Ronald E. Dahl

Childhood and Adolescent Depression: A Review of the Past 10 Years. Part II

OBJECTIVE To qualitatively review the literature of the past decade covering the epidemiology, clinical characteristics, natural course, biology, and other correlates of early-onset major depressive disorder (MDD) and dysthymic disorder (DD). METHOD A computerized search for articles published during the past 10 years was made and selected studies are presented. RESULTS Early-onset MDD and DD are frequent, recurrent, and familial disorders that tend to continue into adulthood, and they are frequently accompanied by other psychiatric disorders. These disorders are usually associated with poor psychosocial and academic outcome and increased risk for substance abuse, bipolar disorder, and suicide. In addition, DD increases the risk for MDD. There is a secular increase in the prevalence of MDD, and it appears that MDD is occurring at an earlier age in successive cohorts. Several genetic, familial, demographic, psychosocial, cognitive, and biological correlates of onset and course of early-onset depression have been identified. Few studies, however, have examined the combined effects of these correlates. CONCLUSIONS Considerable advances have been made in our knowledge of early-onset depression. Nevertheless, further research is needed in understanding the pathogenesis of childhood mood disorders. Toward this end, studies aimed at elucidating mechanisms and interrelationships among the different domains of risk factors are needed.

Adolescent Brain Development: A Period of Vulnerabilities and Opportunities. Keynote Address

Abstract: This article introduces and summarizes the goals of the symposium. It also provides an overview of a conceptual framework for understanding adolescence, which emphasizes how the very nature of this developmental transition requires an interdisciplinary approach—one that focuses on brain/behavior/social‐context interactions during this important maturational period. More specifically it describes a set of neurobehavioral changes that appear to be linked to pubertal development, which appear to have a significant effect on motivation and emotion, and considers these puberty‐specific changes in affect in relation to a much larger set of developmental changes in adolescence. This framework is used to argue for the need for a transdisciplinary dialogue that brings together work in several areas of neuroscience (including animal models) and normal development with clinical and social policy research aimed at early intervention and prevention strategies.

Pathways to adolescent health sleep regulation and behavior

There are several converging reasons to focus on sleep regulation in relation to healthy adolescent development: (a) Sleep appears to be particularly important during periods of brain maturation; (b) there are substantial biological and psychosocial changes in sleep and circadian regulation exist across pubertal development; (c) interactions between physical and psychosocial domains can lead to dramatic alterations in sleep patterns and habits during adolescence; (d) increasing evidence that many adolescents frequently obtain insufficient sleep exists; (e) there is mounting evidence that sleep deprivation has its greatest negative effects on the control of behavior, emotion, and attention, a regulatory interface that is critical in the development of social and academic competence, and psychiatric disorders; (f) the most obvious direct health consequences of insufficient sleep are high-risk behaviors associated with substance abuse and automobile accidents; (g) substantial evidence for bidirectional effects between sleep and behavioral/emotional regulation exists. Although the past decade has seen research progress in these areas, there continue to be major gaps in existing knowledge and a paucity of well-controlled studies to guide specific health policy decisions and recommendations regarding sleep in adolescence. In particular, there is need for improved understanding of the acute and chronic effects of inadequate sleep in adolescents, guidelines for defining adequate sleep in adolescents, and a better delineation of the links among sleep, behavior, and affect regulation. Finally, this paper briefly examines one specific application of this knowledge area regarding early starting times among some high schools.

The regulation of sleep and arousal: Development and psychopathology

Throughout early development, a child spends more time asleep than in any waking activity. Yet, the specific role of sleep in brain maturation is a complete mystery. In this article, the developmental psychobiology of sleep regulation is conceptualized within the context of close links to the control of arousal, affect, and attention. The interactions among these systems are considered from an ontogenetic and evolutionary biological perspective. A model is proposed for the development of sleep and arousal regulation with the following major tenets: 1. Sleep and vigilance represent opponent processes in a larger system of arousal regulation. 2. The regulation of sleep, arousal, affect, and attention overlap in physiological, neuroanatomical, clinical, and developmental domains. 3. Complex interactions among these regulatory systems are modulated and integrated in regions of the prefrontal cortex (PFC). 4. Changes at the level of PFC underlie maturational shifts in the relative balance across these regulatory systems (such as decreases in the depth/length of sleep and increased capacity for vigilance and attention), which occur with normal development. 5. The effects of sleep deprivation (including alterations in attention, emotions, and goal-directed behaviors) also involve changes at the level of PFC integration across regulatory systems. This model is then discussed in the context of developmental pathology in the control of affect and attention, with an emphasis on sleep changes in depression.

The impact of inadequate sleep on children's daytime cognitive function +

This report describes the relationship between sleep and cognitive function in children. As reviewed, the empiric data to directly address the effects of sleep loss or disruption on childrens cognitive function are quite sparse. However, a wide range of clinical and observational data support a general picture that inadequate sleep results in tiredness, difficulties with focussed attention, low threshold to express negative affect (irritability and easy frustration), and difficulty modulating impulses and emotions. In some cases these symptoms may resemble attention deficit hyperactivity disorder. These findings are discussed in relation to a model of sleep loss influencing prefrontal cortex including executive functions involved in the control of attention and emotions.

Amygdala response to facial expressions in children and adults

BACKGROUND The amygdala plays a central role in the human response to affective or emotionally charged stimuli, particularly fear-producing stimuli. We examined the specificity of the amygdala response to facial expressions in adults and children. METHODS Six adults and 12 children were scanned in a 1.5-T scanner during passive viewing of fearful and neutral faces using an EPI BOLD sequence. All scans were registered to a reference brain, and analyses of variance were conducted on the pooled data to examine interactions with age and gender. RESULTS Overall, we observed predominantly left amygdala and substantia innominata activity during the presentation of nonmasked fearful faces relative to fixation, and a decrease in activation in these regions with repeated exposure to the faces. Adults showed increased left amygdala activity for fearful faces relative to neutral faces. This pattern was not observed in the children who showed greater amygdala activity with neutral faces than with fearful faces. For the children, there was an interaction of gender and condition whereby boys but not girls showed less activity with repeated exposure to the fearful faces. CONCLUSIONS This is the first study to examine developmental differences in the amygdala response to facial expressions using functional magnetic resonance imaging.

The role of puberty in the developing adolescent brain.

Adolescence refers to the period of physical and psychological development between childhood and adulthood. The beginning of adolescence is loosely anchored to the onset of puberty, which brings dramatic alterations in hormone levels and a number of consequent physical changes. Puberty onset is also associated with profound changes in drives, motivations, psychology, and social life; these changes continue throughout adolescence. There is an increasing number of neuroimaging studies looking at the development of the brain, both structurally and functionally, during adolescence. Almost all of these studies have defined development by chronological age, which shows a strong—but not unitary—correlation with pubertal stage. Very few neuroimaging studies have associated brain development with pubertal stage, and yet there is tentative evidence to suggest that puberty might play an important role in some aspects of brain and cognitive development. In this paper we describe this research, and we suggest that, in the future, developmental neuroimaging studies of adolescence should consider the role of puberty. Hum Brain Mapp, 2010.

Transitions Into Underage and Problem Drinking: Developmental Processes and Mechanisms Between 10 and 15 Years of Age

Numerous developmental changes occur across levels of personal organization (eg, changes related to puberty, brain and cognitive-affective structures and functions, and family and peer relationships) in the age period of 10 to 15 years. Furthermore, the onset and escalation of alcohol use commonly occur during this period. This article uses both animal and human studies to characterize these multilevel developmental changes. The timing of and variations in developmental changes are related to individual differences in alcohol use. It is proposed that this integrated developmental perspective serve as the foundation for subsequent efforts to prevent and to treat the causes, problems, and consequences of alcohol consumption.

Further studies on periodic limb movement disorder and restless legs syndrome in children with attention-deficit hyperactivity disorder

Fourteen consecutive children who were newly diagnosed with attention‐deficit hyperactivity disorder (ADHD) and who had never been exposed to stimulants and 10 control children without ADHD underwent polysomnographic studies to quantify Periodic Limb Movements in Sleep (PLMS) and arousals. Parents commonly gave both false‐negative and false‐positive reports of PLMS in their children, and a sleep study was necessary to confirm their presence or absence. The prevalence of PLMS on polysomnography was higher in the children with ADHD than in the control subjects. Nine of 14 (64%) children with ADHD had PLMS at a rate of >5 per hour of sleep compared with none of the control children (p <0.0015). Three of 14 children with ADHD (21%) had PLMS at a rate of >20 per hour of sleep. Many of the PLMS in the children with ADHD were associated with arousals. Historical sleep times were less for children with ADHD. The children with ADHD who had PLMS chronically got 43 minutes less sleep at home than the control subjects (p = 0.0091). All nine children with ADHD who had a PLMS index of >5 per hour of sleep had a long‐standing clinical history of sleep onset problems (>30 minutes) and/or maintenance problems (more than two full awakenings nightly) thus meeting the criteria for Periodic Limb Movement Disorder (PLMD). None of the control children had a clinical history of sleep onset or maintenance problems. The parents of the children with ADHD were more likely to have restless legs syndrome (RLS) than the parents of the control children. Twenty‐five of 28 biologic parents of the children with ADHD and all of the biologic parents of the control children were reached for interview. Eight of twenty‐five parents of the children with ADHD (32%) had symptoms of RLS as opposed to none of the control parents (p = 0.011). PLMS may directly lead to symptoms of ADHD through the mechanism of sleep disruption. Alternative explanations for the association between ADHD and RLS/PLMS are that they are genetically linked, they share a common dopaminergic deficit, or both.

Pubertal development and behavior: Hormonal activation of social and motivational tendencies

Adolescence is a time of dramatic changes including rapid physical growth, the onset of sexual maturation, the activation of new drives and motivations, and a wide array of social and affective changes and challenges. This review focuses on behavioral changes in this interval and is organized by the claim that a key set of these adolescent changes are part of a more general re-orientation of social behavior. More specifically we hypothesize that pubertal maturation is associated with the activation of social and motivational tendencies, which in turn influence behavior and emotion in adolescence depending upon interactions with social context. We focus on evidence for two examples of these motivational changes: (1) increases in sensation-seeking (motivational tendency to want to experience high-intensity, exciting experiences) and (2) stronger natural interest in--and pursuit of--contact with peers and potential romantic partners. We consider how these motivational changes contribute to the broader social re-orientation of adolescence, including exploration of social experiences, development of skills and knowledge relevant to taking on adult social roles, individuation from family, and establishment of an individual identity, all of which represent core developmental tasks during this period in the life span (Blakemore, 2008; Dahl & Spear, 2004; Steinberg & Morris, 2000). The paper also emphasizes the importance of investigating and understanding the direct influences of puberty on behavior and disentangling these from the broader set of changes during adolescent development.