This study showed that there is substantial burden of psychoactive substances use among undergraduate students in Axum University. The overall life time and current prevalence of psychoactive substances use among Axum University students were 45.9% and 44.8% respectively. These findings were significantly lower than a similar study done among high school students in Nigeria, in which the life time and current prevalence were 87.3% and 69.2% respectively. These findings were also lower than a similar study done among college students in Eldoret, Western Kenya where the lifetime prevalence rate of any substances use was 69.8% .
The possible explanation for the observed differences in substances use could be due to the differences in knowledge on the health risks of substances use. For instance, the study among high school students in Nigeria showed that 73% of the study subjects were not aware of the health risks associated with substances use, whereas more than 70% of our study subjects were aware of the health risks of substances use.
Our findings indicated that life time and current khat use was 28.7% and 27.9% respectively. These findings were consistent with a study done among college students in North West Ethiopia, in which the life time prevalence of khat chewing was 26.7%. Similarly, these findings were in line with studies done among college and high school students of Jazan region, Saudi Arabia, among staffs of Jimma University and study done in Jimma town with prevalence rate of 21%, 30.8% and 30.6% respectively [12, 14, 15]. However, our findings were higher than study done among undergraduate medical students in Addis Ababa University with the past year and current prevalence of 7% and 4% respectively . A similar study in Somalia revealed that the life time prevalence of khat chewing was 81.6% among men and 43.3% among women, which is higher than the findings of this study where only 36.5% males and 17.6% females chewed khat. This difference could be due to the study in Somalia were composed of individuals reportedly under severe stress and in a context of social disruption which may potentially increases substances use .
Our findings indicated that life time and current alcohol use was 34.5% and 32.8% respectively. These results were lower than a studies done at Federal University of Alagoas, Brazil and among college students in Eldoret, Western Kenya with alcohol consumption rate of 87.6% and 51.9% respectively [10, 17].
Similarly, our reported rate of alcohol consumption was lower than a study done among adolescents in rapidly developing countries with prevalence of 49% and 48% for male and female respectively . However, our reported life-time alcohol consumption was higher than a study done among medical students in Addis Ababa University 22% .
Our findings indicated that life time and current cigarette smoking was 9.5% and 9.3% respectively. The reported rate of cigarette smoking in this study was almost consistent with study conducted among college students in North West Ethiopia where the life time and current prevalence were 13.1% and 8.1% respectively . Our findings were also in agreement with community based study conducted in Butajira town, among adolescents in Ethiopia and among undergraduate medical students of Addis Ababa University in Ethiopia , , . This finding was also consistent with a study conducted among undergraduate students in University of IIorion, Nigeria in which the current prevalence of smoking was 5.7% . However, the results of this study were lower than a studies conducted among adolescents in rural Zambia, among High school students in Harare, Zimbabwe and among college students in Eldoret, Western Kenya with prevalence of cigarette smoking 27%, 28.8% and 42.8% respectively [10, 22–24].
The mean age at which the respondents started khat chewing, alcohol drinking and cigarette smoking was 20.1 years ± 2.75 sd, 19.5 years ± 2.2 sd and 20.5 years ± 2.2 sd respectively, This finding was slightly higher than a study done among college students in North west Ethiopia in which the mean age for starting khat chewing and cigarette smoking was 17.3 and 18.2 years, respectively . The reported mean age for khat chewing was also significantly higher than study done in Eastern Ethiopia in which the mean age was 15.1 ± 2.33 years. This could be explained by the fact that the cultivation and consumption of khat is practiced widely in the Eastern Ethiopia and it is more a part of the culture than that of our study.
Our reported starting time for psychoactive substances use was almost consistent with study conducted in North West Ethiopia, where majority of the lifetime smokers 31.7 % and of the lifetime khat chewers 45.6 % started smoking and chewing while they were senior secondary school students followed by 1st year college . This indicates late high school and freshman university students are at higher risk for experimentation of psychoactive substances use.
A large proportion of the study participants were introduced for khat chewing 81.1%, alcohol drinking 77.8% and cigarette smoking 83.3% by their peer friends. This finding was supported by a study conducted among college students in Eldoret, Western Kenya where about 75.1% of the students were introduced by their peer friends .
Being male, Muslim in religion, Oromo Ethnic group and from urban back ground was significantly and positively associated with khat chewing within the last 12 months. This might be due to the fact that khat growing and the practice of chewing have traditionally been confined to some places where Muslim populations were found. Similarly, khat cultivation could be high in some areas of Oromia region and those students from urban origin might have greater access to khat than students from rural origin. This study is supported by a study conducted among high school students of Jazan region .
Ever alcohol use, cigarette use, family member chew khat, peer friends chew khat were strongly and positively associated with khat chewing within the last 12 months. These findings were consistent with study done among staff of Jimma University which showed that being male, Muslim and habit of alcohol and cigarette intake had significant association with khat chewing . Our reported findings were also supported by similar study done among students in Jimma University and Eastern Ethiopia where majority of khat users were male, Muslim and Oromo in ethnicity [13, 15].
Being male, belonging to Orthodox Christianity, Tigre in ethnicity, ever chewed khat, ever smoked cigarette, family member and peer friends alcohol use were independent predictors of alcohol drinking among the study subjects.
These findings were in line with similar study done among medical students in Addis Ababa University and in rapidly developing countries [4, 18].
With regard to cigarette smoking, there was a statistically significant difference in cigarette smoking between males and females, with males having a higher rate than females [AOR: 2.597, 95%CI: (1.17, 5.76)]. This finding was consistent with what has been found in other studies [4, 10, 12, 24]. Alcohol and khat use was strongly associated with cigarette smoking within the last 12 months. Similarly, having smoker friends has been strongly associated with cigarette smoking. The findings of this study were consistent with similar studies done in Zimbabwe, Zambia and Nigeria where smoking has been associated with gender, having friends that smoke and alcohol use [21, 23, 24].
This study had some limitations; first, the study used a descriptive cross-sectional design that cannot establish trends and causality between substances use and potential risk factors. Second, the data was collected based on self-report of the students and may be subjected to recall bias and under-reporting of substances use due to social desirability bias. Third, findings from this study may not be generalized to the whole young people, because the study involved only university students.