236 CHAPTER 6
Neurological Factors
Because the main risk factors for suicide are associated with depression and im-
pulsivity (as well as past suicide attempts), it’s diffi cult to identify neurological fac-
tors that uniquely contribute to suicide (as distinct from factors that contribute to
depression and impulsivity). Nevertheless, progress is being made in understanding
the neurological factors that contribute to suicide.Brain Systems and Neural Communication
The frontal lobes may play a key role in suicide, which makes sense because they
normally inhibit behavior (and hence disrupted frontal lobe function may be related
to impulsivity). In particular, postmortem studies have documented that the frontal
lobes of suicide victims have structural abnormalities, such as greater-than-normal
neural density (Rajkowska, 1997) and abnormal serotonin receptors (Brunner &
Bronisch, 1999).
Many researchers believe that mood disorders in general refl ect, at least in part,
levels of the neurotransmitter serotonin. Guided by this idea, Bielau and colleagues
(2005) reported a suggestive trend: They found that people who committed sui-
cide tended to have fewer neurons in the part of the brain that produces serotonin
than did people who died of other causes. In addition, researchers have found that
people who commit suicide may have had fewer serotonin receptors in their brains
(Boldrini et al., 2005). Notably, impulsivity is also associated with low serotonin
levels. Given the role of serotonin in impulsivity and aggression (van Heeringen,
2003), its relation to suicide is not surprising: The low levels of serotonin associ-
ated with impulsivity may lead a person to act on a thought or emotion that nor-
mally would be ignored—and might even facilitate a horrible act of aggression
against the self (after all, suicide is murder—the most aggressive of all acts—but
directed toward oneself).Genetics
Suicide seems to “run in families” (Correa et al., 2004), but it is diffi cult to discern
aspecifi c role of genes in infl uencing people to commit suicide. Depression has a
genetic component, which may account for the higher rates of suicide among both
twins in monozygotic pairs (13%) compared to dizygotic pairs (<1%; Zalsman
et al., 2002). Given the apparent role of serotonin in suicide, studying genes related
to serotonin is an obvious way to begin to look for genetic contributions to this be-
havior. However, such investigations have so far been fruitless. Researchers cannot
yet identify genes that specifi cally infl uence whether a person will commit suicide
(Sibille et al., 2004; Stefulj et al., 2004; Tsai et al., 2004).Psychological Factors: Hopelessness and Impulsivity
Why might individuals think seriously about suicide? The obstacles in their lives
may seem to be insurmountable, or suicide may appear to be the only way to end
their excruciating emotional pain. However, suicide is a “permanent solution to
a temporary problem” (National Depressive and Manic Depressive Association,
2002). When people are in the midst of despair, possible solutions to life’s problems
may seem elusive, but these feelings typically will lessen or disappear.
A number of the risk factors in Table 6.12 are psychological factors, such as
poor coping skills (e.g., behaving impulsively) and poor problem-solving skills (e.g.,
diffi culty identifying obstacles that interfere with meeting goals or failing to develop
ways to work around obstacles), distorted and rigid thinking (thought patterns asso-
ciated with depression), and hopelessness. Hopelessness, with its bleak thoughts of
the future, is especially associated with suicide (Beck et al., 1985; Beck et al., 1990).
Moreover, to some extent having depressed thoughts is self-perpetuating: When de-
pressed, people are more likely to remember other bad times (Eich, Macaulay, &
Lam, 1997). Their thoughts become populated with a string of bad times, from past
to present, and onward to the future. They cannot see past their current hopeless-
ness to envision better times or alternative solutions to their problems. And if they