The Psychology of Gender 4th Edition

Mental Health 497

be more likely to pass on their depressive gene

to daughters than sons because fathers give

daughters their X chromosome and sons their

Y chromosome. However, more father–son

pairs are depressed than father–daughter pairs

(Nolen-Hoeksema, 1987). It is also the case

that females have higher rates of depression

than males among other-sex twins (Takkinen

et al., 2004). Thus, sex-linked genes alone can-

not explain depression.

Because genes are present at birth, a

genetic theory of depression has difficulty

explaining the emergence of depression in

females during adolescence. Genetic theo-

ries would have to suggest that women are at

risk for depression and the events of adoles-

cence interact with that risk. One study that

evaluated 8- to 20-year-old monozygotic and

dizygotic twins showed that some genetic

effects are activated around the age of pu-

berty, partly supporting this theory (Kendler,

Gardner, & Lichtenstein, 2008). However,

other genetic effects seemed to wane over

time. Genetic factors may interact with psy-

chological variables to increase depression.

A five-day study in which female twins were

prompted throughout the day to complete

measures of stress and negative affect showed

that the relation of stress to negative affect was

stronger for monozygotic twins than dizy-

gotic twins, especially if there was a history of

depression (Wichers et al., 2007). Wichers and

colleagues concluded that there was a genetic

contribution to reactions to daily stressors.

Hormones. In contrast to genes, hor-

mones change over the life span, and there is

a great deal of hormonal fluctuation during

adolescence when sex differences in depres-

sion emerge. Thus hormones would seem to

be an ideal explanation for the sex difference

in depression. However, no consistent evi-

dence supports the theory that the changes

increases during adolescence. For example,

imagine a poor body image is associated with

depression among girls and being a poor ath-

lete is associated with depression among boys.

This theory could explain the emergence of

sex differences in depression during ado-

lescence if it were true that a negative body

image (i.e., women’s risk factor for depression)

becomes more prevalent during adolescence,

but poor athletic ability (i.e., men’s risk factor

for depression) does not change over time.

Theinteractive theorysuggests be-

ing female always poses a risk for depres-

sion, but the events of adolescence activate

that risk factor. For example, imagine females

are more concerned than males with their

relationships—before and after adolescence—

and that unsatisfying relationships are more

strongly related to girls’ than boys’ distress.

Concern with relationships would be the

“female risk factor.” This concern could inter-

act with events likely to occur during adoles-

cence such as interpersonal conflict. Because

females are more relationship focused than

males, girls will be more likely than boys to re-

act to interpersonal conflict with depression.

In sum, these theories suggest either that

the cause of depression is the same for men

and women, that there are different causes for

male and female depression, or that environ-

mental factors interact with predisposing fac-

tors to predict depression. Each of the theories

that follow supports one of these perspectives.

Biology

Genes. There is undoubtedly a genetic influ-

ence on depression (Mosing et al., 2009). The

question is whether this genetic risk accounts

for the sex difference. If there is a genetic ex-

planation for the sex difference in depression,

we would expect the depression risk factor to

lie on the X chromosome. That being the case,

we would predict that depressed fathers would

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