A descriptive epidemiology of substance use and substance use disorders in Nigeria during the early 21st century.

Abstract

Several studies have examined the use of psychoactive substances among selected groups in Nigeria. Here, we extend the description to include the features of substance dependence.
A stratified multi-stage random sampling of households was used to select respondents in 21 of Nigeria's 36 states (representing 57% of the national population). In-person interviews with 6752 adults were conducted using the World Health Organization Composite International Diagnostic Interview, Version 3. Lifetime history and recent (past year) use, as well as features of dependence on, alcohol, tobacco, cannabis, sedatives, stimulants, and other drugs were assessed.
Alcohol was the most commonly used substance, with 56% (95% confidence interval, CI=54, 58%) ever users and 14% (95% CI=13, 15%) recent (past year) users. Roughly 3% were recent smokers (3%, 95% CI=2.6, 4.2%). Next most common were sedatives, 4% (95% CI=2.3, 4.5%), and cannabis smokers, 0.4% (95% CI=0.1, 0.6%). Males were more likely than females to be users of every drug group investigated, with male preponderance being particularly marked for cannabis. Prevalence of both alcohol and tobacco use was highest among middle aged adults. Moslems were much less likely to use alcohol than persons of other faiths, but no such association was found for tobacco, non-prescription drug use, or illegal drug use. Features of abuse and dependence were more common at the population level for alcohol; but among users, these features were just as likely to be experienced by alcohol users as they were by other drug users.
Alcohol is the most commonly used psychoactive drug in Nigeria. Features associated with drug dependence and abuse are less prevalent but may require attention by public health authorities.

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Drug and Alcohol Dependence 91 (2007) 1–9
A descriptive epidemiology of substance use and substance use
disorders in Nigeria during the early 21st century
Oye Gurejea,∗, Louisa Degenhardtb,c, Benjamin Olleyd, Richard Uwakwee, Owoidoho Udofiaf,
Abba Wakilg, Olusola Adeyemih, Kipling M. Bohnertb, James C. Anthonyb
aDepartment of Psychiatry, University College Hospital, PMB 5116, Ibadan, Nigeria
bDepartment of Epidemiology, Michigan State University, B601 West Fee Hall,
East Lansing, MI 48824, United States
cNational Drug and Alcohol Research Centre, University of NSW, Sydney, NSW 2052, Australia
dDepartment of Psychology, University of Ibadan, Ibadan, Nigeria
eCollege of Health Sciences, Nnamidi Azikiwe University, Nnewi, Nigeria
fPsychiatric Hospital, Calabar, Nigeria
gPsychiatric Hospital, Maiduguri, Nigeria
hFederal Psychiatric Hospital, Kaduna, Nigeria
Received 2 November 2006; received in revised form 19 April 2007; accepted 19 April 2007
This paper is dedicated to the memory of Dr. Michael Ekpo.
Abstract
Background: Several studies have examined the use of psychoactive substances among selected groups in Nigeria. Here, we extend the description
to include the features of substance dependence.
Method: A stratified multi-stage random sampling of households was used to select respondents in 21 of Nigeria’s 36 states (representing 57%
of the national population). In-person interviews with 6752 adults were conducted using the World Health Organization Composite International
Diagnostic Interview, Version 3. Lifetime history and recent (past year) use, as well as features of dependence on, alcohol, tobacco, cannabis,
sedatives, stimulants, and other drugs were assessed.
Results: Alcohol was the most commonly used substance, with 56% (95% confidence interval, CI=54, 58%) ever users and 14% (95% CI=13,
15%) recent (past year) users. Roughly 3% were recent smokers (3%, 95% CI=2.6, 4.2%). Next most common were sedatives, 4% (95% CI=2.3,
4.5%), and cannabis smokers, 0.4% (95% CI=0.1, 0.6%). Males were more likely than females to be users of every drug group investigated, with
male preponderance being particularly marked for cannabis. Prevalence of both alcohol and tobacco use was highest among middle aged adults.
Moslems were much less likely to use alcohol than persons of other faiths, but no such association was found for tobacco, non-prescription drug
use, or illegal drug use. Features of abuse and dependence were more common at the population level for alcohol; but among users, these features
were just as likely to be experienced by alcohol users as they were by other drug users.
Conclusion: Alcohol is the most commonly used psychoactive drug in Nigeria. Features associated with drug dependence and abuse are less
prevalent but may require attention by public health authorities.
© 2007 Elsevier Ireland Ltd. All rights reserved.
Keywords: Nigeria; Composite International Diagnostic Interview; Epidemiological research; Tobacco; Alcohol; Cannabis; Drugs
1. Introduction
The use of psychoactive drugs has long interested Nige-
rian researchers (Leighton et al., 1963). Most of this work has
∗Corresponding author. Tel.: +234 8033464284.
E-mail address: ogureje@comui.edu.ng (O. Gureje).
examined alcohol (Gureje et al., 1992). Limited work has been
conducted upon the use of tobacco and cannabis (Oviasu, 1976;
Asuni, 1964; Elegbeleye and Femi-Pearse, 1976; Ibeh and Ele,
2003). Use of drugs such as stimulants, sedatives, and cocaine
has rarely been studied (Ebie et al., 1981; Agaba et al., 2004).
There are limits to existing work. Much of it is based on
surveys of population subgroups such as students or hospital
patients (Abiodun et al., 1994; Adamson and Akindele, 1994;
0376-8716/$ – see front matter © 2007 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.drugalcdep.2007.04.010

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O. Gureje et al. / Drug and Alcohol Dependence 91 (2007) 1–9
Odejide et al., 1987); few have been carried out in primary
care settings or in the community (Gureje et al., 1992; Gureje
and Obikoya, 1990). Results of existing studies suggest that the
majority of Nigerians do not drink alcohol. Its use is predomi-
nantly among middle aged males, although alcohol and tobacco
consumption by women and young people may be rising (Ibeh
and Ele, 2003; Alakija, 1984). Cannabis use is circumscribed,
rarely occurring before adolescence and after young adulthood.
About 15% of primary care attendees used over-the-counter
sedatives, with many becoming long-term users; use of these
drugsmaybemorecommonamongfemalesthanforotherdrugs
(Gureje and Obikoya, 1990).
Very little is known about occurrence of drug dependence
in Nigeria, and no previous studies assessed a broad range of
drugs with a large and representative sample of the population.
Studies of representative samples addressing level of use and
profile of associated problems are needed to provide empirical
data upon which informed policy response to drug problems
can be based. Such studies are expensive to mount and require
considerable expertise, both of which are not commonly avail-
able in most research centres in sub-Saharan Africa. Surveys
of illegal drug use, of alcohol consumption, tobacco use, and
of use of analgesics have been conducted in localized urban
areas of Benin City and Jos (Ebie et al., 1981; Obot, 1990). The
study of tobacco use in the community by Obot provided data
on a large sample of adult “heads of household” (Obot, 1990),
but not other household residents. Thus, even though a number
of authors have expressed concern about the growing rate of
smoking in Africa (Taha and Ball, 1982; Yach, 1986; Jha and
Chaloupka, 1999) and estimates of per capita alcohol consump-
tion have been made by the World Health Organization (World
Health Organization, 2004; Rehm et al., 1999), there is actu-
ally very little empirical basis upon which to base a categorical
statement about the community profile of smoking or alcohol
consumption in Nigeria.
The Nigerian national survey of mental health and well-
being (NSMHW) was designed to fill the existing gap in the
epidemiology of mental disorders and drug use (and related dis-
orders) in Nigeria using present day assessment tools; based
upon current diagnostic classification systems, principally the
American Psychiatric Association’s Diagnostic and Statistical
Manual(DSM-IV;AmericanPsychiatryAssociation,1994)and
the World Health Organization’s International Classification of
Diseases (ICD-10; World Health Organization, 1992). It was
carried out as part of the World Mental Health Surveys (WMH)
initiative,aWHO-organizedcollaborativeeffort,nowwithmore
than 20 countries participating (Demyttenaere et al., 2004).
In this initial report on the descriptive epidemiology of sub-
stance use and substance use disorders in Nigeria, we examine
two specific questions:
1. For the population of Nigeria under study, what is the esti-
mated population prevalence of use of tobacco, alcohol, and
other non-prescription drugs, and what are the prevalence
estimates for features associated with dependence on these
substances?
2. Are there any distinctive subgroups of the population where
cases are more or less likely to be observed, with subgroups
based upon demographic and social correlates of alcohol,
tobacco and other drug use?
2. Methods
Detailed descriptions of the NSMHW methods have been published else-
where (Gureje et al., 2006). Here, we provide a brief summary overview, with
focusupontwoaspectsofthemethodsthatareofspecialimportanceinepidemi-
ologicalfieldresearch:(1)thenatureofthemulti-stageareaprobabilitysampling
for the survey, which creates nested structures within the survey database; (2)
the nature of data collection on the topics of tobacco, alcohol, and other drug
consumption, as well as diagnostic assessments with respect to clinical features
associated with drug dependence and other hazards of drug involvement (e.g.,
recurrent legal difficulties).
2.1. Sample
The research team used a four-stage area probability sample of house-
holds to select non-institutionalized adults aged 18 years and over. The survey
was conducted in five of the six geo-political regions of Nigeria: south-west
(Lagos,Ogun,Osun,Oyo,Ondo,andEkiti),south-east(Abia,Anambra,Enugu,
Ebonyi, and Imo), south–south (Akwa Ibom, cross-river and rivers), north-
central (Kaduna, Kogi, and Kwara), and north-east (Adamawa, Bornu, Gombe,
and Yobe). Collectively, these states represent about 57% of the national pop-
ulation. The survey assessments were conducted in Yoruba, Igbo, Hausa and
Efik languages, with due attention to translation and harmonization described
below.
Selection of local government areas (LGAs) within the states and geograph-
icallydefinedenumerationareas(EAs)withintheLGAsconstitutedthefirstand
secondstagesoftheselectionprocess.AllselectedEAswerevisitedbyresearch
interviewers prior to the interview phase of the survey and conducted an enu-
meration and listing of all the household units contained therein. Respondents
were selected following a complete listing of all members of a household and
the use of the Kish table (Kish, 1965). An eligible member of a household had
to be 18 years of age and able to speak one of the languages of the study. Only
one such person was selected per household. When the primary respondent was
either unavailable following repeated calls (five repeated calls were made) or
refused to participate, no replacement was made within the household. On the
basis of this selection procedure, face-to-face interviews were carried out on
6752 respondents. The overall response rate was just over 79%.
FieldworkwasconductedbetweenFebruary2002andMay2003.Thesurvey
was administered in two parts: part I consisted of a core of diagnoses and was
administeredtoallrespondents;partIIconsistedofsectionsfortheassessmentof
risk factors, consequences and correlates of disorders as well as a few disorders
not included in the core. Part II was administered to respondents who had a
history of past or recent part I disorders plus a probability sub-sample of other
respondents. A total of 6752 respondents completed part I; 2143 completed part
II.
Respondents were informed about the study and provided consent, mostly
verbal but sometimes signed, before interviews were conducted. Verbal consent
was the norm because of widespread illiteracy and because some respondents
seemed somewhat cagy about the implications of appending their signature
to a document. These survey procedures were approved by the University of
Ibadan/University College Hospital, Ibadan Joint Ethical Review Board.
2.2. Measures
Diagnostic assessment were those of the World Health Organization’s
(WHO)CompositeInternationalDiagnosticInterview(CIDI),Version3admin-
istered by trained lay interviewers (Demyttenaere et al., 2004; Gureje et al.,
2006).TheCIDIisafullystructureddiagnosticinterviewthatislay-administered
and can generate diagnoses according to the criteria of both the International
Classification of Diseases, 10th edition (ICD-10) (World Health Organization,
1992)andtheDiagnosticandStatisticalManualofMentalDisorders,4thedition

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O. Gureje et al. / Drug and Alcohol Dependence 91 (2007) 1–9
3
(DSM-IV) (American Psychiatry Association, 1994). We have used earlier ver-
sions of the CIDI in Yoruba. The language versions of the WMH-CIDI used in
thepresentsurveywerederived,asintheearlierYorubaversions,usingstandard
protocols of iterative back translation and harmonization conducted by panels
of bilingual experts.
The substance use sections of the WMH-CIDI first ascertain lifetime history
ofuse.Forsubstanceusers,follow-upquestionsareaskedaboutrecentuse(inthe
prior 12-month), as well as, clinical features associated with drug dependence
syndromes.Thesubstancesassessedwere:alcohol(whichincludesanyalcoholic
beverage from industrial or non-industrial sources—e.g., palm wine); tobacco
smoking (including cigarette, cigar, or pipe); sedatives; stimulants; cannabis
(marijuana, hashish); cocaine; any other non-prescription psychoactive drug
(which includes heroin, glue, opium, etc.).
All part I respondents received the full assessment for alcohol use. Infor-
mation about the use of tobacco and other drugs was obtained from part II
respondents.
2.3. Training and quality control
Considerable experience in the use of the CIDI existed in Ibadan prior to
this survey. Over 1000 interviews had been conducted in previous studies in
which earlier versions of the instrument had been used. The core sections of
the WMH-CIDI were therefore already available in Yoruba. Further translation
and adaptation were conducted, using the WHO translation guidelines. The
experienceintheprevioustranslationtoYorubacameinhandyinthetranslation
exercises to Igbo, Hausa, and Efik languages.
The interviewers received 7 days of intensive training. After training, each
conducted two pilot interviews in a target locality and returned for a 1-day
debriefing session prior to the main survey work. Supervisors checked every
questionnaireandworksheetreturnedtothemforaccuracyandconsistency.They
also conducted random field checks on 10% of the selected households to verify
household listing, appropriate use of the Kish table, and that interviewers had
conducted the interview in full. When interviewers had reported non-response,
supervisors also checked on the reason for such.
2.4. Analysis
Weighted prevalence estimates and their 95% confidence intervals were cal-
culated using Taylor series linearization with STATA 9.0, accounting for the
complex survey sampling design and selection probabilities. Thus, appropriate
weightingwasmadetoallestimatesfortheprobabilityofselectionwithinhouse-
holdandtheprobabilityofselectionintothepartIIsample.Prevalenceestimates
(andtheirestimated95%confidenceintervals)werealsomadeaccordingtosex,
age group, religion, marital status, education and income.
Per capita income was calculated by dividing household income by the
numberofpeopleinthehousehold.Respondents’percapitaincomehasbeencat-
egorized by relating each respondent’s income to the median per capita income
of the entire sample. Thus, an income is rated low if its ratio to the median is
0.5 or less, low-average if the ratio is 0.5–1.0, high-average if it is 1.0–2.0, and
highifitisover2.0.Multiplelogisticregressions,whichincludedallbackground
variablesinthemodels,wererunusingSTATA,withthecomplexsurveysample
design and selection probabilities taken into account.
We present a graphical representation of the cumulative occurrence of sub-
stance use among users, plotted against years of life since birth. The graph
reflects the proportion of users who had commenced use of specified substances
at different ages.
3. Results
Estimates of lifetime and past year psychoactive substance
use are presented in Table 1. Alcohol was the most commonly
useddrug,bothintermsoflifetimehistoryandrecentuse(57.6%
and 19.9%, respectively). Next most common were tobacco
smoking and non-prescription sedative use (lifetime: 17% and
14%;pastyear:both3.4%).Verysmallproportionshadengaged
Table 1
Estimated prevalence of lifetime and past year use of alcohol, tobacco and other
drugs
Lifetime usePast year use
%95%CI% 95%CI
Alcohola
Tobacco
Sedatives
Cannabis
Stimulants
Cocaine
Other drugsd
57.6
16.8
13.6
2.7
2.4
3/2145
0.5
54.1, 57.7
14.8, 18.8
11.6, 15.6
1.7, 3.7
1.5, 3.2
–
0.02, 0.9
19.9
3.4
3.4
0.4
3/2147b
–c
5/2145b
16.4, 23.4
2.6, 4.2
2.2, 4.5
0.2, 0.7
–
–
–
aAlcohol use in the past year was defined as at least monthly use.
bDue to the small numbers, the prevalence estimate was not statistically
robust; the raw numbers have been presented for illustrative purposes.
cNo participants reported cocaine use in the past year.
dIncluded heroin, opium, LSD, inhalants, peyote.
in non-prescription drug use, and the use of cannabis, cocaine
or other drugs was very rare (Table 1).
Table 2 presents estimates for cumulative occurrence of non-
prescription drug use, by drug type, for population subgroups
of interest. Males are more likely to have become users of these
drugs, but the male–female difference is least pronounced for
non-prescription use of sedatives: an estimated 16% of males
had become non-prescription users of sedative drugs; the cor-
responding estimate for females in Nigeria is 11–12%. The
male–femaleprevalencedifferencefortobaccosmokingexceeds
30%; only 1.2% of the women had started to smoke tobacco
(95% CI=0.9%, 2.1%). The lifetime histories of alcohol and
tobacco use were more common among older age groups, but
that of sedative drugs was more common among younger age
groups.
The prevalence of lifetime alcohol and tobacco use appeared
to be somewhat higher among those who were currently mar-
ried or cohabiting (Table 2). The prevalence of other lifetime
drug use, however, did not appear to be associated with rela-
tionship status. Similarly, there did not appear to be significant
associations between educational attainment and lifetime drug
use.
There were differences in patterns of drug use according to
religiousaffiliations(Table2).Moslemswerelesslikelytoreport
lifetime alcohol and sedative use than Christians (Protestants or
Catholics) and less than those subscribing to other religions;
they did not differ for other substances. Income appeared to be
related to lifetime drug use, with those who had higher incomes
being more likely to report lifetime alcohol, tobacco use and
non-prescription sedative use.
Table 3 presents adjusted odds ratios of lifetime substance
useaccordingtothesebackgroundvariables.Afteradjustingfor
all background variables examined here, males remained more
likely to have ever used alcohol, tobacco and non-prescription
stimulantdrugs.Ageremainedsignificantlyassociatedwithlife-
time alcohol and tobacco use, with older age groups more likely
to report such use. Income was no longer significantly asso-
ciated with substance use, with the exception of a significant
association remaining for sedative use.

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O. Gureje et al. / Drug and Alcohol Dependence 91 (2007) 1–9
Table 2
Prevalence of lifetime drug use according to selected socio-demographic characteristics
Characteristics (n) Alcohol use Tobacco useCannabis use Sedative use Stimulant use
%95%CI% 95%CI% 95%CI%95%CI% 95%CI
Sex
Male (3307)
Female (3445)
69.4
46.5
66.2, 72.6
42.1, 50.8
32.8
1.5
29.1, 36.5
0.9, 2.1
5.4
1/1107
3.3, 7.5
–
15.6
11.6
13.1, 18.2
9.0, 14.3
4.0
1/1108
2.6, 5.4
–
Age
18–34 years (3717)
35–49 years (1656)
50–64 years (965)
65+ years (414)
52.0
64.3
65.8
63.6
47.5, 56.6
58.8, 69.7
58.6, 73.1
53.7, 73.5
9.0
24.4
28.7
29.7
6.6, 11.4
19.1, 29.7
22.7, 34.8
21.4, 38.0
2.2
4.3
2.5
4/254
0.9, 3.4
2.2, 6.5
0.5, 4.5
–
13.1
15.1
13.4
12.2
10.4, 15.8
11.7, 18.4
7.5, 19.3
5.1, 19.3
2.2
2.2
3.3
2.6
0.9, 3.5
1.1, 3.3
1.1, 5.4
0.5, 4.7
Marital status
Married/cohabitating (4618)
Othera(2633)
59.3
55.2
55.8, 62.7
50.1, 60.4
21.0
10.5
18.4, 23.6
7.4, 13.5
2.9
2.4
1.8, 4.0
0.8, 4.0
14.5
12.2
12.1, 16.8
8.9, 15.4
2.6
2.1
1.8, 3.3
0.4, 3.8
Education
0–11 years (4618)
12+ years (2134)
58.6
56.0
54.9, 62.3
50.0, 62.1
18.7
13.5
16.2, 21.3
10.7, 16.3
2.6
2.9
1.2, 4.0
1.5, 4.3
12.0
16.3
9.5, 14.6
12.6, 20.0
2.0
3.0
0.9, 3.2
1.7, 4.3
Religion
Protestant (1067)
Catholic (195)
Moslem (559)
Other (49)
62.2
69.6
46.4
70.7
57.7, 66.6
60.6, 78.7
42.0, 50.9
45.4, 96.0
15.1
15.1
20.5
5/22b
12.9, 17.2
9.1, 21.1
15.6, 25.4
–
2.6
2.8
2.9
1/25
1.5, 3.6
1.3, 4.4
0.7, 5.1
–
14.9
16.5
10.7
4/25
11.8, 18.0
10.0, 23.0
8.4, 13.0
–
2.4
1.7
2.6
–c
1.3, 3.6
0.2, 3.2
0.8, 4.4
–
Incomed
Low
Low-average
High-average
High
51.7
54.9
58.3
66.1
44.2, 59.1
49.5, 60.3
54.0, 62.7
61.2, 71.0
11.8
14.6
20.2
20.5
8., 14.8
10.6, 18.6
16.5, 23.8
16.6, 24.4
2.7
2.4
2.6
3.1
0.7, 4.8
0.4, 4.4
1.0, 4.2
1.4, 4.9
8.7
10.3
13.6
22.2
4.7, 12.7
6.7, 14.0
9.8, 17.3
16.5, 28.0
–
0.2, 4.3
1.2, 4.2
2.1, 5.1
2.2
2.7
3.6
aIncludes separated, widowed, divorced, never married.
bDue to the small numbers, the prevalence estimate was not statistically robust; the raw numbers have been presented for illustrative purposes.
cIndicates no participants in this category reported lifetime use.
dCategories as described in Analysis section.
In general, between 20–25% of lifetime users reported past
yearuse.Otherthansedativeuse,whichwassimilaramongmen
andwomen,menwereconsiderablymorelikelytohaveahistory
of both lifetime and past year use of most substances. In partic-
ular, cannabis use occurred more predominantly among males.
Table4showspastyearprevalenceestimates,andadjustedodds
ratios,ofdruguseandadjustedoddsratiosarepresentedaccord-
ing to these background demographics. As can be seen, sex
differences also existed across past year alcohol and tobacco
use, but no difference existed for non-prescription sedative use.
There appeared to be no age differences for past year use of any
of these drugs, with the exception of higher rates of tobacco use
among middle aged adults compared to young adults.
Education and income categories were not significantly
related to past year drug use, although the proportion of sub-
stance use tended to be higher among those in higher income
categories. Finally, differences in drug use were observed
according to religious affiliation: Moslems were less likely than
Christians (Catholics or Protestants) to have used alcohol or
sedatives in the past year; and more likely than the latter two
groups to have used tobacco (Table 4).
The lifetime prevalence of features of DSM-IV abuse and
dependence is presented in Table 5. Clearly, the proportions
reporting problems were low for alcohol and other drugs; but
among users of these drugs, proportions of problems were sim-
ilar for both alcohol and other drugs. Male lifetime users had
higher proportions of all problems than females.
Fig. 1 shows the cumulative occurrence of drug use among
users, plotted against years of life since birth. The figure shows
that the age of first use clearly differed across drugs. The figure
reflects information obtained in 2002–2003 from respondents
who had been born by 1984. About 25% of lifetime users of
alcohol had started its use by the age of about 12 years; for
tobacco and cannabis, this proportion was achieved at about the
age of 15 and 18 years, respectively. First use of prescription
drugs was right-shifted with most first use occurring between
age 20 and 40 years.
4. Discussion
In this large study of a representative sample of Nigerian
adults, we found lifetime proportions of drug use as follows:
alcohol 58%, tobacco 17%, sedatives 14%, stimulants 2.4%,
and 3%, cannabis.
The studies conducted by Obot in the north-central part of
Nigeria are the closest with which our results can be compared

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5
Table 3
Associations of socio-demographic characteristics with lifetime drug use
Alcohol useTobacco useCannabis useSedative useStimulant use
ORa
95%CIORa
95%CI ORa
95%CI ORa
95%CIORa
95%CI
Sex
Male
Female
3.0
1
2.5, 3.7
–
14.7
1
25.4, 68.5
–
79.3
1
10.1, 621.3
–
1.3
1
0.9, 1.7
–
4.6
1
1.5, 14.1
–
Age (years)
18–34
35–49
50–64
65+
1
1.5
1.6
1.5
–
1.1, 2.1
1.1, 2.3
0.9, 2.4
1
3.64
4.97
6.24
–
2.2, 6.1
3.1, 7.9
3.4, 11.6
1
2.0
1.1
0.5
–
0.8, 4.7
0.4, 2.9
0.1, 2.1
1
1.1
1.0
1.0
–
0.7, 1.7
0.5, 1.8
0.5, 2.0
1
0.9
1.6
1.3
–
0.5, 1.9
0.7, 3.8
0.5, 3.8
Marital status
Married/cohabitating
Othera
1.0
1
0.8, 1.4
–
1.2
1
0.8, 1.9
–
1.2
1
0.5, 3.1
–
1.2
1
0.8, 1.7
–
1.2
1
0.5, 2.8
–
Education (years)
0–11
12+
1
0.8
–
0.6, 1.1
1
0.7
–
0.5, 1.01
1
0.9
–
0.4, 2.2
1
1.3
–
0.8, 2.0
1
1.5
–
0.6, 3.6
Religion
Protestant
Catholic
Moslem
Other
1
1.6
0.5
1.9
–
0.97, 2.7
0.3, 0.6
0.5, 6.8
1
1.06
1.25
0.9
–
0.60, 1.9
0.8, 1.9
0.2, 4.3
1
1.4
0.9
0.8
–
0.7, 3.1
0.4, 1.8
0.1, 7.3
1
1.3
0.7
0.4
–
0.8, 2.1
0.5, 1.1
0.1, 1.6
1
0.8
1.0
–
–
0.3, 2.1
0.4, 2.4
–
Income
Low
Low-average
High-average
High
1
1.2
1.2
1.5
–
0.8, 1.9
0.9, 1.7
1.02, 2.4
1
0.96
1.41
1.10
–
0.59, 1.56
0.92, 2.16
0.70, 1.72
1
1.08
0.95
1.28
–
0.36, 3.22
0.42, 2.17
0.55, 3.00
1
1.2
1.6
2.6
–
0.7, 2.1
0.8, 2.9
1.4, 5.0
1
2.3
2.3
2.7
–
0.4, 14.3
0.5, 11.6
0.6, 12.6
aAdjusted OR from multiple regression models: each model adjusted for all other variables in table.
(Obot, 1990, 1993). Studying a large sample of “adult heads
of households” (primarily male), he reported much higher lev-
els of alcohol and tobacco use than we have reported here. For
example,hereportedthat22.6%ofhissamplesmokedregularly,
a level that is considerably higher than our finding of 16.8% of
lifetimeuse(Obot,1990).Eventhoughthestudywasconducted
about 15 years before the present one and drug use trends might
have changed significantly during the interval, we suspect that
the differences in sample selection may be the main reason for
these very divergent rates. Both by our sampling procedure and
the statistical adjustments made to reflect the general popula-
tion demographics, our results are more likely to be closer to
Fig. 1. Age of initiation of psychoactive drug use among lifetime users of alcohol, marihuana, prescription drugs and tobacco.

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6
O. Gureje et al. / Drug and Alcohol Dependence 91 (2007) 1–9
Table 4
Associations of socio-demographic characteristics with past year alcohol, tobacco and sedative use
Alcohol use Tobacco useSedative use
%95%CI ORa
95%CI%95%CI ORa
95%CI%95%CI ORa
95%CI
Sex
Male
Female
32.7
5.3
27.8, 37.6
2.5, 8.1
10.1
1
5.8, 17.5
–
6.7
0.2
5.2, 8.3
0.0, 0.4
36.81
1
12.6, 107.6
–
3.9
2.8
2.4, 5.4
1.3, 4.4
1.4
1
0.7, 2.7
–
Age (years)
18–34
35–49
50–64
65+
16.7
25.7
23.6
13.8
12.4, 21.0
19.6, 31.9
17.3, 29.8
8.5, 19.1
1
1.4
1.2
0.6
–
0.9, 2.3
0.8, 1.8
0.3, 0.98
2.1
4.4
7.1
2.2
1.0, 3.2
2.3, 6.5
3.6, 10.7
0.7, 3.8
1
1.92
2.75
0.82
–
0.59, 6.24
1.01, 4.46
0.25, 2.67
4.2
1.9
9/369
1.8
2.5, 6.0
0.6, 3.2
–
0.05, 3.6
1
0.4
0.7
0.4
–
0.2, 0.96
0.2, 2.0
0.1, 1.3
Marital status
Married/cohabitating
Otherb
21.6
16.9
18.5, 24.8
11.3, 22.5
1.2
1
0.8, 1.9
–
4.1
2.3
3.2, 5.0
0.6, 4.0
1.28
1
0.39, 4.23
–
3.1
3.7
1.7, 4.5
1.6, 5.9
1.2
1
0.5, 2.8
–
Education (years)
0–11
12+
20.4
18.9
17.1, 23.8
12.8, 24.9
1
0.6
–
0.4, 1.0
4.2
2.0
2.9, 5.5
1.1, 3.0
1
0.50
–
0.23, 1.10
2.8
4.4
1.4, 4.1
1.8, 7.0
1.2
1
0.5, 2.5
–
Religion
Protestant
Catholic
Moslem
Other
22.9
23.2
13.8
30.7
17.9, 27.9
13.0, 33.5
10.8, 16.9
0.4, 61.1
1
1.4
0.4
1.6
–
0.7, 2.9
0.3, 0.6
0.5, 5.5
2.2
9/207c
5.1
4/25c
1.3, 3.1
–
3.3, 7.0
–
1
1.62
1.90
11.15
–
0.52, 5.02
1.02, 3.56
2.51, 49.57
4.1
4/208c
1.8
–
2.7, 5.6
–
0.6, 2.9
–
1
1.2
0.4
–
0.3, 4.3
0.2, 0.9
–
Incomed
Low
Low-average
High-average
High
11.4
12.6
16.2
22.4
6.7, 15.9
9.5, 15.7
12.5, 19.9
17.5, 27.4
1
0.9
1.0
1.6
–
0.5, 1.9
0.6, 1.9
0.96, 2.8
3.1
2.7
3.8
4.0
0.8, 5.5
1.2, 4.1
1.8, 5.8
2.4, 5.5
1
0.59
0.86
0.77
–
0.20, 1.69
0.27, 2.73
0.31, 1.92
2.5
3.0
3.3
4.8
0.1, 4.8
1.1, 4.9
1.0, 5.5
2.4, 7.1
1
1.3
1.3
1.8
–
0.4, 4.4
0.3, 5.1
0.5, 5.9
Indicates no participants in this category reported lifetime use.
aAdjusted OR from multiple regression models: each model adjusted for all other variables in the table.
bIncludes separated, widowed, divorced, never married.
cDue to the small numbers, the prevalence estimate was not statistically robust; the raw numbers have been presented for illustrative purposes.
dBased upon WMHS categories.
the extant national drug use profile of the Nigerian adult pop-
ulation than those presented by Obot. Nevertheless, our results
are similar to previous findings in regard to the male predom-
inance among drinkers and smokers (Obot, 1990, 1993). We
found higher education to be related with a lower likelihood of
both lifetime and past year use of alcohol and tobacco, but no
suchtrendwasapparentinregardtoeconomicstatusasindicated
by income.
In line with many previous studies in Nigeria and elsewhere
in Africa (Abiodun et al., 1994; Odejide et al., 1987; Flisher et
al., 2003), we found that users of drugs commonly start in ado-
lescence and young adulthood. About half of lifetime users had
commencedusebytheageof20yearsforalcohol,cannabis,and
tobacco, and 25 years for non-prescription use of sedatives and
stimulants.Inoursetting,alcoholtendstogainearlyprominence
followed by tobacco and then by cannabis.
Lifetime use of alcohol was higher among persons aged
35–64 years than it was among those aged 18–34 years. How-
ever, past year use remained elevated (relative to young adults)
only among those aged 35–49 years. A cross-sectional study
does not permit a clear inference about trend; however, the
pattern of association of alcohol use could suggest a tendency
towards abstinence in the fifth decade of life and onwards. This
may also be related, however, to differential mortality of drug
users, among whom it is known that there are higher mortality
rates. Alternatively, it could reflect cohort or period differences
in drug use. The pattern for tobacco was also somewhat similar.
Clear sex differences existed for the use of all drug types with
the exception of non-prescription sedative.
Moslemshadasignificantlylowerlikelihoodofbothlifetime
and past year use of alcohol among compared to persons of
other faiths. The Islamic injunction against the use of alcohol
seems to be having a strong deterrent effect among its adherents
in Nigeria. It is interesting to note that Moslems were no less
likely than those of other religions to use other drugs, including
cannabis and stimulants, both of which are illegal in Nigeria. It
maybethatwhatisatplayhereistherelativepotencyofreligious
belief rather than fear of legal (or even societal) sanctions.
We presented here the prevalence of features of alcohol and
other drug DSM-IV dependence, rather than diagnosis (Gureje
et al., 1996, 1997; Room, 2006). The most common feature was
failure to fulfil role obligations as a result of drug use; legal
problems were very infrequently reported. The most common
featureofalcoholandotherdrugdependencewasimpairedcon-

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O. Gureje et al. / Drug and Alcohol Dependence 91 (2007) 1–9
7
Table 5 Lifetime prevalence of clinical features of alcohol and other drug DSM-IV abuse and dependence
Alcohol
Other drugsa
Population
Users
Male lifetime users
Female lifetime users
Population
Users
Male lifetime users
Female lifetime users
%
95%CI
%
95%CI
%
95%CI
%
95%CI
%
95%CI
%
95%CI
%
95%CI
%
95%CI
Abuse features
Use resulted in failure to fulfill role obligations
2.4
1.6, 3.2
4.1
2.8, 5.5
6.7
4.5, 9.0
4/559
0.7
0.3, 1.0
4.0
1.9, 6.0
6.0
2.8, 9.2
2/154
–
Recurrent use in hazardous situations
1.0
0.6, 1.3
1.7
1.1, 2.3
2.9
1.8, 4.0
–
–
6/2147
–
6/402
–
6/248
–
–
–
Recurrent legal problems
0.2
0.02, 0.3
0.3
0.03, 0.5
0.4
0.05, 0.8
–
–
3/2147
–
3/402
–
3/248
–
–
–
Continued use despite problems
0.6
0.3, 0.9
1.1
0.6, 1.6
1.9
1.0, 2.8
–
–
0.4
0.04, 0.7
2.1
0.3, 3.8
2.5
0.09, 4.9
1/154
–
Dependence features
Tolerance
0.8
0.4, 1.1
1.3
0.6, 2.0
2.2
1.1, 3.4
–
–
0.3
0.04, 0.6
1.9
0.3, 3.5
3.0
0.5, 5.6
–
–
Withdrawal or use to avoid withdrawal
0.8
0.4, 1.2
1.4
0.7, 2.1
2.4
1.1, 3.6
1/559
0.3
0.09, 0.6
1.9
0.4, 3.3
2.7
0.5, 4.9
1/154
–
Taken in larger amounts or longer
1.8
1.2, 2.4
3.1
2.0, 4.1
5.2
3.4, 7.0
1/559
0.4
0.07, 0.7
2.1
0.5, 3.8
3.1
0.5, 5.8
1/154
–
Desire, attempts to cut down use
1.4
0.8, 2.0
2.4
1.3, 3.5
4.1
2.2, 5.9
–
–
0.3
0.004, 0.6
1.7
0.1, 3.2
2.7
0.2, 5.2
–
–
Much time spent obtaining, using or recovering
from use
0.8
0.4, 1.3
1.5
0.7, 2.2
2.5
1.2, 3.8
1/559
5/2147
–
5/402
–
5/248
–
–
–
Social, occupational or recreational activities
reduced
0.8
0.3, 1.3
1.3
0.5, 2.2
2.3
0.8, 3.7
–
–
4/2147
–
4/402
–
4/248
–
–
–
Continued use despite harm caused by use
0.6
0.2, 0.9
1.0
0.4, 1.6
1.7
0.7, 2.8
–
–
0.2
0.03, 0.4
1.2
0.2, 2.2
1.9
0.3, 3.6
–
–
Confidence intervals calculated using Taylor series linearization, adjusting for clustering using sampling strata and primary sampling units.
aOther drugs includes: cannabis, cocaine, non-prescription use of sedatives or stimulants, and other drugs.
trol over use of the drug; for alcohol, the least common feature
wastolerance,andforotherdrugs,reductioninrolefunctioning.
Even though the population prevalence of features of depen-
dence on alcohol was higher than that of other drugs, there was
no difference among users of these drugs. That is, our data sug-
gested that similar proportions of alcohol and other drug users
experienced problems related to their psychoactive drug use.
Clearly, while at a community level, problems related to alco-
hol may be higher, problems occur similarly for users of other
drugs.
Alldrug-relatedproblemsweremorecommonamongmales,
with many being exclusively present only among them. This
observationissimilartothatmadeinapreviousstudyofalcohol-
related problems among primary care attendees in which it was
noted that most identified cases of alcohol problems were males
(Gureje et al., 1992). This may relate to the observation made in
an earlier study in primary care that, even though the prevalence
ofsedativeusebymalesandfemalesweresimilar,femaleswere
morelikelytohavebeenusingthedrugsforamuchlongerperiod
than males (Gureje and Obikoya, 1990).
Heavy episodic drinking, rather than regular moderate drink-
ing, is common among users of alcohol in Nigeria (and in most
parts of sub-Saharan Africa) (Room et al., 2002; Parry, 2005).
This pattern of drinking is more likely to be associated with
intoxication, accidents, and violence (Rehm et al., 1999; Parry,
2005). This profile of alcohol-related problems accounts for the
societyburdenresultingfromdrinkinginAfricaandmuchofthe
developingworld(Roometal.,2002).Itmightbeexpected,then,
that problems related to regular, heavy drinking, such as those
of features of DSM-IV alcohol dependence, might be less fre-
quent than problems related to risky binge drinking, as assessed
by DSM-IV abuse features. The present study found suggestive
evidence that this was the case. Symptoms such as withdrawal
and tolerance to the effects of alcohol were reported by only
around 1%; whereas about 4% of lifetime users experienced a
failure to fulfil role obligations as a result of recurrent alcohol
use. Our observation is in accord with findings from epidemio-
logicalstudiesofclinicalsamplesinNigeriawheredependence,
as a discrete diagnostic construct, is often found to be relatively
rare and often predominantly a male problem (Gureje et al.,
1992).
Two important limitations are of note. First, we have used
self-reports to assess drug use; there may have been differential
reporting biases for self-reported illegal versus more socially
acceptabledrugusesuchastobaccoandalcohol.Therehasbeen
no study conducted specifically in Nigeria to assess the extent
of underreporting of illegal drug use; but others have found self-
report to be an acceptable method for collecting information on
substance use (Darke, 1998). Second, our survey was limited to
only about 57% of the national population. Nigeria is a multi-
ethnic country and the sections not covered by our survey might
have different profile of substance use than what we report here.
Nevertheless,thisisthelargestsurveyofitskindeverconducted
on substance use in Nigeria. Also, we have used appropriate
weightingadjustmentstoapproximateoursamples,boththepart
I and II samples, to the national age and sex distribution. We are
thereforeconfidentthat,withinthemarginsoferrorreported,the

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8
O. Gureje et al. / Drug and Alcohol Dependence 91 (2007) 1–9
profile of drug use we have reported reflects the extant profile
for the majority of adult Nigerians.
5. Conclusions
In this first large-scale study of the use of a broad range
of drugs by adult Nigerians, we found alcohol to be the most
commonly used drug, and tobacco and sedatives to have about
similar level of use. Cannabis use occurs, but is not prevalent.
Males were most likely to use any of the drugs investigated. Use
wascommonlyinitiatedinearlyadolescencetoearlyadulthood.
Although a relatively under-recognised area, problems related
to the use of sedatives and stimulants clearly cause harm for
users and may constitute a hitherto unrecognised societal
burden. Future research on possible birth cohort differences in
drug use appears warranted, given the age differences observed
in this study.
Acknowledgements
The Nigerian Survey of Mental Health and Well-being
was carried out in conjunction with the World Health Orga-
nization World Mental Health (WMH) Survey Initiative. We
thank the WMH staff for assistance with instrumentation,
fieldwork, and data analysis. These activities were supported
by the United States National Institute of Mental Health
(R01MH070884), the John D. and Catherine T. MacArthur
Foundation, the Pfizer Foundation, the US Public Health Ser-
vice (R13-MH066849, R01-MH069864, and R01 DA016558),
the Fogarty International Center (FIRCA R01-TW006481),
the Pan American Health Organization, Eli Lilly and Com-
pany, Ortho-McNeil Pharmaceutical, Inc., GlaxoSmithKline,
and Bristol-Myers Squibb. A complete list of WMH publica-
tions can be found at http://www.hcp.med.harvard.edu/wmh/.
AdditionalfundingfortheNigeriansurveycamefromtheNige-
rian Federal Ministry of Health, and support was obtained from
the University of Ibadan. Nigerian collaborators were: Oye
Gureje (Principal Investigator, University of Ibadan), Richard
Uwakwe (Nnamdi Azikiwe University, Nnewi), Michael Ekpo
(FederalPsychiatricHospital,Calabar),OwoidohoUdofia(Uni-
versity of Calabar), Abba Wakil (Federal Psychiatric Hospital,
Maiduguri), Olusola Adeyemi (Psychiatric Hospital, Kaduna)
and Nonyenim Enyidah (Rivers Psychiatric Hospital, Port Har-
court). We acknowledge the administrative support provided by
Olusola Odujinrin (WHO Country Office, Abuja). The work
on this paper was supported by NIH/NIDA research project
award R01DA016558 and a NIDA KO5 Senior Scientist award
(K05DA015799) to the last author (JCA), as well as funds
from Michigan State University and the Australian Government
DepartmentofHealthandAgeing.KiplingM.Bohnert’sappren-
ticeship is supported under an NIH/NIDA institutional training
program award, T32DA021129.
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