FRIDAY, July 12 (HealthDay News) -- Clear differences exist between the minds of people who kill on impulse and those who plan murders, a new study says.
Researchers looked at 77 murderers in prisons in Illinois and Missouri and concluded that impulsive killers -- who often commit their crimes out of rage -- were more likely than premeditated murderers to have mental development disabilities (59 percent versus 36 percent). Impulsive killers were also more likely than premeditated killers to have a history of alcohol or drug abuse or to have been intoxicated at the time of the crime (93 percent versus 76 percent).
On the other hand, people who committed premeditated murders were more likely than impulsive killers to have a history of mood disorders or psychotic disorders (61 percent versus 34 percent), according to the Northwestern University study recently published online in the journal Criminal Justice and Behavior.
The study, which included extensive testing of the criminals, is thought to be the first to examine how the minds of impulsive and premeditated killers differ.
"It's important to try to learn as much as we can about the thought patterns and the psychopathology, neuropathology and mental disorders that tend to characterize the types of people committing these crimes," study senior author Robert Hanlon, an associate professor of clinical psychiatry and clinical neurology, said in a university news release.
"Ultimately, we may be able to increase our rates of prevention and also assist the courts, particularly helping judges and juries be more informed about the minds and the mental abnormalities of the people who commit these violent crimes," he said.
The U.S. Centers for Disease Control and Prevention offers resources about violence prevention.