Researchers Sketch Complex Profile of Suicide Risk

Research is making progress in uncovering some of the determinants of suicide, yielding increasingly specific indicators for recognizing the at-risk individual.

Reports in the August American Journal of Psychiatry (AJP) underscore the role of family history of suicide in attempts by individuals at risk for killing themselves, with particular emphasis on familial transmission of “impulsive aggression.”

Further, comorbidity of Axis I and Axis II disorders—increasing the likelihood of aggression and impulsivity—appears to heighten the risk for suicide, presenting special challenges to the clinician treating at-risk patients (Original article: see box).

Maria Oquendo, M.D., co-author of one of the AJP studies on familial influences, said that while a “profile” of the at-risk patient cannot yet be drawn, research suggests several key elements.

“We know that a variety of risk factors increases the likelihood of future attempts,” she told Psychiatric News. “These include previous history of attempts, family history of suicidal behavior, the presence of cluster B personality disorders, impulsive aggression, and childhood history of sexual abuse. Although about 50 studies have prospectively examined risk factors for suicidal acts, none has taken into account all these different risk factors to determine the ‘profile’ of the person at risk.”

Oquendo is a clinical professor of psychiatry at Columbia University and director of clinical studies in the department of neuroscience at the New York State Psychiatric Institute.

In the AJP study, titled “Peripubertal Suicide Attempts in Offspring of Suicide Attempters With Siblings Concordant for Suicidal Behavior,” Oquendo and 10 other authors found that greater familial “loading” for suicide—indicated by having a parent and an aunt or uncle who attempted suicide—affects the risk for suicide and is associated with younger age of first suicide attempt among offspring.

Oquendo and colleagues reanalyzed a study on people at high risk for suicide, comparing rates of suicide in three groups: 41 offspring of suicide attempters with a sibling who attempted suicide (group A); 186 offspring of suicide attempters without a sibling who attempted suicide (group B); and 166 offspring of parents who did not attempt suicide and whose siblings did not attempt suicide (group C). Parents in all of the groups had a history of nonpsychotic mood disorder.

The rate of suicide in group A was significantly higher (18.8 percent) than those in group B (8.5 percent) and group C (4.2 percent). The average age of first suicide attempt was also lower in group A (12.2 years) than in group B (20 years) and group C (14 years).

In addition, scores on a standardized scale for impulsive aggression were higher among group A than in the other two groups.

“In a way, suicidal behavior is an aggressive act, and often it is impulsive,” Oquendo told Psychiatric News. “The best way to assess impulsive aggression is by obtaining a history of the patient’s aggressive behavior. As clinicians, we often neglect to ask about assaultive behavior, history of problems with the law, and history of vandalism or behaviors such as destroying inanimate objects.”

Oquendo said a history of such behaviors can provide clues about how a patient processes frustration and anger.

“These types of behaviors are associated with suicidal behavior, as well as with decreased serotonergic function,” she said. “Similarly, decreased serotonergic function is associated with suicidal acts as well.”

In related research, a large-scale comparison of deaths by suicide over a 20-year period with deaths in the same period from other causes found that a family history of suicide was twice as likely among suicide victims as among those who had died of other causes.

Also, a family history of suicide predicted suicide independent of severe mental disorder, according to the report.

“When a physician encounters a family bereaved by suicide of a family member, he or she ought to be aware of the risk for a second suicide within the family,” study author Bo Runeson, M.D., Ph.D., told Psychiatric News. “When supporting the bereaved family, [the clinician should] ask family members about their own thoughts of death and suicidal ideation. If the family is already affected by mental disorder, this certainly implies an increased risk for suicide in a second family member, but the risk appears independent of the mental disorder.”

Runeson works in the division of psychiatry in the department of clinical neuroscience at St. Goran’s Hospital at the Karolinska Institutet in Stockholm.

Runeson and Marie Asberg, M.D., Ph.D., also of the Karolinska Institutet, used the Swedish cause-of-death register to identify 8,396 people who had committed suicide between 1949 and 1969. A comparison group comprised 7,568 persons who were of the same age and died of other causes. A total of 33,173 first-degree relatives of the suicide victims and 28, 945 first-degree relatives of the comparison group were identified.

Among the families of the suicide victims there were 287 suicides, representing 9.4 percent of all deaths among the family members. Among the comparison families, there were 120 suicides, or 4.6 percent of all deaths.

Runeson said that both the size of the sample and the comparison with deaths by other causes is unique in the literature.

Runeson and Oquendo both speculated that genetic transmission of personality traits, especially impulsivity and aggression, predispose individuals to suicidal thoughts when confronted with the stress of loneliness or separation.

Apart from the genetic transmission of personality traits, suicide in a family may serve as a “contagion,” much like any other infectious or communicable disease.

“The suicide of a father or a mother has a strong impact on a son or daughter, being a role model for the children,” Runeson said. “It can sometimes be seen that younger family members use the same method for committing suicide as a parent, so that exposure to a certain method may have a suggestive effect.”

Oquendo said that teasing out the pathways for transmission of impulsive aggression and suicidal behavior—whether genetic or environmental—is a challenge for research.

“There is likely to be both genetic and environmental factors that contribute to the heritability of suicidal behavior and impulsive aggression,” she said. For example, parents who are more impulsive and aggressive may be more likely to abuse their children. Those children, in turn, are at higher risk for impulsive aggression.

“It is difficult to tease out, however, whether the heritability of impulsive aggression in the parent-child dyad is due to a shared genetic vulnerability that predisposes both of them toward impulsive aggression, whether it is due to the fact that the child was exposed to abuse, or both. We are currently analyzing data to try to address the environmental and genetic contributions to the heritability or familiality of suicidal acts.”

Research has yet to elucidate how to translate identification of risk factors into clinical strategies aimed at prevention. “We have barely begun to address putative protective factors,” Oquendo said. “Are there cultural, familial, or genetic factors that protect some individuals from suicidal acts even when they are very depressed? Can we learn from ethnic or demographic groups that appear to be at lower risk for suicidal acts whether there are specific environmental or social changes that can lower risk for suicidality?”

Moreover, she said, there are almost no controlled data available about pharmacologic or psychosocial approaches to the prevention of suicidal acts.

“Are there certain medications, such as lithium, that can lower suicide risk in high-risk groups?,” she asked. “Are there specific psychotherapeutic approaches that can give patients alternate skills to dealing with depression, anger, and frustration?” ▪