Salutary change after frontal brain trauma

Gender and Hemispheric Asymmetries in Acquired Sociopathy

The emergence of enduring antisocial personality changes in previously normal individuals, or "acquired sociopathy," has consistently been reported in patients with bilateral injuries of the ventromedial prefrontal cortex. Over the past three decades, cases of acquired sociopathy with (a) bilateral or (b) unilateral sparing of the ventromedial prefrontal cortex have been reported. These cases indicate that at least in a few individuals (a') neural structures beyond the ventromedial prefrontal cortex are also critical for normal social behavior, and (b') the neural underpinnings of social cognition may be lateralized to one cerebral hemisphere. Moreover, researchers have presented evidence that lesion laterality and gender may interact in the production of acquired sociopathy. In the present review, we carried out a comprehensive literature survey seeking possible interactions between gender and hemispheric asymmetry in acquired sociopathy. We found 85 cases of acquired sociopathy due to bilateral (N = 48) and unilateral (N = 37) hemispheric injuries. A significant association between acquired sociopathy and right hemisphere damage was found in men, whereas lesions were bilateral in most women with acquired sociopathy. The present survey shows that: (i) the number of well-documented single-cases of acquired sociopathy is surprisingly small given the length of the historical record; (ii) acquired sociopathy was significantly more frequent in men after an injury of the right or of both cerebral hemispheres; and (iii) in most women who developed acquired sociopathy the injuries affected both cerebral hemispheres. These findings may be especially valuable to neuroscientists and to functional neurosurgeons in particular for the planning of tumor resections as well as for the choice of the best targets for therapeutic neuromodulation.

Neuropsychiatry of frontal lobe dysfunction in violent and criminal behaviour: a critical review

OBJECTIVES

To establish the link between frontal lobe dysfunction and violent and criminal behaviour, based on a review of relevant literature.

METHODS

Articles relating evidence of frontal lobe dysfunction with violence or crime were collected through a MEDLINE search using the keyword "frontal lobe" combined with the terms "aggression," "violence," "crime," "antisocial personality disorder," "psychopathy," "impulse control disorders", and "episodic dyscontrol." Reference lists were then searched for additional articles.

RESULTS

High rates of neuropsychiatric abnormalities reported in persons with violent and criminal behaviour suggest an association between aggressive dyscontrol and brain injury, especially involving the frontal lobes. The studies reviewed support an association between frontal lobe dysfunction and increased aggressive and antisocial behaviour. Focal orbitofrontal injury is specifically associated with increased aggression. Deficits in frontal executive function may increase the likelihood of future aggression, but no study has reliably demonstrated a characteristic pattern of frontal network dysfunction predictive of violent crime.

CONCLUSIONS

Clinically significant focal frontal lobe dysfunction is associated with aggressive dyscontrol, but the increased risk of violence seems less than is widely presumed. Evidence is strongest for an association between focal prefrontal damage and an impulsive subtype of aggressive behaviour.