Adolescents' internalizing symptoms predict dating violence victimization and perpetration 2 years later.

The aim of this longitudinal study was to examine bidirectional associations of adolescents' internalizing symptoms with dating violence victimization and perpetration. We conducted secondary analyses of the Québec Longitudinal Study of Child Development data (n = 974). Each adolescent completed items from the Conflict Tactics Scale (at ages 15 and 17 years) to assess psychological, physical, and sexual dating violence victimization and perpetration in the past 12 months. Adolescents' symptoms of depression and general anxiety in the past 12 months were self-reported (at ages 15 and 17 years) using The Mental Health and Social Inadaptation Assessment for Adolescents. There were concurrent associations of adolescents' internalizing symptoms with dating violence victimization and perpetration. Internalizing symptoms at age 15 years were positively associated with dating violence victimization and perpetration 2 years later in both males and females, even after adjusting for baseline characteristics. However, neither dating violence victimization nor perpetration at age 15 years was associated with internalizing symptoms 2 years later. For males and females, internalizing symptoms put adolescents at risk for future dating violence victimization and perpetration. Interventions that target internalizing symptoms may have the potential to decrease subsequent dating violence.

Maternal depressive symptoms and children's academic performance: sex differences in the mediating role of school experiences.

BACKGROUND: Maternal depressive symptoms (MDSs) are negatively associated with children's academic performance, with stronger effects sometimes reported in boys. However, few studies have tested the mechanisms of this association. We examined the mediating role of school engagement and peer victimization in this association and tested for sex differences. METHODS: Participants were 1173 families from a population-based longitudinal Canadian study. MDSs were self-reported annually using the Centre for Epidemiologic Studies Depression Scale (child's age: 5 months to 5 years). Data on mediators (peer victimization, cognitive, behavioral, and emotional school engagement) were reported annually from ages 6-10 by multiple informants including children, parents, and teachers using items from validated scales. Mathematics, reading, and writing exam scores at age 12 were obtained from standardized exams administered by Québec's Ministry of Education and Teaching. Structural equation modeling was used to test mediation by school experiences in boys and girls. RESULTS: Exposure to MDSs was negatively associated with mathematics, reading, and writing scores in girls and with mathematics only in boys. Cognitive and behavioral engagement significantly mediated the association between MDSs and mathematics, reading, and writing scores in girls. There were no significant mediators for boys. CONCLUSIONS: Prevention and intervention strategies aiming to improve school engagement might be beneficial for daughters of mothers experiencing depressive symptoms. Further research is needed to replicate these findings and to identify the mechanisms explaining this association in boys.

The mediating role of adolescents' loneliness and social withdrawal in the association between maternal depressive symptoms and suicidality in adolescence: A 20-year population-based study.

We examined whether adolescents' loneliness and social withdrawal mediated the association between maternal depressive symptoms and adolescent suicidality. Secondary analyses on the Québec Longitudinal Study of Child Development data were conducted (n = 1,623). Each mother completed the Centre for Epidemiologic Studies Depression Scale (at child ages 5 months, 1.5, 3.5, 5, and 7 years). Adolescent's social withdrawal (adolescent, father, and teacher reported at 10, 12, and 13 years) and loneliness (adolescent reported at 10, 12, and 13 years), were assessed using items from the Social Behavior Questionnaire and the Loneliness and Social Satisfaction Questionnaire, respectively. Adolescents completed self-reports to assess suicidal thoughts and attempts at 13, 15, 17, and 20 years. Children of mothers with higher levels of maternal depressive symptoms had an increased risk for suicidality (OR = 1.15, 95% CI: 1.03-1.28). Loneliness explained 16% of the total effect of maternal depressive symptoms on adolescent suicidality (indirect effect OR = 1.02, 95% CI: 1.00-1.04). There was no indirect effect of maternal depressive symptoms on adolescent suicidal outcomes via social withdrawal (indirect effect OR = 1.00, 95% CI: 0.99-1.02). Interventions that target loneliness may be beneficial for decreasing the risk for suicidality among adolescents of mothers with depressive symptoms.

Examining the relationship between anhedonia symptoms and trait positive appraisal style in adolescents: A longitudinal survey study.

INTRODUCTION: Anhedonia, defined as a loss of interest and pleasure in previously enjoyable activities, is a core symptom of depression that predicts a poor treatment response in adolescents. We know little about the cognitive vulnerability factors that contribute to the development of anhedonia in youth. This cross-sectional and longitudinal survey study investigated the link between anhedonia symptoms and cognitive appraisal of positive affect. METHODS: Baseline data were collected from 392 secondary school students in the UK (aged 13-16, 54 % Female), 170 of whom went on to complete the three-month follow-up assessment (a 43 % response rate). Participants rated their anhedonia symptoms and appraisal styles which were measured in terms of use of amplifying appraisals, dampening appraisals, and fear of positive emotion. RESULTS: At baseline, greater anhedonia was significantly associated with increased levels of dampening and reduced levels of amplifying but was not significantly related to fear of positive emotion. Prospectively, greater baseline levels of amplifying uniquely predicted lower anhedonia severity at three-month follow-up, and vice-versa. There was no evidence for reciprocal prospective associations between anhedonia and, appraisal styles of dampening and fear of positive emotion. CONCLUSION: These results indicate that cognitive appraisal of positive affect is associated with concurrent and to some extent can predict future symptoms of anhedonia in youth.

Does fathers' and mothers' rumination predict emotional symptoms in their children?

OBJECTIVES: Although rumination can have a negative influence on the family environment and the quality of parent-child interactions, there is little research on the role of parental rumination in predicting adverse child outcomes over time. This longitudinal study examined whether mothers' and fathers' brooding rumination would each uniquely predict emotional symptoms in preschool children. METHODS: The initial sample consisted of 160 families (including 50 mothers with past depression, 33 fathers with past depression, and 7 fathers with current depression according to the Structural Clinical Interview for DSM-IV). Families were seen at two times separated by 16 months. Children's mean age at the entry into the study was 3.9 years (SD = 0.8). Each parent independently completed the Ruminative Response Scale, the Child Behavior Checklist, the Patient Health Questionnaire, and the Dyadic Adjustment Scale. RESULTS: Fathers' brooding rumination significantly predicted children's emotional symptoms over 16 months when controlling for child emotional symptoms, couple adjustment, parents' depressive symptoms, mothers' brooding and reflective rumination, and fathers' reflective rumination at baseline. Unexpectedly, mothers' brooding rumination did not significantly predict child emotional symptoms over time. Correlational analyses showed significant associations between parents' rumination and lower levels of couple adjustment. CONCLUSIONS: Findings suggest that fathers' brooding rumination may play a unique role in their children's emotional outcomes. If these findings are replicated, studies should examine the processes by which these links occur and their implications for clinical interventions. PRACTITIONER POINTS: Rumination is prevalent among individuals with depression, but to date no studies have examined the possible role of mothers' and fathers' brooding rumination in predicting children's emotional symptoms. Fathers' brooding rumination was positively associated with children's emotional symptoms over time when controlling for mothers' rumination and other important characteristics. Parental rumination might be a promising target for both prevention and intervention strategies for parents with depression and their children. The findings of this study could inform parenting interventions (e.g., educate parents about the possible effects of rumination on family interactions and children's outcomes, help parents notice when they ruminate, teach them to replace rumination with more adaptive strategies). The findings should be interpreted with caution. The study relied on self-reports, and therefore, the data are subject to shared method variance which may have artificially inflated associations between parent and child outcomes. The sample consisted of well-educated parents, and therefore, the findings should be generalized to other populations with caution.

FATHER-CHILD INTERACTIONS AT 3 MONTHS AND 24 MONTHS: CONTRIBUTIONS TO CHILDREN'S COGNITIVE DEVELOPMENT AT 24 MONTHS.

The quality of father-child interactions has become a focus of increasing research in the field of child development. We examined the potential contribution of father-child interactions at both 3 months and 24 months to children's cognitive development at 24 months. Observational measures of father-child interactions at 3 and 24 months were used to assess the quality of fathers' parenting (n = 192). At 24 months, the Mental Developmental Index (MDI) of the Bayley Scales of Infant Development, Second Edition (N. Bayley, ) measured cognitive functioning. The association between interactions and cognitive development was examined using multiple linear regression analyses, adjusting for paternal age, education and depression, infant age, and maternal sensitivity. Children whose fathers displayed more withdrawn and depressive behaviors in father-infant interactions at 3 months scored lower on the MDI at 24 months. At 24 months, children whose fathers were more engaged and sensitive as well as those whose fathers were less controlling in their interactions scored higher on the MDI. These findings were independent of the effects of maternal sensitivity. Results indicate that father-child interactions, even from a very young age (i.e., 3 months) may influence children's cognitive development. They highlight the potential significance of interventions to promote positive parenting by fathers and policies that encourage fathers to spend more time with their young children.

The prevalence of depressive symptoms among fathers and associated risk factors during the first seven years of their child's life: findings from the Millennium Cohort Study.

BACKGROUND: Increasing evidence suggests that postnatal paternal depression is associated with adverse emotional, behavioural and cognitive outcomes in children. Despite this, few studies have determined the prevalence of fathers' depressive symptoms during the first few years of their children's lives and explored what factors are related to these symptoms. We estimated the prevalence and examined associated risk factors of paternal depressive symptoms in a nationally representative sample of fathers with children aged between 9 months and 7 years old from the Millennium cohort study. The risk factors examined were maternal depressive symptoms, marital conflict, child temperament, child gender, paternal education, fathers' ethnic background, fathers' employment status, family housing, family income and paternal age. METHODS: Secondary data analysis was conducted using the UK Millennium cohort study, which consisted of data from England, Scotland, Wales and Northern Ireland of families with infants born in the year 2000/2001. Data from four sweeps were used from when children in the cohort were aged 9 months, 3, 5 and 7 years old (n = 5155-12,396). RESULTS: The prevalence of paternal depressive symptoms over time was 3.6 % at 9 months, 1.2 % at 3 years old, 1.8 % at 5 years and 2.0 % at 7 years (using Kessler cut-off points to categorise high depressive symptoms vs low depressive symptoms). Linear regression trends (using continuous measures of depressive symptoms) indicated that both paternal and maternal depressive symptoms decreased over time, suggesting similar patterns of parents' depressive symptoms after the birth of a child, but the decrease was more evident for mothers. Paternal depressive symptoms were consistently associated with fathers' unemployment, maternal depressive symptoms and marital conflict. Socioeconomic factors such as rented housing when child was 9 months and low family income when child was 5 and 7 years were also associated with higher paternal depressive symptoms. CONCLUSIONS: Paternal depressive symptoms decreased among fathers when their children were aged between 9 months to 3 years old. Paternal unemployment, high maternal depressive symptoms and high marital conflict were important risk factors for paternal depressive symptoms. In light of our findings, we would recommend a more family centred approach to interventions for depression in the postnatal period.

Postnatal paternal depressive symptoms associated with fathers' subsequent parenting: findings from the Millennium Cohort Study.

Impaired parenting may lie on the causal pathway between paternal depression and children's outcomes. We use the first four surveys of the Millennium Cohort Study to investigate the association between paternal depressive symptoms and fathers' parenting (negative, positive and involvement). Findings suggest that postnatal paternal depressive symptoms are associated with fathers' negative parenting. This has implications for the design of intervention programmes for parents with depression and young children.

Intergenerational transmission of parenting: findings from a UK longitudinal study.

BACKGROUND: The quality of parenting is associated with a wide range of child and adult outcomes, and there is evidence to suggest that some aspects of parenting show patterns of intergenerational transmission. This study aimed to determine whether such intergenerational transmission occurs in mothers and fathers in a UK birth cohort. METHODS: The study sample consisted of 146 mothers and 146 fathers who were recruited from maternity wards in England and followed up for 24 months ['Generation 2' (G2)]. Perceptions of their own parenting [by 'Generation1' (G1)] were assessed from G2 parents at 12 months using the Parental Bonding Instrument (PBI). G2 parents were filmed interacting with their 'Generation 3' (G3) children at 24 months. RESULTS: We found that G1 mothers' 'affection' was associated with positive parenting behaviour in the G2 fathers ('positive responsiveness' ß = 0.19, P = 0.04 and 'cognitive stimulation' ß = 0.26, P < 0.01). G1 mothers' 'control' was associated with negative parenting behaviour in G2 mothers (decreased 'engagement' ß = -0.19, P = 0.04), and negative parenting behaviour in G2 fathers (increased 'control' ß = 0.18, P = 0.05). None of the G1 fathers' parenting variables were significantly associated with G2 parenting. CONCLUSIONS: There is evidence of intergenerational transmission of parenting behaviour in this highly educated UK cohort, with reported parenting of grandmothers associated with observed parenting in both mothers and fathers. No association was seen with reported parenting of grandfathers. This raises the possibility that parenting interventions may have benefits that are realised across generations.

Do early father-infant interactions predict the onset of externalising behaviours in young children? Findings from a longitudinal cohort study.

BACKGROUND: Factors related to parents and parenting capacities are important predictors of the development of behavioural problems in children. Recently, there has been an increasing research focus in this field on the earliest years of life, however, relatively few studies have addressed the role of fathers, despite this appearing to be particularly pertinent to child behavioural development. This study aimed to examine whether father-infant interactions at age 3 months independently predicted child behavioural problems at 1 year of age. METHOD: A sample of 192 families was recruited from two maternity units in the United Kingdom. Father-infant interactions were assessed in the family home and coded using the global rating scales. Child behaviour problems were assessed by maternal report. Hierarchical and logistic regression analyses were used to examine associations between father-infant interaction and the development of behavioural problems. RESULTS: Disengaged and remote interactions between fathers and their infants were found to predict externalising behavioural problems at the age of 1 year. The children of the most disengaged fathers had an increased risk of developing early externalising behavioural problems [disengaged (nonintrusive) interactions--adjusted odds ratio 5.33 (95% confidence interval; 1.39, 20.40): remote interactions adj. OR 3.32 (0.92, 12.05)]. CONCLUSIONS: Disengaged interactions of fathers with their infants, as early as the third month of life, predict early behavioural problems in children. These interactions may be critical factors to address, from a very early age in the child's life, and offer a potential opportunity for preventive intervention.

Paternal depression: an examination of its links with father, child and family functioning in the postnatal period.

BACKGROUND: Maternal depression is common and is known to affect both maternal and child health. One of the mechanisms by which maternal depression exerts its effects on child health is through an increased rate of parental disharmony. Fathers also experience depression, but the impact of this on family functioning has been less studied. The aim of this study was to investigate the association between paternal depressive disorder and family and child functioning, in the first 3 months of a child's life. METHODS: A controlled study comparing individual and familial outcomes in fathers with (n = 54) and without diagnosed depressive disorder (n = 99). Parental couple functioning and child temperament were assessed by both paternal and maternal report. RESULTS: Depression in fathers is associated with an increased risk of disharmony in partner relationships, reported by both fathers and their partners, controlling for maternal depression. Few differences in infant's reported temperament were found in the early postnatal period. CONCLUSIONS: These findings emphasize the importance of considering the potential for men, as well as women, to experience depression in the postnatal period. Paternal symptoms hold the potential to impact upon fathers, their partners, and their children.

Paternal psychiatric disorders and children's psychosocial development.

Psychiatric disorders of parents are associated with an increased risk of psychological and developmental difficulties in their children. Most research has focused on mothers, neglecting psychiatric disorders affecting fathers. We review findings on paternal psychiatric disorders and their effect on children's psychosocial development. Most psychiatric disorders that affect fathers are associated with an increased risk of behavioural and emotional difficulties in their children, similar in magnitude to that due to maternal psychiatric disorders. Some findings indicate that boys are at greater risk than girls, and that paternal disorders, compared with maternal disorders, might be associated with an increased risk of behavioural rather than emotional problems. Improved paternal mental health is likely to improve children's wellbeing and life course.

Does the cortisol response to stress mediate the link between expressed emotion and oppositional behavior in Attention-Deficit/Hyperactivity-Disorder (ADHD)?

BACKGROUND: Expressed Emotions (EE) are associated with oppositional behavior (OPB) in children with Attention Deficit/Hyperactivity Disorder (ADHD). EE has been linked to altered stress responses in some disorders, but ADHD has not been studied. We test the hypothesis that OPB in ADHD is mediated by altered stress-related cortisol reactivity to EE. METHODS: Two groups of children (with/without ADHD) and their respective parents were randomly assigned to two different conditions with/without negative emotion and participated in an emotion provocation task. Parents' EE, their ratings of their children's OPB and their children's salivary cortisol levels were measured. RESULTS: Low parental warmth was associated with OPB in ADHD. High levels of parental EE elicited a larger cortisol response. Stress-related cortisol reactivity mediated the EE-OPB link for all children. This highlights the general importance of parent-child interactions on externalizing behavior problems. CONCLUSION: High EE is a salient stressor for ADHD children that leads to increased levels of cortisol and OPB. The development of OPB might be mediated by the stress-response to high EE.

Parents' postnatal depressive symptoms and their children's academic attainment at 16 years: Pathways of risk transmission.

The aim of the study was to examine whether parents' increased postnatal depressive symptoms predicted children's academic attainment over time and whether the parent-child relationship, children's prior academic attainment, and mental health mediated this association. We conducted secondary analyses on the Avon Longitudinal Study of Parents and Children data (12,607 mothers, 9,456 fathers). Each parent completed the Edinburgh-Postnatal Depression Scale at 8 weeks after the child's birth (predictor) and a questionnaire about the mother-child and father-child relationship at 7 years and 1 month (mediator). The children's mental health problems were assessed with the teacher version of the Strengths and Difficulties Questionnaire at 10-11 years (mediator). We used data on the children's academic attainment on UK Key Stage 1 (5-7 years; mediator) and Key Stage 4 (General Certificate of Secondary Education 16 years) (outcome). We adjusted for the parents' education, and child gender and cognitive ability. The results revealed that parents' depressive symptoms at 8 weeks predicted lower academic performance in children at 16 years. Mothers' postnatal depressive symptoms had an indirect effect through children's mental health problems on academic outcomes at 16 years via negative mother-child relationship, and prior academic attainment. There was a significant negative indirect effect of fathers' postnatal depressive symptoms on academic attainment at 16 years via negative father-child relationship on child mental health. The findings suggest that the family environment (parental mental health and parent-child relationship) and children's mental health should be potential targets for support programmes for children of depressed parents.

Delay Aversion in Attention Deficit/Hyperactivity Disorder: an empirical investigation of the broader phenotype.

BACKGROUND: Delay-related motivational processes are impaired in children with Attention Deficit/Hyperactivity Disorder (ADHD). Here we explore the impact of ADHD on the performance of three putative indices of Delay Aversion (DAv): (i) the choice for immediate over delayed reward; (ii) slower reaction times following delay; and (iii) increased delay-related frustration-to see whether these tap into a common DAv construct that differentiates ADHD cases from controls and shows evidence of familiality. METHOD: Seventy seven male and female individuals (age range 6-17) with a research diagnosis combined type ADHD, 65 of their siblings unaffected by ADHD and 50 non-ADHD controls completed three delay tasks. RESULTS: As predicted the size of the correlation between tasks was small but a common latent component was apparent. Children with ADHD differed from controls on all tasks (d=.4-.7) and on an overall DAv index (d=.9): The battery as a whole demonstrated moderate sensitivity and specificity. In general, deficits were equally marked in childhood and adolescence and were independent of comorbid ODD. IQ moderated the effect on the MIDA. Scores on the DAv factor co-segregated within ADHD families. DISCUSSION: There is value in exploring the broader DAv phenotype in ADHD. The results illustrate the power of multivariate approaches to endophenotypes. By highlighting the significant, but limited, role of DAv in ADHD these results are consistent with recent accounts that emphasize neuropsychological heterogeneity.

Dopamine and serotonin transporter genotypes moderate sensitivity to maternal expressed emotion: the case of conduct and emotional problems in attention deficit/hyperactivity disorder.

BACKGROUND: Mothers' positive emotions expressed about their children with attention deficit/hyperactivity disorder (ADHD) are associated with a reduced likelihood of comorbid conduct problems (CP). We examined whether this association with CP, and one with emotional problems (EMO), is moderated by variants within three genes, previously reported to be associated with ADHD and to moderate the impact of environmental risks on conduct and/or emotional problems; the dopamine transporter gene (SLC6A3/DAT1), the dopamine D4 receptor gene (DRD4) and the serotonin transporter gene (SLC6A4/5HTT). METHODS: Seven hundred and twenty-eight males between the ages of 5 and 17 with a DSM-IV research diagnosis of combined type ADHD were included in these analyses. Parents and teachers rated children's conduct and emotional problems. Positive maternal expressed emotion (PMEE) was coded by independent observers on comments made during a clinical assessment with the mother based on current or recent medication-free periods. RESULTS: Sensitivity to the effects of PMEE on CP was moderated by variants of the DAT1 and 5HTT genes. Only children who did not carry the DAT1 10R/10R or the 5HTT l/l genotypes showed altered levels of CP when exposed to PMEE. The effect was most marked where the child with ADHD had both these genotypes. For EMO, sensitivity to PMEE was found only with those who carried the DAT1 9R/9R. There was no effect of DRD4 on CP or EMO. CONCLUSION: The gene-environment interactions observed suggested that genetic make-up can alter the degree of sensitivity an ADHD patients has to their family environment. Further research should focus on distinguishing general sensitivity genotypes from those conferring risk or protective qualities.

Autism symptoms in Attention-Deficit/Hyperactivity Disorder: a familial trait which correlates with conduct, oppositional defiant, language and motor disorders.

It is hypothesised that autism symptoms are present in Attention-Deficit/Hyperactivity Disorder (ADHD), are familial and index subtypes of ADHD. Autism symptoms were compared in 821 ADHD probands, 1050 siblings and 149 controls. Shared familiality of autism symptoms and ADHD was calculated using DeFries-Fulker analysis. Autism symptoms were higher in probands than siblings or controls, and higher in male siblings than male controls. Autism symptoms were familial, partly shared with familiality of ADHD in males. Latent class analysis using SCQ-score yielded five classes; Class 1(31%) had few autism symptoms and low comorbidity; Classes 2-4 were intermediate; Class 5(7%) had high autism symptoms and comorbidity. Thus autism symptoms in ADHD represent a familial trait associated with increased neurodevelopmental and oppositional/conduct disorders.

A small-scale randomized controlled trial of the revised new forest parenting programme for preschoolers with attention deficit hyperactivity disorder.

The revised new forest parenting programme (NFPP) is an 8-week psychological intervention designed to treat ADHD in preschool children by targeting, amongst other things, both underlying impairments in self-regulation and the quality of mother-child interactions. Forty-one children were randomized to either the revised NFPP or treatment as usual conditions. Outcomes were ADHD and ODD symptoms measured using questionnaires and direct observation, mothers' mental health and the quality of mother-child interactions. Effects of the revised NFPP on ADHD symptoms were large (effect size >1) and significant and effects persisted for 9 weeks post-intervention. Effects on ODD symptoms were less marked. There were no improvements in maternal mental health or parenting behavior during mother-child interaction although there was a drop in mothers' negative and an increase in their positive comments during a 5-min speech sample. The small-scale trial, although limited in power and generalizability, provides support for the efficacy of the revised NFPP. The findings need to be replicated in a larger more diverse sample.

Making the worst of a good job: Induced dampening appraisals blunt happiness and increase sadness in adolescents during pleasant memory recall.

Previous work has shown that dampening appraisals (e.g., thinking "this is too good to last") reduce happiness and enhance sadness when adults recall positive events. In contrast, amplifying appraisals (e.g., thinking "this is the sign of good things to come") do not significantly alter affective experience during the same task. The present study examined whether this pattern holds in adolescence. Eighty-nine adolescents completed an uninstructed positive recall task before being randomized to either dampening, uninstructed control or amplifying instructions during a second positive recall task. Participants experienced a significantly smaller increase in happiness and a significantly less marked reduction in sadness when recalling a positive memory under dampening instructions, relative to both the amplifying and no instruction control conditions. There was no significant difference between the amplifying and control conditions. This broadly replicates adult findings, but the detrimental effects of dampening were less marked in adolescents than adults. Nevertheless, given that elevated dampening appraisals are associated with depressed mood, dampening may partly account for why depressed adolescents struggle to experience positive emotions, and represent a promising target for clinical intervention.

DSM-IV combined type ADHD shows familial association with sibling trait scores: a sampling strategy for QTL linkage.

Attention deficit hyperactivity disorder (ADHD) is a discrete clinical syndrome characterized by the triad of inattention, hyperactivity, and impulsivity in the context of marked impairments. Molecular genetic studies have been successful in identifying genetic variants associated with ADHD, particularly with DSM-IV inattentive and combined subtypes. Quantitative trait locus (QTL) approaches to linkage and association mapping have yet to be widely used in ADHD research, although twin studies investigating individual differences suggest that genetic liability for ADHD is continuously distributed throughout the population, underscoring the applicability of quantitative dimensional approaches. To investigate the appropriateness of QTL approaches, we tested the familial association between 894 probands with a research diagnosis of DSM-IV ADHD combined type and continuous trait measures among 1,135 of their siblings unselected for phenotype. The sibling recurrence rate for ADHD combined subtype was 12.7%, yielding a sibling recurrence risk ratio (lambda(sib)) of 9.0. Estimated sibling correlations around 0.2-0.3 are similar to those estimated from the analysis of fraternal twins in population twin samples. We further show that there are no threshold effects on the sibling risk for ADHD among the ADHD probands; and that both affected and unaffected siblings contributed to the association with ADHD trait scores. In conclusion, these data confirm the main requirement for QTL mapping of ADHD by demonstrating that narrowly defined DSM-IV combined type probands show familial association with dimensional ADHD symptom scores amongst their siblings.