Biomedical subjects

M T Lynskey

Publications and source records attributed to M T Lynskey.

At least 55 records · Page 3Linked to original sources

PubMed1994

The comorbidities of adolescent problem behaviors: a latent class model.

The correlations and comorbidities of a series of adolescent problem behaviors were studied in a sample of 739 New Zealand 15-year-olds. This analysis revealed the presence of strong comorbidities between different problem behaviors. The data were modeled using methods of unrestricted latent class analysis and this suggested that the best fitting model to describe the data was one which assumed that adolescent problem behaviors were described by four general classes of children. While the same general four-class model applied to males and females, there were marked gender differences in the rates of problems. Specifically, the predominant problem behaviors in females were those relating to an accelerated transition to adulthood marked by early sexual activity, alcohol abuse, and cannabis use whereas the predominant problems for boys were related to antisocial and law-breaking behaviors. Rates of children with no problems (85%) and with multiple problems (3%) were similar for boys and girls.

Adolescent↗

PubMed1994

Parental separation, adolescent psychopathology, and problem behaviors.

OBJECTIVE: This paper examines the effects of parental separation on the occurrence of adolescent psychopathology and problem behaviors at age 15 years. METHODS: Data collected during the course of a 15-year longitudinal study were used to examine a sample of 935 children with respect to exposure to parental separation during childhood, measures of adolescent psychopathology and problem behaviors at age 15 years, and prospectively collected confounding factors. RESULTS: Children exposed to parental separation during childhood had elevated risks of a range of adolescent problems, including substance abuse or dependence, conduct or oppositional disorders, mood and anxiety disorders, and early-onset sexual activity. However, adjustment for confounding factors explained a large amount of the increased risks of adolescent disorder, and after adjustment for confounders the odds ratios between exposure to parental separation and adolescent outcomes ranged from 1.07 to 3.32 with a median value of 1.46. The ways in which boys and girls responded to parental separation were similar. CONCLUSIONS: While the results suggested that children exposed to parental separation had increased risks of adolescent problems, much of this association appeared to be spurious and arose from confounding social and contextual factors that were present in the child's family before parental separation. However, even after such control, the results suggested that exposure to parental separation during childhood was associated with small but detectable increases in risks of adolescent conduct disorder, mood disorder, and substance abuse disorders.

Adolescent↗

PubMed1994

Structure of DSM-III-R criteria for disruptive childhood behaviors: confirmatory factor models.

OBJECTIVE: The aims of this analysis were to examine the extent to which DSM-III-R criteria for disruptive behavior patterns were consistent with the system of diagnoses proposed. Particular attention was paid to (1) whether oppositional defiant disorder is factorially distinct from conduct disorder (CD) and (2) the extent to which CD can be further classified into overt and covert CD behaviors. METHOD: Data were gathered on DSM-III-R criteria for disruptive behavior patterns for a sample of 739 New Zealand 15-year-olds using data provided by parental and self-report. These data were supplemented by officially recorded police contact data. RESULTS: Application of methods of confirmatory factor analysis suggested that the diagnostic criteria in DSM-III-R reflected a constellation of distinct but highly correlated behavioral domains, with these domains corresponding to oppositional defiant disorder, overt CD (aggression, violence), covert CD (theft, dishonesty), and attention-deficit hyperactivity disorder behavior. Results of second-order factor analysis methods suggested that these dimensions reflected two general higher-order factors, with the first factor reflecting the extent to which the individual displayed behavioral symptoms of oppositional defiant disorder and attention-deficit hyperactivity disorder and the second reflecting the extent to which the individual expressed antisocial, conduct-disordered behaviors. CONCLUSIONS: The results of confirmatory factor analysis generally support and validate the diagnostic classifications proposed in DSM-III-R but suggest possible refinements that draw distinctions between overt and covert expressions of CD.

Adolescent↗

PubMed1994

The effect of parental alcohol problems on rates of adolescent psychiatric disorders.

The relationships between parental alcohol problems and risks of psychiatric disorders including substance abuse, conduct, attention deficit, mood and anxiety disorders were examined in a birth cohort of New Zealand children studied to the age of 15 years. This analysis showed that children exposed to alcoholic parents had risks of adolescent psychiatric disorders that were between 2.2 (95% Confidence Interval (CI) = 1.4; 3.3) to 3.9 (95% CI = 2.40; 6.0) times higher than children whose parents did not report alcohol problems. After adjustment for a range of confounding factors these associations tended to reduce but even after adjustment, children of alcoholic parents had rates of disorder that were between 1.6 (95% CI = 1.1; 2.6) to 3.0 (95% CI = 1.8; 4.5) times higher than the offspring of parents who did not have alcohol problems. The analysis suggested approximately linear relationships between the extent of reported parental alcohol problems and risks of disorder. There was no evidence to suggest that, in general, males responded to parental alcohol problems in a way that differed from the response of females.

Adolescent↗

PubMed1994

Childhood exposure to alcohol and adolescent drinking patterns.

This paper examines the relationships between age at first exposure to alcohol and four measures of drinking behaviour (frequency of drinking, typical and most amount consumed, alcohol-related problems) at age 15 years in a birth cohort of New Zealand children. There were small but consistent correlations (r = -0.10 to -0.16) between self-reported age at first exposure to alcohol and the four measures of alcohol consumption. These associations remained statistically significant (p < 0.05) after control for a wide range of potentially confounding covariates including measures of family socio-demographic background, parental alcohol use and attitudes to alcohol use and early childhood behaviour. After control for these factors, children who had been introduced to alcohol before the age of 6 years were 1.9 to 2.4 times more likely to report frequent, heavy or problem drinking at age 15 years than children who did not drink alcohol before the age of 13. It is concluded that young people reared in home environments that have permissive attitudes to alcohol use and who are introduced to alcohol at an earlier age may be more vulnerable to alcohol-related problems in adolescence.

Adolescent↗

PubMed1994

The effects of parental separation, the timing of separation and gender on children's performance on cognitive tests.

The relationship between exposure to parental separation and measures of cognitive ability and school achievement was examined in a birth cohort of New Zealand children studied to the age of 13 years. Children who were exposed to parental separation following the point of school entry had mean test scores that were between .1 and .3 standard deviations lower than children who had not been exposed to separation even when due allowance was made for potentially confounding variables. Separation prior to school entry was found to be unrelated to later outcomes after adjustment for confounding factors. There was no evidence to suggest that the effects of separation varied with the child's gender. The association between parental separation after school entry and cognitive test scores was similar for children whose custodial parents remarried and those who did not remarry.

Adolescent↗

PubMed1993

Sexual activity and contraceptive use amongst teenagers under the age of 15 years.

AIMS: The aims of this study were to document patterns of sexual activity and contraceptive use in a sample of 952 Christchurch born children studied to the age of 15 years. METHOD: Data on sexual activity and contraceptive use was collected on the basis of self report at ages 14 and 15 years. RESULTS: By the age of 15 years, 8.5% of this sample had engaged in sexual intercourse. Early sexual activity was more common amongst girls, amongst children of Maori or Pacific Island ethnicity and among children from families of unskilled or semi-skilled socioeconomic status. Of those who were sexually active just under half (49.4%) reported having intercourse with only one partner while 17.3% (1.5% of the total sample) reported sexual experience with more than three partners by the age of 15 years. There was a high rate of contraceptive usage in the sample with 88.9% of those who were sexually active having used a recognised form of contraception and it was estimated that approximately 87% of sexual acts reported by this sample involved the use of contraception. The high rate of contraceptive usage for the sample was accounted for largely by the use of the condom and over 80% of those who were sexually active reported using this method. Despite the high rate of contraceptive usage evident for the sample just under one third of those who were sexually active reported having unprotected intercourse on at least one occasion. CONCLUSIONS: Bearing in mind the possibility of under reporting of sexual activity, the results suggest that by the age of 15 years in the region of 1 in 10 teenagers were sexually active. The major finding to emerge from the study was a high rate of utilisation of contraceptive methods, particularly the condom. It seems likely that this high rate of condom usage is a reflection of the effects of publicity and public education campaigns about the risks of HIV infection, AIDS and the need for safe sex. Despite the high rate of contraceptive usage for this sample it is suggested that those engaging in early sexual behaviour are a high risk population in need of support, assistance and counselling.

Adolescent↗

PubMed1993

Patterns of cannabis use among 13-14 year old New Zealanders.

AIMS: The aims of this study were to document the prevalence and frequency of use of cannabis, the sources of supply of cannabis and reactions to cannabis use in a sample of 949 Christchurch born children studied to the age of 15 years. METHOD: Data on cannabis use was collected on the basis of parental and self report at ages 14 and 15 years. RESULTS: By the age of 15 years, 9.8% of this cohort had used cannabis on one or more occasions and 2.2% of the cohort reported using cannabis on more than 10 occasions. Rates of cannabis use amongst boys and girls were identical. Most of those using cannabis had been provided with the drug by same aged or older teenagers and in most cases it was supplied free. In most cases cannabis was used in small informal groups of 2-8 young people. The majority of cannabis users (75.3%) reported positive reactions to cannabis use and many (58%) said that they would use cannabis again. However, just under one third (30.9%) of users reported some adverse reaction to cannabis use including feeling ill, dizzy or frightened. CONCLUSIONS: By the age of 15 years approximately 10% of young people reported using cannabis. This rate of utilisation appears to be supported by the presence of informal peer networks which provide a source of supply and support for young people experimenting with the use of cannabis. It is conjectured that the source of supply for these informal networks reflects a trickle down of the relatively large amounts of cannabis which circulate amongst adolescent and young adult populations.

Adolescent↗

PubMed1993

The effects of maternal depression on child conduct disorder and attention deficit behaviours.

The relationships between maternal history of depressive symptoms during children's middle childhood (8-11 years) and/or concurrent maternal depressive symptoms on the one hand and teacher and self reports of conduct disorder and attention deficit behaviours when the children were 12 and 13 years old on the other were studied in a birth cohort of New Zealand children. Examination of the joint effects of maternal history of depression and concurrent depressive symptoms on child behavior showed consistent and statistically significant associations between maternal history of depression and behaviour reports. However, associations between maternal concurrent depressive symptoms and child behaviour were generally non-significant when the effects of maternal history of depression were controlled. These results persisted when errors of measurement in behaviour reports were taken into account. However, after adjustment for potentially confounding social and contextual factors the correlations between maternal history of depression and child behaviour reduced to the point of both practical and statistical non-significance. We concluded that, for this cohort, the association between maternal depressive symptoms and externalising behaviour in early adolescence arose largely from the effects of common contextual factors (principally social disadvantage and marital instability) that influenced both rates of maternal symptomatology and rates of childhood problem behaviours.

Adolescent↗

PubMed1993

The effect of maternal depression on maternal ratings of child behavior.

There have been continuing concerns about the extent to which maternal depression may influence maternal reports of child behavior. To examine this issue, a series of structural equation models of the relationships between maternal depression and errors in maternal reports of child behavior was proposed and tested. These models assumed that (a) maternal depression was unrelated to maternal reporting behavior; (b) maternal depression causally influenced maternal reporting accuracy; (c) maternal depression was correlated with reporting accuracy. These models were fitted to data on maternal depression and multiple-informant (mother, teacher, child) reports of conduct disorder and attention deficit behaviors for a birth cohort of 12- and 13-year-old New Zealand children. The results of model fitting suggested the presence of small to moderate correlations (r = +.13 to +.40) between maternal depression and maternal reporting errors, indicating the presence of a tendency for increasing maternal depression to be associated with a tendency for mothers to over-report child behavior problems. However, independently of any effects of maternal depression on maternal reporting errors there was evidence of small but significant associations (r = .10 to .17; p < .05) between maternal depression and child conduct disorder and attention deficit behaviors.

Adolescent↗

PubMed1993

Prevalence and comorbidity of DSM-III-R diagnoses in a birth cohort of 15 year olds.

OBJECTIVE: To document the prevalence and comorbidities of a range of DSM-III-R diagnoses in a birth cohort of approximately 1,000 New Zealand children. METHOD: Parent and child reports were obtained on levels of DSM-III-R symptomatology in the child for five major groups of diagnoses: anxiety disorders, mood disorders, conduct/oppositional disorders, attention-deficit hyperactivity disorder, and substance abuse/dependence. Two methods, optimal informant and latent class modeling, were used to combine parent and child reports to produce a "best estimate" of the prevalence of disorder. RESULTS: Both methods produced very similar results. Overall approximately 25% of children met criteria for at least one DSM-III-R diagnosis. Rates of disorder were higher for girls (33% approximately) than for boys (20% approximately), this difference being largely owing to higher rates of anxiety and mood disorders among girls. There were strong tendencies for disruptive behavior and substance use disorders to cluster together and more diffuse tendencies for anxiety and mood disorders to be comorbid with each other and with other disorders. Only a minority (21%) of children with disorders were in contact with any service for their problems. CONCLUSION: These findings are consistent with a number of other studies of adolescent populations, both in terms of the prevalence of disorder and the comorbidities between disorders.

Adolescent↗

PubMed1993

Maternal age and cognitive and behavioural outcomes in middle childhood.

The relationships between maternal age and childhood cognitive and behavioural outcomes were analysed in a birth cohort of New Zealand children studied until the age of 13 years. Increasing maternal age was associated with increasing scores on tests of cognitive ability and achievement and with decreasing reports of conduct problems. The correlations between maternal age and childhood cognitive/behavioural outcomes ranged from 0.11 to 0.21 with a median value of 0.18. These associations were adjusted statistically for the effects of maternal social background at the time of birth and for childhood history subsequent to birth. This analysis suggested that the poorer outcomes for children born to younger mothers reflected the cumulative effects of two sets of factors which placed these children at a disadvantage. Firstly, the offspring of younger mothers tended to be born into relatively poorly educated, socially disadvantaged families and secondly, these children were exposed to less nurturant and more changeable home environments. The net effects of differences in social background at birth and childrearing environments subsequent to birth were sufficient to explain most of the apparent correlation between maternal age and childhood cognitive/behavioural outcomes.

Adolescent↗

PubMed1993

Early dentine lead levels and subsequent cognitive and behavioural development.

While a number of studies have reported associations between lead levels and cognitive development and behaviour in cross-sectionally studied child samples, there have been relatively few studies of the long term effects of early lead exposure. This issue was studied in a birth cohort of 1265 New Zealand children who were assessed with respect to: (a) dentine lead levels at ages 6-8 years; (b) cognitive and behavioural outcomes at 12, 13 years; (c) various confounding factors. The results of the analysis show: (a) the presence of small but consistent bivariate associations (ranging in absolute size from r = .08 to .20) between early lead levels and later school performance and behaviour; (b) after adjustment for both errors of measurement in test scores and lead levels and adjustment for confounding factors these correlations reduced to between .07 and .14. Nonetheless these correlations remained statistically significant. The evidence is consistent with the view that early mildly elevated lead levels are associated with small but relatively long term deficits in cognitive ability and attentional behaviours.

Achievement↗

PubMed1993

The effects of conduct disorder and attention deficit in middle childhood on offending and scholastic ability at age 13.

The relationship between conduct disorder and attention deficit behaviours in middle childhood (6, 8 and 10 years) and juvenile offending and academic achievement were examined in a birth cohort of New Zealand children. The application of structural equation modelling methods suggested that early behavioural tendencies are related to later developmental outcomes by two highly correlated but distinct developmental progressions. In the first such progression, early conduct disorder behaviours acted as a precursor of future offending patterns but these behaviours were unrelated to later school performance when the correlation between conduct disorder and attention deficit was taken into account. In the second developmental progression early attentional/cognitive behaviours were related to future school performance but were unrelated to the development of antisocial behaviours when the correlations between conduct disorder and cognitive/attentional variables were taken into account. The implications of these findings for validating the distinction between conduct disorder and attention deficit behaviours is discussed and the problems of analysing and explaining the high comorbidity between conduct disorder and attention deficit behaviours are considered.

Achievement↗

PubMed1993

Conduct problems and attention deficit behaviour in middle childhood and cannabis use by age 15.

The relationship between conduct problems and attention deficit behaviours at ages 6, 8, 10 and 12 years and the early onset of cannabis usage by the age of 15 years was studied in a birth cohort of New Zealand children. The analysis showed that while conduct problems during middle childhood were significantly associated with later cannabis use (p < 0.05) there was no association between early attention deficit behaviours and cannabis use (p > 0.40) when the associations between conduct problems and attention deficit behaviours were taken into account. It was estimated that children who showed tendencies to conduct disorder behaviour in middle childhood were between 2.1 to 2.7 times more likely to engage in early cannabis use than children not prone to conduct problems even when a range of factors including family social background, parental separation and parental conflict were taken into account. It is concluded that early conduct disorder behaviours are a risk factor for later cannabis use when due allowance is made for social and contextual factors associated with both early conduct problems and later cannabis use.

Adolescent↗

PubMed1993

Maternal smoking before and after pregnancy: effects on behavioral outcomes in middle childhood.

OBJECTIVE: The aim of this research was to examine the extent to which maternal smoking before and after pregnancy was associated with childhood disruptive behaviors when due allowance was made for potentially confounding factors which may have been associated with both maternal smoking habits and childhood problem behaviors. METHODS: During the course of a 15-year longitudinal study of a birth cohort of 1265 New Zealand children, the following measures were obtained: (1) measures of daily cigarette intake during pregnancy and after pregnancy; (2) measures of childhood disruptive behaviors including conduct problems and attention deficit behaviors based on both maternal and teacher report data; and (3) measures of a series of potentially confounding family, social, parental, and related factors. RESULTS: Before adjustments for confounding, maternal smoking both before and after pregnancy was found to be associated with significant increases in rates of childhood problem behaviors: children whose mothers smoked in excess of 20 cigarettes per day had mean problem behavior scores that were between 0.16 and 0.56 standard deviations higher than those of children whose mothers were nonsmokers. The results were then adjusted using regression methods to take account of (1) correlations between pregnancy and postpregnancy smoking and (2) potentially confounding factors. The results of regression adjustment suggested that maternal smoking during pregnancy was associated with small but statistically detectable increases in rates of childhood problem behaviors, with children whose mothers smoked in excess of 20 cigarettes per day having mean scores that were 0.10 to 0.36 standard deviations higher than those of the offspring of nonsmokers, even after adjustment for a series of confounding factors. However, smoking after pregnancy was not significantly associated with increased rates of childhood problem behavior after adjustment for sources of confounding. CONCLUSION: The results are generally consistent with the hypothesis that smoking during pregnancy may be associated with small but detectable increases in the risks of problem behaviors in childhood. This suggests that possible adverse effects on childhood behavioral adjustment should be added to the growing list of adverse consequences of parental smoking for childhood health and well-being.

Adolescent↗

PubMed1992

Family change, parental discord and early offending.

The relationship between exposure to family change, exposure to parental discord during the period from birth to 10 years and risks of offending by the age of 13 years was studied in a birth cohort of New Zealand children. This analysis showed that while exposure to parental discord during middle and early childhood led to increased risks of early offending, exposure to family change in the absence of parental discord did not lead to increased risks of offending. The results also suggested that children with a history of early conduct problems were particularly susceptible to parental discord but that the effects of discord did not vary with the child's gender. These results persisted when errors of measurement in the reporting of offending were taken into account using latent class methods.

Adolescent↗

PubMed1978

Interrelationships between maternal and cord prolactin, progesterone, estradiol, 13,14-dihydro-15-keto-prostaglandin F2alpha, and cord cortisol at delivery with respect to initiation of parturition.

Estradiol, progesterone, prolactin, and 13,14-dihydro-15-keto prostaglandin F2alpha (PGFM) were measured in both maternal and cord venous blood obtained at the time of delivery in 24 maternal infant pairs evenly divided among six different physiologic groups. Progesterone and prolactin were significantly higher and estradiol was significantly lower in cord than in maternal blood. There were no significant differences between the groups for cortisol, estradiol, or progesterone in maternal or cord blood. A significant increase in prolactin was demonstrated in women receiving oxytocin for induction of labor. Both estradiol and PGFM were highly correlated between maternal and cord blood. PGFM was significantly higher in cesarean section patients in labor than in those not in labor in both the maternal and cord circulations. Among those delivered vaginally, PGFM tended to be higher in those in spontaneous labor than in those with induced labor. PGFM in induced labor was intermediate between spontaneous labor aptients delivered by cesarean section and those delivered vaginally. Duration of labor was negatively correlated with cord estradiol concentration. The physiologic significance of these findings is discussed.

Animals↗