wedded to one school of thought and can incorpo-
rate biological, psychological, and environmental
factors. Adiathesisrefers to a vulnerability or predis-
position to possibly develop the disorder in ques-
tion. A diathesis can be biological (e.g., a genetic
predisposition, a deficit or excess in neurotransmit-
ter functioning) or psychological (e.g., maladaptive
cognitive schema, maladaptive personality style). A
diathesis is necessary but not sufficient to produce a
mental disorder. Predispositions, whether they are
biological or psychological, do not guarantee that
people develop psychological disorders like anxiety
disorder or depression. According to the diathesis-
stress model, thecombinationof a predisposition and
stress (or stressors) may produce psychological
problems.
One way to think of a predisposition or diathesis
is in terms of vulnerability. You can be vulnerable to
a disorder or condition, but that does not ensure that
you will develop the disorder. What is required in
addition to a diathesis is sufficientstress. It is the inter-
play between the predisposition and stress that will
determine whether a disorder develops. Within this
framework,stresscan be environmental (e.g., victim
of an assault), biological (e.g., poor nutrition), inter-
personal (e.g., acrimonious marriage), or even psy-
chological (e.g., toxic family environment).
Two other features of this model are important
to note as well. First, it is important to recognize that
a diathesis or predisposition, be it biological or psy-
chological, caninfluence the perception of stress. Stress is,
after all, subjective in nature. The same event may be
perceived and experienced as much more stressful by
one person than another person who has a different
level of the diathesis or vulnerability.
Second, one’s predisposition is likely toinflu-
ence a person’s own life course and choice of experiences.
In other words, individuals’choices of life experi-
ence and their preferences are likely guided, at least
in part, by the diathesis. This makes some sense, if
we think about it for a moment. Our experiences
are influenced by a number of preferences and deci-
sions we make. The kinds of friends or romantic
partners we choose, the experiences we seek out,
the jobs we take, the place we choose to live—all of
these are likely influenced by diatheses we bring to
each decision. These choices and experiences, in
turn, influence the people, places, and events we
encounter in life. So, the point here is that a diath-
esis will at least partially determine the range and
varieties of life events that we experience, some of
which may be perceived as stressful.
Both the diathesis and the stress are necessary to
produce the disorder in question. Possessing the
diathesis increases the likelihood of developing the
disorder but does not guarantee this outcome.
Moreover, as may be apparent, the exact nature
of the diathesis and stress necessary for developing
a specific disorder is likely to vary from disorder to
disorder. Finally, the interaction between the diath-
esis and stress is also likely to be disorder-specific
(see, e.g., Monroe & Simons, 1991).
But how do these two interact to lead to psy-
chological disorders, according to the diathesis-
stress model? Is a predisposition an all-or-nothing
vulnerability? What about stress? As it turns out, a
dimensional perspective on both diathesis and stress
is most consistent with current research and theory.
This has important implications. For most of us,
some degree of diathesis or predisposition is present,
ranging from low vulnerability to high vulnerabil-
ity. Figure 5-4 presents an example of how different
levels of diathesis (vulnerability) may interact with
different levels of stress to produce symptoms of
psychological disorder (y-axis; rated on a scale
from 0 to 10). As you can see, when the diathesis
is absent or very low, even moderate levels of stress
may not result in many features of psychology dis-
order (rating of 5). However, with increasing levels
of vulnerability (e.g., Diathesis High), even moder-
ate and high levels of stress result in significant fea-
tures of psychological disorder.
This model helps us begin to understand why
two people exposed to the same adverse conditions
and levels of stress may have different outcomes.
For example, why does one soldier develop severe
symptoms of post-traumatic stress disorder after
serving in the Gulf War while another who fought154 CHAPTER 5