Irritability , defined as low tolerance for frustration and characterized by outbursts of anger and bad temper, is a common, stable and damaging mood symptom in youth and one of the most common reasons for referral to treatment . Irritability is a criterion for several emotional and behavioral disorders, including major depressive disorder (MDD), generalized anxiety disorder (GAD), and oppositional defiant disorder (ODD), and is the cardinal feature of disruptive mood dysregulation disorder. .
Longitudinal studies found that chronic irritability in schoolchildren and adolescents predicts emotional disorders, specifically depressive and anxiety disorders, and suicidality in adulthood. Youth irritability has also been associated with significant functional impairment, even in the absence of psychiatric disorders, with less educational and economic achievement. Furthermore, it has been linked to externalizing behavior problems in youth, which may explain the comorbidity between internalizing and externalizing disorders and the link between ODD in youth and depression in adulthood.
Based on findings in older youth, the authors observed that chronic irritability predicted depression at age three and oppositional defiant disorder (ODD) and poor functioning at age six, above baseline psychopathology. Although irritability is relatively common in early childhood, these findings provide compelling evidence that frequent irritability in early childhood is useful in identifying high-risk children.
In this article, we aim to extend the findings by testing the longitudinal associations between preschool irritability and clinical outcomes at nine years of age. The primary objective was to examine whether chronic irritability assessed at age three predicts psychiatric disorders and symptoms, functional impairment, and service use at age nine. It was hypothesized that preschool chronic irritability would prospectively predict depression, anxiety, and disruptive behavioral disorders (DBD) at age nine. It would also predict greater functional disability and service use at that age, even after accounting for baseline psychiatric disorders. Additionally, we assessed whether associations between preschool irritability and clinical outcomes at age nine differed by gender.
| Method |
The Stony Brook Temperament Study is a longitudinal study that investigated the role of early temperament in the development of psychiatric disorders. To do this, families with three-year-old children without significant medical problems or developmental disabilities were recruited. 541 families were enrolled, and 446 participated in the nine-year follow-up.
At 3 years of age, potential psychiatric disorders were evaluated using the Preschool Psychiatric Evaluation (EPEP). Disorders included any MDD (dysthymic disorder, depressive disorder not otherwise specified [NDD]); any anxiety disorder (specific phobia, separation anxiety, social phobia, GAD, agoraphobia, selective mutism); attention deficit/hyperactivity disorder (ADHD) and ODD. Six items from the EPEP were used to assess preschool irritability: 1) irritable mood (depression section), 2) feelings of anger/bad mood under minor provocation (depression section), 3) displays of anger under minor provocation. (depression section), (4) feelings of frustration under minor provocation (depression section), 5) discrete episodes of tempering without violence (TOD section), and 6) discrete episodes of excessive tempering, manifested by screaming, crying, or kicking , and/or with violence/harm (TOD section). EPEP items were rated according to their intensity, frequency, and duration.
The nine-year assessment included an interview with the parents and the child using the Kiddie-Schedule of Affective Disorders and Schizophrenia–Present and Lifetime (K-SADS-PL). Summary ratings for each symptom were derived based on the combined parent and child reports. Diagnoses were derived for any depressive disorder (MDD, dysthymic disorder, depressive disorder-NDD); any anxiety disorder (specific phobia, social phobia, separation anxiety, GAD, panic, agoraphobia, obsessive-compulsive, post-traumatic stress, acute stress, anxiety disorder-NDD); any TCD (ODD, conduct disorder, TCD-TDNE); and any ADHD (ADHD-inattention, hyperactivity or combined type, ADHD-NDD).
Parents and children also completed the Children’s Depression Inventory (IDI) and the Screening for Childhood Anxiety-Related Disorders (SCARED) to assess children’s depressive and anxiety symptoms, respectively.
The K-SADS interviewer completed the Child Global Assessment Scale (EEGI), which allows for a global measure of children’s level of functioning. Scores range from 0 to 100, where 0 indicates the worst functioning and 100 indicates the best functioning. Impairment was also rated in several domains (relationship with parents, domestic and recreational activities, relationships with siblings and peers, school life, general satisfaction) on a 5-point scale ranging from 0 (very good functioning/no impairment) to 4 (very poor functioning/severe impairment) and averaged across domains for a total score. The same interviewer assessed whether the child ever received psychotherapy or was prescribed psychotropic medication for a mental health problem, and the age at which treatment began.
| Results |
Sex, child age, and parental education were examined as covariates. Boys were more likely to meet current and lifetime criteria for ADHD and TCD, higher IDI scores, higher rates of impairment, and lower EEGI scores at age nine than girls. If neither parent was a college student, children were more likely to meet current and lifetime social phobia criteria, higher mother-rated IDI and SCARED scores, higher impairment ratings, and lower EEGI scores at nine years old than children with at least one university-educated parent.
> Preschool irritability as a predictor of psychiatric disorders at nine years of age. Irritability at age three significantly predicted anxiety disorders, specific phobia, separation anxiety, GAD, ADHD, and TCD at age nine. After controlling for the corresponding baseline disorder, preschool irritability remained a significant predictor of any current and lifetime anxiety disorder and GAD, and current separation anxiety disorder.
> Preschool irritability as a predictor of psychiatric symptoms at nine years of age. Irritability at age three significantly predicted K-SADS, ADHD, and TCD current anxiety symptom scale scores, and parent-reported IDI and SCARED total scores at age nine. All associations remained significant in adjusted models, except for ADHD symptoms.
> Preschool irritability as a predictor of functional impairment and use of services at nine years of age. Irritability at three years significantly predicted lower EEGI scores and higher mean impairment ratings at nine years. These associations remained significant after controlling for any psychiatric disorder at three years. Furthermore, preschool irritability significantly predicted the use of outpatient treatment and a younger age of treatment initiation.
> Possible gender differences. Preschool irritability predicted lifetime anxiety disorder at age nine for girls, but not for boys. In contrast, preschool irritability predicted current and lifetime ADHD at age nine for boys, but not for girls. Because children with current or lifetime ADHD were the same subgroup of 58 children, the results were identical for current and lifetime ADHD.
| Discussion |
The authors previously reported that chronic irritability at age three predicted depression, ODD, and poorer functioning at age six, above baseline psychopathology.
For this report, they examined longitudinal associations between chronic irritability symptoms at three years and clinical outcomes at nine years. They found that chronic irritability at three years predicted any current and lifetime anxiety disorder, current and lifetime GAD, and current separation anxiety, after controlling for baseline anxiety disorders. Additionally, preschool irritability predicted increases in anxiety symptoms and TCD symptoms on the K-SADS, and maternal and paternal reports of depressive and anxious symptoms on the IDI and SCARED. Finally, preschool irritability predicted greater functional impairment and use of outpatient treatment, even after controlling for psychiatric disorders at baseline.
In contrast to the associations observed at age six, preschool irritability showed the most consistent predictive associations with anxiety disorders at age nine, including GAD and separation anxiety and predicted increases in anxiety symptoms between ages three and nine. nine years. These findings are consistent with long-term follow-up studies of irritability in older youth demonstrating that irritability predicts anxiety disorders, particularly GAD, in adulthood. The association between preschool irritability and childhood GAD is especially notable given that childhood GAD predicts poorer adult outcomes across functional domains and accounts for the longitudinal association between childhood anxiety and adult depression.
Although preschool irritability did not predict current or lifetime depressive disorders or symptoms based on the K-SADS, it did predict increases in parental reports of depressive symptoms on the IDI. The association between preschool irritability and increased depressive symptoms at age nine is consistent with evidence linking irritability in youth with later depressive disorders and findings supporting their shared genetic influences.
While current and lifetime depressive disorders were rare at age nine according to the K-SADS, the IDI was more sensitive to variations in depressive symptoms among youth at the lower end of the continuum. Furthermore, depressive symptoms in middle childhood are moderately stable and have clinical importance in predicting the onset of depressive disorders and functional impairment.
Preschool irritability also predicted current and lifetime TCD and ADHD disorders and symptoms. However, in adjusted models controlling for diagnosis or baseline symptoms, only the association between preschool irritability and CDD symptoms at age 9 remained. Studies in older youth have also reported that irritability is simultaneously and longitudinally associated with both emotional and behavioral disorders in adolescence. Irritability predicts both externalizing and internalizing problems and likely plays a role in the longitudinal associations between externalizing problems and depression. Irritability may be an important phenotype that crosses diagnostic categories and may help identify unique and overlapping mechanisms in youth psychopathology.
Chronic irritability at age three predicted impairment across multiple functional domains, mental health service use, and younger age at treatment initiation. The associations between preschool irritability and later functional impairment and service use persisted even after controlling for preschool psychiatric disorders. These findings strongly argue for early identification of chronic irritability in young children and the importance of intervening as early as possible.
Furthermore, to develop effective interventions for this high-risk group, the processes and mechanisms by which irritability in young children leads to disability and referral to treatment need to be identified. Irritable youth are likely to have a wide variety of deficits in social, emotional, and cognitive control processes, and in underlying neurodevelopmental brain circuit processes that contribute to functional impairment. Thus, identifying the multiple determinants involved in the etiology and maintenance of irritability will help determine treatment goals.
Differences are frequently observed in psychiatric symptoms and disorders across the lifespan. The authors found that preschool irritability predicted lifetime anxiety disorder at age nine only for girls, and preschool irritability predicted current and future ADHD at age nine only for boys. No gender differences were observed for other diagnoses, symptom scales, impairment, or service use.
Because these associations were specific, they should be interpreted with caution. However, these findings provide important information: irritability may play a different role in the pathways of psychopathology for girls and boys. It will be important for future research to continue examining gender differences in developmental trajectories from childhood irritability to later psychopathology.
In summary, the findings underscore the clinical importance of irritability in early childhood.
Preschool irritability predicted anxiety disorders, increased anxiety, depression, and CDD symptoms, functional impairment, and service use six years later, even after controlling for baseline psychopathology. More longitudinal work is needed to delineate the processes through which preschool irritability develops into adolescent and adult phenotypes. Finally, future research should examine the mechanisms involved in early chronic irritability, including genetic factors and environmental influences, as well as the associated affective and cognitive processes and neurological circuits.
