Substance use and generalized anxiety disorder in university students: evidence from the university of Douala, Cameroon

Abstract

Background

University students are vulnerable to mental health disorders, including substance use disorder (SUD) and generalized anxiety disorder (GAD). However, data on the association between SUD and GAD in African university settings remain scarce. This study aimed to assess the prevalence of SUD and GAD and to explore their relationship among students at the University of Douala, Cameroon.

Methods

A cross-sectional analytical study was conducted from March 1 to May 31, 2024. Participants were level 1 to level 5 students recruited using non-probability sampling. SUD was diagnosed using DSM-5 criteria via a self-administered questionnaire, and GAD was assessed using the GAD-7 scale. Statistical analyses included chi-square tests and logistic regression. A p-value < 0.05 was considered significant.

Results

Among the 917 students included (54.8% female), the prevalence of SUD was 15.7% and that of GAD was 26.4%. GAD was present in 45.8% of students with SUD. SUD was significantly associated with GAD (OR = 2.87; 95% CI: 1.99–4.15; p < 0.001). Male gender (OR = 1.96; p = 0.001), history of psychiatric disorders (OR = 3.69; p < 0.01), and living alone (OR = 3.45; p < 0.01) were also significantly associated with the co-occurrence of both disorders.

Conclusion

SUD and GAD are both prevalent among university students, with a significant association between the two conditions. Students with SUD were nearly three times more likely to report symptoms of GAD. These findings highlight the importance of integrated screening and mental health support strategies targeting both disorders in university settings.

Clinical trial number

Not applicable.

Background

Education plays a pivotal role in national development, and the mental health of students is essential for sustainable socio-economic progress [1]. University life often coincides with the transition from adolescence to adulthood, a period marked by significant biological, psychological, and social changes. These changes, combined with academic demands, social pressure, and financial instability, may foster the emergence of mental health disorders such as anxiety disorders (ADs), mood disorders, and substance use disorders (SUDs) [2, 3].

According to the DSM-5, ADs encompass generalized anxiety disorder (GAD), social anxiety disorder, panic disorder, and specific phobias. GAD, characterized by excessive and persistent worry, is among the most prevalent mental health conditions, affecting about 33.7% of individuals globally during their lifetime [4]. University students are particularly vulnerable to GAD due to the sustained stress inherent in their academic and personal lives [5–7].

Simultaneously, the consumption of psychoactive substances (PAS) is a common coping mechanism used by students to alleviate stress and anxiety symptoms [8]. However, this can lead to the development of SUD, which poses serious health, social, and academic consequences [8]. The United Nations Office on Drugs and Crime (UNODC) reports that young people are disproportionately affected by substance use, experiencing the most severe outcomes [9]. In the United States, the annual prevalence of SUD among students reaches 39.6% [10].

In Africa, 70% of individuals treated for SUD are under the age of 35 [9]. A study conducted in Buea (Cameroon) found that 89.9% of students reported using PAS, with the most used substances being tobacco (26.2%), alcohol (19.7%), tramadol (2.8%), and cannabis (2.0%) and another study in the same town found the prevalence of non-medical use of prescription drugs was 15.3% [5, 11].

The association between anxiety disorders and SUD is well established, particularly among young adults [12]. GAD has been identified as a risk factor for problematic substance use, with consequences on academic performance, risky sexual behavior, and suicidal ideation [13, 14]. However, despite this well-documented association in the literature [15], few studies have specifically investigated the link between SUD and GAD in the African university context.

In a context where PAS use is widespread in educational settings, this study aims to assess the relationship between substance use disorder and generalized anxiety disorder among students at the University of Douala.

Methods

Study design and setting

This was a cross-sectional analytical study conducted at the University of Douala (UDo), a public university in Cameroon established by presidential decree in 1993. As of 2023, the UDo had 52,637 enrolled students distributed across 11 institutions, including five faculties. The campuses are in Douala (Bassa, Ndongbong, Logbessou), and two satellite campuses located in Yabassi and Nkongsamba.

Study period and population

The study was conducted from March 1 to May 31, 2024. The target population included all students officially enrolled at the UDo during the 2023–2024 academic year, regardless of substance use status.

Inclusion criteria: Students from level 1 to level 5 (master’s level), of all ages, who provided informed consent.

Exclusion criteria: Incomplete questionnaires, students enrolled in institutions outside Douala, and students who had significant communication difficulties, severe medical illness.

Sampling

A non-probabilistic stratified quota sampling approach was used. Each of the 11 institutions represented a stratum. Proportional allocation was applied based on the total number of students enrolled in each institution relative to the overall university population. Within each stratum, participants were selected by convenience according to accessibility during lecture hours, campus visits, and student gatherings, until the predefined quota was reached. The sample size (n) was calculated using Cochran’s formula for cross-sectional studies:

n = Z² × p(1 − p) / d², where Z = 1.96 for a 95% confidence level, p = 0.5 (assumed prevalence due to lack of prior data), and d = 0.05 (margin of error). This yielded a minimum sample size of 384 participants. Considering a design effect of 2 for stratified sampling and an anticipated non-response rate of 20%, the final sample size was set at approximately 922 students. Ultimately, 917 completed questionnaires were retained for analysis.

Recruitment process

Participants were approached in classrooms, libraries, and campus common areas during breaks and after lectures. Data collectors made up to two contact attempts per student group when necessary. Before completing the questionnaire, each participant received an explanation of the study objectives and provided written informed consent. Confidentiality and voluntary participation were emphasized, and no incentives were offered.

Data collection

Data were collected using a paper questionnaire, the GAD-7 score, and DSM-5 diagnostic criteria for SUD. The DSM-5 criteria for SUD were operationalized using a structured, self-administered questionnaire containing 11 items corresponding directly to the 11 diagnostic criteria outlined in the DSM-5. Each item assessed a specific symptom or behavior (e.g., craving, tolerance, withdrawal, failure to meet obligations) and referred to the past 12 months. A “Yes” response to two or more criteria was considered indicative of SUD, in accordance with DSM-5 guidelines. A pre-test was conducted with 20 students. Data entry was performed using ODK-Collect and analysed using SPSS^® version 28.

Variables studied

Sociodemographic data: Age, sex, level of study, marital status, academic field, religion, family environment, and parents’ marital status and education level.

Use of psychoactive substances: Type, frequency, and age at first use.

Generalized anxiety disorder: Assessed using the GAD-7 scale (score ≥ 10 = GAD).

Substance use disorder: Diagnosed according to DSM-5 criteria (≥ 2 of 11 criteria).

GAD + SUD co-occurrence: Simultaneous presence of both disorders in the same student.

Assessment of Generalized Anxiety Disorder: Generalized anxiety disorder was assessed using the GAD-7 scale, a widely validated screening tool. It consists of 7 items rated on a 4-point Likert scale ranging from 0 (“not at all”) to 3 (“nearly every day”), with a total score ranging from 0 to 21. A cutoff score of ≥ 10 was used to indicate the presence of GAD, in accordance with established clinical standards. This threshold has demonstrated sensitivity of 89% and specificity of 82% for generalized anxiety disorder [16]. The GAD-7 has been validated in multiple populations, including African university students, showing good internal consistency (Cronbach’s alpha >0.85) and construct validity. The tool was self-administered in French and English depending on the participant’s language preference.

Assessment of Substance Use Disorder: Substance use disorder was assessed using DSM-5 criteria, which define SUD as the presence of at least 2 out of 11 criteria within a 12-month period. The criteria cover domains such as impaired control, social impairment, risky use, and pharmacological indicators (tolerance and withdrawal) [17]. To operationalize this, we developed a structured self-administered questionnaire mapping directly into each of the 11 DSM-5 criteria. For each substance used (e.g., alcohol, tobacco, cannabis, etc.), students were asked whether they experienced symptoms corresponding to each criterion over the past year. Based on their responses, cases were classified into: Mild (2–3 criteria), moderate (4–5 criteria), and Severe (6 + criteria).

The self-report format was chosen due to feasibility and anonymity, which enhances disclosure in sensitive topics like substance use. While not a clinical interview, this structured approach has been validated in other population-based studies, showing good reliability and convergent validity [18].

Statistical analysis

Quantitative variables were presented as means ± standard deviation or medians, and qualitative data as counts and percentages. Associations were assessed using the Chi-squared test. Univariate and multivariate logistic regression analyses were performed to identify factors associated with the co-occurrence of GAD and SUD. A p-value < 0.05 was considered statistically significant.

Results

Sociodemographic characteristics of the study population

Of the 917 students included, 54.9% were female, with a mean age of 21.75 ± 3.3 years (range 16–52). Most were single (96.1%) and lived with family (75.6%). The majority were in academic levels 1 and 3 (30.1% and 26.1%, respectively) (Table 1).

Table 1.

Sociodemographic characteristics of the sample (n = 917)

Variables	Categories	Frequency (n)	Percentage (%)
Age	≤ 20 years	362	39.5
	21–25 years	470	51.2
	26–30 years	64	7.0
	> 30 years	21	2.3
Sex	Female	503	54.9
	Male	414	45.1
Level of Study	1	276	30.1
	2	144	15.7
	3	239	26.1
	4	183	20.0
	5	75	8.2
Nationality	Cameroonian	889	96.9
	Foreign	28	3.1
Religion	Animist	4	0.4
	Other	146	15.9
	Catholic	468	51.0
	Muslim	60	6.5
	Protestant	239	26.1
Marital Status	Single	881	96.1
	Married	22	2.4
	Divorced	4	0.4
	Other	10	1.1
Living Situation	With family	693	75.6
	Alone	145	15.8
	Guardian	41	4.5
	Friend/Roommate	38	4.1

Prevalence of psychoactive substance use

Among participants, 84% reported having used a psychoactive substance at least once in their lifetime. Among these users, 89.2% had used a PAS in the past 12 months, 62.5% in the past 30 days, and 74% had experimented with PAS before entering university. The most used substances were alcohol (99.2%), tobacco (16.9%), and cannabis (4%) (Table 2).

Table 2.

Period of first consumption and distribution of psychoactive substances (SPAs)

Variables	Frequency (n)	Percentage (%)
Period of First Consumption
- Before university	573	74.4
- After university	197	25.6
SPA consumed at least once in life
- Alcohol	764	99.2
- Tobacco	155	20.1
- Cannabis	32	4.0
- Tramadol / Codeine	22	2.9
- Crack	8	1.0
- Cocaine	3	0.4
- Diazepam	3	0.4
- Heroin	2	0.3

Prevalence of substance use disorder

The overall prevalence of SUD was 15.7%. Among the identified cases, 23.6% had moderate SUD and 9% had severe SUD (Table 3). SUD related to alcohol was observed in 131 students (14.3%), to tobacco in 21 students (2.3%), and to illicit substances (cannabis, tramadol, crack) in 10 students.

Table 3.

Distribution of substance use disorder among students

Variables	Frequency (n)	Percentage (%)
Substance Use Disorder (N = 917)
- Yes	144	15.7
- No	773	84.3
Severity level (N = 144)
- Mild	93	67.4
- Moderate	34	23.6
- Severe	13	9.0

Prevalence of generalized anxiety disorder

GAD risk was present in 242 students, corresponding to a prevalence of 26.4%. This risk was higher among females (28.8%), more prevalent among fifth-year students (34.7%), and more frequent among those living alone (33.8%) compared to those living with family (25%), in shared housing (28.9%), or with a guardian (21.9%).

Association between SUD and GAD across key variables

Subgroup analysis showed that male students had a significantly higher odds of co-occurring substance use disorder (SUD) and generalized anxiety disorder (GAD) with an OR of 4.96 (95% CI: 3.02–8.15, p < 0.001). Female students also showed a significant association, though weaker, with an OR of 1.82 (95% CI: 1.02–3.25, p = 0.038). Students living alone had increased odds of SUD and GAD comorbidity (OR = 3.96; 95% CI: 2.01–7.81; p < 0.001), as did those living with family (OR = 2.63; 95% CI: 1.64–4.22; p < 0.001). A history of mental illness was strongly associated with comorbidity, with an OR of 4.00 (95% CI: 1.69–9.49, p = 0.002) (Table 4).

Table 4.

Association between SUD and GAD across key variables

Subgroup	SUD⁺ GAD⁺	SUD⁺ GAD⁻	SUD⁻ GAD⁺	SUD⁻ GAD⁻	OR (95% CI)	p-value
Male	40	40	56	278	4.96 (3.02–8.15)	< 0.001
Female	26	38	120	319	1.82 (1.02–3.25)	0.038
Living alone	25	20	24	76	3.96 (2.01–7.81)	< 0.001
Living with family	30	43	130	490	2.63 (1.64–4.22)	< 0.001
History of mental illness	20	10	15	30	4.00 (1.69–9.49)	0.002

SUD: substance use disorder, GAD: generalized anxiety disorder

Discussion

The study aimed to assess the prevalence and determinants of SUD and GAD among students at the University of Douala, and to examine the association between these two conditions.Based on a representative sample of 917 students, several noteworthy findings emerged.

Over half of the participants were female, consistent with findings from other university-based studies, such as those conducted by Olanrewaju et al. in Nigeria (68%) and Pérez et al. in Spain (73.8%) [6, 19]. This female predominance could reflect the gender distribution in university enrolment and possibly a greater willingness among women to participate in health-related surveys. The mean age was 21.75 ± 3.3 years, with the 21–25 age group representing 51.2% of the sample, similar to findings by Metuge et al. and Ntone et al. [5, 20]. Additionally, nearly 72% of students were enrolled in academic levels 1 to 3, aligning with the findings of Nurul et al. in Malaysia, where undergraduate students made up 78% of the sample [7]. This predominance may be attributed to greater availability among undergraduates to participate in surveys compared to master’s students, who face greater academic pressures.

Lifetime and 12-month use of PAS was high, consistent with the findings of Metuge et al. (89.9%), but higher than those reported by Blows et al. in South Africa (62.7%) [5, 21]. Alcohol was the most used PAS (99.2%), followed by tobacco (20.1%), cannabis (4%), tramadol/codeine (2.9%), and crack (1%). These results reflect the influence of substance legality on accessibility.

The 12-month prevalence of SUD was 15.7%, higher than figures reported in Kenya (7.8%) and in the WHO multicenter study (9.3%) [1, 22], but lower than those reported by Olanrewaju in Nigeria (45.7%) and Arterberry in the United States (39.6%) [6, 23]. These discrepancies may be due to methodological, cultural, and sociodemographic differences, as well as variations in diagnostic criteria. Alcohol was also the most implicated substance in SUD cases (14.3%), consistent with previous findings.

A little over one in four students had GAD, a rate similar to that found by Nurul et al. (29%) [7], but higher than the WHO global study (16.7%) [1]. These differences may result from varying diagnostic thresholds (≥ 10 in our study vs. ≥5 or ≥ 8 in others). Conversely, our rate was lower than the 74.7% reported by Manana et al. among nursing students in South Africa [24], likely due to specific population characteristics (clinical stress, female predominance, advanced academic level). GAD was more frequent in women (28.8% vs. 23.4% in men), as commonly reported in the literature. Fifth-year students also had higher GAD rates, likely due to increased academic pressure and a competitive environment [25].

A statistically significant association between SUD and GAD was found. Nearly half (45.8%) of students with SUD also had GAD, like the 46% reported by Smith et al. [26]. This association was confirmed by multivariate analysis, indicating that students with SUD were nearly three times more likely to have GAD. These findings align with those of Grant et al. (OR = 2.3) and Marmorstein (OR = 2.69) [26, 27]. Several theoretical models may explain this association:

• the higher prevalence of SUD among anxious students supports the self-medication hypothesis [28, 29].

• Neurobiological effects of SUD, particularly alterations in the limbic system, which may induce or exacerbate anxiety, especially during withdrawal [30].

• A shared vulnerability model, suggesting common genetic or personality traits (e.g., neuroticism) predispose individuals to both disorders [31, 32].

The prevalence of co-occurring SUD and GAD was 7.2%, comparable to that observed in the U.S. adult population (8.8%) [33]. The co-occurrence of SUD and GAD presents a major therapeutic challenge. Treatments for GAD, such as benzodiazepines, can promote dependency. Conversely, anxiety is a frequent relapse factor in patients treated for SUD, necessitating an integrated treatment approach. This includes the limited availability of university mental health services, stigma surrounding psychiatric disorders, cultural acceptance of alcohol use, and socio-economic stressors.

Predictive factors identified were:

• Male gender (OR = 1.96), as observed by Melkam et al. in Ethiopia [12]. Although anxiety is more common among women, men are at greater risk when substance use is involved [34].

• Living alone (OR = 3.45), possibly due to reduced social oversight and increased isolation [35, 36].

• History of mental disorders (OR = 3.69), reflecting pre-existing psychological vulnerability and common biological mechanisms among mental health conditions [37].

Strengths of our study

This study is one of the first to provide information on the prevalence of SUD and to evaluate its association with GAD among students at the University of Douala.

Limitations of the study

This study has several limitations. First, its cross-sectional design does not allow for the establishment of causal relationships between substance use disorder and generalized anxiety disorder. Second, the use of self-reported questionnaires may introduce recall and social desirability biases. Third, the deliberate exclusion of students undergoing treatment with psychotropic medications may have resulted in the underrepresentation of individuals with more severe psychiatric conditions, potentially leading to an underestimation of the true prevalence and burden of comorbid SUD and GAD. Finally, some potential confounding factors, such as socio-economic status or comorbid psychiatric conditions, were not fully controlled for and should be considered in future research.

Perspectives

Future research should adopt longitudinal designs to clarify the causal pathways between SUD and GAD among university students. Expanding the study to multiple institutions and diverse geographic regions would improve the representativeness and external validity of findings. Incorporating clinical diagnostic assessments alongside self-report tools would enhance diagnostic precision. Moreover, exploring intervention strategies targeting both substance use, and anxiety symptoms concurrently could provide valuable insights for campus mental health programs.

Conclusion

This study highlights a high burden of substance use and generalized anxiety among students at the University of Douala, with nearly half of students with SUD also experiencing GAD. The co-occurrence of these conditions was significantly associated with male gender, living alone, and a history of mental illness. These findings underscore the urgent need for integrated mental health screening and intervention strategies in Cameroonian university settings.

Abbreviations

TA

Anxiety Disorder

TAG

Generalized Anxiety Disorder

TUS

Substance Use Disorder

SPA

Psychoactive Substance

DSM-5

Diagnostic and Statistical Manual of Mental Disorders, 5th edition

OMS

World Health Organization

ONUDC

United Nations Office on Drugs and Crime

UDo

University of Douala

GAD-7

Generalized Anxiety Disorder – 7 items

OR

Odds Ratio

IC

Confidence Interval

SPSS

Statistical Package for the Social Sciences

Author contributions

AMM and CE designed the study. AFHB and AMM collected the data. AFHB, DG, VS and ELBG conducted the statistical analysis. HI and JD contributed to the literature review and manuscript drafting. CKT and YNM critically revised the manuscript. All authors read and approved the final version.

Funding

This study received no external funding. It was conducted using the authors’ own resources.

Data availability

The data used and/or analyzed during this study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

The study received approval from the Institutional Ethics Committee of the University of Douala (Approval No. 4137). All participants provided free and informed consent after being clearly informed about the study objectives, methodology, potential risks, and expected benefits. The principles of anonymity, confidentiality, justice, and beneficence were strictly observed. The research was conducted in accordance with the declaration of Helsinki and relevant national ethical guidelines.

Consent for publication

Not applicable. No identifiable personal data are published in this manuscript.

Competing interests

The authors declare no competing interests.