282 CHAPTER 7
Brain Systems and Neural Communication
Social phobia involves fear, and researchers have shown repeatedly that the amygdala
is strongly activated when animals—including humans—are afraid (Rosen & Donley,
2006). Thus, it’s no surprise that the amygdala is more strongly activated when
people with social phobia see faces with negative expressions (such as anger) than
when they see happy faces, and that this difference is greater than observed in con-
trol participants who do not have the disorder (Phan et al., 2006). In addition, the
more symptoms of social phobia a person has, the more strongly the amygdala is
activated when the person views faces with negative expressions. Although it’s not
possible to identify cause and effect here, this correlation has the potential to pro-
vide an objective way to diagnose the severity of the disorder.
The amygdala is not the only brain area that responds differently in people with
social phobia. Researchers have shown that a number of brain areas, including the
hippocampus and cortical areas near it, do not function normally in people who
have the disorder (Furmark et al., 2002). Moreover, the right hemisphere appears
to play a part in this disorder, which is not surprising, given its role in withdrawal
emotions (Davidson, 1992; see Chapter 2).
Virtually all of the major neurotransmitters may function abnormally in indi-
viduals who have social phobia, but impaired dopamine activity may be particularly
important (Li, Chokka, & Tibbo, 2001). Researchers have examined regions of the
brain that rely on dopamine and found that patients with social phobia show less
activation in these regions than do control participants. Specifi cally, parts of the
basal ganglia that control automatic behaviors, such as those learned when one
becomes adept at playing the piano, rely on dopamine—and these areas are less ac-
tivated in patients with social phobia than in control groups when participants are
learning automatic behaviors (Sareen et al., 2007). But dopamine dysfunction can-
not be the whole story; for example, evidence that people with social phobia have
too little serotonin may suggest why SSRIs have sometimes been found to help these
patients (Gorman & Kent, 1999; Lykouras, 1999).Genetics
As is the norm for anxiety disorders, social phobia appears to arise from both genetic
factors and environmental factors (Mathew, Caplan, & Groman, 2001; Stein, Jang, &
Livesley, 2002). The heritability of social phobia is about 37% on average (with a
range of 12–60% in various studies) (Beatty et al., 2002; Fyer, 2000; Kendler et al.,
1992; Li, Chokka, & Tibbo, 2001; Neale et al., 1994). However, the genetic basis
for this disorder appears not to lie in specifi c genes that affect only social behavior;
rather, the genetic characteristics that predispose a person to develop this disor-
der may also predispose a person to develop autism or have fragile X syndrome
(Coupland, 2001).
Given a general genetic predisposition, why would one person develop social
phobia and another develop, say, autism? The answer may lie in the feedback loops
among factors. Specifi cally, if a child is confronted with negative social events (such
as those that occur in an abusive or overcontrolling family) and the social setting
does not help him or her develop good ways to cope with such situations (as may
occur when other family members exhibit poor ways to cope with anxiety), the
child may respond by developing certain behavioral tendencies that (perhaps via
reinforcement mechanisms, as discussed shortly) develop into social phobia.
Furthermore, we noted earlier that some people with social phobia were ex-
tremely shy as children; they had what is called a shy temperament, or behavioral
inhibition (Biederman et al., 2001; Kagan, 1989), which has a genetic component.
These patients cannot really be said to have developed a phobia, since they always
had a basic level of discomfort in particular social situations (Coupland, 2001).
This was certainly true of Howard Hughes, who was shy as a child and continued
to be shy in his adult years; he preferred small dinner parties in people’s homes to
large social events.P SN