What do you call the transition stage from childhood to adulthood that occurs between ages 13 19?

Summary

Adolescence is a transitory period in which an individual shifts from childhood into adulthood. For most, this period is a time of physical, social, and emotional changes. The development that occurs within adolescence is key in setting the stage for adulthood. The age range when an individual will experience adolescence will vary depending on maturity and cultural norms. However, researchers have recently begun to conceptualize adolescence as spanning more years than previously believed. Because adolescence is filled with ambiguity and uncertainty in many areas, self-exploration and identity development are important goals within this transitory period. Although a portion of adolescents will experience a significant amount of turmoil during this time that may interfere with healthy development, most will make the transition into adulthood successfully.

Introduction

Adolescence is the developmental phase during which individuals begin to consolidate a sense of identity, marked by autonomous functioning that will lead to independent living while maintaining secure connections to family, peers, and the broader community. Published research and theory on adolescence appropriately represents the critical importance of understanding this phase in life with numerous journals devoted specifically to this life stage and more than 500 000 articles published in the last decade. The breadth of this research is not only a reflection of the remarkable growth that occurs during this developmental period, but also a reflection of changing perspectives on how to characterize adolescence. Advances in research methodology and changes in the sociohistorical contexts in which development unfolds have created the need to redefine the patterns of adolescent development. Advances in measures of brain functioning and physiological processes have yielded information on developmental change at a more discrete level of analysis. Differences in the social and environmental experiences of today’s adolescents have also created new contexts in which the developmental transitions of this life phase unfold. Adolescents of the twenty-first century are more technologically savvy than previous generations and live in a world marked by increasing cultural and ethnic diversity.

This article reviews some of the most significant normative developmental transitions of adolescence using a contemporary framework. Distinct from the historical and more traditional approaches to development, which are based on linear models of developmental task achievement (i.e., conceptualizing development as a stage-wise progression of changes in separate and different domains), the present framework is defined by two features: First, it stresses an integrative approach that focuses on the interaction and reciprocity of development across different domains of functioning. For example, the biological changes associated with adolescence can be influenced by the familial environment and the physical manifestation of these changes can, in turn, influence the nature of family relationships. Second, this framework acknowledges the heterogeneity in adolescent development. A number of factors, experienced uniquely by individuals during development, can influence the path and timing to reach developmental milestones. Because of these factors, common comparative approaches in research should be replaced by approaches that reflect sensitivity to cultural and other differences in development. The developmental patterns identified among samples of White middle-class adolescents no longer represent this population, and comparing groups of adolescents defined by racial, cultural, socioeconomic, and other group-defining variables obscures the variability in patterns of adaptation and resilience. For example, identity development among immigrant adolescents can be affected by the level of acculturation of the parents and by the demographic constitution of the neighborhood in which the adolescent lives. The article concludes with a discussion of issues which help to link an integrative approach to normative development that is sensitive to individual differences, to prevention, and intervention strategies.

Abstract

During adolescence, major changes take place in NREM sleep slow-wave activity (SWA), a marker of the homeostatic regulation of sleep and its relationship to circadian rhythms. The exponential decrease of SWA during adolescence seems to parallel cortical maturation and may reflect changes in synapse density. This change in the homeostatic regulation of sleep is accompanied by a delay in the circadian phase that reorganizes the alignment of the two processes. As a result, even a well-slept adolescent becomes sleepy in the morning hours and is reluctant to fall asleep at night.

Changes in sleep intensity

Whereas the quantity of NREM sleep (and REM sleep) shows only minor changes during adolescence, the quality does exhibit significant changes. Increased sleep pressure or sleepiness cannot only be reduced by increasing sleep duration but also by an increase in sleep intensity, i.e., an increase in sleep depth. The well-established electrophysiological correlate of sleep intensity is slow wave activity (SWA, electroencephalographic (EEG) power in the low frequency range between 0.5 and 4.5 Hz) during NREM sleep (Borbély and Achermann, 2005). It was noticed early on that high amplitude slow waves predominate in the first 2 h of sleep and decrease thereafter (Blake and Gerard, 1937). It was later shown that the amount of slow wave sleep is positively correlated with the duration of prior waking (Webb and Agnew, 1971), suggesting that this aspect of sleep is homeostatically regulated. Hence, as repeatedly shown in both humans and mammals, SWA increases exponentially with the duration of prior wakefulness and decreases, also exponentially, during sleep, thus reflecting the accumulation of sleep pressure during wakefulness and its release during sleep (Borbély and Achermann, 2005). However, so far it is unknown what mechanism is responsible for the accumulation of sleep pressure during wakefulness and its release during sleep.

Intriguingly, SWA varies strongly with age: In the first years of life, SWA increases with a maximum before puberty and then decreases during adolescence into adulthood, as reported recently using longitudinal data (Campbell and Feinberg, 2009) and earlier with cross-sectional data (Jenni et al., 2005). While the factors underlying such changes are not clear, increasing evidence points to the importance of changes in neural plasticity. During early childhood, neurons grow bushier and establish more numerous connections to other neurons. Moreover, axons initially explore areas much wider than their final targets. Then, in the course of adolescence, more synapses are eliminated than formed (Zuo et al., 2005), in part through activity-dependent processes (Hua and Smith, 2004). Synaptic refinement during adolescence is accompanied by a reorganization of neuronal connections whereby mistargeted axons and unused synapses are eliminated, and connectivity becomes more specific.

As illustrated in Fig. 1, changes in slow-wave amplitude are paralleled by changes in synaptic density (Feinberg, 1982; Huttenlocher and Dabholkar, 1997). This observation has been confirmed both in humans and in rats (Glantz et al., 2007). Moreover, glucose consumption shows a similar profile (Chugani, 1998), presumably due to the increased energy requirements associated with increased synaptic activity. Finally, studies using volume based morphometry and surface based analysis of structural magnetic resonance images directly relate the age dependent changes in SWA to anatomical markers of cortical maturation (Buchmann et al., 2010). The studies show significant associations between the decrease in SWA and gray matter loss predominantly in frontal and parietal brain regions, i.e., areas undergoing maturational changes during adolescence. Of note, the decrease of gray matter volume may be an indirect measure of the reduction in synaptic density, but may also reflect an increased proportion of myelinated axons (Sowell et al., 2004). Interestingly, white matter microstructure, i.e., myelin, seems also to be related to sleep SWA (LeBourgeois et al., 2019; Piantoni et al., 2013).

The changes in connectivity (synaptic or axonal) during adolescence, which are reflected in changes in gray matter, proceeds asynchronously in different brain areas (Paus, 2005), in line with the maturation of specific cognitive functions (Shaw et al., 2006). A study found that the location on the scalp showing maximal SWA underwent a shift from posterior to anterior regions from early childhood to late adolescence (Kurth et al., 2010). This shift along the postero-anterior axis was only present in the SWA frequency range and remained stable across the night. Because anatomical maturation starts in posterior areas and spreads rostrally over the frontal cortex, this observation supports the notion that SWA reflects processes of cortical maturation.

The close relationship between cortical plasticity and sleep SWA may also be reflected by the association of slow waves and synaptic density or strength (Tononi and Cirelli, 2006). For example, using multi-unit activity recordings in rats, Vyazovskiy et al. (Vyazovskiy et al., 2009) demonstrated a relationship between sleep homeostasis and the synchronization of neuronal population activity. Specifically, in early sleep, when sleep SWA is high, they found that most individual neurons stop or resume firing in near synchrony; however, in late sleep, when SWA has dissipated, the entry into “on” and “off” periods was much more variable across neurons. On the other hand, computer simulations, electrophysiological and molecular data support a relationship between sleep homeostasis and synaptic strength, i.e., synaptic strength generally decreases during sleep and increases during wakefulness (Vyazovskiy et al., 2007). Together it seems that synchronization depends on the level of synaptic strength: The denser and stronger synapses are, the faster they synchronize their activity and the larger is the resulting potential change measured by standard EEG over the cortex.

Several studies established the slope of slow waves as a good measure of the synchronization level of neurons in the cortex; i.e., the slope of slow waves may represent a direct electrophysiological measure of changes in synaptic strength or density (Vyazovskiy et al., 2007, 2009). Kurth et al. (2010) compared the slope of slow waves during NREM sleep in pre-pubertal children and mature adolescents and found that the slow wave slope was steeper in pre-pubertal children than in mature adolescents, even when accounting for amplitude differences. This increased slow wave slope in pre-pubertal children likely reflects increased synchronization of cortical activity due to increased synaptic strength or density.

If synaptic strength is a key determinant for the level of synchronization in cortical networks, frequency ranges other than SWA should exhibit age-dependent changes. Indeed, the decrease of sleep EEG power across adolescence is not limited to the SWA frequency range, but also includes the theta range (Buchmann et al., 2010; Campbell and Feinberg, 2009; Kurth et al., 2010). Moreover, the effects of changes in the level of synchronization may not be limited to sleep. EEG recordings during wakefulness showed a similar inverted U-shape time course of EEG power in the alpha frequency range (Gasser et al., 1988). In summary, EEG power during sleep and wakefulness shows a close relationship to anatomical markers of cortical maturation. The strongest relationship is found for SWA during NREM sleep (Buchmann et al., 2010).

An intriguing question is whether the activity of sleep slow waves may not only reflect cortical maturation but also play an active role in restructuring networks. Such a role of slow waves is proposed by the synaptic homeostasis hypothesis (Tononi and Cirelli, 2006). This hypothesis proposes that sleep slow waves contribute to synaptic downscaling, a generalized decrease in synaptic strength that recalibrates neural circuits. Up to now, causal evidence for the specific role of sleep slow waves is limited. However, we have good evidence that sleep SWA can be taken as a reliable indicator of the net changes in average synaptic density/strength in the course of the night (sleep homeostasis), as well as in the course of development. Thus, sleep SWA may be used to monitor synaptic remodeling during childhood and adolescence. Such indicators are of importance because “overpruning” during adolescence has been linked to schizophrenia, mood disorders (Saugstad, 1994), autism, and mental retardation (Tessier and Broadie, 2009). On the other hand, the lack of pruning might also be related to cognitive retardation, as found for instance in continuous spike wave epilepsy (e.g., Tassinari and Rubboli, 2006). The relationship between synaptic restructuring during maturation and psychiatric disorders is of high relevance, as more than 50% of lifetime mental disorders have developed up until the end of adolescence (Kessler et al., 2005).

See also:

Adolescence, Sociology of; Adolescent Behavior: Demographic; Adolescent Development, Theories of; Adolescent Health and Health Behaviors; Adolescent Vulnerability and Psychological Interventions; Adolescent Work and Unemployment; Adolescents: Leisure-time Activities; Adult Development, Psychology of; Adulthood: Developmental Tasks and Critical Life Events; Antisocial Behavior in Childhood and Adolescence; Childhood and Adolescence: Developmental Assets; Cognitive Development in Childhood and Adolescence; Friendship: Development in Childhood and Adolescence; Identity in Childhood and Adolescence; Life Course in History; Social Competence: Childhood and Adolescence; Socialization in Adolescence; Youth Culture, Anthropology of

The concept of adolescence as a stage in the life course has undergone several important changes since the term adolescence was first popularized in the early 1900s. This article details the development of the cultural construct of adolescence in Western societies, as well as the evolution of the study of adolescence in the social sciences. The effects of cultural, economic, and political influences on the length and nature of adolescence are described, as well as the role of institutions in shaping adolescence. The impact of changes in adolescence on family life and parenting are also discussed. The article concludes by addressing the public policy issues surrounding the changing nature of adolescence, the current place of adolescence in social science research, and directions for further research.

Abstract

Adolescence is the phase of transition from being a child to an adult which is roughly considered to be the period between 11 and 19 years of age. The adolescent experiences not only physical growth and change, but also emotional, psychological, social, and mental change and growth. Adolescence can be broadly categorized as three stages – early adolescence (approximation age 11 to 13 years), middle adolescence (approximation age 14 to 17 years), and late adolescence (approximation age 17 to 19 years). Moreover, a stage of emerging adulthood has been introduced for the years 18 to 25 which is, however, a controversial and conditional phase. I will present and discuss the first three stages of the development of adolescence, and why they differ from one another. The biological perspective in terms of physical, sexual, brain, and related emotional development is discussed first. Cognitive development is then discussed, followed by social development, and then identity and mental health development. Finally, the emerging adulthood period is presented.

Key Facts of Adolescence

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Adolescence is a transitional period between childhood and adulthood, generally considered to last between from about 12 years old until the mid-20s.

Adolescence is an evolutionarily conserved developmental period across species, including in laboratory rats and mice.

The brain continues to develop during adolescence, with the PFC among the last brain regions to reach maturity.

Many disorders that are characterized by prefrontal cortex dysregulation, such as schizophrenia, drug dependence, and mood disorders, have their onset during adolescence.

The extensive cognitive, behavioral, and neurobiological development that occurs during adolescence is thought to confer heightened vulnerability to disorders with an adolescent onset.

Introduction

Adolescence has been a social stage of keen interest in anthropology with culture the distinguishing feature that sets this disciplinary approach apart from others. An anthropology of adolescence encompasses both sociocultural and biological aspects with the latter focusing on reproduction and the physical maturation of the young person. Of course, pubescence and the associated physical changes occur universally, but it is their meanings within sociocultural contexts along with other domains of development that have been of interest in anthropology. Puberty, as a signifier of biological adolescence, is recognized cross-culturally, but the question is whether a social adolescence is also universal. Accounting for variations in timing, meaning, and expectations, there is something of an intervening social stage of adolescence in numerous traditional cultures worldwide. An anthropological approach to adolescence is also characterized by interest in the impacts of society on the young person as well as the young person's impacts on and contributions toward maintenance and stability of society. The functions of initiations, rites of passage, and coming-of-age ceremonies encompass both aspects and are examined in this article.

Abstract

Adolescence is marked by rapid and dramatic intraindividual changes in the realms of biology, cognition, emotion, and interpersonal relationships, and by equally impressive transformations in the major contexts in which youth spend their time. As a formative period, adolescence is important to the study of developmental psychopathology because of critical changes in patterns of emotional and behavioral difficulty that occur during this period. In this article, we use a developmental psychopathology perspective to discuss the specific challenges and opportunities associated with adolescence. We first describe several principles associated with the developmental psychopathology perspective that are particularly relevant to adolescence research. We provide illustrations of these principles using recent research involving risk taking, internalizing, externalizing, and substance use problems. We then provide evidence for adolescence as a unique developmental period characterized by heightened vulnerability to psychological symptoms and maladjustment. We conclude with implications for prevention and intervention efforts that stem from this developmental psychopathology perspective.