Biomedical subjects

L J Horwood

Publications and source records attributed to L J Horwood.

At least 19 recordsLinked to original sources

PubMed2006

Firearms legislation and reductions in firearm-related suicide deaths in New Zealand.

OBJECTIVE: To examine the impact of introducing more restrictive firearms legislation (Amendment to the Arms Act, 1992) in New Zealand on suicides involving firearms. METHOD: National suicide data were examined for 8 years before, and 10 years following the introduction of the legislation. RESULTS: After legislation, the mean annual rate of firearm-related suicides decreased by 46% for the total population (p < 0.0001), 66% for youth (15-24 years; p < 0.0001) and 39% for adults (> or = 25 years; p < 0.01). The fraction of all suicides accounted for by firearm-related suicides also reduced for all three populations (p < 0.0001). However, the introduction of firearms legislation was not associated with reductions in overall rates of suicide for all three populations. CONCLUSIONS: Following the introduction of legislation restricting ownership and access to firearms, firearm-related suicides significantly decreased, particularly among youth. Overall rates of youth suicide also decreased over this time but it is not possible to determine the extent to which this was accounted for by changes in firearms legislation or other causes.

Adolescent↗

PubMed2003

Arrests and convictions for cannabis related offences in a New Zealand birth cohort.

AIMS: To examine the associations between the use of cannabis and arrest/conviction for cannabis related offences. METHODS: Data on cannabis use and arrests/convictions for cannabis related offences were gathered during the course of a 21-year longitudinal study of a birth cohort of Christchurch (New Zealand) born children (N=983). Information on cannabis use, arrests and convictions was gathered over the period from 16 to 21 years. RESULTS: By the age of 21, over two thirds of the cohort had used cannabis on at least one occasion with 5% using cannabis on more than 400 occasions. Amongst cannabis users, 5.1% had been arrested for a cannabis related offence and 3.6% had been convicted of an offence. There was a strong association between the extent of cannabis use and risks of arrest/conviction: over a quarter of those using cannabis on more than 400 occasions had been arrested or convicted for a cannabis related offence compared with less than 1% of those using cannabis on fewer than ten occasions. Māori, those with a previous arrest record for non cannabis related offences and those reporting involvement in violent/property offending were more likely to be arrested or convicted than other cohort members having the same level of cannabis use; in addition, males were more likely to be convicted than females with the same level of cannabis use. Arrest/conviction for a cannabis related offence did not reduce the use of cannabis: of those arrested/convicted, 95% either increased their use or continued with the same level of cannabis use subsequent to their arrest. CONCLUSIONS: The results of this study reinforce concerns about laws relating to the use and possession of cannabis. The findings show that the law was administered in an inefficient way, the application of the law was biased, and the law was ineffective in reducing cannabis use.

Adolescent↗

PubMed2003

Cannabis dependence and psychotic symptoms in young people.

BACKGROUND: The aims of this research were to use data gathered over the course of a 21 year longitudinal study to examine the linkages between cannabis dependence at ages 18 and 21 and rates of psychotic symptoms taking into account previous symptom levels and other confounding factors. METHOD: Data were gathered during the course of the Christchurch Health and Development Study (CHDS). The CHDS is a longitudinal study of a birth cohort of 1,265 children who have been studied from birth to age 21. As part of this study, data were gathered on cannabis dependence and psychotic symptoms at ages 18 and 21. RESULTS: Young people meeting DSM-IV criteria for cannabis dependence had elevated rates of psychotic symptoms at ages 18 (rate ratio = 3.7; 95% CI 2.8-5.0; P < 0.0001) and 21 (rate ratio = 2.3; 95% CI 1.7-3.2; P < 0.0001). These associations were adjusted for previous psychotic symptoms and a range of other confounding factors using a generalized estimating equation model. This analysis showed that after adjustment for confounding factors, those meeting criteria for cannabis dependence still had an increased rate of psychotic symptoms (rate ratio = 1.8; 95 % CI 1.2-2.6; P < 0.005). CONCLUSIONS: The results show that the development of cannabis dependence is associated with increased rates of psychotic symptoms in young people even when pre-existing symptoms and other background factors are taken into account.

Adolescent↗

PubMed2003

Vulnerability and resiliency to suicidal behaviours in young people.

BACKGROUND: We aimed to examine factors that influence vulnerability/resiliency of depressed young people to suicidal ideation and suicide attempt. METHOD: Data were gathered during a 21-year longitudinal study of a birth cohort of 1,265 New Zealand young people. Measures included: suicide attempt; suicidal ideation; major depression; childhood, family, individual and peer factors. RESULTS: Young people who developed major depression had increased rates of suicidal ideation (OR = 54: 95% CI 4.5-6.6) and suicide attempt (OR = 12.1; 95% CI 7.9-18.5). However, the majority of depressed young people did not develop suicidal ideation or make suicide attempts, suggesting that additional factors influence vulnerability or resiliency to suicidal responses. Factors influencing resiliency/vulnerability to suicidal responses included: family history of suicide; childhood sexual abuse; neuroticism; novelty seeking; self-esteem; peer affiliations; and school achievement. These factors operated in the same way to influence vulnerability/resiliency among those depressed and those not depressed. CONCLUSIONS: Vulnerability/resiliency to suicidal responses among those depressed (and those not depressed) is influenced by an accumulation of factors including: family history of suicide, childhood sexual abuse, personality factors, peer affiliations and school success. Positive configurations of these factors confer increased resiliency, whereas negative configurations increase vulnerability.

Adolescent↗

PubMed2003

Neuroticism in adolescence and psychotic symptoms in adulthood.

BACKGROUND: The aims of this research were to examine the associations between the personality trait of neuroticism in adolescence and later psychotic symptoms, taking into account potential confounding factors. METHOD: Data were gathered over the course of a longitudinal study of a birth cohort of New Zealand born young people (N=1265). Over the course of the study, data were gathered on: (a) neuroticism at age 14; (b) psychotic symptoms predominantly subclinical, assessed on the Symptom Checklist (SCL-90), at ages 18 and 21; (c) a range of potential confounding factors including measures of childhood adversity and co-morbid mental disorders. RESULTS: Young people in the highest quartile of neuroticism at age 14 had rates of psychotic symptoms that were two to three times higher than those in the lowest quartile. After statistical adjustment for confounding factors, including childhood adversity and co-morbid mental disorders, the association between neuroticism and later psychotic symptoms reduced but remained statistically significant (P<0.05). After adjustment for confounding, young people with high levels of neuroticism had rates of psychotic symptoms that were between 1.5 to 1.8 times higher than those with low levels of neuroticism. CONCLUSIONS: Early neuroticism may be a precursor to the onset of psychotic symptoms. The mechanisms underlying this association are unclear, but may relate to overlapping features between prodromal phases of psychosis and items that measure neuroticism.

Adolescent↗

PubMed2003

Major depression and cigarette smoking: results of a 21-year longitudinal study.

BACKGROUND: The aim of this paper was to examine the association between major depression and cigarette smoking among young adults in a birth cohort before and after adjusting for confounding factors. METHOD: Data were gathered over the course of the Christchurch Health and Development Study (CHDS). The CHDS is a longitudinal study of a birth cohort of 1265 New Zealand children studied to age 21. Data were gathered by interview on: (a) major depression over the period 16-21 years; (h) daily smoking and nicotine dependence over the period from 16-21 years. In addition, the study included extensive information on social, family, and behavioural factors in childhood and adolescence. RESULTS: Young people meeting DSM-IV criteria for major depression had elevated rates of daily smoking and nicotine dependence. These associations were reduced substantially by control for potential confounding child and adolescent factors. Nonetheless, even after such control, major depression was associated with increased rates of daily smoking (IRR = 1.19; 95% CI = 1.03, 1.39) and elevated rates of nicotine dependence (OR = 1.75; 95% CI = 1.13, 2.70). CONCLUSIONS: The results suggest that much of the association between smoking and depression reflects common confounding factors that are associated with both outcomes. Nonetheless, even after control for these factors there is evidence of a possible causal linkage between smoking and depression. The direction of causality between smoking and depression remains unknown.

Adolescent↗

PubMed2002

Does sexual violence contribute to elevated rates of anxiety and depression in females?

BACKGROUND: It is well documented that females have higher rates of internalizing disorders (anxiety, depression) than males. It is also well known that females have higher exposure to childhood sexual abuse and sexual assault. Recently, it has been proposed that the higher levels of internalizing disorders in females may be caused by their greater exposure to sexual violence. METHOD: Data were gathered as part of the Christchurch Health and Development Study. In this study a cohort of 1265 children born in Christchurch, New Zealand, in 1977 have been studied from birth to age 21 years. The measures collected included: major depression and anxiety, childhood sexual abuse and adolescent sexual assault. RESULTS: Findings confirmed the established conclusion that internalizing disorders are over twice as common in females than males (ORs 2.2-2.7). In addition, it was found that females were exposed to higher rates of sexual violence than males (ORs 5.1-8.4). Statistical control for gender related differences in exposure to sexual violence reduced the associations between gender and anxiety and depression. Nonetheless, even after such control, gender was significantly (P < 0.0001) related to both anxiety (OR = 1.8; 95% CI, 1.3-2.4) and depression (OR = 1.9; 95% CI, 1.4-2.3). CONCLUSIONS: Greater female exposure to sexual violence may be a factor that contributes to greater female susceptibility to internalizing disorders. However, even after adjustment for gender differences in exposure to sexual violence it is clear that a substantial relationship between gender and internalizing disorder persists.

Adolescent↗

PubMed2002

Romantic relationships of young people with childhood and adolescent onset antisocial behavior problems.

Using prospective longitudinal data from the Christchurch Health and Development Study, this paper examines the extent to which early onset, life course persistent and adolescent limited antisocial behavior problems place young people at risk of violent and unsatisfactory romantic relationships in early adulthood. Results revealed the presence of clear linear associations between the developmental timing of antisocial behavior and later partnership risks, with these risks including partner violence perpetration and victimization, interpartner conflict, and increased ambivalence about the relationship. Young people with childhood onset antisocial behavior problems reported higher rates of partnership difficulties than young people with adolescent limited antisocial behavior problems, while those with adolescent limited antisocial behavior reported higher levels of partnership difficulties than young people without a history of antisocial behavior problems. These associations persisted even after extensive control for a range of social, family, and individual factors that were correlated with the timing of antisocial behavior. Results highlight the importance of distinguishing between early and late onset antisocial behavior, and provide further support for existing life course models of the development of antisocial behavior problems in children and adolescents.

Adolescent↗

PubMed2002

Posthaemorrhagic ventricular dilatation in the premature infant: natural history and predictors of outcome.

OBJECTIVE: To investigate the natural history and predictors of outcome of posthaemorrhagic ventriculomegaly in the very low birthweight (VLBW) infant. METHODS: All VLBW infants admitted between September 1994 and September 1997 to the neonatal intensive care units of Brigham and Women's Hospital (Boston), Children's Hospital (Boston), and Christchurch Women's Hospital (New Zealand) with germinal matrix intraventricular haemorrhage (IVH) were identified. All charts and ultrasound scans were reviewed to define the natural history and perinatal and/or postnatal factors of value in prediction of the course of posthaemorrhagic ventriculomegaly. Progressive ventricular dilatation (PVD) was defined from the results of serial cranial ultrasound scans. RESULTS: A total of 248 VLBW infants had evidence of IVH (22% of all VLBW infants, mean (SD) gestational age 26.8 (2.6) weeks). A quarter of the infants exhibited PVD. Spontaneous arrest of PVD occurred without treatment in 38% of infants with PVD. Of the remaining 62% with persistent PVD, 48% received non-surgical treatment only (pharmacological and/or drainage of cerebrospinal fluid by serial lumbar punctures), 34% received surgical treatment with insertion of a ventriculoperitoneal reservoir and/or shunt, and 18% died. The development of PVD after IVH and adverse short term outcome, such as the requirement for surgery, were predicted most strongly by the severity of IVH. CONCLUSIONS: These data reflect the natural history of PVD in the 1990s and show that, despite a slight reduction in its overall incidence, there appears to be a more aggressive course, with appreciable mortality and morbidity in the extremely premature infant. The major predictor of adverse short term outcome, defined as death or need for surgical intervention, was the severity of IVH. These findings may be valuable for the management of very small premature infants.

Boston↗

PubMed2002

Long term psychosocial outcomes after mild head injury in early childhood.

OBJECTIVES: The question of whether any adverse cognitive or psychosocial outcomes occur after mild head injury in early childhood has evoked considerable controversy. This study examined mild head injury before age 10 and potential differences in late childhood/early adolescence as a function of severity of mild injury and age at injury. METHODS: A fully prospective longitudinal design tracked a large birth cohort of children. Confirmed cases of mild head injury before age 10 were divided on the basis of outpatient medical attention (n=64-84) or inpatient observation (hospital overnight; n=26-28 ) and compared with the non-injured remainder of the cohort (reference group; n=613-807). A range of pre-injury and post-injury child and family characteristics were used to control for any potential confounds. Outcome after injury before and after age 5 was also assessed. RESULTS: After accounting for several demographic, family, and pre-injury characteristics, the inpatient but not the outpatient group displayed increased hyperactivity/inattention and conduct disorder between ages 10 to 13, as rated by both mothers and teachers. Psychosocial deficits were more prevalent in the inpatient subgroup injured before age 5. No clear effects were evident for various cognitive/academic measures, irrespective of severity of mild injury or age at injury. CONCLUSIONS: Most cases of mild head injury in young children do not produce any adverse effects, but long term problems in psychosocial function are possible in more severe cases, perhaps especially when this event occurs during the preschool years. The view that all mild head injuries in children are benign events requires revision and more objective measures are required to identify cases at risk.

Achievement↗

PubMed2001

Teenage pregnancy: cause for concern.

AIMS: To describe the lifetime prevalence of teenage pregnancy and parenthood, in addition to the psychosocial backgrounds and current circumstances of young parents in a sample of 533 young women studied from bith to 21 years. METHODS: The data were gathered as part of the Christchurch Health and Development Study. This study consists of a cohort of 1265 young people born in the Christchurch urban area during mid 1977 and who have been regularly assessed up to the age of 21 years. Information was collected on all pregnancies and births from ages 14-21 years. RESULTS: By age 21 years, 26% of the sample had been pregnant and 14% had become parents. Most pregnancies occurred between ages 17-21 years. Young women who became pregnant were characterised by higher rates of educational under-achievement, conduct problems, sexual risk taking, family adversity, and were more likely to identify themselves as Maori. Amongst those who became pregnant, there was a tendency for young women with a personal history of family adversity to proceed with their pregnancy and become young mothers. CONCLUSIONS: By age 21 years, at least a quarter of all young women studied had been pregnant at least once. The wide range of personal and social factors associated with teenage pregnancy and parenthood suggests that teenage pregnancy does not solely reflect the effects of problematic adolescent sexual practices. Implications for teen pregnancy prevention and the health and development of children born to younger mothers are discussed.

Adolescent↗

PubMed2001

Cannabis use and traffic accidents in a birth cohort of young adults.

OBJECTIVE: to examine linkages between cannabis use and traffic accident risks in a birth cohort of 907 young New Zealanders studied from 18 to 21 years. METHODS: during the course of a 21-year longitudinal study of a birth cohort of 907 New Zealand born children information was gathered on (a) annual frequency of cannabis use over the period from 18 to 21 years; (b) annual rates of traffic accidents during the period 18-21 years; (c) measures of driver behaviours and characteristics. The association between cannabis use and traffic accident risk was examined among the 907 sample members who reported driving a motor vehicle between the ages of 18 and 21 years. RESULTS: there were statistically significant relationships between reported annual cannabis use and annual accident rates. This association was present only for 'active' accidents in which driver behaviours contributed to the accident; those using cannabis more than 50 times per year had estimated rates of active accidents that were 1.6 (95% CI 1.2-2.0) times higher than the rate for non-users. However, statistical control for driver behaviours and characteristics related to cannabis use (drink driving behaviour; risky/illegal driving behaviours; driver attitudes; gender) eliminated the association between cannabis use and traffic accident risks. CONCLUSIONS: although cannabis use was associated with increased risks of traffic accidents among members of this birth cohort, these increased risks appear to reflect the characteristics of the young people who used cannabis rather than the effects of cannabis use on driver performance.

Accidents, Traffic↗

PubMed2001

Unemployment and psychosocial adjustment in young adults: causation or selection?

This study investigates the relationships between unemployment following school leaving and psychosocial adjustment problems (mental health, substance use, crime, suicidal behaviours and teenage pregnancy) in a birth cohort of over 1000 New Zealand born young people. The data were gathered during the course of the Christchurch Health and Development Study (CHDS). The CHDS is a longitudinal study of a birth cohort of 1265 children born in the Christchurch (NZ) urban region who have been studied from birth to age 21. Data were gathered by personal interview on: (a) exposure to unemployment and (b) personal adjustment over the period from age 16 to age 21. Measures of personal adjustment included mental health (depression, anxiety), substance use, crime, suicidal behaviours and (for females) teenage pregnancy. Data were analysed using a fixed effects regression model that took into account both observed and non-observed sources of confounding and the possibility of reverse causal associations between personal adjustment and unemployment. Before adjustment for confounding and reverse causality there were significant (p < 0.001) associations between exposure to unemployment and measures of mental health, substance use, crime, suicidal behaviours and teenage pregnancy. Adjustment for confounding factors and reverse causality reduced these associations quite substantially and after control for sources of confounding a number of associations became nonsignificant. Nonetheless, after such control, exposure to unemployment remained significantly (p < 0.05) associated with suicidal ideation, substance abuse and criminal behaviours. It is concluded that, in part, the associations between unemployment and personal adjustment are spurious and reflect the presence of confounding factors that are related to both unemployment and adjustment. Nonetheless, the findings suggest that exposure to unemployment may be associated with increased risks of suicidal thoughts, crime and substance use.

Adolescent↗

PubMed2001

The Christchurch Health and Development Study: review of findings on child and adolescent mental health.

OBJECTIVE: This paper provides an overview of the Christchurch Health and Development Study (CHDS) and a summary of findings relating to child and adolescent mental health. METHOD: The CHDS is a longitudinal study of a birth cohort of 1265 children born in the Christchurch (New Zealand) urban region during mid 1977. This cohort has now been studied from birth to age 21. RESULTS: The paper examines the ways in which the study has been able to examine a wide range of issues. Key issues examined include: (i) measurement of disorder (respondent effects; dimensionality; scales vs categories); (ii) prevalence and treatment of disorder; (iii) stability and continuity of disorders; (iv) the contribution of risk and aetiological factors (e.g. lead exposure, parental divorce, child abuse, family adversity, sexual orientation) to psychosocial adjustment; and (v) the psychosocial consequences of mental health problems in adolescence. CONCLUSIONS: The study findings illustrate the many advantages of a longitudinal study, such as the CHDS, in providing methodologically sound, theoretically relevant and cost effective research that caters for the interests of multiple end-users including the scientific community, clinicians and applied policy makers.

Adolescent↗

PubMed2001

Breast milk feeding and cognitive ability at 7-8 years.

OBJECTIVE: To examine the association between duration of breast milk feeding and cognitive ability at 7-8 years in a birth cohort of very low birthweight infants. DESIGN: 280 survivors from a national birth cohort of 413 New Zealand very low birthweight infants born in 1986 were assessed at age 7-8 years on measures of verbal and performance intelligence quotient (IQ) using the WISC-R. At the same time mothers were questioned as to whether they had elected to provide expressed breast milk at birth and the total duration of breast milk feeding. RESULTS: Some 73% of mothers provided expressed breast milk and 37% breast fed for four months or longer. Increasing duration of breast milk feeding was associated with increases in both verbal IQ (p < 0.001) and performance IQ (p < 0.05): children breast fed for eight months or longer had mean (SD) verbal IQ scores that were 10.2 (0.56) points higher and performance IQ scores that were 6.2 (0.35) points higher than children who did not receive breast milk. These differences were substantially reduced after control for selection factors associated with receipt of breast milk. Nevertheless, even after control for confounding, there remained a significant (p < 0.05) association between duration of breast milk feeding and verbal IQ: children breast fed for eight months or longer had adjusted mean (SD) verbal IQ scores that were 6 (0.36) points higher than the scores of those who did not receive breast milk. CONCLUSIONS: These findings add to a growing body of evidence to suggest that breast milk feeding may have small long term benefits for child cognitive development.

Analysis of Variance↗

PubMed2000

Cannabis use and dependence in a New Zealand birth cohort.

AIM: To describe the development of cannabis use in a birth cohort studied to the age of 21 years. METHODS: The data were gathered during the Christchurch Health and Development Study. In this study a cohort of 1265 children born in the Christchurch urban region in mid 1997 has been studied to the age of 21 years. Information was gathered on patterns of cannabis use and dependence during the period from fifteen to 21 years. RESULTS: By age 21 years, 69% of the cohort had used cannabis. The extent varied widely with 24% reporting use of cannabis on less than ten occasions while 5% reported use on over 400 occasions. Over 9% of the cohort met DSM-IV criteria for cannabis dependence by the age of 21 years. Cannabis use and dependence were higher in males and in Maori. Key predictors were gender and measures of adolescent risk taking behaviours including cigarette smoking, adolescent conduct problems, affiliations with delinquent peers and novelty seeking. CONCLUSIONS: Levels of cannabis use in this cohort reached a point where it was considered 'normal'. For the majority of users cannabis use did not lead to problems of dependence. Nonetheless, nearly 10% of the cohort showed clear symptoms of cannabis dependence by the age of 21 years, especially males who were prone to other forms of risk taking behaviours.

Adolescent↗

PubMed2000

Very low birthweight and asthma by age seven years in a national cohort.

Several studies have suggested that very low birthweight (VLBW < 1500 g) is associated with increased rates of respiratory problems in childhood and that the presence of chronic lung disease further increases the risk. We aimed to assess rates of asthma at 7-8 years of age in a national cohort of VLBW infants born in 1986 and for whom perinatal data were available. Two hundred ninety-nine former VLBW children (96% of surviving children living in New Zealand) were assessed at a home visit. Parents were asked a comprehensive questionnaire, including three questions aimed at assessing morbidity from asthma: 1) was the child diagnosed as having asthma before age 7 years; 2) was the child still experiencing asthma at the age of 7 years; and 3) was the child prescribed daily medication for asthma at the age of 7 years. Overall, 50% of the cohort had been diagnosed with asthma before age 7, compared with 27% of a sample of New Zealand children assessed contemporaneously in an international study; 32% had asthma at age 7, and 11% were taking daily medication. All three categories of asthma were associated with a family history of asthma, but there was no association with any perinatal factors. A diagnosis of asthma before age 7 was more likely when the mother smoked in pregnancy (P < 0.005) and currently smoked (P < 0.01), and trended so when parents lacked high school qualifications and in Maori or Pacific Island families (P < 0.10). In contrast, daily medication was more frequent when parents had educational qualifications and in non-Maori or Pacific Island families (P < 0.05). On multiple logistic regression, a family history of asthma was a significant predictor for any and current asthma (P < 0.001) and daily medication (P < 0.05); maternal smoking in pregnancy was a significant predictor for any asthma (P < 0.05); and non-Maori or Pacific Island ethnicity was a significant predictor for asthma treatment (P < 0.05). We conclude that rates of childhood asthma are high in this VLBW cohort, but the high prevalence appears to be unrelated to perinatal factors, including respiratory morbidity. There are suggestions that social factors contribute to both asthma risk and treatment.

Asthma↗

PubMed2000

Drink driving and traffic accidents in young people.

The relationship between drink driving behaviours and rates of traffic accidents was analysed in a birth cohort of 907 New Zealand young people studied to the age of 21. Drink driving was significantly (P < 0.0001) related to active traffic accidents in which the driver's behaviour contributed to the accident but was not related to passive accidents in which driver behaviours did not contribute to the accident (P > 0.15). Those engaging in high rates of drink driving had rates of active traffic accidents that were 2.6 times higher than those who did not drink and drive. Further analysis suggested that much of this association was explained by confounding factors (and notably driver behaviour) that were associated with both drink driving and accident rates. After adjustment for confounding factors, those engaging in high rates of drink driving had rates of active accidents that were 1.5 (P < 0.01) times higher than those who did not drink and drive. It is concluded that although the study findings support the view that the regulation of drink driving behaviour amongst young people is likely to contribute to a reduction in traffic accidents, to be fully effective attempts at regulation of drink driving also need to be accompanied by a similar level of investment in regulating other aspects of risky or illegal driving behaviour amongst young people.

Accidents, Traffic↗