Professor Alison Yung, Associate Professor Dan Lubman, Dr Elizabeth Cosgrave, Dr Kathryn Baker
Orygen Youth Health Research Centre
Beyond Blue Victorian Centre of Excellence
Project completion year
This project investigated the influence of sub-threshold depressive symptoms in combination with early onset substance use on the subsequent development of mental health problems in young people.
The study followed up a 2005 survey of 881 Year 10 students from secondary schools in Melbourne. At that time, information was collected about the participants’ mental health and substance use. In this baseline data set, early alcohol use and smoking were significantly associated with illicit drug use, suicidal ideation and poor academic performance. Early alcohol use was significantly associated with high levels of depressive symptoms.
The present study followed up 521 of the original survey participants approximately three and a half years after the baseline assessment. Participants were assessed for depressive symptoms, suicidality, and use of cigarettes, alcohol and other drugs. They were also rated for levels of psychosocial functioning, mood, anxiety and psychiatric disturbance. The aim was to determine whether a combination of sub-threshold depressive symptoms and early substance use can predict mood and anxiety disorders and poor psychosocial functioning longitudinally in secondary school students.
The study found that at the baseline assessment, 81 of the 521 participants (15.5 per cent) met the criteria to be considered “at risk”; that is, they had a combination of depressive symptoms and early and/or current alcohol or tobacco use. Five participants were excluded due to missing data, leaving 435 (83.5 per cent) who did not meet the at-risk criteria.
At follow-up, the Global Assessment Scale (GAS) was used (among other measures) to rate levels of psychosocial functioning. There was a significant difference in scores with the at-risk group demonstrating lower levels of functioning.
There was also a significant difference in subjective depressive symptoms, with the at-risk group reporting a higher level of subjective depressive symptoms (measured using CES-D) than the not-at-risk.
As hypothesised, the at-risk group had significantly worse functioning at follow-up, with significantly higher levels of depressive symptoms and rates of mood and anxiety disorders, compared to the not-at-risk group.
Implications for policy, practice and further research
The combined effect of depression and alcohol/tobacco use should be highlighted as a risk factor for poor functioning, depression and anxiety in the future. The results from this study have broad implications including:
- Early intervention: teenagers with mild depressive symptoms and substance use could be identified through schools. In conjunction with schools, early treatment could attempt to prevent later poor outcomes. For example, teenagers could be directed towards reducing use of substances, managing depression and enhancing coping skills.
- Universal prevention in schools: the study highlighted the need for community awareness campaigns about the harm caused by tobacco and alcohol and the need to seek help for depression. It also underscored the need to better integrate drug and alcohol services with mental health services.
- Clinical practice in mental health services: young people presenting with depressive symptoms and substance abuse need to be directed towards treatment programs.