Chapter 6: Adolescence
Growth in Adolescence
Puberty is a period of rapid growth and sexual maturation. These changes begin sometime l
between eight and fourteen. Girls begin puberty at around ten years of age and boys begin
approximately two years later. Pubertal changes take around three to four years to complete.
Adolescents experience an overall physical growth spurt. The growth proceeds from the
extremities toward the torso. This is referred to as distalproximal development. First the hands
grow, then the arms, hand finally the torso. The overall physical growth spurt results in 10-11
inches of added height and 50 to 75 pounds of increased weight. The head begins to grow
sometime after the feet have gone through their period of growth. Growth of the head is
preceded by growth of the ears, nose, and lips. The difference in these patterns of growth result
in adolescents appearing awkward and out-of-proportion. As the torso grows, so do the internal
organs. The heart and lungs experience dramatic growth during this period.
During childhood, boys and girls are quite similar in height and weight. However, gender
differences become apparent during adolescence. From approximately age ten to fourteen, the
average girl is taller, but not heavier, than the average boy. After that, the average boy becomes
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both taller and heavier, although individual differences are certainly noted. As adolescents
physically mature, weight differences are more noteworthy than height differences. At eighteen
years of age, those that are heaviest weigh almost twice as much as the lightest, but the tallest
teens are only about 10% taller than the shortest (Seifert, 2012).
Both height and weight can certainly be sensitive issues for some teenagers. Most modern
societies, and the teenagers in them, tend to favor relatively short women and tall men, as well as
a somewhat thin body build, especially for girls and women. Yet, neither socially preferred
height nor thinness is the destiny for many individuals. Being overweight, in particular, has
become a common, serious problem in modern society due to the prevalence of diets high in fat
and lifestyles low in activity (Tartamella et al., 2004). The educational system has, unfortunately,
contributed to the problem as well by gradually restricting the number of physical education
courses and classes in the past two decades.
Average height and weight are also related somewhat to racial and ethnic background. In
general, children of Asian background tend to be slightly shorter than children of European and
North American background. The latter in turn tend to be shorter than children from African
societies (Eveleth & Tanner, 1990). Body shape differs slightly as well, though the differences
are not always visible until after puberty. Asian background youth tend to have arms and legs
that are a bit short relative to their torsos, and African background youth tend to have relatively
long arms and legs. The differences are only averages, as there are large individual differences as
well.
Sexual Development
Typically, the growth spurt is followed by the development of sexual maturity. Sexual changes
are divided into two categories: Primary sexual characteristics and secondary sexual
characteristics. Primary sexual characteristics are changes in the reproductive organs. For
males, this includes growth of the testes, penis, scrotum, and spermarche or first ejaculation of
semen. This occurs between 11 and 15 years of age. For females, primary characteristics include
growth of the uterus and menarche or the first menstrual period. The female gametes, which
are stored in the ovaries, are present at birth, but are immature. Each ovary contains about
400,000 gametes, but only 500 will become mature eggs (Crooks & Baur, 2007). Beginning at
puberty, one ovum ripens and is released about every 28 days during the menstrual cycle. Stress
and higher percentage of body fat can bring menstruation at younger ages.
Male Anatomy: Males have both internal and external genitalia that are responsible for
procreation and sexual intercourse. Males produce their sperm on a cycle, and unlike the female's
ovulation cycle, the male sperm production cycle is constantly producing millions of sperm
daily. The main male sex organs are the penis and the testicles, the latter of which produce
semen and sperm. The semen and sperm, as a result of sexual intercourse, can fertilize an ovum
in the female's body; the fertilized ovum (zygote) develops into a fetus which is later born as a
child.
Female Anatomy: Female
external genitalia is collectively
known as the vulva, which
includes the mons veneris, labia
majora, labia minora, clitoris,
vaginal opening, and urethral
opening. Female internal
reproductive organs consist of
the vagina, uterus, fallopian
tubes, and ovaries. The uterus
hosts the developing fetus,
produces vaginal and uterine
secretions, and passes the male's
sperm through to the fallopian
tubes while the ovaries release
the eggs. A female is born with
all her eggs already produced.
The vagina is attached to the
uterus through the cervix, while the uterus is attached to the ovaries via the fallopian tubes.
Females have a monthly reproductive cycle; at certain intervals the ovaries release an egg, which
passes through the fallopian tube into the uterus. If, in this transit, it meets with sperm, the sperm
might penetrate and merge with the egg, fertilizing it. If not fertilized, the egg is flushed out of
the system through menstruation.
Secondary sexual characteristics are visible physical
changes not directly linked to reproduction but signal
sexual maturity. For males this includes broader shoulders
and a lower voice as the larynx grows. Hair becomes
coarser and darker, and hair growth occurs in the pubic
area, under the arms and on the face. For females, breast
development occurs around age 10, although full
development takes several years. Hips broaden, and pubic
and underarm hair develops and also becomes darker and
coarser.
Acne: An unpleasant consequence of the hormonal changes in puberty is acne, defined as
pimples on the skin due to overactive sebaceous (oil-producing) glands (Dolgin, 2011). These
glands develop at a greater speed than the skin ducts that discharges the oil. Consequently, the
ducts can become blocked with dead skin and acne will develop. According to the University of
California at Los Angeles Medical Center (2000), approximately 85% of adolescents develop
acne, and boys develop acne more than girls because of greater levels of testosterone in their
systems (Dolgin, 2011). Experiencing acne can lead the adolescent to withdraw socially,
especially if they are self-conscious about their skin or teased (Goodman, 2006).
Effects of Pubertal Age: The age of puberty is getting younger for children throughout the
world. According to Euling et al. (2008) data are sufficient to suggest a trend toward an earlier
breast development onset and menarche in girls. A century ago the average age of a girl’s first
period in the United States and Europe was 16, while today it is around 13. Because there is no
clear marker of puberty for boys, it is harder to determine if boys are maturing earlier too. In
addition to better nutrition, less positive reasons associated with early puberty for girls include
increased stress, obesity, and endocrine disrupting chemicals.
Cultural differences are noted with Asian-American girls, on average, developing last, while
African American girls enter puberty the earliest. Hispanic girls start puberty the second earliest,
while European-American girls rank third in their age of starting puberty. Although African
American girls are typically the first to develop, they are less likely to experience negative
consequences of early puberty when compared to European-American girls (Weir, 2016).
Research has demonstrated mental health problems linked to children who begin puberty earlier
than their peers. For girls, early puberty is associated with depression, substance use, eating
disorders, disruptive behavior disorders, and early sexual behavior (Graber, 2013). Early
maturing girls demonstrate more anxiety and less confidence in their relationships with family
and friends, and they compare themselves more negatively to their peers (Weir, 2016).
Problems with early puberty seem to be due to the mismatch between the child’s appearance and
the way she acts and thinks. Adults especially may assume the child is more capable than she
actually is, and parents might grant more freedom than the child’s age would indicate. For girls,
the emphasis on physical attractiveness and sexuality is emphasized at puberty and they may lack
effective coping strategies to deal with the attention they may receive.
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Figure 6.4
Source
Additionally, mental health problems are more likely to occur when
the child is among the first in his or her peer group to develop.
Because the preadolescent time is one of not wanting to appear
different, early developing children stand out among their peer group
and gravitate toward those who are older. For girls, this results in
them interacting with older peers who engage in risky behaviors such
as substance use and early sexual behavior (Weir, 2016).
Boys also see changes in their emotional functioning at puberty.
According to Mendle, Harden, Brooks-Gunn, and Graber (2010),
while most boys experienced a decrease in depressive symptoms
during puberty, boys who began puberty earlier and exhibited a rapid
tempo, or a fast rate of change, actually increased in depressive
symptoms. The effects of pubertal tempo were stronger than those of
pubertal timing, suggesting that rapid pubertal change in boys may be a more important risk
factor than the timing of development. In a further study to better analyze the reasons for this
change, Mendle et al. (2012) found that both early maturing boys and rapidly maturing boys
displayed decrements in the quality of their peer relationships as they moved into early
adolescence, whereas boys with more typical timing and tempo development actually
experienced improvements in peer relationships. The researchers concluded that the transition in
peer relationships may be especially challenging for boys whose pubertal maturation differs
significantly from those of others their age. Consequences for boys attaining early puberty were
increased odds of cigarette, alcohol, or another drug use (Dudovitz, et al., 2015).
Gender Role Intensification: At about the same
time that puberty accentuates gender, role
differences also accentuate for at least some
teenagers. Some girls who excelled at math or
science in elementary school, may curb their
enthusiasm and displays of success at these
subjects for fear of limiting their popularity or
attractiveness as girls (Taylor et al/, 1995; Sadker,
2004). Some boys who were not especially
interested in sports previously may begin
dedicating themselves to athletics to affirm their
masculinity in the eyes of others. Some boys and
girls who once worked together successfully on
class projects may no longer feel comfortable
doing so, or alternatively may now seek to be working partners, but for social rather than
academic reasons. Such changes do not affect all youngsters equally, nor affect any one
youngster equally on all occasions. An individual may act like a young adult on one day, but
more like a child the next.
Adolescent Brain
The brain undergoes dramatic changes during adolescence. Although it does not get larger, it
matures by becoming more interconnected and specialized (Giedd, 2015). The myelination and
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development of connections between neurons continues. This results in an increase in the white
matter of the brain and allows the adolescent to make significant improvements in their thinking
and processing skills. Different brain areas become myelinated at different times. For example,
the brain’s language areas undergo myelination during the first 13 years. Completed insulation
of the axons consolidates these language skills but makes it more difficult to learn a second
language. With greater myelination, however, comes diminished plasticity as a myelin coating
inhibits the growth of new connections (Dobbs, 2012).
Even as the connections between neurons are strengthened, synaptic pruning occurs more than
during childhood as the brain adapts to changes in the environment. This synaptic pruning
causes the gray matter of the brain, or the cortex, to become thinner but more efficient (Dobbs,
2012). The corpus callosum, which connects the two hemispheres, continues to thicken allowing
for stronger connections between brain areas. Additionally, the hippocampus becomes more
strongly connected to the frontal lobes, allowing for greater integration of memory and
experiences into our decision making.
The limbic system, which regulates emotion
and reward, is linked to the hormonal changes
that occur at puberty. The limbic system is
also related to novelty seeking and a shift
toward interacting with peers. In contrast, the
prefrontal cortex which is involved in the
control of impulses, organization, planning,
and making good decisions, does not fully
develop until the mid-20s. According to
Giedd (2015) the significant aspect of the
later developing prefrontal cortex and early
development of the limbic system is the
“mismatch” in timing between the two. The
approximately ten years that separates the
development of these two brain areas can result in risky behavior, poor decision making, and
weak emotional control for the adolescent. When puberty begins earlier, this mismatch extends
even further.
Teens often take more risks than adults and according to research it is because they weigh risks
and rewards differently than adults do (Dobbs, 2012). For adolescents the brain’s sensitivity to
the neurotransmitter dopamine peaks, and dopamine is involved in reward circuits, so the
possible rewards outweighs the risks. Adolescents respond especially strongly to social rewards
during activities, and they prefer the company of others their same age. Chein et al. (2011)
found that peers sensitize brain regions associated with potential rewards. For example,
adolescent drivers make risky driving decisions when with friends to impress them, and teens are
much more likely to commit crimes together in comparison to adults (30 and older) who commit
them alone (Steinberg et al., 2017). In addition to dopamine, the adolescent brain is affected by
oxytocin which facilitates bonding and makes social connections more rewarding. With both
dopamine and oxytocin engaged, it is no wonder that adolescents seek peers and excitement in
their lives that could end up actually harming them.
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Because of all the changes that occur in the adolescent brain, the chances for abnormal
development can occur, including mental illness. In fact, 50% of the mental illness occurs by the
age 14 and 75% occurs by age 24 (Giedd, 2015). Additionally, during this period of
development the adolescent brain is especially vulnerable to damage from drug exposure. For
example, repeated exposure to marijuana can affect cellular activity in the endocannabinoid
system. Consequently, adolescents are more sensitive to the effects of repeated marijuana
exposure (Weir, 2015).
However, researchers have also focused on the highly adaptive qualities of the adolescent brain
which allow the adolescent to move away from the family towards the outside world (Dobbs,
2012; Giedd, 2015). Novelty seeking and risk taking can generate positive outcomes including
meeting new people and seeking out new situations. Separating from the family and moving into
new relationships and different experiences are actually quite adaptive for society.
Adolescent Sleep
According to the National Sleep Foundation (NSF) (2016), adolescents need about 8 to 10 hours
of sleep each night to function best. The most recent Sleep in America poll in 2006 indicated
that adolescents between sixth and twelfth grade were not getting the recommended amount of
sleep. On average adolescents only received 7 ½ hours of sleep per night on school nights with
younger adolescents getting more than older ones (8.4 hours for sixth graders and only 6.9 hours
for those in twelfth grade). For the older adolescents, only about one in ten (9%) get an optimal
amount of sleep, and they are more likely to experience negative consequences the following
day. These include feeling too tired or sleepy, being cranky or irritable, falling asleep in school,
having a depressed mood, and drinking caffeinated beverages (NSF, 2016). Additionally, they
are at risk for substance abuse, car crashes, poor academic performance, obesity, and a weakened
immune system (Weintraub, 2016).
Troxel et al. (2019) found that insufficient sleep in adolescents is a predictor of risky sexual
behaviors. Reasons given for this include that those adolescents who stay out late, typically
without parental supervision, are more likely to engage in a variety of risky behaviors, including
risky sex, such as not using birth control or using substances before/during sex. An alternative
explanation for risky sexual behavior is that the lack of sleep negatively affects impulsivity and
decision-making processes.
Figure 6.7
Source
Why do adolescents not get adequate sleep? In addition
to known environmental and social factors, including work,
homework, media, technology, and socializing, the
adolescent brain is also a factor. As adolescent go through
puberty, their circadian rhythms change and push back their
sleep time until later in the evening (Weintraub, 2016).
This biological change not only keeps adolescents awake at
night, it makes it difficult for them to wake up. When they
are awake too early, their brains do not function optimally.
Impairments are noted in attention, academic achievement,
and behavior while increases in tardiness and absenteeism
are also seen.
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To support adolescents’ later sleeping schedule, the Centers for Disease Control and Prevention
recommended that school not begin any earlier than 8:30 a.m. Unfortunately, over 80% of
American schools begin their day earlier than 8:30 a.m. with an average start time of 8:03 a.m.
(Weintraub, 2016). Psychologists and other professionals have been advocating for later school
times, and they have produced research demonstrating better student outcomes for later start
times. More middle and high schools have changed their start times to better reflect the sleep
research. However, the logistics of changing start times and bus schedules are proving too
difficult for some schools leaving many adolescent vulnerable to the negative consequences of
sleep deprivation. Troxel et al. (2019) cautions that adolescents should find a middle ground
between sleeping too little during the school week and too much during the weekends. Keeping
consistent sleep schedules of too little sleep will result in sleep deprivation but oversleeping on
weekends can affect the natural biological sleep cycle making it harder to sleep on weekdays.
Adolescent Sexual Activity
By about age ten or eleven, most children experience increased sexual attraction to others that
affects social life, both in school and out (McClintock & Herdt, 1996). By the end of high
school, more than half of boys and girls report having experienced sexual intercourse at least
once, though it is hard to be certain of the proportion because of the sensitivity and privacy of the
information. (Center for Disease Control, 2004; Rosenbaum, 2006).
Adolescent Pregnancy: As
can be seen in Figure 6.8, in
2018 females aged 15–19
years experienced a birth rate
(live births) of 17.4 per 1,000
women. The birth rate for
teenagers has declined by
58% since 2007 and 72%
since 1991, the most recent
peak (Hamilton, Joyce,
Martin, & Osterman, 2019).
It appears that adolescents
seem to be less sexually
active than in previous years,
and those who are sexually
active seem to be using birth
control (CDC, 2016).
Figure 6.8
Source
Risk Factors for Adolescent Pregnancy: Miller et al. (2001) found that parent/child closeness,
parental supervision, and parents' values against teen intercourse (or unprotected intercourse)
decreased the risk of adolescent pregnancy. In contrast, residing in disorganized/dangerous
neighborhoods, living in a lower SES family, living with a single parent, having older sexually
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active siblings or pregnant/parenting teenage sisters, early puberty, and being a victim of sexual
abuse place adolescents at an increased risk of adolescent pregnancy.
Consequences of Adolescent Pregnancy: After the child is born life can be difficult for a
teenage mother. Only 40% of teenagers who have children before age 18 graduate from high
school. Without a high school degree her job prospects are limited, and economic independence
is difficult. Teen mothers are more likely to live in poverty, and more than 75% of all unmarried
teen mother receive public assistance within 5 years of the birth of their first child.
Approximately, 64% of children born to an unmarried teenage high-school dropout live in
poverty. Further, a child born to a teenage mother is 50% more likely to repeat a grade in school
and is more likely to perform poorly on standardized tests and drop out before finishing high
school (March of Dimes, 2012).
Research analyzing the age that men father their first child and how far they complete their
education have been summarized by the Pew Research Center (2015) and reflect the research for
females. Among dads ages 22 to 44, 70% of those with less than a high school diploma say they
fathered their first child before the age of 25. In comparison, less than half (45%) of fathers with
some college experience became dads by that age. Additionally, becoming a young father occurs
much less for those with a bachelor’s degree or higher as just 14% had their first child prior to
age 25. Like men, women with more education are likely to be older when they become
mothers.
Eating Disorders
Figure 6.9
According to the DSM-5-TR (American Psychiatric
Association, 2022), eating disorders are characterized by a
persistent disturbance of eating or eating-related behavior that
results in the altered consumption or absorption of food and
that significantly impairs physical health or psychosocial
functioning. Although eating disorders can occur in children
and adults, they frequently appear during the teen years or
young adulthood (National Institute of Mental Health (NIMH),
2016). Eating disorders affect both genders, although rates
among women are 2½ times greater than among men. Similar
to women who have eating disorders, men also have a distorted
sense of body image, including muscle dysmorphia, which is
an extreme desire to increase one’s muscularity (Bosson et al.,
2019). The prevalence of eating disorders in the United States is similar among Non-Hispanic
Whites, Hispanics, African-Americans, and Asians, with the exception that anorexia nervosa is
more common among Non-Hispanic Whites (Hudson et al., 2007; Wade et al., 2011).
Source
Risk Factors for Eating Disorders: Because of the high mortality rate, researchers are looking
into the etiology of the disorder and associated risk factors. Researchers are finding that eating
disorders are caused by a complex interaction of genetic, biological, behavioral, psychological,
and social factors (NIMH, 2016). Eating disorders appear to run in families, and researchers are
working to identify DNA variations that are linked to the increased risk of developing eating
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disorders. Researchers from King’s College London (2019) found that the genetic basis of
anorexia overlaps with both metabolic and body measurement traits. The genetic factors also
influence physical activity, which may explain the high activity level of those with anorexia.
Further, the genetic basis of anorexia overlaps with other psychiatric disorders. Researchers have
also found differences in patterns of brain activity in women with eating disorders in comparison
with healthy women.
The main criteria for the most common eating disorders: Anorexia nervosa, bulimia nervosa,
and binge-eating disorder are described in the DSM-5-TR (American Psychiatric Association,
2022) and listed in Table 6.1.
Table 6.1 DSM-5-TR Eating Disorders
Anorexia Nervosa
Restriction of energy intake leading to a significantly low
body weight
Intense fear of gaining weight
Disturbance in one’s self-evaluation regarding body
weight
Bulimia Nervosa
Binge-Eating
Disorder
Recurrent episodes of binge eating
Recurrent inappropriate compensatory behaviors to
prevent weight gain, including purging, laxatives, fasting
or excessive exercise
Self-evaluation is unduly affected by body shape and
weight
Recurrent episodes of binge eating
Marked distress regarding binge eating
The binge eating is not associated with the recurrent use
of inappropriate compensatory behavior
Health Consequences of Eating Disorders: For those suffering from anorexia, health
consequences include an abnormally slow heart rate and low blood pressure, which increases the
risk for heart failure. Additionally, there is a reduction in bone density (osteoporosis), muscle
loss and weakness, severe dehydration, fainting, fatigue, and overall weakness. Anorexia
nervosa has the highest mortality rate of any psychiatric disorder (Arcelus et al., 2011).
Individuals with this disorder may die from complications associated with starvation, while
others die of suicide. In women, suicide is much more common in those with anorexia than with
most other mental disorders.
The binge and purging cycle of bulimia can affect the digestives system and lead to electrolyte
and chemical imbalances that can affect the heart and other major organs. Frequent vomiting can
cause inflammation and possible rupture of the esophagus, as well as tooth decay and staining
from stomach acids. Lastly, binge eating disorder results in similar health risks to obesity,
including high blood pressure, high cholesterol levels, heart disease, Type II diabetes, and gall
bladder disease (National Eating Disorders Association, 2016).
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Figure 6.10
Source
Eating Disorders Treatment: To treat
eating disorders, adequate nutrition and
stopping inappropriate behaviors, such as
purging, are the foundations of treatment.
Treatment plans are tailored to individual
needs and include medical care, nutritional
counseling, medications (such as
antidepressants), and individual, group,
and/or family psychotherapy (NIMH, 2016).
For example, the Maudsley Approach has
parents of adolescents with anorexia
nervosa be actively involved in their child’s
treatment, such as assuming responsibility
for feeding the child. To eliminate binge
eating and purging behaviors, cognitive
behavioral therapy (CBT) assists sufferers by identifying distorted thinking patterns and
changing inaccurate beliefs
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