Michael T. Lynskey

Prevalence and Comorbidity of DSM-III-R Diagnoses in a Birth Cohort of 15 Year Olds

OBJECTIVEnTo document the prevalence and comorbidities of a range of DSM-III-R diagnoses in a birth cohort of approximately 1,000 New Zealand children.nnnMETHODnParent 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.nnnRESULTSnBoth 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.nnnCONCLUSIONnThese 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.

Childhood sexual abuse, adolescent sexual behaviors and sexual revictimization

OBJECTIVEnThe aims of this study were to examine the extent to which exposure to childhood sexual abuse (CSA) was associated with increased rates of sexual risk taking behaviors and sexual revictimization during adolescence.nnnMETHODnA birth cohort of 520 New Zealand born young women was studied at regular intervals from birth to the age of 18. At age 18 retrospective reports of CSA were obtained from sample members. Over the course of the 18 year study information was gathered on: (a) childhood, family, and related circumstances; and (b) the young womens history of sexual experiences from 14 to 18 years.nnnRESULTSnYoung women reporting CSA, and particularly severe CSA involving intercourse, had significantly higher rates of early onset consensual sexual activity, teenage pregnancy, multiple sexual partners, unprotected intercourse, sexually transmitted disease, and sexual assault after the age of 16. Logistic regression analyses suggested that the associations between CSA and sexual outcomes in adolescence arose by two routes. First, exposure to CSA was associated with a series of childhood and family factors including social disadvantage, family instability, impaired parent child relationships, and parental adjustment difficulties that were also associated with increased sexual vulnerability in adolescence. Second, there appeared to be a causal chain relationship between CSA and sexual experiences in which CSA was associated with early onset sexual activity which, in turn, led to heightened risks of other adverse outcomes in adolescence.nnnCONCLUSIONSnThe findings of this study suggest that those exposed to CSA have greater sexual vulnerability during adolescence. This appears to arise because: (a) the childhood and family factors that are associated with CSA are also associated with increased sexual risks during adolescence; and (b) exposure to CSA may encourage early onset sexual activity which places those exposed to CSA at greater sexual risk over the period of adolescence.

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 multipleinformant (mother, teacher, child) reports of conduct disorder and attention deficit behaviors for a birth cohort of 12 and 13yearold 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 overreport 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.

Childhood circumstances, adolescent adjustment, and suicide attempts in a New Zealand birth cohort

OBJECTIVEnTo estimate the prevalence of attempted suicide during adolescence in a birth cohort of New Zealand children studied to the age of 16 years and to examine the relationships among adolescent problems of adjustment, psychopathology, childhood circumstances, and risks of adolescent suicide attempts.nnnMETHODnAttempted suicide, adolescent problems of adjustment, psychopathology, and childhood circumstances were assessed as part of a longitudinal study of a birth cohort of 954 New Zealand children studied at annual intervals to the age of 16 years.nnnRESULTSnBy 16 years, 3.0% of the sample (4.2% of girls and 1.9% of boys) reported having made a suicide attempt. There were strong associations between attempted suicide and rates of adolescent problem behaviors or psychopathology; teenagers having problems of adjustment or psychiatric disorders were up to 22 times more likely to attempt suicide. Risks of attempted suicide were also higher among children from disadvantaged or dysfunctional family backgrounds. A loglinear model fitted to the measures of attempted suicide, adolescent psychopathology, problems of adjustment, and childhood circumstances suggested the presence of a causal chain process in which childhood problems were significantly (p < .005) related to increased risks of later psychopathology and problems of personal adjustment which were, in turn, related to significantly (p < .05) increased rates of attempted suicide.nnnCONCLUSIONSnA common pathway that leads to increased vulnerability to suicidal behavior involves early disadvantageous childhood and family circumstances, which lead to increased risks of adolescent psychopathology and problems of adjustment, which lead to increased risks and vulnerability to adolescent suicidal behaviors.

Suicide attempts and suicidal ideation in a birth cohort of 16-year-old New Zealanders

OBJECTIVEnTo describe the prevalence of suicide attempts and suicidal ideation in a birth cohort of New Zealand children studied to the age of 16 years; to examine the extent to which risks of suicide attempts and suicidal ideation varied with levels of adolescent psychopathology, problems of adjustment, and exposure to adverse conditions during childhood; and to examine the extent to which those attempting suicide could be distinguished from those reporting suicidal ideation alone.nnnMETHODnData were gathered on suicide attempts, suicidal ideation, psychiatric diagnoses, adjustment problems, and childhood factors during the course of a 16-year longitudinal study of a birth cohort of New Zealand children.nnnRESULTSnTwelve percent of this cohort reported suicidal ideation before the age of 16 years and 3% attempted suicide. The extent to which young people expressed suicidal tendencies varied with the extent to which the young person met criteria for psychiatric disorder, the extent of adjustment problems, and the extent to which the young person had been exposed to adverse family circumstances. Those attempting suicide were distinguished from those reporting suicidal ideation by having significantly higher rates of psychopathology (p < .05), higher rates of adjustment problems (p < .005), and greater exposure to childhood and family adversity (p < .05).nnnCONCLUSIONnThe results of this analysis were consistent with a dimensional model of suicidal behaviors in which those attempting suicide are distinguished from those reporting suicidal ideation alone by having a greater burden of psychosocial risk factors including psychiatric disorder, adjustment problems, and adverse childhood circumstances.

Parental Separation, Adolescent Psychopathology, and Problem Behaviors

OBJECTIVEnThis paper examines the effects of parental separation on the occurrence of adolescent psychopathology and problem behaviors at age 15 years.nnnMETHODSnData 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.nnnRESULTSnChildren 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.nnnCONCLUSIONSnWhile 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 childs 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.

Factors associated with continuity and changes in disruptive behavior patterns between childhood and adolescence

The relationships between disruptive behaviors in middle childhood (7 to 9 years) and conduct disorder in adolescence (14 to 16 years) were studied in a birth cohort of New Zealand children. Latent class analysis suggested strong behavioral continuity, with children showing early disruptive behaviors having odds of adolescent conduct disorder that were over 16 times higher than children who did not display early disruptive behavior. Nonetheless, in the region of 12% of children showed a discontinuous history, with 5% of children showing an early onset of conduct problems and later remission while 7% showed later onset conduct problems. Children showing discontinuous histories of behavior problems came from backgrounds in which levels of risk were intermediate between those of children who showed a persistent pattern of conduct problems and those who were consistently nonproblem children. Peer factors played an influential role in behavioral change in adolescence, with individuals showing late onset of conduct problems having high rates of affiliation with delinquent peers but those showing remission of problem behaviors in adolescence having relatively low rates of such affiliations.

Origins of Comorbidity between Conduct and Affective Disorders

OBJECTIVEnThis analysis used methods of structural equation modeling to assess the extent to which comorbidity between conduct and affective disorders could be explained by (1) common or correlated causal factors that influenced both outcomes or (2) reciprocal causation between these conditions.nnnMETHODnData were obtained during the course of a 16-year longitudinal study of a birth cohort of New Zealand children. The data analyzed comprised measures of conduct and affective disorders at ages 15 and 16 years and data on a series of antecedent childhood factors.nnnRESULTSnStructural equation modeling suggested that a substantial component of the comorbidity between conduct and affective disorders arose because the risk factors associated with the development of conduct disorders in teenagers overlapped and were correlated with the risk factors for adolescent affective disorders; of the shared variance between conduct disorder and affective disorders, more than two thirds was explained by common risk factors. These conclusions were replicated using diagnostically scored measures and methods of categorical data analysis. Model extensions suggested an absence of direct causal pathways between conduct and affective disorders.nnnCONCLUSIONSnA substantial amount of the correlation and comorbidity between conduct and affective disorders arises because the risk factors and life pathways that predispose adolescents to one outcome are also associated with the risk factors and life pathways that predispose adolescents to the other outcome. Nonetheless, even after control for common causal factors, there was evidence of some unexplained comorbidity between conduct and affective disorders.

The effects of unemployment on psychiatric illness during young adulthood

BACKGROUNDnThe aims of this study were to examine the associations between exposure to unemployment following school leaving and rates of psychiatric disorder using data gathered on a birth cohort of New Zealand young people studied up to the age of 18.nnnMETHODSnAt age 18 cohort members were assessed on: (a) duration of exposure to unemployment from age 16; (b) DSM-IV diagnostic criteria for major depression, anxiety disorders, conduct disorder, nicotine dependence, other substance abuse/dependence and attempted suicide. This information was integrated into longitudinal data gathered on the social circumstances, family background and adjustment of the cohort up to the age of 18.nnnRESULTSnIncreasing exposure to unemployment was associated with increasing risks of psychiatric disorder in adolescence. Those exposed to 6 months or more unemployment had rates of disorder that were 1.5 to 5.4 times higher than those not exposed to unemployment. However, most of the elevated risk of disorder among those unemployed was explained by family and personal factors that were present prior to school leaving age. Nonetheless, even after control for these factors those exposed to unemployment had significantly higher rates of anxiety disorder and substance use disorders.nnnCONCLUSIONSnTo a large extent the relationships between unemployment and psychiatric disorder seen in this cohort were explained by social, family and personal factors that were present before school leaving age. Nonetheless, young people exposed to unemployment had higher rates of substance use and anxiety disorder.

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.