MRI: Antisocial personality disorder, prefrontal deficits linked

People diagnosed with antisocial personality disorder (APD) fill thousands of America's prison cells, and even those who aren't convicted of crimes cause serious problems due to their deceitfulness, recklessness, impulsiveness, irresponsibility, and lack of remorse and empathy. For decades, psychiatrists and sociologists blamed APD almost solely on sociological influences including poverty and poor upbringing. A new study by Adrian Raine and colleagues, however, adds to a growing body of evidence implicat ting brain abnormalities as a primary cause of APD.

Raine and colleagues used magnetic resonance imaging (MRI) to study the brains of 21 non-incarcerated men with APD, 34 healthy male controls, and 26 male controls with substance dependence. In addition, they compared APD subjects to individuals in either control group who had been diagnosed with psychiatric illnesses other than APD. The researchers also evaluated subjects' autonomic nervous system function by measuring skin conductance and heart rates during a stressful activity (preparing and giving a sp peech).

The researchers report that the APD group showed an 11 percent reduction in prefrontal gray matter volume, when compared with normal controls. This reduction could not be accounted for by substance abuse or mental illness. In addition, APD subjects showed d significantly reduced autonomic activity compared to the control groups.

While prior research has demonstrated a link between prefrontal damage and antisocial or psychopathic behavior, Raine et al. say their findings extend this research by showing that even slight, visually imperceptible reductions in prefrontal gray matter v volume can cause antisocial behavior. Raine, whose previous research has revealed poor prefrontal function in murderers (see related article, Crime Times, 1995, Vol. 1, No. 1-2, Pages 1 & 6), says the new research is also significant because the subjects were not prisoners but men in the community.

From abnormal brains to abnormal behavior

What is the link between pre-frontal gray matter reduction and antisocial behavior? The researchers note that the prefrontal cortex plays a strong role in fear conditioning and response to stress. "Poor conditioning is theorized to be associated with poor r development of the conscience," they note, "and persons who are less autonomically responsive to aversive stimuli such as social criticism during childhood would be less susceptible to socializing punishments, and hence become predisposed to antisocial behavior."

Also, Raine and colleagues note, the prefrontal cortex helps regulate arousal, and deficits in nervous system arousal may lead individuals to compensate by engaging in sensation-seeking antisocial behaviors. In addition, prefrontal damage is linked to an inability to make good choices, and the researchers say that "this inability to reason and decide advantageously in risky situations is likely to contribute to the impulsivity, rule-breaking, and reckless, irresponsible behavior" characteristic of APD.

> Raine et al. note that other studies involving antisocial, violent offenders also have revealed strong evidence of impaired prefrontal functioning. They conclude, "Different clinical neuroscience paradigms are beginning to converge on the conclusion that there is a significant brain basis to APD over and above contributions from the psychosocial environment, and that these neurobehavioral processes are relevant to understanding violence in everyday society."

Raine et al. say that the discovery of brain abnormalities linked to APD could eventually help clinicians identify and help children at risk of becoming criminals. Raine suggests that cognitive and behavioral therapies, biofeedback, or drug treatments mig ght be useful. In addition, he says, children exhibiting prefrontal deficits that put them at risk for sensation-seeking behaviors could be channeled into legal activities providing the same type of stimulation." Noting that clinicians are rarely able to successfully treat people with APD, Raine says, "I think one reason we have failed to provide effective e treatments and interventions is that we have ignored the biological side of the equation."

Raine and colleagues caution that their study involved only male subjects, and that their findings may not be applicable to women with APD. They also note that prefrontal abnormalities are only one of many potential causes of APD. Raine emphasizes, "We ar re talking about a predisposition to antisocial behavior. Some people who have prefrontal deficits do not become antisocial, and some antisocial individuals do not have prefrontal deficits. It's important to make clear that biology is not destiny."

Reviewing the study, researcher Antonio Damasio, who recently reported on the link between early prefrontal cortex damage and psychopathic-like behavior (see related article, Crime Times, 2000, Vol. 6, No. 1, Page 3), notes that Raine et al.'s research and his own indicate that "malfunctioning circuitry in certain prefrontal sectors can cause [antisocial] behavioral manifestations." He warns, however, that pathological behaviors linked to one brain area frequently stem m from deficits elsewhere in the brain, and suggests that the frontal lobe abnormalities being detected in people with antisocial behavior are "probably accompanied by malfunction in varied subcortical territories."