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Biomedical subjects

W Hall

Publications and source records attributed to W Hall.

At least 37 records · Page 2Linked to original sources
PubMed2000

Cannabis use and psychosis: a review of clinical and epidemiological evidence.

OBJECTIVE: This paper evaluates evidence for two hypotheses about the relationship between cannabis use and psychosis: (i) that heavy cannabis use causes a 'cannabis psychosis', i.e. a psychotic disorder that would not have occurred in the absence of cannabis use and which can be recognised by its pattern of symptoms and their relationship to cannabis use; and (ii) that cannabis use may precipitate schizophrenia, or exacerbate its symptoms. METHOD: Literature relevant to drug use and schizophrenia is reviewed. RESULTS: There is limited clinical evidence for the first hypothesis. If 'cannabis psychoses' exist, they seem to be rare, because they require very high doses of tetrahydrocannabinol, the prolonged use of highly potent forms of cannabis, or a preexisting (but as yet unspecified) vulnerability, or both. There is more support for the second hypothesis in that a large prospective study has shown a linear relationship between the frequency with which cannabis had been used by age 18 and the risk over the subsequent 15 years of receiving a diagnosis of schizophrenia. CONCLUSIONS: It is still unclear whether this means that cannabis use precipitates schizophrenia, whether cannabis use is a form of 'self-medication', or whether the association is due to the use of other drugs, such as amphetamines, which heavy cannabis users are more likely to use. There is better clinical and epidemiological evidence that cannabis use can exacerbate the symptoms of schizophrenia.

Adolescent↗
PubMed2000

Australia's mental health: an overview of the general population survey.

OBJECTIVES: The objectives of this study were to estimate the 1-month and 1-year prevalence of mental disorders in the Australian adult population; to determine the amount of disablement associated with this; and to determine the use of health and other services by persons with common mental disorders. METHOD: For the Adult Survey, a household sample of 10600 persons aged 18 years and over were interviewed across Australia by experienced field staff of the Australian Bureau of Statistics. This was 78% of the target sample. The interview consisted of the composite international diagnostic interview in its automated presentation (CIDI-A) and other components to determine disablement, use of services and satisfaction with services received. The diagnostic classifications used in the analyses were both ICD-10 and DSM-IV. Only the results from ICD-10 are reported here. RESULTS: A total of 17.7% of the sample had one or more common mental disorders, anxiety, depression, alcohol or substance abuse and neurasthenia. This morbidity was associated with considerable disablement in daily life: 3 days of impaired social role performance in the previous 4 weeks, compared with 1 day for the general population. Of all cases, 64.6% had had no contact with health services in the previous year; 29.4% had seen GPs and 7.5% had seen psychiatrists. CONCLUSION: Australia now has its own national estimates of psychiatric morbidity. The morbidity is associated with considerable disablement, but most of it is untreated. General practitioners encounter by far the largest proportion of those reaching services.

Adolescent↗
PubMed2000

Alcohol- and drug-use disorders in Australia: implications of the National Survey of Mental Health and Wellbeing.

OBJECTIVE: This study reports the prevalence and correlates of ICD-10 alcohol- and drug-use disorders in the National Survey of Mental Health and Wellbeing (NSMHWB) and discusses their implications for treatment. METHOD: The NSMHWB was a nationally representative household survey of 10641 Australian adults that assessed participants for symptoms of the most prevalent ICD-10 and DSM-IV mental disorders, including alcohol- and drug-use disorders. RESULTS: In the past 12 months 6.5% of Australian adults met criteria for an ICD-10 alcohol-use disorder and 2.2% had another ICD-10 drug-use disorder. Men were at higher risk than women of developing alcohol- and drug-use disorders and the prevalence of both disorders decreased with increasing age. There were high rates of comorbidity between alcohol- and other drug-use disorders and mental disorders and low rates of treatment seeking. CONCLUSIONS: Alcohol-use disorders are a major mental health and public health issue in Australia. Drug-use disorders are less common than alcohol-use disorders, but still affect a substantial minority of Australian adults. Treatment seeking among persons with alcohol- and other drug-use disorders is low. A range of public health strategies (including improved specialist treatment services) are needed to reduce the prevalence of these disorders.

Adolescent↗
PubMed2000

Cohort trends in youth suicide in Australia 1964-1997.

OBJECTIVE: This paper examines trends in the rate of suicide among young Australians aged 15-24 years from 1964 to 1997 and presents an age-period-cohort analysis of these trends. METHOD: Study design consisted of an age-period-cohort analysis of suicide mortality in Australian youth aged between 15 and 24 for the years 1964-1997 inclusive. Data sources were Australian Bureau of Statistics data on: numbers of deaths due to suicide by gender and age at death; and population at risk in each of eight birth cohorts (1940-1944, 1945-1949, 1950-1954, 1955-1959, 1960-1964, 1965-1969, 1970-1974, and 1975-1979). Main outcome measures were population rates of deaths among males and females in each birth cohort attributed to suicide in each year 1964-1997. RESULTS: The rate of suicide deaths among Australian males aged 15-24 years increased from 8.7 per 100,000 in 1964 to 30.9 per 100,000 in 1997, with the rate among females changing little over the period, from 5.2 per 100,000 in 1964 to 7.1 per 100,000 in 1997. While the rate of deaths attributed to suicide increased over the birth cohorts, analyses revealed that these increases were largely due to period effects, with suicide twice as likely among those aged 15-24 years in 1985-1997 than between 1964 and 1969. CONCLUSIONS: The rate of youth suicide in Australia has increased since 1964, particularly among males. This increase can largely be attributed to period effects rather than to a cohort effect and has been paralleled by an increased rate of youth suicides internationally and by an increase in other psychosocial problems including psychiatric illness, criminal offending and substance use disorders.

Adolescent↗
PubMed2000

The THC content of cannabis in Australia: evidence and implications.

OBJECTIVE: To examine evidence on three claims that: 1) the THC content of Australian cannabis plants has increased up to 30 times; 2) problems experienced by cannabis users have increased in Australia in recent years; and 3) an increase in THC content is the most likely explanation of any increase in cannabis-related problems. METHODS: These claims were assessed by examining data: 1) on THC potency in Australia, the United States and New Zealand; 2) on cannabis-related problems; and 3) from the 1998 National Drug Strategy Household Survey on patterns of cannabis use. RESULTS: 1) Published data do not show a 30-fold increase in THC potency of cannabis but show a more modest increase in the US. 2) There is suggestive evidence of an increase in cannabis-related problems among people seeking treatment for alcohol and drug problems, juvenile offenders and young adults with psychosis. 3) There are two other more plausible explanations for these reportedly higher rates of cannabis-related problems among adolescents and young adults: (i) more potent forms of cannabis ('heads') are more widely used; and (ii) cannabis users are initiating cannabis at an earlier age, thereby increasing the prevalence of harmful patterns of use. CONCLUSIONS: There has probably been a modest increase in the THC content of cannabis, but changing patterns of cannabis use have probably made a larger contribution to any increase in rates of cannabis-related problems among young Australian adults. IMPLICATIONS: Better data on the THC content of cannabis, the extent of cannabis-related problems and the ability of users to titrate the dose of cannabis would contribute to more informed debate.

Adolescent↗
PubMed2000

Impact of increasing the re-supply interval on the seasonality of subsidised prescription use in Australia.

OBJECTIVE: To evaluate the impact of increasing the minimum re-supply period for prescriptions on the Pharmaceutical Benefits Scheme (PBS) in November 1994. The intervention was designed to reduce the stockpiling of medicines used for chronic medical conditions under the PBS safety net. METHODS: Interrupted times series regression analyses were performed on 114 months of PBS drug utilisation data from January 1991 to June 2000. These analyses assessed whether there had been a significant interaction between the onset of the intervention in November 1994 and the extreme levels of drug utilisation in the months of December (peak utilisation) and January (lowest utilisation) respectively. Both serial and 12-month lag autocorrelations were controlled for. RESULTS: The onset of the intervention was associated with a significant reduction in the December peak in drug utilisation; after the introduction of the policy there were 1,150,196 fewer prescriptions on average for that month (95% CI 708,333-1,592,059). There was, however, no significant change in the low level of utilisation in January. The effect of the policy appears to be decreasing across successive post-intervention years, though the odds of a prescription being dispensed in December remained significantly lower in 1999 compared to each of the pre-intervention years (11% vs. 14%). CONCLUSION: Analysis of the impact of increasing the re-supply period for PBS prescriptions showed that the magnitude of peak utilisation in December had been markedly reduced by the policy, though this effect appears to be decreasing over time. Continued monitoring and policy review is warranted in order to ensure that the initial effect of the intervention be maintained.

Australia↗
PubMed2000

Cohort trends in the age of initiation of drug use in Australia.

AIM: To examine birth cohort trends in the prevalence of use and the age of initiation of use of: alcohol, tobacco, cannabis, amphetamines, LSD, and heroin. METHOD: Data were taken from the 1998 National Drug Strategy Household Survey, a survey of a representative sample of Australians aged 14 years and over. Nine five-year cohorts were examined among persons born between 1940 and 1984. The weighted prevalence of use by ages 15 years, 21 years, and lifetime use, was estimated, as was the average age of first use among users. The significance of trends was tested using logistic regression (for lifetime use, use by 15 and 21 years) and linear regression (for age of first use). RESULTS: Lifetime prevalence of alcohol and tobacco use was similar among all birth cohorts. The prevalence of illicit drug use--cannabis, amphetamines, LSD and heroin--increased with successive birth cohorts and more recent birth cohorts reported using licit and illicit drugs at a younger age. CONCLUSIONS: More recent cohorts are more likely to use illicit drugs at some point in their lives. Greater numbers of persons from more recent birth cohorts may be at risk of developing substance-related problems.

Adolescent↗
PubMed2000

Differences in the ability of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 tax to inhibit p53 function.

We have analyzed the functional activity of the p53 tumor suppressor in human T-cell lymphotropic virus type 2 (HTLV-2)-transformed cells. Abundant levels of the p53 protein were detected in both HTLV-2A and -2B virus-infected cell lines. The p53 was functionally inactive, however, both in transient-transfection assays using a p53 reporter plasmid and in induction of p53-responsive genes in response to gamma irradiation. We further investigated HTLV-2A Tax and HTLV-2B Tax effects on p53 activity. Interestingly, although Tax-2A and -2B inactivate p53, the Tax-2A protein appears to inhibit p53 function less efficiently than either Tax-1 or Tax-2B. In transient-cotransfection assays, Tax-1 and Tax-2B inactivated p53 by 80%, while Tax2A reduced p53 activity by 20%. In addition, Tax-2A does not increase the steady-state level of cellular p53 as well as Tax-1 or -2B does in the same assays. Cotransfection assays demonstrated that Tax-2A could efficiently transactivate CREB-responsive promoters to the same level as Tax-1 and Tax-2B, indicating that the protein was functional. This report provides evidence of the first functional difference between the HTLV-2A and -2B subtypes. This comparison of the action of HTLV-1 and HTLV-2 Tax proteins on p53 function will provide important insights into the mechanism of HTLV transformation.

Cell Line, Transformed↗
PubMed1999

Assessment of physician performance in Alberta: the physician achievement review.

The College of Physicians and Surgeons of Alberta, in collaboration with the Universities of Calgary and Alberta, has developed a program to routinely assess the performance of physicians, intended primarily for quality improvement in medical practice. The Physician Achievement Review (PAR) provides a multidimensional view of performance through structured feedback to physicians. The program will also provide a new mechanism for identifying physicians for whom more detailed assessment of practice performance or medical competence may be needed. Questionnaires were created to assess an array of performance attributes, and then appropriate assessors were designated--the physician himself or herself (self-evaluation), patients, medical peers, consultants and referring physicians, and non-physician coworkers. A pilot study with 308 physician volunteers was used to evaluate the psychometric and statistical properties of the questionnaires and to develop operating policies. The pilot surveys showed good statistical validity and technical reliability of the PAR questionnaires. For only 28 (9.1%) of the physicians were the PAR results more than one standard deviation from the peer group means for 3 or more of the 5 major domains of assessment (self, patients, peers, consultants and coworkers). In post-survey feedback, two-thirds of the physicians indicated that they were considering or had implemented changes to their medical practice on the basis of their PAR data. The estimated operating cost of the PAR program is approximately $200 per physician. In February 1999, on the basis of the operating experience and the results of the pilot survey, the College of Physicians and Surgeons of Alberta implemented this innovative program, in which all Alberta physicians will be required to participate every 5 years.

Alberta↗
PubMed1999

Fluctuations in heroin purity and the incidence of fatal heroin overdose.

In order to determine the role played by heroin purity in fatal heroin overdoses, time series analyses were conducted on the purity of street heroin seizures in south western Sydney and overdose fatalities in that region. A total of 322 heroin samples were analysed in fortnightly periods between February 1993 to January 1995. A total of 61 overdose deaths occurred in the region in the study period. Cross correlation plots revealed a significant correlation of 0.57 at time lag zero between mean purity of heroin samples per fortnight and number of overdose fatalities. Similarly, there was a significant correlation of 0.50 at time lag zero between the highest heroin purity per fortnight and number of overdose fatalities. The correlation between range of heroin purity and number of deaths per fortnight was 0.40. A simultaneous multiple regression on scores adjusted for first order correlation indicated both the mean level of heroin purity and the range of heroin purity were independent predictors of the number of deaths per fortnight. The results indicate that the occurrence of overdose fatalities was moderately associated with both the average heroin purity and the range of heroin purity over the study period.

Adolescent↗
PubMed1999

Role of maintenance treatment in opioid dependence.

Methadone maintenance treatment (MMT) involves the daily administration of the oral opioid agonist methadone as a treatment for opioid dependence-a persistent disorder with a substantial risk of premature death. MMT improves health and reduces illicit heroin use, infectious-disease transmission, and overdose death. However, its effectiveness is compromised if low maintenance doses of methadone (<60 mg) are used and patients are pressured to become prematurely abstinent from methadone. Pregnancy and psychiatric comorbidity are not contraindications for MMT. As an alternative to MMT, other oral opioid agents (eg, naltrexone, buprenorphine) may increase patient choice and avoid some of the more unpleasant aspects of MMT. The public-health challenge for the future is to develop and continue to deliver safe and effective forms of opioid maintenance treatment to as many opioid-dependent individuals as can benefit from them.

Humans↗
PubMed1999

Role of cytomegalovirus in the T cell changes seen in elderly individuals.

The effect of prior cytomegalovirus (CMV) infection on the immune system was evaluated in young and elderly volunteers. Prevalence of IgG antibodies to CMV was higher in the elderly volunteers. In both age groups, there was a strong association with CMV seropositivity and increased number of CD28- CD4 or CD8 T cells, as well as with increased numbers of T cells expressing CD56 or DR. Although these changes have previously been reported to be age-related, they were independent of age when CMV serological status was taken into account. In contrast, both age group and CMV status were important determinants of the total number of T cells, the number of CD8 T cells, and the number of CD8 T cells expressing CD45RA or CD28. These findings indicate that prior infection with CMV, as reflected by CMV serological status, has important effects on T cell subsets and surface markers and must be considered whenever evaluating age-related changes in immunological parameters.

Adult↗
PubMed1999

Prevalence of illicit drug use among youth: results from the Australian School Students' Alcohol and Drugs Survey.

OBJECTIVE: To estimate the prevalence of illicit drug use among Australian secondary school students. METHOD: Data was collected as part of the Australian School Student's Alcohol and Drugs Survey, a national survey of 29,447 secondary school students. RESULTS: Of all students aged 12-17 years, 39.9% (44.1% of males and 35.9% of females) reported having used at least one illicit drug in their lifetime. Cannabis was the most widely used illicit drug with 36.4% of all students reporting having used cannabis. Substantially fewer students reported using other drugs: hallucinogens (8.6%), amphetamines (6.1%), cocaine (3.6%), ecstasy (3.6%), opiates (3.7%) and steroids (1.8%). There were clear gender and age differences in the prevalence of illicit drug use: more males than females reported illicit drug use and the lifetime prevalence of illicit drug use increased with age. Most of those who reported illicit drug use had used drugs on relatively few occasions although there was a small minority of the sample who reported more frequent use. Finally, there were strong association between regular cannabis use and the use of other illicit drugs in the past year, and moderate associations between illicit drug use and the extent of both tobacco and alcohol use. CONCLUSIONS: The findings of this, the first national survey of illicit drug use among Australian school students, indicate a high prevalence of illicit drug use. Comparisons with previous regionally based surveys suggest there may have been a recent increase in the prevalence of cannabis use and highlight the need for further monitoring of and prevention efforts aimed at reducing illicit drug use among students.

Adolescent↗
PubMed1999

The 12-month prevalence of substance use and ICD-10 substance use disorders in Australian adults: findings from the National Survey of Mental Health and Well-Being.

AIMS: To present the prevalence of substance use and ICD-10 substance use disorders in the adult Australian population using data from the National Survey of Mental Health and Well-Being (NSMHWB). DESIGN: A cross-sectional survey assessing substance use and ICD substance use disorders (harmful use and dependence). SETTING AND PARTICIPANTS: A household survey of a nationally representative sample of 10,641 Australian adults (aged 18 years or older). MEASUREMENTS: Trained survey interviewers administered a structured interview based on the Composite International Diagnostic Interview (CIDI). FINDINGS: In the past 12 months 6.5% of the sample had an ICD-10 alcohol use disorder (95% CI: 6.2, 6.9), and 2.2% had another drug use disorder (95% CI: 2.0, 2.4). More males than females had substance use disorders: 9.5% of males (95% CI: 8.5, 10.5) and 3.6% of females (95% CI: 3.2, 4.0) met criteria for an alcohol use disorder, and 3.2% of males (95% CI: 2.8, 3.6) and 1.3% of females (95% CI: 0.9, 1.7) met criteria for another drug use disorder within the past 12 months. The prevalence of substance use disorders decreased with increasing age: 10.5% of respondents aged 18-34 years met criteria for an alcohol use disorder and 4.8% met criteria for a drug use disorder. The rates of these disorders among those aged 55 years or older were 1.8% and 0.1%, respectively. Substance use disorders were more prevalent among the unemployed, those who had never married and those who were Australian-born. CONCLUSIONS: The prevalence of substance use disorders in the Australian population is comparable to that in other English-speaking countries.

Adult↗
PubMed1998

Adverse effects of cannabis.

Cannabis is the most widely used illicit drug in many developed societies. Its health and psychological effects are not well understood and remain the subject of much debate, with opinions on its risks polarised along the lines of proponents' views on what its legal status should be. An unfortunate consequence of this polarisation of opinion has been the absence of any consensus on what health information the medical profession should give to patients who are users or potential users of cannabis. There is conflicting evidence about many of the effects of cannabis use, so we summarise the evidence on the most probable adverse health and psychological consequences of acute and chronic use. This uncertainty, however, should not prevent medical practitioners from advising patients about the most likely ill-effects of their cannabis use. Here we make some suggestions about the advice doctors can give to patients who use, or are contemplating the use, of this drug.

Adolescent↗
PubMed1998

Trends in opiate overdose deaths in Australia 1979-1995.

AIMS: To determine if there had been an increase in the rate of opioid overdose deaths between 1979 and 1995, and to describe the characteristics of persons who died of an opioid overdose. METHOD: Opioid overdose deaths were defined according to ICD-9 as deaths due to drug dependence (codes 304.0 and 304.7) and accidental opiate poisoning (code E850.0). Data were obtained from a national register of deaths compiled by the Australian Bureau of Statistics on: age at death, sex and jurisdiction of all such deaths between 1979 and 1995 inclusive. Mortality rates were calculated for each sex for the 15-24, 25-34 and 35-44 age groups. RESULTS: The number of opioid overdose deaths rose from 70 in 1979 to 550 in 1995. The rate (per million of the population aged 15-44) increased from 10.7 to 67.0. The increase was more marked among males than females, increasing 6.8 times among males (from 15.3 in 1979 to 104.6 in 1995) and 4.7 times among females (from 5.9 in 1979 to 27.9 in 1995). New South Wales consistently accounted for around a half of all male overdose fatalities and its overdose mortality rate was almost twice that in Victoria, and three times that in the remaining states. The average age at death for males increased from 24.5 years in 1979 to 30.6 years in 1995. The increase in overdose mortality was greatest among men and women aged 35 to 44 years, and 25 and 34 years. An analysis by birth cohort showed that 46% of male overdose deaths and 50% of female overdose deaths in the period occurred among those born between 1960 and 1969. Deaths among persons born between 1950 and 1959 accounted for 38% of male and 33% of female deaths. CONCLUSIONS: There has been a statistically significant increase in opioid overdose mortality between 1979 and 1995, most of it occurring among persons who initiated heroin use in the late 1970s and early 1980s. Recent initiations of heroin use among those born between 1970 and 1979 have begun to be reflected in an increased rate of opioid overdose deaths. If their mortality experience replicates that of earlier birth cohorts then opioid overdose mortality will continue to increase.

Adolescent↗