A further explanation for the importance of Cluster B personality
disorder in predicting future attempts among depressed ideators
relates to Joiner’s interpersonal-psychological theory (Joiner, 2005).
This theory posits that three domains must be present in an individual
for suicide to occur. The first two domains, perceived burdensomeness
and thwarted belongingness, confer the desire for
suicide (e.g., suicidal ideation). The third domain, acquired capability,
is believed to be necessary in order for an individual to
undertake potentially lethal self-harm. Habituating to physical pain
and thoughts of death helps one overcome the fearsomeness of
attempting suicide. Cluster B personality disorders include two
important symptoms from borderline personality disorder that
may directly increase the acquired capability for suicide. The first is
non-suicidal self-injury, which, though a distinct behavior from
suicide, facilitates habituation to causing pain and injury to oneself.
The second is engaging in impulsive and damaging behaviors such
as reckless driving, risky drug use, and binge eating, many of which
increase exposure to painful and frightening events. These symptoms
may make individuals more capable of acting on suicidal
thoughts and thus help explain the relationship of Cluster B
personality disorder to risk of future suicide attempts.