Pathological Aggression

Many people with pathological aggression go undiagnosed. Currently, no drugs for aggression have been approved by the Food and Drug Administration, and social programs are often under-funded or under pressure to serve all who need help. However, researchers have uncovered specific brain chemicals that can be manipulated to control different kinds of aggression in humans. This may lead to anti-aggression drugs that provide the first effective treatments for this disorder.

And each day, violence claims many victims. In 2003, 5,570 people between 10 and 24 years old were murdered in the United States -- an average of 15 a day. Figures from the U.S. Department of Justice (DOJ) estimate that roughly 3.5 million violent crimes were committed against family members between 1998 and 2002. Although DOJ figures suggest that violent crime in the United States is declining overall, a person still faces an 80 percent chance of being a victim of a violent crime -- including homicide, rape, assault, and theft -- at some point in their lifetime.

Aggression is a complex social behavior, and it also can signal another clinically defined condition, such as bipolar disorder or post-traumatic stress disorder. Researchers place most aggression by individuals into one of three general categories: predatory aggression against other species, social aggression against the same species, and defensive aggression in response to a threat. The latter two categories are the ones behind many of the headlines.

Recent research on juvenile delinquency suggests that aggressive behavior can be divided between reactive and proactive. Distinguishing between the two can help determine the most effective medications or treatment for aggressive behavior. Reactive aggression more commonly relates to an emotional disorder, such as bipolar disorder, and may potentially be treated or prevented with appropriate medication. Proactive aggression usually occurs under some form of rational control and may be better treated with behavioral intervention.

Scientists suspect that both genetic and environmental factors contribute to the complexity of aggressive behavior. Studies have shown that the amygdala, one of the brain structures responsible for controlling emotions, has an important role in mediating violence. Other advances include:

• Identifying a host of specific genes and chemical reactions in the brain that are linked to violent behavior.
• Discovering that dysfunctional regulation of the brain chemical serotonin, which affects mood, affects impulsiveness in humans.

Recent advances involving the mood-influencing brain chemical serotonin identified specific abnormal genes responsible for weakening the brain's ability to control impulsive behavior. Although not directly responsible for violent behavior, a variant of one of these genes breaks down serotonin and biases the brain toward impulsive, aggressive behavior. The gene variant was found mostly in men who tended to have smaller brain structures related to emotion and less activity in brain circuits that control impulsiveness. Less control over emotions may reduce one's ability to control stressful situations and increase the chances of violent behavior.

Findings involving monkeys implicate another specific gene that affects the function of serotonin depending on the gene's length. Monkeys carrying a short version of the gene and reared away from their mother were aggressive toward their offspring, which, in turn, were aggressive toward their own young. In contrast, both monkeys carrying a long version of the gene and monkeys reared by their mother showed lower levels of aggression. This suggests that maternal rearing has a "buffer" effect, somehow preventing serotonin from malfunctioning and, thereby, causing aggressive behavior.

Neuroimaging has emerged as a means of locating brain irregularities in aggressive individuals. A positron emission tomography study of 41 convicted murderers suggests that abnormal activity in specific regions of the brain, including the amygdala and medial temporal lobe, may contribute to a predisposition to violence in some individuals.

Alcohol also has been implicated in aggression. While most people who drink alcohol do not become aggressive, some who drink low to moderate amounts can become very aggressive. This suggests that individual responses to alcohol consumption may be linked to aggression-related personality traits. Alcohol's action on a specific inhibitory amino acid that influences, and possibly intensifies, aggressive behavior is a subject of ongoing research.

Scientists are pursuing drug therapies to treat aggressive behavior. A recent study focused on Risperdal (risperidone), a drug primarily used to treat schizophrenia, as a possible treatment of uncontrolled aggression seen in juvenile conduct disorder -- repeated patterns of bullying, vandalism, cruelty to animals, stealing, or other aggressive behaviors. In a pilot study of children and adolescents with conduct disorder, doctors and parents noticed an improvement in behavior and a reduction in aggression after seven weeks of drug treatment. Other research focuses on drugs targeting brain chemicals that affect aggression, including dopamine, serotonin, and gamma-aminobutyric acid.

By helping those who suffer from aggressive disorders, new treatments developed from these and other avenues of research also could help reduce the number of violent crimes. This may save the lives of many innocent victims, including those who might otherwise make the headlines.

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