In south and south-east Asia, an estimated 54 lakh people use cannabis, 28 lakh opioid and another four lakh cocaine. According to World Health Organization, 250,000 deaths worldwide are due to illicit drug use compared with 2.25 million due to alcohol. Years of life lost due to drug use (2.1 million) were more than those recorded for alcohol (1.5 million), because drug deaths generally affect younger people, while alcohol deaths (and tobacco deaths) tend to affect middle-aged and senior citizens.
Opioids - heroin and morphine and their synthetic analogues like methadone and fentanyl have been shown to have all four types of health effects - have the highest risks of dependence affecting perhaps one in four of lifetime users and are major contributors to premature death due to overdoses as well as accident, suicide and violence, HIV/AIDS and hepatitis. They are major contributors to disability, through dependence and chronic infections. Illicit drugs for which non-medical use has been prohibited by international drug control treaties for half a century because they are believed to present unacceptable risks of addiction to users.
International control has since been extended from plant-based drugs - heroin, cocaine, and cannabis - to synthetic drugs, such as amphetamines and methylenedioxymetamfetamine (MDMA) and pharmaceutical drugs such as buprenorphine, methadone, and benzodiazepines. A systematic review of data for the prevalence of injecting drug use suggested that, worldwide, 11-21 million people injected drugs in 2007. Injecting drug use has been documented in 151 countries and its prevalence has been estimated in 61 National estimates varied from 0·02% of people aged 15-64 years in India and Cambodia, to typically 1%-2% in Mauritius, Russia, Malaysia. Russia, China, and the US accounted for more than 40% of the estimated population of injecting drug users (IDUs) worldwide. In 2009, UNODC estimated that there were 15-39 million problem drug users globally (IDUs or problem users of opioids and cocaine).
Professor Louisa Degenhardt, National Drug and Alcohol Research Centre, University of New South Wales, has conducted the study. Individual risk factors for drug abuse include being male, the personality traits of novelty and sensation seeking, conduct disorders in childhood, and poor school performance, low commitment to education and early school leaving.
Affiliating with antisocial and drug-using peers is one of the strongest predictors of adolescent alcohol and other drug use that operates independently of individual and family risk factors. Young people who initiate substance use at an early age are often exposed to many social and family disadvantages, come from families with problems and a history of parental substance use, are impulsive, have performed poorly at school, and are affiliated with delinquent peers.
"Young people with many of these risk factors start alcohol, tobacco, and illicit drug use at an early age," the authors said.
The study says cannabis use is associated with dependence and mental disorders, including psychoses, but does not seem to substantially increase mortality. Illicit opioid use is a major cause of mortality from fatal overdose and dependence. HIV, Hepatitis C, and Hepatitis B infections from unsafe injection practices are important consequences in people who inject opioids, cocaine, or amphetamines.