34 CHAPTER 2
neurological factors and social factors, continuing the interaction among these
different infl uences. Thus, considering only one type of factor would lead to an
incomplete understanding of psychological disorders. That is why we consider each
type of factor—neurological, psychological, and social—in detail in this chapter,
to provide information that we will use in later chapters as we probe the etiology
of specifi c psychological disorders. It is important to note, however, that the neu-
ropsychosocial approach does not focus on each type of factor individually; rather,
we must always consider how the three factors interact and affect one another via
feedback loops.Neurological Factors in Psychological Disorders
Big Edie had always been unconventional. She didn’t seem to care what other peo-
ple thought of her behavior. And although she loved performing—seemingly to the
point of compulsion—she was a recluse for most of her adult life, seeing almost no
one but her children. How did such a lifestyle arise? And what about Little Edie’s
paranoid beliefs? Could neurological factors account for the odd beliefs and be-
haviors of this mother and daughter? In fact, accumulating research indicates that
genes can contribute to the development of disorders by affecting both the struc-
ture and function of the brain (Hasler et al., 2004; Gottesman, 1991; Greenwood &
Kelsoe, 2003).
Neurological factors that contribute to psychological disorders include abnor-
malities in the structure of the brain, in the operations of specifi c chemicals (such
as those that affect transmission of information among brain cells), and in specifi c
genes. Researchers and clinicians sometimes focus on neurological factors when
they explain psychopathology—noting, for example, that depression is correlated
with abnormal levels of a particular chemical (serotonin) in the brain, or that an
irrational fear of spiders develops partly from an overly reactive brain structure
involved in fear (the amygdala; Larson et al., 2006). However, as you know, the
neuropsychosocial approach maintains that explanations based on neurological
factors alone rarely provide the whole story. For instance, one person’s serotonin
levels might become abnormal because of his social position (Raleigh et al., 1984),
and another person’s amygdala might be overly reactive because of her experiences
with threatening people (Phelps et al., 2000). Each thought, feeling, and behavior,
as well as each social experience and the environment in which we live and work,
affects our neurological functioning. In other words, as noted above, the three types
of factors typically interact with one another through feedback loops. Neurological
factors contribute to psychopathology, but they must be considered in the context
of the other factors.
To understand the role of neurological factors in explanations of psychopathol-
ogy, we next consider brain structure and function, neurons and neurotransmitters,
and genetics and the ways that genes interact with the environment.Brain Structure and Brain Function
Have you ever been high in the mountains and looked up at a crystal clear night
sky? The number of stars is staggering. In fact, there are about 100 billion stars in
our galaxy—which nicely approximates the number of brain cells in each of our
brains. Think of packing all those points of light into a single skull! And just as the
stars in a galaxy are organized into clusters and arms, and the entire ensemble turns
majestically around the galactic core, our billions of brains cells are organized into
brain structures that work together in specifi c ways. In fact, the number of possible
connections among the brain’s cells is truly astronomical—by some estimates, there
are more possible connections among brain cells than there are atoms in the universe
(Thompson, 1993)!P SN