A substance can be anything that is ingested in order to produce a high, alter one's senses, or otherwise affect mood, perception and consciousness. There are nine separate classes of drugs identified in the DSM-5 (1) that can involved in a substance use disorder: alcohol; cannabis; hallucinogens; inhalants; opioids; sedatives, hypnotics, and anxiolytics; stimulants (amphetamine-type substances, cocaine, and other stimulants); tobacco; and other (or unknown) substances.
Substance use can be common in young people, and individuals have different patterns of use (bingeing, occasional or continual) and reasons for use (for example as an 'experiment', for 'fun' or to 'escape', to 'join in' with peers, or to get through a certain situation- such as the desire to stay awake).
Where use is prolonged, heavy, or creating social or personal problems, it may meet a diagnosis for a substance use disorder. See Assessment section for diagnostic criteria.
Onset, prevalence, and burden of substance use disorders in young people
Substance use is common among young people, and alcohol is the most common substance used by youth. A survey of Australian secondary students aged between 12 and 17 years, found that 74% had tried alcohol, 15% had used cannabis, and 17% had used inhalants at some time in their lives (2).
Substance use disorders are among the most common of mental health disorders experienced by young people. In Australia, 12.7% of people aged 16-24 are estimated to have a substance use disorder, with higher rates among young men than young women (around 16% of males and 10% of females) (3). Harmful use of alcohol was the most commonly reported substance use disorder (at around 9%).
Studies have consistently demonstrated that the prevalence of substance use and abuse increases with age during adolescence and peaks in early adulthood. Overall, about half of people with substance use disorders first experience substance use issues by the age of 20 years (4).
Despite the high prevalence, people with substance use disorders often don't recognise or seek help for the problem. They also may not be screened for substance use when they seek treatment for other health conditions, which means that substance use disorders are often under-recognised and undertreated. An Australia survey found that despite disproportionately high rates of substance use disorders in young people, there was a very low rate of help-seeking associated with these, particularly in young men (5).
In those aged 10-24 years, alcohol use is the fourth leading contributor to the burden of disease in males (6). The burden from substance abuse is more than three times as high in males as in females (7).
A number of adverse outcomes have been associated with excessive substance use (8-11). They include the following:
- In the short-term, excessive alcohol consumption increases the risk of physical injury from falls, violence and road accidents
- Long-term harms include liver and cardiovascular disease, cancers, obesity, as well as increased risk of mental illness
- Young drinkers have also been found to be particularly at risk of memory loss, violence, and unwanted sexual activity, as a result of alcohol use
- Substance use (cannabis use in particular has been researched in a number of studies) poses a risk for delayed social and academic development, and may also impact on brain development among adolescents
There is a close relationship between substance use disorders and other mental disorders, and use of some substances may increase the risk of developing certain disorders (12). However it is often unclear whether one issue causes the other. An Australian survey found high rates of comorbidity in those with substance use disorders (13). 1 in 5 Australians with a substance use disorder also met criteria for an affective disorder and 1 in 3 met criteria for an anxiety disorder.
A number of factors can increase the likelihood that a young person will develop a substance use disorder (14-16). They include the following:
Related to the individual: