Stimulant Use and Comorbidity in Australia

Aussies and Uppers

Stimulants may cause serious physical and mental health problems, more often in regular or dependent users than in those who use less frequently. In Australia the 12-month prevalence of stimulant use disorders (abuse or dependence) is estimated to be around 0.6%, a rate comparable to the prevalence of dependent heroin use at the height of Australia’s heroin ‘epidemic’ in the late 1990s. For this study, stimulant drug use fell into five categories: (i) Amphetamine/Speed, (ii) Methamphetamine/Base/Ice, (iii) Ecstasy, (iv) Cocaine and (v) Any stimulant (any of i – iv). For each of these drug types, respondents were asked whether they had ever used, their age at first use and whether they had used more than five times in their lifetime. People who reported using any stimulant more than five times in their lifetime were asked whether they had done so in the last twelve months.

Most descriptions of stimulant use disorders are based on treated or convenience samples such as injecting drug users or high-risk populations, rather than the general populace. These studies find that stimulant use disorders are associated with very significant comorbidity: dependent stimulant users are often dependent on other drugs, and have high rates of depression, anxiety, psychotic symptoms, suicidal ideation and suicide attempts. They also found that individuals with stimulant use disorders are significantly disabled or marginalised, with fewer years of education and significantly increased rates of unemployment, homelessness, criminal activity and imprisonment compared with those without stimulant use disorders.

Surveys from the US, UK, Canada, Australia and New Zealand find that stimulant use is more common in men, peaks in the 20s, and is usually preceded by the use of other drugs, particularly cannabis. Australia’s National Drug Strategy Household Survey (NDSHS) found that stimulant use is usually infrequent; only 36% of those who had used any stimulant in the preceding year had done so monthly or more often.

Nearly half (46%) of people who have used stimulants on more than five occasions met criteria for a lifetime stimulant use disorder. For an individual, the vulnerability to develop abuse or dependence is likely to reflect a mix of genetic, psychological and environmental factors along with drug-related factors. To our knowledge, no study has compared the personal, family and social correlates of persons with stimulant use disorders against those of stimulant users who do not have features of abuse or dependence. However, we do know that Australians with substance use disorders seek help less often than people with other mental disorders, and rates of help seeking are lowest in younger adults and males, who are the group most likely to have stimulant use disorders.

Compared to Australians without stimulant use disorder, people with stimulant use disorders were younger, more likely to be male, of non-heterosexual orientation and born in Australia, but were not more socially disadvantaged. Lifetime comorbidity rates were high: 79% of persons with stimulant use disorders had a lifetime alcohol use disorder, 73% a lifetime cannabis use disorder, and more than one third a lifetime mood or anxiety disorder. Stimulant use disorders were associated with a family history of substance use, affective disorders and psychosis. There was an approximately twofold higher risk of stimulant dependence in those with a family history of alcohol and drug problems, depression or anxiety. One in five people with lifetime stimulant use disorders had been imprisoned, homeless or hospitalised for substance or mental health problems, and 13% reported at least one symptom of psychosis. Persons with a lifetime history of stimulant use disorder reported significant psychosocial harms, with one third reporting suicidal ideation and nearly half of these reporting a suicide attempt. Persons with stimulant disorders had increased rates of family history of schizophrenia or bipolar disorder compared to those without stimulant disorders. Thirteen percent reported one or more psychotic experiences on the NSMHWB psychosis screener, almost five times the rate of those without stimulant disordersNearly half had sought help for substance or mental health problems, primarily from General Practitioners (GPs), psychologists or psychiatrists. There were no significant associations between lifetime stimulant use disorders and education, household measures of income or disadvantage, or urban/rural location. Stimulant use disorders were more common in those who reported a non-heterosexual orientation and less common in persons born outside Australia.

Reference: Sara, et al. (2012). Characteristics and comorbidity in an Australian population sample, 2012. Australian & New Zealand Journal of Psychiatry, 46 (12). Pages 1173– 1181.