Jacob M. Najman

Are child and adolescent mental health problems increasing in the 21st century? A systematic review

Objective: Up to one in five children experience mental health problems. Social and cultural factors may influence emergence of mental health problems. The 21st century has led to changes in many of these factors, but it is unclear whether rates of internalizing and externalizing problems have also changed in recent cohorts of young people. Methods: A comprehensive literature search was undertaken to locate cohort or population studies that examined changes in mental health of children over time, where participants were aged 18 years and under, and the time frame for change was at least 10 years, with data for at least one time point in the 21st century being statistically compared to at least one time point in the 20th century. Studies were reviewed for quality and outcome. Results: Nineteen studies met criteria for review. These included studies of toddlers, children, and adolescents. Seventeen studies examined internalizing problems, and 11 studies examined externalizing problems. For both children and toddlers, recent cohorts did not exhibit worsening of mental health symptoms. In adolescents, the burden of externalizing problems appear to be stable. However, the majority of studies report an increase in internalizing problems in adolescent girls. The findings for internalizing problems in boys were mixed. Conclusions: These findings suggest that recent cohorts of adolescent girls are experiencing increases in internalizing symptoms compared to previous cohorts. Approaches for prevention and early intervention should be explored.

Maternal depressive, anxious, and stress symptoms during pregnancy predict internalizing problems in adolescence.

Studies have shown a link between maternal–prenatal mental health and offspring behavior problems. In this paper, we derived longitudinal trajectories of maternal depressive, anxious, and stress symptoms over early life to predict offspring behavior in adolescence.

Fetal growth and behaviour problems in early adolescence: findings from the Mater University Study of Pregnancy

BACKGROUND The nature of the association between birth weight and behavioural problems in adolescence is unclear. Recent studies are limited by their capacity to adjust for important obstetric and measurement issues. Aim To examine the nature of the association between birth weight and a range of behavioural symptoms, including anxiety/depression and social problems, in adolescence. METHODS Data from 4971 mothers and their children participating in the Mater University Study of Pregnancy (MUSP), a prospective, population-based birth cohort, are presented. This study commenced in Brisbane, Australia, in 1981. Mothers and their children were followed up at 3-5 days post-birth, and 6 months, 5 years and 14 years after the initial interview. Internalizing and externalizing behaviour problems, social problems and anxiety/depressive symptoms were assessed using Achenbachs Youth Self Report (YSR) of the Child Behaviour Check List (CBCL). RESULTS There was no evidence of a linear association between birth weight and behavioural symptoms, when birth weight z-scores were examined as a continuous variable. However, a non-linear association was identified when birth weight z-scores were categorized into quintiles. Children in the lowest and highest quintiles were at higher risk of increased anxiety/depressive and social problems symptoms. After adjustment for potential confounders, birth weight showed a non-linear association with the log odds of social problems {Quintile 1 odds ratio (OR) 1.59 [95% confidence interval (CI) 1.13, 2.23] Quintile 5 OR 1.57 (95% CI 1.12, 2.20)}. CONCLUSIONS Our findings provide further support for an association between birth weight and some adolescent behaviour problems. This association is likely to be non-linear, affecting babies at both the lower and higher ends of the birth weight distribution.

The role of sleep disturbance in the relationship between post-traumatic stress disorder and suicidal ideation

We tested if the risk of suicidal ideation in individuals with PTSD symptoms was dependent on comorbid sleep disturbance. Our cross-sectional sample included 2465 participants with complete data from the 21 year follow-up of the Mater University Study of Pregnancy (MUSP), a birth cohort study of young Australians. Using structural equation modelling with indirect pathways we found that 12 month PTSD symptoms did not directly predict suicidal ideation at 21 when adjusting for major depression symptoms, polyvictimization and gender. However, PTSD symptoms had an indirect effect on suicidal ideation via past-month sleep disturbance. Our results suggest that increased suicidal ideation in those with PTSD may result from the fact that PTSD sufferers often exhibit other comorbid psychiatric conditions which are themselves known to predict suicidal behaviours. Sleep disturbance may be targeted in those who experience PTSD to help prevent suicidal ideation.

The association between birth weight and anxiety disorders in young adults.

Recent evidence has linked birth weight to later behaviour/mental disorders, yet studies have hitherto neglected to investigate the relationship between birth weight and adult anxiety disorders. Prospectively collected data from 2210 mother/offspring pairs of the Mater University Study of Pregnancy (MUSP) birth cohort was used to test for associations between birth weight z-score and four major groupings of DSM-IV anxiety disorders. Birth weight z-score was linearly and inversely associated with lifetime diagnosis of post-traumatic stress disorders at 21 years, with those falling within the smallest birth weight quintile group at almost two-fold increased odds (OR=1.96, 95% CI: 1.10, 3.52) of being diagnosed with the disorder compared to those falling within the largest group. The association remained when subsequent analysis restricted the sample to those exposed to trauma. This is the first study in which birth weight has been found to be associated with post-traumatic stress disorders in adults.

Exploring the Female Specific Risk to Partial and Full PTSD Following Physical Assault

Previous studies have shown that females are at an increased risk of developing posttraumatic stress disorder (PTSD) in response to physical assault compared with males. Our aims were to (a) test if this gender-specific risk generalised to subclinical levels of PTSD, (b) observe how this relationship was affected by including possible confounding factors, and (c) estimate how this trauma contributed to the overall prevalence of PTSD in females. Data came from an Australian birth cohort study (n = 2,547) based in Brisbane, Australia that commenced in 1981. Using ordinal logistic regression adjusted for a wide range of confounding factors, including polyvictimisation and internalising and externalising symptoms, we found females were at a significantly greater risk compared to males of developing either partial or full PTSD, odds ratio (OR) = 7.68; 95% confidence interval (CI) = [2.94, 20.08], as well as full PTSD only, OR = 9.23; 95% CI = [2.77, 30.79], following the experience of assaultive violence (p value for test of interaction = .004). In addition to the high prevalence of sexual assault (12.9%), attributable risk analysis suggested that due to the strong risk of PTSD in females exposed to physical assault, physical assault is possibly a contributor to the overall female increased prevalence of PTSD.

Maternal prenatal infection, early susceptibility to illness and adult psychotic experiences: A birth cohort study

BACKGROUND Existing evidence has established that maternal infection during pregnancy and illness during early life are associated with later schizophrenia. No research has examined how the combination of these prenatal and postnatal exposures is linked to an increased risk to later schizophrenia and psychotic disorders. METHODS Participants from the Mater University Study of Pregnancy (MUSP), an Australian based, pre-birth cohort study were examined for lifetime DSM-IV positive psychotic experiences at 21 years by a semi-structured interview. Structural equation modelling was used to derive a general factor of psychotic experiences at age 21. Next, we undertook a number of separate analyses to investigate how prenatal infections and infant illness susceptibility are related to positive psychotic experiences in early adulthood, allowing for tests of moderation and mediation between the two risk factors. RESULTS After adjustment for important confounders, infant illness susceptibility was found to play a mediating role in the association between prenatal vaginal infection and later psychotic experiences. Whereby, infant illness susceptibility showed a direct association with psychotic experiences, while prenatal vaginal infection indirectly predicted psychotic experiences via infant illness susceptibility. CONCLUSION Our findings suggest that illness susceptibility in early infancy may be central to the relationship between prenatal vaginal infection and later psychotic experiences. Further research is needed to establish the mechanisms that link these prenatal and postnatal exposures with psychotic illness in later life.

The association between lower birth weight and comorbid generalised anxiety and major depressive disorder.

OBJECTIVE Studies testing the association between birth weight and depression or anxiety have found inconsistent results and there has been a lack of research on the possible relationship between birth weight and comorbid anxiety and depression. We tested for an association between lower birth weight and major depression, generalised anxiety and comorbid generalised anxiety and major depression. METHOD Data was taken from 2113 mothers and their offspring participating in the Mater University Study of Pregnancy (MUSP) birth cohort. Generalised anxiety, major depression and comorbid generalised anxiety and major depression at 21 years were tested for associations with birth weight using multinomial logistic regression. RESULTS Lower birth weight was found to predict comorbid generalised anxiety and major depression, but did not predict either generalised anxiety or major depression. LIMITATIONS We were unable to specify comorbidity by the primary disorder, or by the severity or recurrence of the depression. CONCLUSION Previous associations found between birth weight and mental health may reflect a specific link between lower birth weight and comorbid generalised anxiety and major depressive disorders. As neither disorder individually was associated with lower birth weight, this may suggest that this developmental origin represents a unique risk pathway to comorbidity not shared with either discrete disorder.

Pre-trauma verbal ability at five years of age and the risk of post-traumatic stress disorder in adult males and females

Previous studies have shown that high cognitive ability, measured in childhood and prior to the experience of traumatic events, is protective of PTSD development. Our aim was to test if the association between pre-trauma verbal ability ascertained at 5 years with DSM-IV lifetime post-traumatic stress disorder (PTSD) at 21 years was subject to effect modification by gender, trauma type or prior behaviour problems. Using a prospective birth cohort of young Australians, we found that both trauma type and behaviour problems did not change the association between cognitive ability and PTSD. During multivariate analysis, testing for the interactive effect of gender revealed that verbal ability was linearly and inversely associated with PTSD in females only, with those in the lowest verbal ability quintile having strongly increased odds of PTSD (OR=3.89: 95% CI; 1.50, 10.10) compared with those in the highest quintile. A graph of the interaction revealed lower verbal ability placed females, but not males, at an increased risk of PTSD. Our results indicate that lower verbal ability in early childhood is a vulnerability factor for PTSD in females but not in males, and may constitute a gender-specific risk factor responsible for part of the increased risk of PTSD found in females compared with males.

Predicting spectrums of adult mania, psychosis and depression by prospectively ascertained childhood neurodevelopment

BACKGROUND We used a novel approach to investigate early neurodevelopmental factors of later adult spectrums of mania, depression and psychosis as a means to identify etiological similarities and differences among the three constructs. METHODS Participants were from the Mater University Study of Pregnancy (MUSP), a pre-birth cohort study started in Brisbane, Australia in 1981. A range of neurodevelopmental variables were ascertained at age 5, including measures of cognitive ability, developmental delay and behaviour problems. At age 21, offspring were assessed using a semi-structured psychiatric interview. We used structural equation modelling to establish three latent factors of mania, depression and psychotic symptoms. We then regressed these factors on the neurodevelopmental variables and covariates. RESULTS In both univariate and multivariate analysis premorbid cognitive ability predicted only psychotic symptoms, developmental delay predicted only manic symptoms, while behaviour problems predicted both depressive and psychotic symptoms. In a supplementary analysis the three factors were also found to have unique relationships with a number of outcomes also measured at age 21, including anxiety and substance use. CONCLUSION By assessing the impact of early childhood neurodevelopment on the continuous spectrums which underlie three serious adult psychiatric disorders in a general population sample, we provide unique evidence regarding potential etiological similarities and differences. Perhaps of most interest is that our findings suggest that the manic and depressive symptoms in bipolar depression, despite often overlapping in clinical presentations, may in fact be somewhat separate entities with origins that are at least partly unique to either disorder.