Suicide rates also vary across ethnic and racial
groups in the United States. For example, Native
Americans have the highest rates of suicide, while
White men have the second highest rates. The risk is
relatively lower for Black women. Creative or success-
ful scientists, artists, and professionals have a higher-
than-average lifetime suicide risk.
Suicide is best understood as a desperate act
designed to end seemingly inescapable emotional,
physical, or interpersonal suffering. Some suicidal
gestures are also intended to convey to others the
depth of one’s despair, as a “cry for help.” Most per-
sons who have suicidal thoughts experience some
ambivalence; this is often reflected in the chosen
method and in prior communications of intentions.
The majority of people who commit suicide have pre-
viously communicated their suicidal intent with oth-
ers, often in explicit terms. However, highly distressed
persons who are determined to die will use highly
lethal methods and are unlikely to have shared their
intentions with others. Using a very deadly method
without sharing the plan with others nearly guarantees
that it will be successful.
Suicide notes can be useful for understanding the
motives and desperation that drive suicidal gestures.
Approximately one-third of individuals who commit
suicide do leave behind a note, usually for the ben-
efit of surviving relatives and friends. Many notes
are brief and to the point, and they betray profound
distress. Suicide notes may be designed to explain
the act or relieve surviving relatives’ feelings of
guilt.Causes of Mood Disorders
BBiioollooggiiccaall FFaaccttoorrss
It has long been known that severe mood disorders
run in families, which suggests that heredity plays a
role in their development. The rates of mood disor-
ders are nearly three times higher than average
among the blood relatives of persons with depressive
disorders. Studies of twins, of which one has a mood
disorder, show a higher rate of mood disorders among
identical twins than among fraternal twins. Heredity
plays a greater role in the causation of bipolar disor-
ders. Twin studies reveal that approximately two-
thirds of identical twins who have bipolar disorder
have a co-twin who shares a mood disorder. In fact,
the best predictor of a person’s risk of developing a
Bipolar Disorder is having a family history. Biologicalfactors, however, play a smaller role in the onset of
minor mood disorders.
A growing body of research reveals that severe
mood disorders are related to abnormalities in the
brain areas that regulate emotions and basic biological
needs, such as hunger and sleep. Problems with the
brain’s internal biological clock are related to ineffi-
ciencies in the brain’s chemistry. There is evidence
that the brain’s own chemical signals, known as neuro-
transmitters,are not functioning properly in persons
with severe depression. It is believed that imbalances
in the brain’s chemical signals, combined with disrup-
tions in the sequencing of the brain’s biological clock,
may account for most of the common symptoms of
mood disorders. Specifically, the disruptions in the
internal clock could lead to problems with sleep,
energy, and loss of enjoyment. Some people may
be especially vulnerable to these problems, either
because of their family history or because of other
nongenetic risk factors.LLiiffee EExxppeerriieenncceess
The link between stressful life experiences and
depression is well established. Several specific stress-
ful events seem to be especially troubling for persons
who are prone to mood disorders. Major losses, such
as the death of a loved one or financial losses, often
precede significant depression. Losses that are ego
threatening (such as a divorce or job termination) are
usually difficult for persons who are at risk for mood
disorders, especially if they feel personally responsi-
ble for the event. In other words, being fired from a
job for poor performance will be more threatening
than losing a job to downsizing. Chronic and ongoing
stressors also increase the risk of becoming depressed,
in contrast to an abrupt and isolated source of stress.PPeerrssoonnaalliittyy aanndd IInntteerrppeerrssoonnaall FFaaccttoorrss
Certain personality traits, such as negative affectiv-
ity,may help predict a person’s risk of developing a
depressive disorder in the face of stressful life events.
Negative affectivity is a personality type that is prone
to negative emotions, including worry, anxiety, and
sadness. Because of this proneness to negative emo-
tions, the individual is ill equipped to deal with major
losses or threats to the ego. From another perspective,
it is suggested that some people are prone to depres-
sion because of distorted beliefs about themselves, the
world, and the future. Rigid and distorted beliefs514 ———Mood DisordersM-Cutler (Encyc)-45463.qxd 11/18/2007 12:43 PM Page 514