68 CHAPTER 2
ends in terminal buttons, and dendrites that
receive signals from other neurons. The neuron
is covered by a cell membrane that has chan-
nels that open when the neuron fi res. When a
neuron fi res, neurotransmitters released from
the terminal button travel across the synaptic
cleft to receptors on the dendrite or cell body
of another neuron. Neuromodulators may
affect the functioning of neurotransmitters by
altering events at the synapse.
Neurotransmitter substances include do-
pamine, serotonin, acetylcholine, adrenaline and
noradrenaline, gluatamate, GABA, and endog-
enous cannabinoids.
Neurotransmitters can bind to different
types of receptors; the type of receptor a neu-
rotransmitter binds to determines its effect.
Neuronal communication can go awry when
(1) neurons have an abnormal number of den-
drites or receptors, affecting sensitivity to
neurotransmitters in the synapse; (2) sending
neurons release abnormal amounts of neu-
rotransmitter into the synapse; (3) reuptake of
neurotransmitter molecules does not operate
correctly. Hormones, produced by glands in
the endocrine system, often function as neu-
romodulators; an important hormone related
to some psychological disorders is cortisol.
Genes can infl uence the development of
psychopathology. Complex inheritance best
explains the infl uence of genes on psychologi-
cal disorders. Scientists who study behavioral
genetics seek to determine the roles of genes,
the environment, and their interactions in
both normal and abnormal thoughts, feelings,
and behaviors. Heritability is an estimate of
how much of the variation of a characteristic
across a population, in a specifi c environment,
is determined by genes.
Behavioral geneticists may use twin and
adoption studies to determine the relative
influences of genes and environment. Twins
may be monozygotic or dizygotic. Genes can
affect the environment in three ways: (1) pas-
sive interaction, (2) evocative interaction, and
(3) active interaction.Thinking like a clinician
Dominic is adopted, and his biological father
was an alcoholic; alcoholism has a genetic
component. Dominic’s adoptive parents are
very religious and don’t drink alcohol. What fac-
tors in Dominic’s environment might affect the
expression of any genes that he might have that
can contribute to alcoholism? Suppose scientists
determine that, among alcoholics, a particular
brain area has an abnormally high level of activ-
ity of the neurotransmitter dopamine. Further
suppose that Dominic has too much activation of
dopamine neurons in this area. Does this mean
that his brain is wired wrong, and he should
just resign himself to eventually becoming analcoholic? How might psychological and social
factors affect dopamine levels?Summary of Psychological
Factors
Three types of learning can contribute to
psychological disorders: (1) Classical con-
ditioning of emotional responses, such as
fear and anxiety, produces conditioned emo-
tional responses that can generalize from the
original conditioned stimulus to other, similar
stimuli. (2) Operant conditioning of voluntary
behaviors occurs through positive and nega-
tive reinforcement and positive and negative
punishment. (3) Observational learning can
guide the observer’s behavior and expecta-
tions, leading to maladaptive behaviors.
Mental processes and mental contents
play important roles in the etiology and main-
tenance of psychological disorders. Mental
processes infl uence what people pay attention
to, how they perceive and interpret various situ-
ations and events, and what they remember.
Mental contents can be associated with various
psychological disorders in the form of irrational
thoughts that are cognitive distortions of real-
ity, creating cognitive vulnerabilities.
Emotional disturbances such as the
following contribute to some psychological dis-
orders: not feeling or expressing emotions to
a suffi cient degree, expressing emotions that
are inappropriate or inappropriately excessive
for the situation, and having diffi culty regulat-
ing emotions. Emotions, behaviors, mental
contents, and mental processes are often inter-
twined, and so disturbances in one will affect
the others. Moreover, a person’s attributions
and mood can affect each other.
Researchers distinguish between two
basic types of emotions—approach (positive)
and withdrawal (negative)—each of which
relies on different brain systems. Some people
are temperamentally more likely to experience
approach emotions, whereas others are more
likely to experience withdrawal emotions.
Having a particular temperament may
make a person especially vulnerable to certain
psychological disorders, even at an early age.
In some cases, a psychological disorder may
be an extreme form of a normal variation in
temperament. Evidence indicates that genes
contribute strongly to temperament; however,
the effects of genes need to be considered
within the context of specifi c environments.
Temperament is conceived of as having
four dimensions: novelty seeking, harm avoid-
ance, reward dependence, and persistence.Thinking like a clinician
Maya is depressed; she’s often tearful and
feels hopeless about the future and helplessto change the negative things in her life. Give
specific examples of the ways that types of
learning might have infl uenced her negative
expectations of life and led to her current
depression. (It’s okay to speculate here, but
be specific.) Based on what you have read,
how can Maya’s thought patterns and emo-
tions lead to her feeling depressed (or make
the depression worse)?Summary of Social Factors
Social factors can help to protect us from
developing psychological disorders, or they
can make us more vulnerable to or exacerbate
psychological disorders. Such factors begin to
exert their infl uence during childhood and can
affect each generation differently, as a culture
changes over time.
A family’s style of interacting that involves
high expressed emotion can contribute to
relapse in patients with schizophrenia from
particular ethnic or cultural groups. Being
maltreated as a child indirectly contributes to
psychological disorders by increasing stress,
teaching maladaptive behaviors, promoting
biases in discriminating among and respond-
ing to facial expressions, creating diffi culties
in attachment, and increasing social isola-
tion. Psychological disorders in parents can
contribute to psychological disorders in their
children, although it is diffi cult to pinpoint the
specifi c mechanism through which this infl u-
ence occurs.
Social support can buffer against stress,
and a lack of social support can make people
more vulnerable to psychological disorders.
Low SES is associated with a higher rate of
psychological disorders; both social causa-
tion and social selection contribute to this
relationship. Being the object of discrimina-
tion is associated with an increased risk of
distress and psychological disorders. Different
personality traits and behaviors are valued in
different cultures; thus, acculturation can lead
to conflict among family members, creating
stress and a risk of psychological disorders.Thinking like a clinician
Gonsalvo and Bill, roommates, are both fi rst-
year college students. Gonsalvo has left his
family and country and moved to another
continent to study in the United States; Bill’s
family lives a few hours’ drive away. What
social factors may influence whether either
young man develops a psychological disorder
during the time at college? Be specifi c about
possible factors that might lead each man to
be vulnerable. What social factors may protect
them from developing a disorder? What addi-
tional information would you want to help you
answer these questions, and how might such
information affect your predictions?dd i t ilbtt dd d it tht lhli?H iht hl i l d il t hth tithi i h lif GGi