Science: Insane or merely psychotic?

Byline: Stephanie Rice

Jun. 18--David B. Sullivan walked into a McDonald's restaurant last year and did what most people would think of as "insane": He went up to a teenage employee, witnesses said, and knifed her for no apparent reason. The victim, Anna Svidersky, died.

But keep one thing in mind when Sullivan, 29, and two other Vancouver residents go on trial this year for equally chilling crimes: A defendant can be insane in the colloquial sense but not the legal one.

Despite advances in brain research that have shed light on how we learn, why we have cravings and where we store memory, what provokes violent behavior can be answered only with an educated guess.

"You can't look (at a brain scan or any other test) and say, 'Aha!'" said Dr. Bruce Gage, a psychiatrist at Western State Hospital near Tacoma.

When a defendant pleads insanity, doctors for the defense and the prosecution will often give differing opinions on the severity of his psychosis.

That's the word they'll use: "psychosis." The word "insanity" is left to the court.

Many people who commit crimes have psychosis, a syndrome marked by delusional thoughts, hallucinations or disorganized thinking.

"Just because you're psychotic doesn't mean you will be found insane," Gage said.

The state's bar for insanity is …