5 Tweens and Teens 113of the brain yields more accurate judgments and allows adolescent and adult
thinkers to develop a more socially competent brain with more capacity for
balanced judgment (Blakemore, 2008; Siegel, 2013). Teens begin to weigh their
risks more realistically as the brain pruning continues.
Changes in the adolescent brain seem to set the stage for “hard-wiring”
brain pathways: For instance, use of drugs like THC, methamphetamine, and
MDMA (“ecstasy”) seem to lay down “wiring” that raises the risk that an
individual will succumb to addictions and/or, some assert, to schizophrenia
(Moore et al., 2007). Likewise, engagement in learning a language or even a
video game lays down neuronal “traces” that enable skills. The “use it or lose
it” aphorism is at work as skills and thinking patterns that are used frequently
become “hard-wired” (neuronal connections are developed) while skills and
thinking patterns that are not used end up being lost (Underwood, 2006). This
may have implications for adolescents who experience loss and grief at this
stage of rapid brain modification.
The most obvious biological changes have to do with puberty and its
accompanying body changes, usually leading to the secondary sex charac-
teristic development that leaves boys looking like men and girls looking like
women. Further, sexual and reproductive functions, such as nocturnal emis-
sions (male) and menses (female), develop even when the individual’s experi-
ence in Western society usually has not prepared them for full adulthood and
reproductive function. Teens both impatiently wait for, and later are embar-
rassed by, these dramatic bodily changes. There is growing evidence that the
age of physical maturation is dropping in Westernized countries (Ong, Ahmed,
& Dinger, 2006). Lower levels of exercise and activity (Davison, Werder, Trost,
Baker, & Birch, 2007), higher body mass index (Biro, Khoury, & Morrison,
2006) and better nutrition (Gluckman & Hanson, 2006), socioeconomic status
(Obeidallah, Brennan, Brooks-Gunn, Kindlon, & Earls, 2000), and/or expo-
sures to chemicals and hormones (Den Hond & Schoteres, 2006) have all been
implicated in lowering the age of puberty and of menarche (first menses or
period).
Aside from early onset of secondary sex characteristics like pubic and
underarm hair, breast growth in females, and genital maturation, early puberty
is correlated with social outcomes such as early sexual activity (Halpern,
Kaestle, & Hallfors, 2007), substance use (Ge et al., 2006), and other risk-taking
behavior (van Jaarsveld, Fidler, Simon, & Wardle, 2007). This engagement
in “adult” types of behaviors occurs when the individual’s body has only
recently assumed biological maturation. Pregnancy at earlier ages is fraught
with complications, substance use appears to have a greater negative impact
on the brain that is still developing (Moore et al., 2007; Smith, 2013), and other
risk taking behavior can lead to accidents that have life-changing (or ending)
consequences. In short, when tweens’ bodies mature to adulthood before their
minds and abilities do, they are left feeling odd at best, and risk poor outcomes
(Gluckman & Hanson, 2006).
Even when occurring at customary ages, the physical changes of adoles-
cence may inspire a sense of loss because they indicate movement away from
the less responsibility-filled time of childhood. For those who mature early,
the “out-of-sync” sense may also be experienced as a loss of social conformity,
albeit possibly compensated for by the cachet of feeling adult. Because change