Substance use and educational attainment.
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Achievement↗
Biomedical subjects
Michael Lynskey
Publications and source records attributed to Michael Lynskey.
One year outcomes for heroin dependence: findings from the Australian Treatment Outcome Study (ATOS).
AIM: To determine 1 year outcomes for drug use, criminality, psychopathology and injection-related health problems in those entering treatment for heroin dependence in Australia. DESIGN: Longitudinal prospective cohort study. PARTICIPANTS: Seven hundred and forty five individuals entering treatment (methadone/buprenorphine maintenance therapy; detoxification; residential rehabilitation) and 80 heroin users not seeking treatment. SETTING: Sydney, Melbourne and Adelaide, Australia. FINDINGS: A total of 657 individuals were re-interviewed at 1 year, 80% of the original sample. There were substantial reductions in heroin and other drug use across all three treatment modalities. The majority of those who had entered treatment were heroin abstinent at 1 year (maintenance therapy 65%, detoxification 52%, residential rehabilitation 63%) compared to 25% of the non-treatment sample. The reduction in heroin use among the treatment samples was paralleled by reductions in poly drug use. There were also substantial reductions in risk-taking, crime and injection-related health problems across all treatment groups, and less marked reductions among the non-treatment group. Psychopathology was dramatically reduced among the treatment modalities, while remaining stable among the non-treatment group. Positive outcomes at 1 year were associated with a greater number of cumulative treatment days experienced over the 1 year follow-up period ('treatment dose') and fewer treatment episodes undertaken in that time ('treatment stability'). CONCLUSIONS: At 1 year, there were impressive reductions in drug use, criminality, psychopathology and injection-related health problems following treatment exposure. The positive findings were associated with a greater "dose" of treatment, and with more treatment stability over the follow-up period.
Adolescent↗
Substance use, dependence and treatment seeking in the United States and Australia: a cross-national comparison.
AIMS: To compare the prevalence of alcohol and drug use, dependence and treatment seeking in the United States of America and Australia. DESIGN: Two cross-sectional national surveys assessing substance use and DSM-IV substance dependence in the USA and Australia. SETTING AND PARTICIPANTS: Age-matched cohorts (18-54 years old) were selected from nationally representative Australian (National Survey of Mental Health and Well-being, 1997, n=7570) and American (National Comorbidity Survey, 1992, n=7423) household surveys. MEASUREMENTS: Both studies utilised a structured interview based on the Composite International Diagnostic Interview (CIDI). FINDINGS: The 12-months prevalence of alcohol use was substantially higher in Australia (77.2%) than in the U.S. (46.3%) and the rates of alcohol dependence were also higher in Australia, although rates of alcohol dependence conditional on use were similar (6.8 and 6.5%, respectively). In contrast, although rates of use of drugs were similar in the two countries, rates of drug dependence and the probability of dependence conditional on use were higher in Australia than in the U.S. Importantly, the absence of significant interactions between correlates of alcohol and drug use disorders and country indicated that the influence of these factors was consistent across the two countries. CONCLUSIONS: Despite relatively similar cultural influences in Australia and the U.S. interesting cross-national differences emerged in the use of alcohol and drug dependence among those who used drugs and treatment seeking among people diagnosed with dependence. The cross-national generalizability of the associations between common correlates and rates of alcohol and drug use and dependence indicates that similar process of vulnerability to dependence may be operating in the two countries. Future research could usefully exploit these cross-national differences to help elucidate the cultural and structural factors influencing drug use, the development of dependence and treatment seeking.
Adolescent↗
Depression among entrants to treatment for heroin dependence in the Australian Treatment Outcome Study (ATOS): prevalence, correlates and treatment seeking.
AIM: To determine the rate of current major depressive disorder (MDD) among entrants to treatment for heroin dependence in three treatment modalities and a non-treatment comparison group; and to ascertain factors associated with depression. DESIGN: Cross sectional structured interview. SETTING: Sydney, Australia. PARTICIPANTS: 615 current heroin users: 201 entering methadone/buprenorphine maintenance (MT), 201 entering detoxification (DTX), 133 entering drug free residential rehabilitation (RR) and 80 not in treatment (NT). FINDINGS: Current major depressive episode was reported by 25%. The rates of major depressive disorder ranged from 26% in the treatment groups (23% MT, 25% DTX, 31% RR) to 16% of those not in treatment. Females were more likely to have current major depressive episode (31% versus 21% OR 1.70, 95% CI 1.16-2.48). Factors associated with depression in the treatment groups were post traumatic stress disorder (PTSD), attempted suicide in the last 12 months and severe physical disability. Among the non-treatment group those with depression were also more likely to have PTSD. Women entering treatment were three times more likely to meet criteria for current major depression than women not in treatment. Among men however, the rates were not significantly different. CONCLUSION: Depression is a significant concern among entrants to treatment for heroin dependence. An essential component of treatment should be a consideration of depression, with the provision of appropriate treatment were required.
Adult↗
Post-traumatic stress disorder among people with heroin dependence in the Australian treatment outcome study (ATOS): prevalence and correlates.
This study documents the prevalence and correlates of post-traumatic stress disorder (PTSD) among Australian individuals with heroin dependence. Data was obtained from a cohort of 615 people dependent on heroin, 535 entering treatment for their heroin dependence and 80 individuals not in treatment. Trauma exposure (92%) and lifetime PTSD (41%) were highly prevalent. PTSD was prevalent across all treatment modalities, most commonly residential rehabilitation (52%) followed by maintenance therapies (42%), and detoxification (37%). The lowest prevalence was reported among those not in treatment (30%). Although men and women were equally likely to have experienced trauma (93% vs. 89%), women were more likely to develop lifetime PTSD (61% vs. 37%). For the large majority of those with PTSD, the condition was chronic (84%), with symptoms continuing for an average of 9.5 years. Those with PTSD had more extensive polydrug use histories, poorer general physical and mental health, and more extensive health service utilisation. It is concluded that PTSD is highly prevalent among individuals with heroin dependence, presenting a significant challenge to treatment providers.
Adolescent↗
Factors associated with 12 months continuous heroin abstinence: findings from the Australian Treatment Outcome Study (ATOS).
AIMS: To determine the role of treatment and client characteristics associated with the achievement of continuous heroin abstinence. DESIGN: Longitudinal cohort study. SETTING: Sydney and Adelaide, Australia. PARTICIPANTS: 570 heroin users re-interviewed at 12 month follow-up for the Australian Treatment Outcome Study (ATOS). FINDINGS: Continuous heroin abstinence was reported by 14% of participants. Continuous abstinence was associated with no previous treatment history, having entered treatment at baseline, and cumulative treatment exposure over the follow-up period. Longer retention times in index maintenance and residential rehabilitation treatments, but not detoxifications, were most associated with abstinence. At baseline, abstinent participants were more likely to have been classified as treatment ready, or to have used heroin less frequently; and less likely to have been daily injectors, using cocaine or criminally involved. CONCLUSIONS: Approximately 14% of ATOS participants achieved continuous heroin abstinence over 12 months. Such an achievement was strongly associated with a longer "dose" of treatment, and with more treatment stability over the follow-up period.
Adolescent↗
Is cannabis a gateway drug? Testing hypotheses about the relationship between cannabis use and the use of other illicit drugs.
We outline and evaluate competing explanations of three relationships that have consistently been found between cannabis use and the use of other illicit drugs, namely, (1) that cannabis use typically precedes the use of other illicit drugs; and that (2) the earlier cannabis is used, and (3) the more regularly it is used, the more likely a young person is to use other illicit drugs. We consider three major competing explanations of these patterns: (1) that the relationship is due to the fact that there is a shared illicit market for cannabis and other drugs which makes it more likely that other illicit drugs will be used if cannabis is used; (2) that they are explained by the characteristics of those who use cannabis; and (3) that they reflect a causal relationship in which the pharmacological effects of cannabis on brain function increase the likelihood of using other illicit drugs. These explanations are evaluated in the light of evidence from longitudinal epidemiological studies, simulation studies, discordant twin studies and animal studies. The available evidence indicates that the association reflects in part but is not wholly explained by: (1) the selective recruitment to heavy cannabis use of persons with pre-existing traits (that may be in part genetic) that predispose to the use of a variety of different drugs; (2) the affiliation of cannabis users with drug using peers in settings that provide more opportunities to use other illicit drugs at an earlier age; (3) supported by socialisation into an illicit drug subculture with favourable attitudes towards the use of other illicit drugs. Animal studies have raised the possibility that regular cannabis use may have pharmacological effects on brain function that increase the likelihood of using other drugs. We conclude with suggestions for the type of research studies that will enable a decision to be made about the relative contributions that social context, individual characteristics, and drug effects make to the relationship between cannabis use and the use of other drugs.
Adolescent↗
The characteristics of heroin users entering treatment: findings from the Australian treatment outcome study (ATOS).
The current study aimed to describe the characteristics (demographics, drug use, mental and physical health) of entrants to treatment for heroin dependence in three treatment modalities; and to compare these characteristics with heroin users not in or seeking treatment. Participants were 825 current heroin users recruited from Sydney, Adelaide and Melbourne: 277 entering methadone/buprenorphine maintenance treatment (MT), 288 entering detoxification (DTX), 180 entering drug-free residential rehabilitation (RR) and 80 not in treatment (NT). Treatment entrants were generally long-term heroin users with previous treatment experience. The majority of the sample (55%) were criminally active in the month preceding interview. Injection-related health problems (74%) and a history of heroin overdose (58%) were commonly reported. There were high degrees of psychiatric co-morbidity, with 49% reporting severe psychological distress, 28% having current major depression, 37% having attempted suicide and 42% having a lifetime history of post-traumatic stress disorder. Personality disorders were also prevalent, with 72% meeting criteria for antisocial personality disorder and 47% screening positive for borderline personality disorder. Striking similarities were noted between the non-treatment and treatment groups in length of heroin use career, drug use and treatment histories.
Adult↗
Reverse gateways? Frequent cannabis use as a predictor of tobacco initiation and nicotine dependence.
AIMS: To examine the risk posed by cannabis use in young people for tobacco use disorders. Specifically we examined whether cannabis use in non-smokers predicted later initiation of tobacco use and whether cannabis use predicted later nicotine dependence in tobacco users. DESIGN: A 10-year eight-wave cohort study. SETTING: State of Victoria, Australia. PARTICIPANTS: A community sample of 1943 participants initially aged 14-15 years. MEASUREMENTS: Self-report of tobacco and cannabis use was assessed in the teens using a computerized interview assessment and in young adulthood with a CATI assessment. The Fagerström Test for Nicotine Dependence was used to define nicotine dependence. FINDINGS: For teen non-smokers, at least one report of weekly cannabis use in the teens predicted a more than eightfold increase in the odds of later initiation of tobacco use (OR 8.3; 95% CI 1.9-36). For 21-year-old smokers, not yet nicotine-dependent, daily cannabis use raised the odds of nicotine dependence at the age of 24 years more than threefold (OR 3.6, 1.2, 10) after controlling for possible confounders, including level of tobacco use and subsyndromal signs of nicotine dependence. CONCLUSIONS: Weekly or more cannabis use during the teens and young adulthood is associated with an increased risk of late initiation of tobacco use and progression to nicotine dependence. If this effect is causal, it may be that a heightened risk of nicotine dependence is the most important health consequence of early frequent cannabis use.
Adolescent↗
Borderline personality disorder, antisocial personality disorder and risk-taking among heroin users: findings from the Australian Treatment Outcome Study (ATOS).
AIM: To determine the relationship between borderline personality disorder (BPD), antisocial personality disorder (ASPD) and harm among current heroin users. DESIGN: Cross-sectional survey. SETTING: Sydney, Australia. PARTICIPANTS: 615 current heroin users. FINDINGS: Forty-six percent met criteria for BPD, 71% for ASPD, and 38% met criteria for both diagnoses. ASPD was related to attempted suicide, lifetime overdose, polydrug use, depression and overall psychological distress. BPD was also related to each of these risk domains, and to needle risk and recent suicide as well. When analysed separately, both BPD and ASPD thus appeared to predict harm. For the purposes of further analysis, the relationships between BPD, ASPD and harm, the sample was divided into four independent diagnostic groups: no diagnosis (ND, 21%), ASPD only (ASPD, 33%), BPD only (BPD, 7%), ASPD plus BPD (DUAL, 38%). The division of the sample into four distinct diagnostic groups produced substantially different results. There were strong relationships between BPD and attempted suicide, needle sharing and psychopathology. In none of these domains did the ASPD group significantly differ from the ND group. Also, the levels of harm among the DUAL group were identical to BPD, suggesting no additive risk from ASPD. Thus, while initial analyses suggested an increased risk for ASPD patients for suicide and psychopathology, these relationships disappeared after BPD was taken into account. The only domain in which there appeared to be an additive risk for ASPD and BPD was heroin overdose. CONCLUSIONS: The extensive comorbidity between BPD and ASPD means that, unless BPD is controlled for, artefactual relationships may emerge between ASPD and harm.
Adolescent↗
Attempted suicide among entrants to three treatment modalities for heroin dependence in the Australian Treatment Outcome Study (ATOS): prevalence and risk factors.
AIMS: To determine the lifetime and recent histories of attempted suicide among entrants to treatment for heroin dependence in three treatment modalities and a non-treatment comparison group; and to ascertain factors associated with a recent history of attempted suicide. DESIGN: Cross-sectional structured interview. SETTING: Sydney, Australia. PARTICIPANTS: Six hundred and fifteen current heroin users: 201 entering methadone/buprenorphine maintenance (MT), 201 entering detoxification (DTX), 133 entering drug free residential rehabilitation (RR) and 80 not in treatment (NT). FINDINGS: A lifetime history of attempted suicide was reported by 34% of subjects, 13% had attempted suicide in the preceding year and 5% had done so in the preceding month. Females were more likely to have lifetime (44% versus 28%) and 12 month (21% versus 9%) suicide attempt histories. The 12 month prevalence of attempted suicide among treatment groups ranged between 11% (MT, NT) and 17% (RR). Factors associated with recent suicide attempts were: being an RR entrant, female gender, younger age, less education, more extensive polydrug use, benzodiazepine use, recent heroin overdose, Major Depression, current suicidal ideation, Borderline Personality Disorder (BPD)and Post-Traumatic Stress Disorder. CONCLUSIONS: Recent suicidal behaviour is a major clinical problem for heroin users, and for females and RR entrants in particular. An essential adjunct to treatment for heroin dependence is routine screening for depression and suicidal ideation, with the provision of appropriate treatment where needed.
Adolescent↗
Young people with heroin dependence: findings from the Australian Treatment Outcome Study (ATOS).
This paper examines the patterns and correlates of heroin use in a cohort of 210 young Australians aged between 18 and 24, who were participants in the Australian Treatment Outcome Study, a longitudinal study of treatment outcomes for heroin dependence. Of major importance were the high rates of psychiatric comorbidity found among this group (37% lifetime Post Traumatic Stress Disorder, 23% current Major Depression, 75% Anti-Social Personality Disorder, and 51% Borderline Personality Disorder). Seventeen percent had attempted suicide in the preceding year. Although both the young (aged 18-24 years) heroin users and their older counterparts (aged 25-56 years) initiated drug use at the same age, young heroin users progressed to heroin use, regular heroin use, and treatment for heroin use, twice as quickly as older heroin users. These findings suggest that there is a limited window of opportunity in which early interventions may be applied before young heroin users progress to problematic use.
Adolescent↗
Non-injecting routes of administration among entrants to three treatment modalities for heroin dependence.
A sample of 535 entrants to opioid dependence treatments across three treatment modalities were administered a structured interview to ascertain the prevalence of non-injecting heroin use. Ten per cent of participants had used heroin primarily by smoking/inhaling in the month preceding interview, and 9% had used heroin and other drugs exclusively by non-injecting routes. Non-injectors were younger (25.3 vs. 29.5 years), had higher levels of education (10.6 vs. 10.0 years), were more likely to be employed (33 vs. 18%) and had lower levels of recent crime (31 vs. 56%). They also had shorter heroin using careers (5.1 vs. 9.9 years), fewer symptoms of dependence (5.1 vs. 5.6), had been enrolled in fewer previous treatment episodes (3.3 vs. 11.5) and had less extensive lifetime (8.0 vs. 9.1 drug classes) and recent (3.6 vs. 4.9) polydrug use. Non-injectors were substantially less likely to report lifetime (13% vs. 58%) or recent (2% vs. 29%) heroin overdoses. There were no differences between the general physical and psychological health of the two groups. While non-injectors had a lower level of post-traumatic stress disorder (29% vs. 34%), there were no differences in levels of major depression, attempted suicide, antisocial personality disorder, or borderline personality disorder. A substantial minority of Australian treatment entrants are now using heroin exclusively by non-injecting routes. While this group is younger, and has substantially reduced risk of overdose and blood borne virus transmission, the physical and psychological health of non-injectors mirrors that of injectors.
Administration, Inhalation↗
Testing hypotheses about the relationship between cannabis use and psychosis.
AIM: To model the impact of rising rates of cannabis use on the incidence and prevalence of psychosis under four hypotheses about the relationship between cannabis use and psychosis. METHODS: The study modelled the effects on the prevalence of schizophrenia over the lifespan of cannabis in eight birth cohorts: 1940-1944, 1945-1949, 1950-1954, 1955-1959, 1960-1964, 1965-1969, 1970-1974, 1975-1979. It derived predictions as to the number of cases of schizophrenia that would be observed in these birth cohorts, given the following four hypotheses: (1) that there is a causal relationship between cannabis use and schizophrenia; (2) that cannabis use precipitates schizophrenia in vulnerable persons; (3) that cannabis use exacerbates schizophrenia; and (4) that persons with schizophrenia are more liable to become regular cannabis users. RESULTS: There was a steep rise in the prevalence of cannabis use in Australia over the past 30 years and a corresponding decrease in the age of initiation of cannabis use. There was no evidence of a significant increase in the incidence of schizophrenia over the past 30 years. Data on trends the age of onset of schizophrenia did not show a clear pattern. Cannabis use among persons with schizophrenia has consistently been found to be more common than in the general population. CONCLUSIONS: Cannabis use does not appear to be causally related to the incidence of schizophrenia, but its use may precipitate disorders in persons who are vulnerable to developing psychosis and worsen the course of the disorder among those who have already developed it.
Adult↗
Health service utilization and benzodiazepine use among heroin users: findings from the Australian Treatment Outcome Study (ATOS).
AIMS: To determine levels of health service utilization among heroin users, the types of prescription drugs obtained by heroin users and the contribution of benzodiazepine use in health service utilization and prescribed drug use. DESIGN: Cross-sectional survey. SETTING: Sydney, Australia. PARTICIPANTS: A total of 615 current heroin users recruited for the Australian Treatment Outcome Study (ATOS). FINDINGS: Sixty per cent of subjects had consulted a general practitioner (GP) and 7% a specialist in the preceding month. An ambulance had attended 11% of subjects in the preceding month. Forty-eight per cent of subjects had prescriptions dispensed for medication in the preceding month. Thirty-nine per cent of participants had prescriptions dispensed for psychotropic medications, representing 80% of all prescriptions. Twenty per cent of subjects had prescriptions dispensed for non-psychotropic medications (20% of prescriptions). The most commonly prescribed drugs were benzodiazepines (59% of prescriptions), which had been obtained by 30% of subjects. Benzodiazepine users had more GP and psychiatrist visits, were more likely to have had an ambulance attendance and had significantly more dispensed prescriptions. CONCLUSIONS: There were high levels of health utilization among heroin users. Prescription drug use was common, and dominated by psychotropic drugs. Benzodiazepine use was a dominant factor in the use of services and in prescriptions dispensed. Despite increased awareness of the harms associated with benzodiazepines, they continue to be prescribed widely to heroin users.
Adolescent↗
Exploring the association between cannabis use and depression.
AIM: To examine the evidence on the association between cannabis and depression and evaluate competing explanations of the association. METHODS: A search of Medline, Psychinfo and EMBASE databases was conducted. All references in which the terms 'cannabis', 'marijuana' or 'cannabinoid', and in which the words 'depression/depressive disorder/depressed', 'mood', 'mood disorder' or 'dysthymia' were collected. Only research studies were reviewed. Case reports are not discussed. RESULTS: There was a modest association between heavy or problematic cannabis use and depression in cohort studies and well-designed cross-sectional studies in the general population. Little evidence was found for an association between depression and infrequent cannabis use. A number of studies found a modest association between early-onset, regular cannabis use and later depression, which persisted after controlling for potential confounding variables. There was little evidence of an increased risk of later cannabis use among people with depression and hence little support for the self-medication hypothesis. There have been a limited number of studies that have controlled for potential confounding variables in the association between heavy cannabis use and depression. These have found that the risk is much reduced by statistical control but a modest relationship remains. CONCLUSIONS: Heavy cannabis use and depression are associated and evidence from longitudinal studies suggests that heavy cannabis use may increase depressive symptoms among some users. It is still too early, however, to rule out the hypothesis that the association is due to common social, family and contextual factors that increase risks of both heavy cannabis use and depression. Longitudinal studies and studies of twins discordant for heavy cannabis use and depression are needed to rule out common causes. If the relationship is causal, then on current patterns of cannabis use in the most developed societies cannabis use makes, at most, a modest contribution to the population prevalence of depression.
Adolescent↗
The relationship of conduct disorder to attempted suicide and drug use history among methadone maintenance patients.
In order to examine the effects of a diagnosis of childhood conduct disorder (CD) on history of attempted suicide and drug use, unconfounded by early onset heroin use, 181 methadone maintenance patients who commenced heroin use after the age of 15 were interviewed. CD was diagnosed in 54% of patients. Compared to other patients, CD patients were younger and less educated. The onset of drug use, injecting drug use and heroin use occurred, on average, 2 years earlier than in other patients, and they had broader histories of injecting polydrug use. CD patients were more likely to have attempted suicide and to have been hospitalized after an attempt, and to have attempted suicide while enrolled in their current treatment. The current study indicates that a history of CD increases the risk of attempted suicide over and above the higher risks associated with injecting drug use per se.
Adolescent↗
Adolescent precursors of cannabis dependence: findings from the Victorian Adolescent Health Cohort Study.
BACKGROUND: Dependence increases the likelihood of adverse consequences of cannabis use, but its aetiology is poorly understood. AIMS: To examine adolescent precursors of young-adult cannabis dependence. METHOD: Putative risk factors were measured in a representative sample (n=2032) of secondary students in the State of Victoria, Australia, six times between 1992 and 1995. Cannabis dependence was assessed in 1998, at age 20-21 years. RESULTS: Of 1601 young adults, 115 met criteria for cannabis dependence. Male gender (OR=2.6, P < 0.01), regular cannabis use (weekly: OR=4.9; daily: OR=4.6, P=0.02), persistent antisocial behaviour (linear effect P=0.03) and persistent cigarette smoking (linear effect P=0.02) independently predicted cannabis dependence. Neither smoking severity (P=0.83) nor persistent psychiatric morbidity (linear effect P=0.26) independently predicted dependence. Regular cannabis use increased risk only in the absence of persistent problematic alcohol use. CONCLUSIONS: Weekly cannabis use marks a threshold for increased risk of later dependence, with selection of cannabis in preference to alcohol possibly indicating an early addiction process.
Adolescent↗