This BBC piece summarizes an extraordinary case report, presented at the recent American Neurological Association annual meeting, of a 40-year-old married schoolteacher with no previous history of sex offenses who was on the point of incarceration after the abrupt onset of escalating sexual aberrations when his complaints of headaches led to the discovery of an egg-sized tumor in his right orbitofrontal cortex. The excision of the tumor extinguished the behavior; the recurrence of the behaviors was shown to correlate with the recurrence of the tumor, and after its re-excision his behaviors again disappeared.
The association of a brain tumor in the prefrontal cortex with such a behavioral disturbance should not be surprising. As neuropsychologically astute FmH readers know, “this is the part of the brain responsible for judgement, impulse control and social behaviour…” The question for me is whether the authors should be forgiven for so limiting the scope of the conclusions they allow themselves to draw:
Russell Swerdlow and Jeffrey Burns of the University of Virginia who treated the patient said it suggested that doctors should consider brain tumours as the reason why some people became sex offenders.
But they warned that this only applied to people who suddenly become obsessed with sex and who have no previous history.
“If someone argues that every paedophile needs a MRI, the difference in this case was that the patient had a normal history before he acquired the problem,” Dr Burns said.
Typical neurologists, they will consider brain influences on behavior only in cases of gross pathological changes (which, I agree, would be the only alterations detectable on MRI scan). The real challenge this case presents is to where we will draw the line about responsibility for antisocial actions, given that there are so many other processes, more subtle than a brain tumor, that can impair orbitofrontal (not to mention other brain) functions. Indeed, as a behavioral neurologist comments close to the end of the article, even in this case the effect of the tumor may have been indirect, via altering hormonal function, rather than structural and direct.
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