattern of abuse, representing approximately 75% to 80% of the total
marijuana use disorder cases, was consistent across age, sex, and
race-ethnic subgroups, and all further results are described for
combined abuse and dependence rates (TABLE 2). For instance, in the
total population, past-year prevalence of marijuana abuse or
dependence increased from 1.2% in 1991- 1992 to 1.5% in 2001-2002
(P=.01). This can be translated into an increase from 2.2 million to
3.0 million, respectively, in terms of population estimates.

While most subgroups showed increases over the decade, these reached
statistical significance for females, blacks, Hispanics, and those
ages 18 to 29 years and 45 to 64 years overall, for 18- to 29-year-old
women, for 45- to 64-year-old men, for black men and women overall,
for 18- to-29-year-old black men and women, and for Hispanic men and
Hispanics ages 18 to 29 years overall as well as 18- to-29-yearold
Hispanic men.

Past-Year Marijuana Abuse and Dependence Among Past-Year Marijuana
Users

Among past-year marijuana users, overall rates of past-year abuse or
dependence increased from 30.2% in 1991- 1992 to 35.6% in 2001-2002
(P?.01) (TABLE 3). Almost without exception, the conditional rates of
abuse or dependence were larger in the more recent survey, although
not all increases were significant. However, significant increases in
the prevalence of marijuana abuse or dependence among users were found
for both males (33.9% to 38.9%) and females (22.7% to 29.2%), and most
notably among 18- to 29-year-old black men (21.8% to 43.0%), 18- to
29-year-old black women (19.1% to 47.2%), and 18- to 29-yearold
Hispanic men (29.8% to 53.7%).

COMMENT

The results of this study show that marijuana use in the total adult
population has remained substantially unchanged over the decade from
1991- 1992 to 2001-2002. However, significant increases in use among
some subgroups are important to note, for instance, young black and
Hispanic women. In contrast to the results for use among the overall
population, rates of abuse or dependence increased from 1991-1992 to
2001-2002. What is perhaps even more significant is that marijuana
abuse or dependence increased among marijuana users by 18% from 30.2%
in 1991-1992 to 35.6% in 2001- 2002.

These results, taken together, suggest that factors affecting
addiction potential are operating to produce the increase in
prevalence in marijuana abuse or dependence. A number of factors could
have led to increases in addiction potential, operating either
independently or conjointly. The first is increased marijuana potency.
The potency of delta-9-tetrahydrocannabinol (delta 9-THC) in
confiscated marijuana from police seizures increased by 66% from 3.08%
in 1992 to 5.11% in 2002.34,35 Average potency of delta 9-THC in these
studies was consistently calculated as the simple arithmetic mean (ie,
the sum of the delta 9-THC concentrations divided by the number of
seizures), which is more useful in discerning changes over time
relative to normalized averages. This increase could have led to
greater addiction potential for marijuana use disorders over the last
decade. Moreover, there was no systematic change in the frequency of
marijuana use between 1991-1992 and 2001-2002: use every day or nearly
every day (18.7% and 21.7%); use 1 to 4 times per week (23.8% and
19.7%); use 1 to 3 times per month (22.6% and 20.2%); and 1 to 11
times per year (34.9% and 38.4%). Similarly, very little change in the
usual quantity (ie, number of joints or joint equivalents) of
marijuana used on smoking days was observed for each time period: 1
joint (65.6% and 63.7%), 2 to 3 joints (26.9% and 22.0%), 4 to 6
joints (4.0% and 8.1%), and 7 or more joints (3.5% and 6.2%).
Increasing rates of marijuana use disorders among marijuana users in
the absence of increased quantity and frequency of use strengthens the
argument that the increasing rates may be attributable, in part, to
increased potency of marijuana.

The increased prevalence of marijuana use disorders among marijuana
users also may be due, in part, to increases in marijuana use among
the youngest individuals observed in this and other studies (such as
the Monitoring the Future and the National Survey of Drug Use and
Health studies) during the past decade.1,2 The early onset of drug use
has been consistently associated with greater risk of the development
of abuse and dependence.5,36,37

Thus, the marked increase in marijuana use among the youngest age
group may be linked to the increases in abuse and dependence. These
factors, combined with factors increasing rates of marijuana use in
certain subgroups, are all possible explanations of the increased
prevalence in rates of marijuana abuse and dependence among marijuana
users.

One of the most striking findings of this study was that the rates of
marijuana use disorders did not increase among white young adults
(ages 18-29 years), but did increase among young adult black men and
women and among young adult Hispanic men. It should also be noted that
the prevalences of marijuana use disorders among white young adults
have remained high, even though these rates have not significantly
increased over the last decade.

The reasons for the rise in marijuana use disorders among these
minority youth are not entirely known. Recently, researchers have
highlighted the deleterious effects of acculturation on marijuana and
other drug use disorders among the growing number of Hispanics faced
with adapting to a new culture. 38,39 Lower educational and
occupational expectations among minorities have also been implicated
in this research. Alternatively, the growing number of minority youth
attending college over the last decade might have been exposed to the
risks of marijuana use commonly noted among college students, among
whom the prevalence of past year marijuana use has increased from
23.0% to 30.0% over the last decade.40,41

What is clear is that no single environmental factor can explain the
increases in marijuana use disorders observed in this study among
certain minority subgroups of the population. Numerous environmental
factors, including sociodemographic (increases in single-parent
households, urbanicity), socioeconomic (education, income), individual
lifestyle (grades, truancy, religious commitment), and economic
factors, are all likely to serve as mediators of the observed
changes.42,43 A recent study also has demonstrated that decreases in
the perceived risk of harmfulness and in disapproval of marijuana use
can explain the recent historic changes in marijuana use among
youth.44 With regard to putative economic factors, recent studies have
examined how changes in prices, taxes, and policies affecting tobacco
and alcoholic beverages may have had an impact on the prevalence of
marijuana use disorders.44 For example, one study has shown that
increases occurring over the past decade in the minimum drinking age
had the unintended consequence of increasing marijuana use among high
school seniors.45 Further research on how prices and policies
affecting tobacco and alcoholic beverages can affect marijuana use
among important subgroups of the population defined in terms of
race/ethnicity and other sociodemographic and socioeconomic
characteristics is sorely needed and may help explain the increases
observed among minority young adults. Historical and cultural factors
that shape the life history of various racial/ ethnic minorities in
the United States are potentially equally important in understanding
the observed changes. Within this context, future research will need
to more fully address the extraordinary heterogeneity within racial/
ethnic groups in the search for the explanations of why rates of
marijuana use disorders increased among some minority young adults as
opposed to white young adults. For example, rates of marijuana use
disorders are likely to differ among Mexican Americans, Cuban
Americans, and Puerto Rican Americans. It is clear that achieving an
understanding of changes in the prevalence of marijuana use disorders
among minority young adults will require further research and is an
important public health priority.

The results of this study indicate that the vast majority of
individuals who use marijuana or have marijuana use disorders are
young. Despite this generalization, this study is the first to report
significant increases in marijuana use among 45- to 64-year-old men
and women combined as well as a modest but significant increase in
marijuana abuse or dependence among 45- to 64- year-old men. This
indicates that the upper age limit for marijuana use, abuse, and
dependence has shifted in a meaningful way. Such a shift is consistent
with increased lifetime exposure to marijuana availability in the
group who were adolescents in the late 1960s or early 1970s and were
ages 45 to 64 years in 2001-2002. Given this shift, the extent to
which marijuana use may be a contributing cause of illness in the
aging population deserves further research attention.

The major findings from this study have significant research and
public health implications. With regard to research, more periodic
epidemiologic observational studies are needed to rapidly detect
emerging epidemics in marijuana use disorders (and other drug use
disorders) as revealed in this study. The apparent epidemic of
marijuana use disorders among young adult minorities has possibly been
occurring formany years and the failure to detect it sooner lies in
the lack of epidemiologic monitoring data. Concerning public health
implications, it is important to communicate that the increased
potency of marijuana over the past decade may, in part, be responsible
for increases in abuse and dependence among users. This is critical
information for parents, teachers, peers, physicians, and other health
professionals. From a broader public health perspective, the results
of this study highlight the need to strengthen existing prevention and
intervention efforts and to develop and implement widely new programs
with the sex, racial/ ethnic, and age differentials observed in this
study in mind. Specifically, programs targeting young adults,
especially black and Hispanic young adults, need to be designed and
tested for their effectiveness as quickly as possible.

Author Contributions:

Dr Grant, primary investigator on both the National Longitudinal
Alcohol Epidemiologic Survey (NLAES) and the National Epidemiologic
Survey on Alcohol and Related Conditions (NESARC), had full access to
all of the data in this study and takes responsibility for integrity
of the data and the accuracy of the data analysis.

Study concept and design: Grant.

Acquisition of data: Grant, Stinson.

Analysis and interpretation of data: Compton, Grant, Colliver, Glantz,
Stinson.

Drafting of the manuscript: Compton, Grant.

Critical revision of the manuscript for important intellectual
content: Compton, Grant, Colliver, Glantz, Stinson.

Statistical expertise:Grant, Colliver, Stinson.

Obtained funding: Compton, Grant.

Administrative, technical, or material support: Grant, Colliver,
Stinson.

Supervision: Grant.

Funding/Support: The National Epidemiologic Survey on Alcohol and Related
Conditions (NESARC) is funded by the National Institute on Alcohol Abuse
and Alcoholism (NIAAA) with supplemental support from the National
Institute on Drug Abuse (NIDA).

Role of the Sponsor: All data collection was performed by the US Census
Bureau under a contract from the NIAAA. Data analysis and manuscript
preparation were completed by the authors of this article, who take
responsibility for its content. Both NIAAA and NIDA leadership approval
submission of the manuscript.

Disclaimer: The views and opinions expressed in this report are those of
the authors and do not necessarily represent the views of the sponsoring
agencies or the US government.

REFERENCES

1. Substance Abuse and Mental Health Services Administration.
Results From the 2001 National Household Survey on Drug Abuse, Volume I:
Summary of National Findings. Rockville, Md: Office of Applied Studies;
2002. NHSDA Series H-17, DHHS Publication SMA 02-3758.

2. Johnston LD, O'Malley PM, Bachman JG. Monitoring the Future National
Survey Results on Drug Use, 1975-2002. Bethesda, Md: National Institute on
Drug Abuse; 2003.

3. Lynskey M, Hall W. The effects of adolescent cannabis use on
educational attainment: a review. Addiction. 2000;95:1621-1630.

4. Lehman WE, Simpson DD. Employee substance abuse and on-the-job
behaviors. J Appl Psychol. 1992; 77:309-321.

5. Lynskey MT, Health AC, Bucholz KK, et al. Escalation of drug use in
early onset cannabis users vs cotwin controls. JAMA.
2003;289:427-433.

6. National Highway Traffic Safety Administration. Traffic Safety Facts
2001. Washington, DC: National Highway Traffic Safety Administration; 2001.

7. Mittleman MA, Lewis RA, Maclure M, Sherwood JB, Muller JE.
Triggering myocardial infarction by marijuana. Circulation.
2001;103:2805-2809.

8. Polen MR, Sidney S, Tekawa IS, Sadler M, Friedman GD. Healthcare
use by frequent marijuana smokers who do not smoke tobacco. West J
Med. 1993; 158:596-601.

9. Tashkin DP. Pulmonary complications of smoked substance abuse. West
J Med. 1990;152:525-530.

10. Zhang ZF, Morgenstern H, Spitz MR, et al. Marijuana use and
increased risk of squamous cell carcinoma of the head and neck. Cancer
Epidemiol Biomarkers Prev. 1999;8:1071-1078.

11. American Psychiatric Association. Diagnostic and Statistical
Manual of Mental Disorders, Fourth Edition. Washington, DC: American
Psychiatric Association; 1994.

12. Brook JS, Cohen P, Brook DW. Longitudinal study of co-occurring
psychiatric disorders and substance use. J Am Acad Child Adolesc
Psychiatry. 1998;37:322- 330.

13. Chen CY, Wagner F, Anthony J. Marijuana use and the risk of major
depressive episode: epidemiological evidence from the United States
National Comorbidity Survey. Soc Psychiatry Psychiatr Epidemiol.
2002;37:199-206.

14. Grant BF. Comorbidity between DSM-IV drug use disorders and major
depression: results of a national survey of adults. J Subst Abuse.
1995;7:481-497.

15. Grant BF, Harford TC, Dawson DA, Chou SP, Dufour M, Pickering RP.
Prevalence of DSM-IV alcohol abuse and dependence: United States,
1992. Alcohol Health Res World. 1992;18:243-248.

16. Grant, BF, Moore TC, Kaplan K. Source and Accuracy Statement: Wave 1
National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).
Bethesda, Md: National Institute on Alcohol Abuse and Alcoholism; 2003.

17. Grant BF, Dawson DA, Hasin DS. The Alcohol Use Disorder and Associated
Disabilities Interview Schedule- DSM-IV Version. Bethesda, Md: National
Institute on Alcohol Abuse and Alcoholism; 2001.

18. American Psychiatric Association. DSM-IV Options Book. Washington, DC:
American Psychiatric Association; 1991.

19. Budney AJ, Hughes JR, Moor BA, Novy PL. Marijuana abstinence
effects in marijuana smokers maintained in their home environment.
Arch Gen Psychiatry. 2001;58:917-924.

20. Budney AJ, Novy P, Hughes JR. Marijuana withdrawal among adults
seeking treatment for marijuana dependence. Addiction.
1999;94:1311-1322.

21. Canino GJ, Bravo M, Ramfrez R, et al. The Spanish Alcohol Use
Disorder and Associated Disabilities Interview Schedule (AUDADIS):
reliability and concordance with clinical diagnoses in a Hispanic
population. J Stud Alcohol. 1999;60:790-799.

22. Chatterji S, Saunders JB, Vrasti R, Grant BF, Hasin DS, Mager D.
The reliability of the Alcohol Use Disorders and Associated
Disabilities Interview Schedule- Alcohol/Drug-Revised (AUDADIS-ADR) in
India, Romania and Australia. Drug Alcohol Depend. 1997; 47:171-185.

23. Cottler LB, Grant BF, Blaine J, et al. Concordance of DSM-IV
alcohol and drug use disorder criteria and diagnoses as measured by
AUDADIS-ADR, CIDI and SCAN. Drug Alcohol Depend. 1997;47:195-205.

24. Grant BF. DSM-IV, DSM-III-R and ICD-10 alcohol and drug
abuse/harmful use and dependence, United States, 1992: a nosological
comparison. Alcohol Clin Exp Res. 1996;20:1481-1488.

25. Grant BF, Dawson DA, Stinson FS, Chou PS, Kay W, Pickering R. The
Alcohol Use Disorder and Associated Disabilities Interview Schedule-IV
(AUDADISIV): reliability of alcohol consumption, tobacco use, family
history of depression and psychiatric diagnostic modules in a general
population sample. Drug Alcohol Depend. 2003;71:7-16.

26. Grant BF, Harford TC,Dawson DA, Chou PS, Pickering R. The Alcohol
Use Disorder and Associated Disabilities Schedule (AUDADIS):
reliability of alcohol and drug modules in a general population
sample. Drug Alcohol Depend. 1995;39:37-44.

27. Hasin D, Carpenter KM, McCloud S, Smith M, Grant BF. The Alcohol
Use Disorder and Associated Disabilities Interview Schedule (AUDADIS):
reliability of alcohol and drug modules in a clinical sample. Drug
Alcohol Depend. 1997;44:133-141.

28. Hasin D, Grant BF, Cottler L, Blaine J, Towle L, Ustun B,
Sartorius N. Nosological comparisons of alcohol and drug diagnoses: a
multisite, multiinstrument international study. Drug Alcohol Depend.
1997;47:217-226.

29. Nelson CB, Rehm J, Usten B, Grant BF, Chatterji S. Factor
structure for DSM-IV substance disorder criteria endorsed by alcohol,
cannabis, cocaine and opiate users: results from the World Health
Organization Reliability and Validity Study. Addiction. 1999; 94:843-855.

30. Pull CB, Saunders JB, Mavreas V, et al. Concordance between ICD-10
alcohol and drug use disorder criteria and diagnoses as measured by
the AUDADISADR, CIDI, and SCAN: results of a cross-national study.
Drug Alcohol Depend. 1997;47:207-216.

31. Ustun B, Compton W, Mager D, et al.WHOstudy on the reliability and
validity of the alcohol and drug use disorder instruments: overview of
methods and results. Drug Alcohol Depend. 1997;47:161-170.

32. Vrasti R, Grant BF, Chatterji S, et al. Reliability of the Romanian
version of the alcohol module of the WHO Alcohol Use Disorder and
Associated Disabilities: Interview Schedule_Alcohol/Drug-Revised. Eur
Addict Res. 1998;4:144-149.

33. Research Triangle Institute. Software for Survey Data Analysis
(SUDAAN), Version 8.0. Research Triangle Park, NC: Research Triangle
Institute; 2002.

34. ElSohly MA, Ross SA, Mehmedic Z, Arafat BS, Yi B, Banahan BF.
Potency trends of delta 9-THC and other cannabinoids in confiscated
marijuana from 1980- 1997. J Forensic Sci. 2000;45:24-30.

35. National Center for the Development of Natural Products. Quarterly
Report Potency Monitoring Project, May 9, 2003-August 8, 2003: NIDA
Marijuana Project. University, Miss: Research Institute of Pharmaceutical
Sciences, School of Pharmacy, University of Mississippi; 2003.

36. Anthony JC, Petronis KR. Early-onset drug use and risk of later
drug problems. Drug Alcohol Depend. 1995;40:9-15.

37. Grant BF, Dawson DA. Age of onset of drug use and its association
with DSM-IV drug abuse and dependence. J Subst Abuse.
1998;10:163-173.

38. Ortega AN, Rosenheck R, Alegria M, Desai RA. Acculturation and the
lifetime risk of psychiatric and substance use disorders among
Hispanics. J Nerv Ment Dis. 2000;188:728-735.

39. Vega WA, Kolody B, Anguilar-Gaxiola S, Alderette E, Catalano R,
Caraveo-Anduaga J. Lifetime prevalence of DSM-III-R psychiatric
disorders among urban and rural Mexican Americans in California. Arch
Gen Psychiatry. 1998;55:771-778.

40. US Department of Education. 2001 Fall Enrollment in Colleges and
Universities. Washington, DC: US Dept of Education; 2001.

41. Gledhill-Hoyt J, Lee H, Strote J, Wechsler H. Increased use of
marijuana and other illicit drugs at US colleges in the 1990s: results
of three national surveys. Addiction. 2000;95:1655-1667.

42. Grant BF. Prevalence and correlates of drug use and DSM-IV drug
dependence in the United States: results of the National Longitudinal
Alcohol Epidemiologic Survey. J Subst Abuse. 1996;8:195-210.

43. Brooks JS, Adams RE, Balka EB, Johnson E. Early adolescent
marijuana use: risks for transition to young adulthood. Psychol Med.
2002;32:79-91.

44. Bachman JG, Johnston LD, O'Malley PM. Explaining recent increases
in students' marijuana use: impacts of perceived risks and
disapproval, 1976 through 1996. Am J Public Health. 1998;88:887- 892.

45. DiNardo J, Lemieux T. Alcohol, marijuana, and American youth: the
unintended consequences of government regulation. J Health Econ.
2001;20:991- 1010.

Author Affiliations:

Division of Epidemiology, Services and Prevention Research, National
Institute on Drug Abuse, National Institutes of Health, Department of
Health and Human Services (Drs Compton, Colliver, and Glantz);
Laboratory of Epidemiology and Biometry, Division of Intramural
Clinical and Biological Research, National Institute on Alcohol Abuse
and Alcoholism, National Institutes of Health,Department of Health and
Human Services (Drs Grant and Stinson), Bethesda, Md.

Corresponding Author

Wilson M. Compton, MD, MPE, Division of Epidemiology, Services and
Prevention Research, National Institute on Drug Abuse, 6001 Executive
Blvd, MSC 9589, Bethesda, MD 20892- 9589 (wcompton@nida.nih.gov).