Despite several studies on the prevalence and pattern of substance use in Nigeria, there is little information on substance use in patients diagnosed with serious mental illness (SMI) such as schizophrenia and bipolar affective disorder (BD).
The aim of the study was to compare the pattern of psychoactive substance use among outpatients with BD and schizophrenia.
The study was conducted in a neuropsychiatric hospital in Nigeria.
Seventy five consecutive patients with a MINI-PLUS diagnosis of BD were compared with an equal number of patients obtained by systematic random sampling with a MINI-PLUS diagnosis of schizophrenia.
The respondents with schizophrenia were aged 18–59 years (37.2 ± 9.99) and were predominantly young adult (49, 65.3%), men (46, 61.3%), who were never married (38, 50.7%). Overall, lifetime drug use prevalence was 52%, while for current use, overall prevalence was 21.3%. Participants with BD were aged 18–63 years (36.7 ± 10.29) and were predominantly young adult (53, 70.7%), women (44, 58.7%), who were married (32, 42.7%), with tertiary education (31, 41.3%). Overall, lifetime drug use prevalence was 46.7%, while current overall prevalence was 17.3%. These rates (lifetime and current) for both diagnostic groups are higher than what was reported by the World Health Organization in the global status report of 2014 (0% – 16%). The statistically significant difference between the two diagnostic groups was related to their sociodemographic and clinical variables and psychoactive substance use.
Psychoactive substance use remains a burden in the care of patients diagnosed with schizophrenia and BD. Future policies should incorporate routine screening for substance use at the outpatient department with a view to stemming the tide of this menace.
Despite worldwide concern and education about psychoactive substance use, there is limited awareness of the prevalence and pattern of psychoactive substance use among mentally ill patients.
Although substance use in both disorders (schizophrenia and BD) makes use of the reward system, the sub-pathways in the reward system may differ in the two disorders. Studies have shown the pathways responsible for psychoactive substance use in schizophrenia and BD but have not indicated which of these are most likely to predispose to psychoactive substance use and abuse.
A cross-sectional comparative study of substance use among patients with the diagnosis of schizophrenia and BD attending the outpatient clinic of the Neuropsychiatric Hospital, Aro, Abeokuta, Ogun State, Nigeria, was carried out between February and March 2015. A systematic random sampling of every fourth patients with schizophrenia was recruited, while consecutive patient with BD were recruited. To be included in the study, patients were between the ages of 18–64 years without chronic and disabling physical conditions (e.g. cerebrovascular disease) or acute medical distress (e.g. acute malaria) and mentally stable to participate in the study. This was determined with the psychotic (clinical judgement section of psychosis M8b, M9b, M10b) and manic (D3c, e, f) modules of the Mini International Neuropsychiatric Interview (MINI PLUS). The sample size was determined using the sample size formula for group comparison according to Whitley and Ball.
A sociodemographic questionnaire designed by the researcher was used to collect biodata. The MINI PLUS was used in this study to confirm the diagnosis of schizophrenia and BD. The Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) Version 3.1 was used to determine the prevalence and pattern of psychoactive substance use. Data were analysed using the Statistical Package for Social Science (SPSS version 21) computer software. Patients’ occupation was classified according to the system of Boroffka and Olatawura.
Ethical clearance was obtained from the Research and Ethics Committee of the Neuropsychiatric Hospital, Aro Abeokuta.
The mean ages of patients with schizophrenia and BD followed a normal distribution.
The mean age of respondents with schizophrenia was not significantly different from that of participants with BD (
Sociodemographic characteristics of respondents (
Variables | Schizophrenia |
Bipolar |
Chi-square |
||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
% | Age range | s.d. | % | Age range | s.d. | χ2 | |||||
≤ 40 | 49 | 65.3 | 18–59 | 9.99 | 53 | 70.7 | 18–63 | 10.29 | 0.490 | 1 | 0.480 |
< 40 | 26 | 34.7 | 22 | 29.3 | |||||||
Male | 46 | 61.3 | - | - | 31 | 41.3 | - | - | 6.004 | 1 | 0.010 |
Female | 29 | 38.7 | - | - | 44 | 58.7 | - | - | |||
Never married | 38 | 50.7 | - | - | 31 | 41.3 | - | - | 1.374 | 2 | 0.500 |
Married | 26 | 34.7 | - | - | 32 | 42.7 | - | - | |||
Separated or widowed or cohabiting | 11 | 14.7 | - | - | 12 | 16.0 | - | - | |||
No formal or primary education | 11 | 14.7 | - | - | 16 | 21.3 | - | - | 1.141 | 2 | 0.560 |
Secondary education | 31 | 41.3 | - | - | 28 | 37.3 | - | - | |||
Tertiary education | 33 | 44.0 | - | - | 31 | 41.3 | - | - | |||
Major | 69 | 92.0 | - | - | 70 | 96.0 | - | - | 1.064 | 1 | 0.300 |
Minor |
6 | 8.0 | - | - | 5 | 4.0 | - | - | |||
Christianity | 52 | 69.3 | - | - | 50 | 66.7 | - | - | 0.123 | 1 | 0.726 |
Islam | 23 | 30.7 | - | - | 25 | 33.3 | - | - | |||
High socioeconomic | 40 | 53.3 | - | - | 43 | 57.3 | - | - | 0.504 | 2 | 0.770 |
Middle socioeconomic | 25 | 33.3 | - | - | 21 | 28.0 | - | - | |||
Low socioeconomic status | 10 | 13.3 | - | - | 11 | 14.7 | - | - |
s.d., standard deviation.
, Other tribes in Nigeria aside from Yoruba, Igbo and Hausa.
The overall lifetime (39, 52%) and overall current (16, 21.3%) pattern of psychoactive substance use among patients with schizophrenia was not statistically different from the overall lifetime (35, 46.7%) and overall current (13, 17.3%) pattern of psychoactive substance use among the BD group and is shown in
Comparison of current and lifetime prevalence of psychoactive substance use among patients with schizophrenia (
Psychoactive substance | Lifetime use |
Current use |
||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schizophrenia |
Bipolar |
χ2 | Schizophrenia |
Bipolar |
χ2 | |||||||||
% | % | % | % | |||||||||||
Any substance | 39 | 52.0 | 35 | 46.7 | 0.427 | 1 | 0.51 | 16 | 21.3 | 13 | 17.3 | 0.385 | 1 | 0.53 |
Tobacco | 15 | 20.0 | 10 | 13.3 | 1.200 | 1 | 0.27 | 5 | 6.7 | 6 | 8.0 | 0.118 | 1 | 1.00 |
Alcohol | 33 | 44.0 | 23 | 30.7 | 2.850 | 1 | 0.09 | 11 | 14.7 | 10 | 13.3 | 0.055 | 1 | 0.81 |
Cannabis | 11 | 14.7 | 10 | 13.3 | 0.055 | 1 | 0.81 | 4 | 5.3 | 4 | 5.3 | 0.000 | 1 | 1.00 |
Stimulant |
16 | 21.3 | 18 | 24.0 | 0.152 | 1 | 0.69 | 7 | 9.3 | 7 | 9.3 | 0.000 | 1 | 1.00 |
Sedative or sleeping pills |
11 | 14.7 | 11 | 14.7 | 0.000 | 1 | 1.00 | 3 | 4.0 | 2 | 2.7 | 0.207 | 1 | 0.64 |
Heroin or morphine or pain medication |
5 | 6.7 | 4 | 5.3 | 0.118 | 1 | 0.73 | 1 | 1.3 | 1 | 1.3 | 0.000 | 1 | 1.00 |
, Ephedrine, coffee and kolanut.
, Lexotan.
, Codeine and tramadol.
The following sociodemographic and clinical variables were statistically significantly associated with lifetime psychoactive substance use in the schizophrenia group: male gender, tertiary education, high socioeconomic status and a single past episode of mental illness. Furthermore, being a young adult was the only statistically significant sociodemographic variable associated with current use of psychoactive substance in the schizophrenia group and no other sociodemographic or clinical variables were statistically significantly associated with current use of psychoactive substance in the schizophrenia group.
Only the following sociodemographic and clinical variables were significantly associated with lifetime use of psychoactive substance in the BD group: male gender, middle socioeconomic status, marital status and duration of illness. In addition, male gender, secondary education, middle socioeconomic status, never married and number of admissions were the only statistically significant sociodemographic and clinical variables associated with current use of psychoactive substance in the BD group, and no other sociodemographic or clinical variables were statistically significantly associated with current use of psychoactive substance in the BD group.
There were no specific types of psychoactive substances used among patients with schizophrenia that demonstrated more than one sociodemographic or clinical variable associated with its use. It was thus unnecessary to subject such associations to multivariate binary logistic regression. Multivariate regression analysis for the BD group is shown in
Multivariate regression analysis showing independent correlates of psychoactive substance use among patients with bipolar affective disorder.
Psychoactive substance use | OR | 95% CI | |
---|---|---|---|
Male | 3.23 | 1.14–9.16 | 0.027 |
Female | 1.00 | - | - |
≤ 6 years | 5.63 | 1.58–20.04 | 0.008 |
7–12 years | 3.97 | 1.10–14.29 | 0.035 |
≥ 13 years | 1.00 | - | - |
Male | 3.14 | 0.89–10.99 | 0.073 |
Female | 1.00 | - | - |
Married | 1.00 | - | - |
Never married | 2.38 | 0.57–9.96 | 0.236 |
Separated or widowed or cohabiting | 6.13 | 1.11–33.98 | 0.038 |
≤ 6 years | 10.03 | 1.65–61.18 | 0.012 |
7–12 years | 8.86 | 1.45–54.09 | 0.018 |
≥ 13 years | 1.00 | - | - |
Married | 1.00 | - | - |
Never married | 3.44 | 0.78–15.28 | 0.104 |
Separated or widowed or cohabiting | 8.44 | 1.54–46.27 | 0.014 |
High socioeconomic | 1.00 | - | - |
Middle socioeconomic | 3.96 | 1.08–14.48 | 0.038 |
Low socioeconomic | 1.83 | 0.34–9.89 | 0.482 |
OR, odds ratio; CI, confidence interval.
The two diagnostic groups were observed to have a similar prevalence of psychoactive substance use, except that in the schizophrenia group cannabis was as prevalent as sedatives or sleeping pills. It should be noted that previous studies in Nigeria did not specifically compare the prevalence rates of these diagnostic groups.
The findings in this study are, however, relatively comparable to previous findings from Nigeria, Europe and the US.
Furthermore, different instruments were used; for example, the composite international diagnostic interview was used in Gureje’s study, whereas this study used the MINI PLUS. Consistent with the results from other studies, the use of cocaine, heroin, hallucinogens and inhalants was absent among respondents in this study.
Gender differences in both diagnostic groups with regard to lifetime and current use of psychoactive substance use were observed in this study. This was similar to earlier studies
Male gender and marital status (never married) were associated with lifetime use of alcohol, while male gender, marital status (separated or widowed or cohabiting) and level of education (no formal or primary education) were associated with current use of alcohol in participants with BD. This is similar to other studies
This is a plausible explanation for the significant difference observed in this study.
In this study, male gender was an important factor in the lifetime use of cannabis, while marital status (never married) is associated with current use of cannabis in both diagnostic groups. In addition, level of education (secondary) and employment status (middle socioeconomic status) were associated with current use of cannabis in respondents with BD. This is different from reports of previous studies
This may be explained by the relatively smaller sample size of this study compared to the previous study (
Furthermore, the level of intellectual development if measured with the level of education was a variable determining the use of stimulants in the schizophrenic group, while the financial stability if measured by employment, marital and socioeconomic status was the determining factor for stimulant use in the bipolar group. This is similar to what was reported in a study by Baethge and his coworkers
On the other hand, the bipolar group, who are relatively cognitively stable, may require large funds to execute this possible self-medication, knowing that extravagance is a symptom of BD. This may explain the difference observed in the diagnostic groups of this study. High socioeconomic status was associated with lifetime use of sedative or sleeping pills in respondents diagnosed with schizophrenia, while sedative or sleeping pills showed no association with the BD group. Fowler, in his study of patterns of current and lifetime use substance use, reported that the use of sedatives or sleeping pills may be associated with dysphoric relief, that is, to relax, and social effect, that is, to beat the boredom and illness and medication-related effects in patients diagnosed with schizophrenia.
The age of onset of illness was not significantly related to the lifetime and current use of any psychoactive substance investigated in this study among respondents with a diagnosis of schizophrenia and BD. This is contrary to what has been reported in previous studies,
The association of alcohol use with duration of illness in participants with BD is in keeping with earlier reports that comorbidity of substance use with BD is the most common dual diagnosis.
The number of admissions was associated with current use of tobacco in both diagnostic groups but only showed association with lifetime use of sedatives in the BD group. BD is a chronic relapsing illness
The finding that male gender was an independent predictor of lifetime use of any substance and lifetime use of alcohol has been reported by several studies both internationally
The study was cross-sectional, and therefore, direction of causality could not be established between sociodemographic and clinical variables of patients and psychoactive substance use. The study population involved only one of the many psychiatric hospitals in Nigeria and as such the findings may not be representative of the whole nation, and hence cannot be generalised. The minimum sample size (as calculated) used for this study did not allow for statistical testing for variables with very low prevalence. Also, unstable patients were excluded from this study and this may have influenced the prevalence of psychoactive substance use in both diagnostic groups. However, this study uses an internationally recognised standardised instrument in assessing psychoactive substance use among patients with major mental illness, which is a strength of the study, and allows for replicability in other settings.
Alcohol was the most prevalent psychoactive substance used by participants with SMI in this study and age group less than 40 is associated with current substance use in participants with schizophrenia, while male gender, secondary education, middle socioeconomic status, marital status and duration of illness were associated with current substance use in participants with BD. Therefore, it is recommended that selective prevention strategies for psychoactive substances should target people with SMI who have the above sociodemographic and clinical variables. Cutting off, cutting down or prevention of substance use from progressing to misuse disorder will have direct and indirect effect on the course of the illness, effectiveness of medication used in treatment and the prognosis. There is a need to increase and provide screening instruments for the use of alcohol and other psychoactive substances. It is also important to educate patients regularly on the negative consequences of psychoactive substance use and its effect on treatment and outcomes. The consequences of psychoactive substance use on the course of schizophrenia and BD can be mitigated by brief drug interventions that can be administered easily by medical practitioners. Medical personnel should be trained in the use of ASSIST, which will help to detect early substance use problems in order to institute early intervention. Future studies could focus on possible associations with other clinical measures such as motivation for use, impulsivity and cognitive decline, as well as biological parameters such as genetics and brain imaging. Finally, a longitudinal study may be helpful in showing direction of causality.
This is to appreciate all the patients with mental illness who not only took time to fill out the questionnaire but were patient during the course of the research. Special thanks to my late father Dr Charles Olabode Sowunmi II.
The authors have declared that no competing interests exist.
O.A.S., G.A. and P.O.O. were responsible for the study conception and design. O.A.S. was responsible for acquisition of data. O.A.S., A.O. and E.B. performed data analysis and interpretation. All authors were responsible for drafting of the manuscript and critical revision of the article.
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Data sharing is not applicable to this article as no new data were created or analysed in this study.
The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of any affiliated agency of the authors.