The present study showed kola nut, alcohol, tranquillizers, tobacco and cannabis as the substances used by the adolescents studied. These findings, agreed with the findings of previous studies in Ilorin Nigeria [25, 26]. None of the respondents in the present study admitted having used amphetamines, cocaine, heroin, hallucinogens, opiates, barbiturates or volatile agents. This is in keeping with earlier reports where it was found that the use of these agents are not yet common among adolescents in Nigeria, though, some few cases have been reported [25, 26].

The present study showed that the prevalence of current use for the substances ranges from 0.4 to 34.9 % while that for lifetime use ranges from 0.8 to 63.5 %. The least being cannabis and the most being kola nuts. The value is lower than those of previous studies. For instance, results from 2010, in the United States, showed that 48.2 % of adolescents reported having used psychoactive substances at some point in their lives [27, 28]. Some methodological differences have been identified as affecting these prevalence rates. This includes populations covered, sampling methods, and mode of data collection, survey setting, questionnaire, and estimation methods [28, 29].

Kola nut emerged the most commonly used psychoactive substance in this study both in the respondents’ life time and the month preceding the study. This is because adolescents use kola nut to achieve long hours of wakefulness during examinations.

Alcohol in the present survey is the second most commonly used psychoactive substance. Earlier reports by Akpala and colleagues 1991 in Nigeria have also shown alcohol to be the second most used psychoactive substance [30]. It is pertinent to note that alcohol is widely available in Nigeria and easily accessible to various age groups. Alcohol did not show a similar trend as the other substances that showed a decline as the respondents moved from primary school to secondary school.

The fact that there is a positive correlation between respondents’ alcohol use and use by the parents as shown in this study is also supported by Cleveland et al. [31]. We noted that age and socio economic class of subjects have significant relationship to the respondents’ lifetime and current use of alcohol. It was noted that some mechanism could explain this variations of socioeconomic class, age and substance abuse. For instance, increased risk of alcohol use and related psychosocial problems with greater household income may reflect greater availability in such households or greater ‘purchasing power’ among children from such households. There may also be cultural norms to explain different alcohol behaviors across the socio-economic spectrum [32, 33].

When multivariate logistic regression was used, we noted that age and socio economic class of subjects have significant relationship to the respondents’ lifetime and current use of alcohol, thus, supporting the result of earlier study [31].

Religious participation also shows a positive correlation with respondents’ intake of alcohol. A study conducted in Ireland, suggested that university students who attended religious services infrequently and university students who did not believe in God reported using more alcohol [34]. Similarly, another study in Australia found that students who believed that religion was unimportant in their lives reported using more alcohol, tobacco, marijuana and hallucinogens.

Dalgalarrondo et al. [35]. Furthermore, a study conducted in a university in the United States, showed that the use of ecstasy was higher among students who stated that religion had little influence on their lives [34].

In Brazil, few studies have focused on the relationship between religious involvement and substance use. The majority of the available studies have found that religiosity is protective against substance use in samples of Brazilian adolescents and a few studies have focused on this relationship among university students [34, 36].

Tobacco, the third psychoactive substance mostly used by the students showed a similar prevalence with that recorded in Kano (In northern Nigeria) by the NDLEA [25]. Tobacco in the form of snuff (powdered form) is enjoyed by most parents. Only few of the respondents reported use of snuff because tobacco use in the form of snuff is not fashionable among the adolescents. The adolescents who admitted using them in this study were only those whose parents use it and who only experimented with it in their homes.

In the Southern parts of the country, people frown at smoking by adolescents hence the low prevalence for both lifetime and current uses obtained in this study. It is noteworthy that result of the present study on cigarette smoking is lower than those obtained in Mexico, England and South Africa [37]. In Mexico and England, cigarette smoking is socially accepted while the high prevalence obtained in the black township of South Africa could be explained by the stress in the then apartheid South Africa which made the black boys to smoke. We also noted in this study that smaller percentage of the respondents smoked before the age of 10 years. This reflects mainly family influence, both parental and sibling.

Tranquillizers are the fifth most commonly used psychoactive substance. The current use prevalence is almost in agreement with NDLEA’s 3.5 % [25]. It is also important to note that students use tranquillizers such as diazepam to induce sleep after using stimulants to keep awake. Furthermore, we did not obtain any statistically significant difference between male and female involvement in the use of tranquillizers as against the work of Emerita et al. who showed female preponderance in the use of tranquillizers [37]. The reason for this could be due to the small sample size used by Emerita. Racial and socio-cultural differences could also explain these gender differences. Today, the commonest psychoactive substance that is found in most home medicine stores is tranquillizers. This is not unconnected with the level of stress in the society. The fact that some of the respondents used tranquillizers before 10 years of age and in primary school shows the influence of the family in introducing their children to the use of this substance.

Cannabis is the least substance used. The current prevalence almost agreed with Adelekan’ s 0.5 % but differs from the high values obtained in Sokoto, Kano and Lagos (North and south west Nigeria) [25]. The low value obtained in this study may be due to under-reporting because not only that the use of cannabis is associated with psychosis and criminal activities, but that the society frowns at its use. The law in Nigeria also prohibits both the use and sales of cannabis. Though the abuse of cannabis is low, it is gradually increasing over the years [38]. Moreover, we noted that only male respondents admitted using cannabis and that all of them started the habit in secondary school. The fact that none of the female respondents admitted using cannabis in this study contradicts the reports of Faeh et al. who found an increasing female involvement in the use of cannabis [38]. It is also noted in this study that while the use of the other substances except alcohol declined as the ages of the respondents increased that of cannabis increased as their ages increased. This implies that most of the respondents give up some of their psychoactive substance use habits as they mature whereas those of them who use cannabis had their number increased instead of declining probably because they started the habit late and are yet to give it up.

Boarding schools tend to enroll a high concentration of high risk or problem prone youths who create risk-taking peer networks [39]. It is noted that many of the adolescents who enroll in these schools have experienced considerable family chaos, violence, stress, and severe disruption in the formative years of their lives. Barrera et el 2001 [39] in India pointed out that boarding students who are exposed to such substances are usually not monitored by their parents at home and for some who do, are away from home for long periods.

In all, our study showed that none of the respondents is a problem drinker, majority of them drink about half a beer bottle of alcohol daily. In the same vein, none of the respondents is a heavy smoker, majority of them smoke one stick of cigarette a day. This study however, showed that a fraction of the respondents have tried to stop or reduce the use of these substances but were unable to do so. These are the respondents who have developed dependence on these drugs. About half of the respondents were initiated into psychoactive substance use by their friends, while father and mother accounted for a third and a fifth respectively. The value does not differ significantly from the 40 % obtained by NDLEA [24]. The fact that none of the respondents answered the question on the fictitious psychoactive substance showed that over-reporting is not a problem in the present study.