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Puberty brings dramatic changes in the body, including the development of primary and secondary sex
characteristics.
A major milestone in puberty for girls is menarche, the first menstrual period, typically
experienced at around 12 or 13 years of age (Anderson, Dannal, & Must, 2003). [5] The age of
menarche varies substantially and is determined by genetics, as well as by diet and lifestyle,
since a certain amount of body fat is needed to attain menarche. Girls who are very slim, who
engage in strenuous athletic activities, or who are malnourished may begin to menstruate later.
Even after menstruation begins, girls whose level of body fat drops below the critical level may
stop having their periods. The sequence of events for puberty is more predictable than the age at
which they occur. Some girls may begin to grow pubic hair at age 10 but not attain menarche
until age 15. In boys, facial hair may not appear until 10 years after the initial onset of puberty.
The timing of puberty in both boys and girls can have significant psychological consequences.
Boys who mature earlier attain some social advantages because they are taller and stronger and,
therefore, often more popular (Lynne, Graber, Nichols, Brooks-Gunn, & Botvin, 2007). [6] At the
same time, however, early-maturing boys are at greater risk for delinquency and are more likely
than their peers to engage in antisocial behaviors, including drug and alcohol use, truancy, and
precocious sexual activity. Girls who mature early may find their maturity stressful, particularly
if they experience teasing or sexual harassment (Mendle, Turkheimer, & Emery, 2007; Pescovitz
& Walvoord, 2007). [7] Early-maturing girls are also more likely to have emotional problems, a
lower self-image, and higher rates of depression, anxiety, and disordered eating than their peers
(Ge, Conger, & Elder, 1996). [8]
Cognitive Development in Adolescence
Although the most rapid cognitive changes occur during childhood, the brain continues to
develop throughout adolescence, and even into the 20s (Weinberger, Elvevåg, & Giedd,
2005). [9] During adolescence, the brain continues to form new neural connections, but also casts
off unused neurons and connections (Blakemore, 2008). [10] As teenagers mature, the prefrontal
cortex, the area of the brain responsible for reasoning, planning, and problem solving, also
continues to develop (Goldberg, 2001). [11] And myelin, the fatty tissue that forms around axons