Globally, it is estimated that in 2012, some 243 million people corresponding to about 5.2% of the world population aged 15-64 had used an illicit drug at least once in the previous year (United Nations Office on Drugs and Crime (UNODC), 2014). Although the extent of illicit drug use among men and women varies from country to country and in terms of the substances used, generally, men are two to three times more likely than women to have used an illicit substance (World Health Organisation: WHO, 1994). While there are varying regional trends in the extent of illicit drug use, overall global prevalence of drug use is considered to be stable. Similarly, the extent of problem drug use, by regular drug users and those with drug use disorders or dependence, also remains stable, at about 27 million people (UNODC, 2014).
Reliable and comprehensive information on the drug situation in Africa is not available. The limited data available suggests, however, that substance use, especially cannabis use is of about 12.4%. In West and Central Africa this percentage is probably higher than the global average of 3.8% (UNODC, 2014). In Nigeria, the expert perception is that there has been a significant increase in the use of cannabis(UNODC, 2012). According to the national survey on alcohol and drug use in Nigeria, conducted in 2009 (Neuropsychiatric Hospital (NPH) 2012), aside from alcohol, the non-medical use of tranquillizers had the highest annual prevalence (5.5%) among the population aged 15-64 years. The misuse of prescription opioids was also reported to be high and more prevalent than the use of heroin (3-6% annual prevalence of other opioids, and 2.2% annual prevalence of heroin). High levels of use of other substances were also reported, with annual prevalence as follows: cannabis, 2.6%; amphetamine, 1%: methamphetamine, 1.6%; “ecstasy”, 1 .7%; cocaine, 1 .6%; and crack, 2%.
Substance abuse is a major public health concern globally due to its association with reduced quality of life as well as substance-related morbidity and mortality. Substance use disorders take heavy toll on the patient in terms of personal suffering, to the families as a result of the burden of care and life-time lost productivity, and on the society at large. According to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), substance-related death is the most extreme form of harm that can result from substance use/abuse (EMCDDA, 2009). The United Nations Office on Drugs and Crime (UNODC) estimates that there were 183,000 drug-related deaths in 2012, corresponding to a mortality rate of 40.0 deaths per million persons aged 15-64.