Biomedical subjects

L John Horwood

Publications and source records attributed to L John Horwood.

At least 19 recordsLinked to original sources

PubMed2006

Anxiety disorders and suicidal behaviours in adolescence and young adulthood: findings from a longitudinal study.

BACKGROUND: The aim of this study was to estimate the extent to which anxiety disorders contribute to an increase in suicidal behaviour after controlling for both observed and non-observed sources of confounding. METHOD: Data were collected from the Christchurch Health and Development Study (CHDS), a 25-year longitudinal study of over 1000 participants. Measures of anxiety disorders [phobia, generalized anxiety disorder (GAD), panic disorder], major depression (MD), substance use disorders, conduct/antisocial personality disorder, stressful life events, unemployment, and suicidal ideation/attempts for subjects aged 16-18, 18-21 and 21-25 years were used to fit random and fixed effects regression models of the associations between anxiety disorders and suicidal behaviours. RESULTS: Anxiety disorders were strongly associated with suicidal ideation/attempts. Any single anxiety disorder increased the odds of suicidal ideation by 7.96 times [95% confidence interval (CI) 5.69-11.13] and increased the rate of suicide attempts by 5.85 times (95% CI 3.66-9.32). Control for co-occurring mental disorders, non-observed fixed confounding factors and life stress reduced these associations [suicidal ideation odds ratio (OR) 2.80, 95% CI 1.71-4.58; suicide attempts incidence rate ratio (IRR) 1.90, 95% CI 1.07-3.39]. Rates of suicidal behaviour also increased with the number of anxiety disorders. Estimates of the population attributable risk suggested that anxiety disorders accounted for 7-10% of the suicidality in the cohort. CONCLUSIONS: Anxiety disorders may be a risk factor for suicidality, even after controlling for confounding, with risks increasing with multiple anxiety disorders. Management of anxiety disorders may be an important component in strategies to reduce population rates of suicide.

Adolescent↗

PubMed2006

Self-esteem, risky sexual behavior, and pregnancy in a New Zealand birth cohort.

This study examined the relationship between self-esteem in adolescence and later risky sexual behavior and pregnancy in late adolescence and early adulthood. The investigation analyzed data from a birth cohort of over 1,000 New Zealand young adults studied to the age of 25. Lower levels of self-esteem at age 15 were associated with greater risks of engaging in unprotected sex (sexual intercourse with either an opposite- or same-sex partner without using a condom), a greater number of sexual partners, and a greater risk of pregnancy at ages 15-25. Adjustment for potentially confounding factors, including family socioeconomic background, family functioning, child abuse, and individual characteristics and behavior, reduced the strength of these associations to statistically non-significant levels. It was concluded that the effects of self-esteem during adolescence on later risky sexual behavior and pregnancy were weak and largely explained by the psychosocial context within which self-esteem develops.

Adolescent↗

PubMed2006

Examining the intergenerational transmission of violence in a New Zealand birth cohort.

OBJECTIVE: This paper examines whether exposure to interparental violence in childhood predicts subsequent involvement in interpartner violence and violent crime after controlling for potentially confounding factors. METHOD: The investigation analyses data from the Christchurch Health and Development Study, a prospective, longitudinal study of a birth cohort of over 1000 New Zealand young adults studied at multiple assessment points from birth to the age of 25. RESULTS: After controlling for potentially confounding risk factors, observed associations between exposure to interparental violence in childhood and increased risks of both (a) psychological interpartner violence perpetration and victimization and (b) violent crime, were reduced to statistical non-significance. No statistically significant associations were observed between exposure to interparental violence in childhood and increased risk of physical interpartner violence perpetration or victimization. CONCLUSIONS: It is concluded that the effects of childhood exposure to interparental violence on subsequent interpartner violence are weak and largely explained by the psychosocial context within which childhood exposure to interparental violence occurs.

Adolescent↗

PubMed2006

Gender differences in the transition to early parenthood.

Data gathered over the course of a 25-year longitudinal study of 1,055 young people was used to examine gender differences in the onset of early parenthood and the developmental processes that place males and females at risk of becoming a young parent. Results revealed clear gender differences in the timing of early parenthood, with females being twice as likely as males to become a parent between the ages of 16 and 25 years. In contrast, the risk factors and life course processes that placed males and females at risk of an early transition to parenthood were very similar. Two exceptions were a gender-specific effect for maternal age and exposure to parental change, suggesting that having been raised by a younger mother and having experienced parental changes in your family of origin increased risks of early parenthood for females but not males. These findings contribute to our understanding of the effects of gender on life course development.

Adolescent↗

PubMed2006

Illicit drug use and dependence in a New Zealand birth cohort.

OBJECTIVE: To describe the patterns of illicit drug use in a birth cohort studied to the age of 25 years. METHOD: The data were gathered during the Christchurch Health and Development Study. In this study a cohort of 1265 children born in the Christchurch, New Zealand urban region in mid-1977 have been studied to the age of 25 years. Information was gathered on patterns of illicit drug use and dependence during the period 15-25 years. RESULTS: By age 25 years, 76.7% of the cohort had used cannabis, while 43.5% had used other illicit drugs on at least one occasion. In addition, 12.5% of the cohort met DSM-IV criteria for dependence on cannabis, and 3.6% of the cohort met criteria for dependence on other illicit drugs at some time by age 25. There was also evidence of substantial poly-drug use among the cohort, with hallucinogens and amphetamines being the most commonly used illicit drugs (excluding cannabis). Illicit drug use and dependence was higher in males, in Māori, and in those leaving school without qualifications. Key risk factors for illicit drug use and dependence included adolescent risk-taking behaviours including cigarette smoking and alcohol consumption, affiliation with substance-using peers, novelty-seeking, and conduct problems in adolescence. Other key risk factors included parental history of illicit drug use and childhood sexual abuse. CONCLUSIONS: Levels of cumulative illicit drug use in this cohort were relatively high, with the majority of respondents having tried illicit drugs by age 25. For the majority of illicit drug users, drug use did not lead to problems of dependence. Nonetheless, nearly 15% of the cohort showed symptoms of illicit drug dependence by the age of 25 years, with cannabis dependence accounting for the majority of illicit drug dependence.

Adolescent↗

PubMed2006

Cannabis use and other illicit drug use: testing the cannabis gateway hypothesis.

AIM: To examine the associations between the frequency of cannabis use and the use of other illicit drugs. DESIGN: A 25-year longitudinal study of the health, development and adjustment of a birth cohort of 1,265 New Zealand children. MEASUREMENTS: Annual assessments of the frequency of cannabis use were obtained for the period 14-25 years, together with measures of the use of other illicit drugs from the same time period. FINDINGS: The frequency of cannabis use was associated significantly with the use of other illicit drugs, other illicit drug abuse/dependence and the use of a diversity of other drugs. This association was found to be particularly strong during adolescence but declined rapidly as age increased. Statistical control for confounding by both fixed and time dynamic factors using random- and fixed-effects regression models reduced the strength of association between frequency of cannabis use and other illicit drug use, but a strong association between frequency of cannabis use and other illicit drug use remained even after control for non-observed and time-dynamic sources of confounding. CONCLUSIONS: Regular or heavy cannabis use was associated with an increased risk of using other illicit drugs, abusing or becoming dependent upon other illicit drugs, and using a wider variety of other illicit drugs. The risks of use, abuse/dependence, and use of a diversity of other drugs declined with increasing age. The findings may support a general causal model such as the cannabis gateway hypothesis, but the actual causal mechanisms underlying such a gateway, and the extent to which these causal mechanisms are direct or indirect, remain unclear.

Adolescent↗

PubMed2006

Abortion in young women and subsequent mental health.

BACKGROUND: The extent to which abortion has harmful consequences for mental health remains controversial. We aimed to examine the linkages between having an abortion and mental health outcomes over the interval from age 15-25 years. METHODS: Data were gathered as part of the Christchurch Health and Development Study, a 25-year longitudinal study of a birth cohort of New Zealand children. Information was obtained on: a) the history of pregnancy/abortion for female participants over the interval from 15-25 years; b) measures of DSM-IV mental disorders and suicidal behaviour over the intervals 15-18, 18-21 and 21-25 years; and c) childhood, family and related confounding factors. RESULTS: Forty-one percent of women had become pregnant on at least one occasion prior to age 25, with 14.6% having an abortion. Those having an abortion had elevated rates of subsequent mental health problems including depression, anxiety, suicidal behaviours and substance use disorders. This association persisted after adjustment for confounding factors. CONCLUSIONS: The findings suggest that abortion in young women may be associated with increased risks of mental health problems.

Abortion, Induced↗

PubMed2006

Structure of internalising symptoms in early adulthood.

BACKGROUND: Debate surrounds the underlying structure of internalising disorders including major depression, generalised anxiety disorder, phobias and panic disorders. AIMS: To model the within-time and across-time relationships of internalising symptoms, incorporating effects from generalised internalising and disorder-specific components of continuity. METHOD: Data were gathered from a 25-year longitudinal study of a birth cohort of 953 New Zealand children. Outcome measures included DSM-IV symptom scores for major depression, generalised anxiety disorder, phobia and panic disorder at the ages of 18, 21 and 25 years. RESULTS: Structural equation modelling showed that, within-times, a common underlying measure of generalised internalising explained symptom score comorbidities. Across-time correlation of symptom scores was primarily accounted for by continuity over time in generalised internalising. However, for major depression and phobia there was also evidence of across-time continuity in the disorder-specific components of symptoms. CONCLUSIONS: Internalising symptoms can be partitioned into components reflecting both a generalised tendency to internalising and disorder-specific components.

Adolescent↗

PubMed2006

Randomized trial of the Early Start program of home visitation: parent and family outcomes.

OBJECTIVE: To examine the extent to which the Early Start program of home visitation had beneficial consequences in the areas of maternal health, family functioning, family economic circumstances, and exposure to stress and adversity. METHODS: The study used a randomized, controlled trial design in which 220 families receiving the Early Start program were contrasted with a control series of 223 families not receiving the program. Families were enrolled in the program after population screening conducted by community health nurses. Families were enrolled in the program for up to 36 months. Outcomes were assessed at 6, 12, 24, and 36 months after trial entry. RESULTS: There was a consistent lack of association between maternal and family outcomes and group membership. There were no significant differences between the Early Start and control series in any comparisons. CONCLUSIONS: This evaluation suggested that the Early Start program failed to lead to parent- and family-related benefits. This absence of benefit for parent/family outcomes is contrasted with the benefits found previously for child-related outcomes, including child health, preschool education, child abuse and neglect, parenting, and behavioral adjustment. This comparison suggests that home visitation programs may provide benefits for child-related outcomes in the absence of parent- or family-related outcomes.

Child Welfare↗

PubMed2006

Circumcision status and risk of sexually transmitted infection in young adult males: an analysis of a longitudinal birth cohort.

OBJECTIVES: Previous research suggests that male circumcision may be a protective factor against the acquisition of sexually transmitted infections; however, studies examining this question have produced mixed results. The aim of this study was to examine the association between circumcision status and sexually transmitted infection risk using a longitudinal birth cohort study. METHODS: Data were gathered as part of the Christchurch Health and Development Study, a 25-year longitudinal study of a birth cohort of New Zealand children. Information was obtained on: (1) the circumcision status of males in the cohort before 15 years old, (2) measures of self-reported sexually transmitted infection from ages 18 to 25 years, and (3) childhood, family, and related covariate factors. RESULTS: Being uncircumcised had a statistically significant bivariate association with self-reported sexually transmitted infection. Adjustment for potentially confounding factors, including number of sexual partners and unprotected sex, as well as background and family factors related to circumcision, did not reduce the association between circumcision status and reports of sexually transmitted infection. Estimates of the population-attributable risk suggested that universal neonatal circumcision would have reduced rates of sexually transmitted infection in this cohort by 48.2%. CONCLUSIONS: These findings suggest that uncircumcised males are at greater risk of acquiring sexually transmitted infection than circumcised males. Male circumcision may reduce the risk of sexually transmitted infection acquisition and transmission by up to one half, suggesting substantial benefits accruing from routine neonatal circumcision.

Adolescent↗

PubMed2005

Stability and instability in alcohol diagnosis from ages 18 to 21 and ages 21 to 25 years.

BACKGROUND: Only in recent years have longitudinal studies of adolescents diagnosed alcohol use disorders and these have not distinguished between abuse and dependence. This study describes the course of disorder from age 18 to age 25 for abuse and dependence and investigates the extent to which continuities in disorder can be explained by background factors. METHODS: A birth cohort of 1,265 individuals from Christchurch, New Zealand, followed annually to age 16 years then at 18, 21 and 25 years (1,003 at age 25). DSM-IV diagnoses were made from reports of alcohol symptoms at 18, 21 and 25 years. RESULTS: The most stable diagnosis was that of no diagnosis, with 83-91% staying the same from one interview to the next. There were high rates of remission to no disorder; 57-75% for those with initial abuse and 50-54% of those with initial dependence. Nonetheless prior diagnosis was a strong predictor of subsequent diagnosis (ORs of 3.7-27.6). Adjustment for background risk factors reduced these odds ratios but all remained significant and substantial (minimum 2.6). CONCLUSIONS: The dual finding of substantial discontinuity and substantial continuity indicates that both public health and treatment interventions are warranted.

Adolescent↗

PubMed2005

Subthreshold depression in adolescence and mental health outcomes in adulthood.

BACKGROUND: There is increasing interest in the extent to which individuals with subthreshold depression face increased risks of subsequent major depression and other disorders. OBJECTIVE: To examine linkages between the extent of depressive symptoms (asymptomatic, subthreshold, major depression) at ages 17 to 18 years and mental health outcomes up to age 25 years in a New Zealand birth cohort. DESIGN: Data were gathered during the Christchurch Health and Development Study, a 25-year longitudinal study of a birth cohort of 1265 New Zealand children (635 males, 630 females). SETTING: General community sample. PARTICIPANTS: The analysis was based on 1006 participants who represented 80% of the original cohort. MAIN OUTCOME MEASURES: Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition symptom criteria for major depression and anxiety disorder, treatment-seeking, suicidal ideation, and suicide attempt. RESULTS: There were significant associations (P<.01) between the extent of depression at ages 17 to 18 years and rates of subsequent depressive symptoms, major depression, treatment for depression, anxiety disorder, treatment for anxiety disorder, suicidal ideation, and suicide attempts. After adjustment for covariate factors, the extent of depression at ages 17 to 18 years remained associated with later depression and suicidal tendencies. Planned comparisons showed that sample members with subthreshold depression had a similar prognosis to those meeting criteria for major depression. CONCLUSIONS: Findings suggest that sample members with subthreshold depression are a group with elevated risks of later depression and suicidal behaviors. Current diagnostic procedures, which classify people with subthreshold depression into complex discrete groups, might obscure the fact that depressive symptoms are dimensional and range from none to severe.

Adolescent↗

PubMed2005

Childhood abuse and familial violence and the risk of panic attacks and panic disorder in young adulthood.

BACKGROUND: The objectives of the study were to examine linkages between exposure to childhood abuse and interparental violence and the subsequent development of panic attacks and panic disorder using data gathered on a birth cohort of 1265 New Zealand young people studied to the age of 21 years. METHOD: Data on: (a) exposure to child abuse and interparental violence; (b) the development of panic attacks and panic disorder; and (c) other childhood and related factors were gathered over the course of a 21-year longitudinal study. RESULTS: After adjustment for childhood and related factors, exposure to childhood physical abuse was associated with a significantly increased risk of later panic attack (OR 2.3, 95% CI 1.1-4.9) and panic disorder (OR 3.0, 95% CI 1.1-7.9); childhood sexual abuse was associated with a significantly increased risk of panic attack (OR 4.1, 95% CI 2.3-7.2) and a marginally significant increase risk of panic disorder (OR 2.2; 95% CI 0.98-5.0). Exposure to interparental violence was unrelated to later panic attack or disorder after adjustment. CONCLUSIONS: Exposure to childhood sexual and physical abuse was associated with increased risks of later panic attack/disorder even after adjustment for prospectively assessed confounding factors. However, exposure to interparental violence during childhood was not related to increased risk of later panic attack/disorder after adjustment. These data suggest the need for clinicians to be aware that patients with histories of childhood physical and sexual abuse may be at increased risk for panic during young adulthood.

Adolescent↗

PubMed2005

Suicidal behaviour in adolescence and subsequent mental health outcomes in young adulthood.

BACKGROUND: The aim of this study was to examine the linkages between suicidal ideation and attempt in adolescence and subsequent suicidal behaviours and mental health in young adulthood. METHOD: Data were gathered during the course of a 25-year longitudinal study of a birth cohort of 1265 New Zealand children. The information collected included: (a) measures of suicidal thoughts and attempts in adolescence (< 18 years); (b) measures of suicidal ideation, suicide attempt, major depression, anxiety disorders, and substance use disorders in young adulthood (18-25 years); and (c) measures of childhood and family background, individual characteristics, and mental disorders in adolescence. RESULTS: After statistical adjustment for confounding factors, suicide attempt in adolescence was associated with increased risks of subsequent suicidal ideation (OR 5.7) suicide attempt (OR 17.8) and major depression (OR 1.5). Those reporting suicidal ideation without suicide attempt showed moderate increases in risks of later suicidal ideation (OR 2.5), suicide attempt (OR 2.0) and major depression (OR 1.6). In addition, there was evidence of an interactive relationship in which suicidal behaviour in adolescence was associated with increased risks of later substance use disorders in females but not males. CONCLUSIONS: Young people reporting suicidal ideation or making a suicide attempt are an at-risk population for subsequent suicidal behaviour and depression. Further research is needed into the reasons for suicidal adolescent females being at greater risk of later substance use disorder.

Adolescent↗

PubMed2005

Sexual orientation and mental health in a birth cohort of young adults.

BACKGROUND: This paper sought to examine the relationship between sexual orientation and mental health in a New Zealand birth cohort studied to age 25 years. METHOD: The analysis is based on a sample of 967 participants (469 males; 498 females) in the Christchurch Health and Development Study. As part of this study information was gathered on: (a) measures of sexual orientation, same-sex behaviour and sexual attraction obtained at ages 21 and 25 years; (b) measures of mental disorders and suicidal behaviours over the interval 21-25 years; (c) measures of childhood and family background. RESULTS: Latent class analysis was used to combine indicators of sexual orientation, same sex behaviour and attraction to form an empirically based classification of sexual orientation. The best-fitting model classified the sample into three groups: exclusively heterosexual orientation (87.6%); predominantly heterosexual but with same-sex inclinations or experience (9.6%); predominantly homosexual (2.8%). Proportionately more women than men were classified as predominantly heterosexual (14.2% v. 4.8% respectively) or predominantly homosexual (3.9% v. 1.5% respectively). Cohort members with a predominantly homosexual orientation had rates of mental disorder and suicidal behaviours that were between 1.5 and 12 times higher than for those with an exclusively heterosexual orientation. These associations persisted after adjustment for confounding. The associations between sexual orientation and mental health were more marked for males than females. CONCLUSIONS. The findings suggest a continuum of sexual preferences amongst young adults. Variations in sexual orientation were clearly associated with mental health. These associations tended to be stronger for males.

Adult↗

PubMed2005

Tests of causal linkages between cannabis use and psychotic symptoms.

AIM: To examine possible causal linkages between cannabis use and psychosis using data gathered over the course of a 25-year longitudinal study. DESIGN: A 25-year longitudinal study of the health, development and adjustment of a birth cohort of 1265 New Zealand children (635 males, 630 females). SETTING: The Christchurch Health and Development Study, a general community sample. PARTICIPANTS: A total of 1055 participants from the Christchurch Health and Development Study (CHDS) cohort for whom data on cannabis use and psychotic symptoms were available on at least one occasion from 18, 21 and 25 years. MEASUREMENTS: As part of this study, data were gathered on frequency of cannabis use and psychotic symptoms at ages 18, 21 and 25 years. FINDINGS: Regression models adjusting for observed and non-observed confounding suggested that daily users of cannabis had rates of psychotic symptoms that were between 1.6 and 1.8 times higher (P < 0.001) than non-users of cannabis. Structural equation modelling suggested that these associations reflected the effects of cannabis use on symptom levels rather than the effects of symptom levels on cannabis use. CONCLUSIONS: The results of the present study add to a growing body of evidence suggesting that regular cannabis use may increase risks of psychosis. The present study suggests that: (a) the association between cannabis use and psychotic symptoms is unlikely to be due to confounding factors; and (b) the direction of causality is from cannabis use to psychotic symptoms.

Adolescent↗

PubMed2005

Show me the child at seven: the consequences of conduct problems in childhood for psychosocial functioning in adulthood.

BACKGROUND: This paper seeks to extend research into the adult sequelae of childhood conduct problems by investigating the associations between conduct problems in middle childhood and psychosocial outcomes in adulthood. METHOD: Data were gathered during the course of a 25-year longitudinal study of a birth cohort of New Zealand young people. Information was collected on: a) parent and teacher reports of child conduct problems at ages 7, 8 and 9 years; b) measures of crime, substance use, mental health, sexual/partner relationships, education/employment; c) confounding factors, including childhood, family and educational characteristics. RESULTS: There were statistically significant associations between childhood conduct problems from 7-9 years and risks of adverse outcomes across all domains of functioning. After control for confounding factors the associations between conduct problems and education/employment outcomes became statistically non-significant. Associations persisted for other outcomes (crime, substance dependence, mental health and sexual/partner relationships). Children in the most disturbed 5% of the cohort had rates of these outcomes that were between 1.5 and 19 times higher than rates for the least disturbed 50% of the cohort. The associations between conduct problems and adult outcomes were similar for males and females. CONCLUSIONS: Childhood conduct problems were associated with a wide range of adverse psychosocial outcomes (crime, substance use, mental health, sexual/partner relationships) even after control for confounding factors. The results reinforce the need for greater investment into interventions to address these problems.

Adaptation, Psychological↗

PubMed2005

Show me the child at seven II: Childhood intelligence and later outcomes in adolescence and young adulthood.

BACKGROUND: There has been ongoing interest in the role of intelligence in longer-term educational and occupational achievement and social adjustment. The aims of this study were to examine the extent to which IQ in middle childhood (8-9 years) was prognostic of future outcomes when due allowance was made for confounding personal and social factors. METHODS: Data were gathered on (WISC-R) IQ at ages 8-9 years and a range of educational and social adjustment measures over the course of the Christchurch Health and Development Study, a 25-year longitudinal study of a birth cohort of 1,265 New Zealand children. RESULTS: IQ assessed at ages 8-9 years was related to a range of outcomes: later crime (offending, arrest/conviction); substance use disorders (nicotine dependence, illicit drug dependence); mental health (anxiety, suicidality); sexual adjustment (number of sexual partners, pregnancy); educational achievement (school leaving qualifications, tertiary qualifications); and occupational outcomes (unemployment, income). However, intelligence was largely unrelated to many of these outcomes: crime, mental health, sexual behaviours, and illicit substance dependence after statistical adjustment for early behaviour problems and family background. Strong relationships remained between childhood intelligence and later educational and occupational outcomes. CONCLUSIONS: Much of the association between early intelligence and later social adjustment is mediated by childhood conduct problems and family social circumstances. However, strong relationships exist between early intelligence and later academic achievement and income independently of these factors.

Achievement↗