In 1998, a Boston University trauma specialist, Dr. Bessel A. van der Kolk, attempted to trace the process by performing photon emission computed tomography (PET scans) on the brains of 12 PTSD sufferers before and after EMDR therapy. Following three EMDR sessions, the patients' PET scans showed increased activity in the frontal lobes of the cerebral cortex, the so-called seat of "reason," and decreased activity in the limbic system, the more primitive area of the brain associated with fear and emotion. Dr. van der Kolk theorized at the time that stress-response chemicals flooding the body and brain during a traumatic event interfere with information processing, causing memories to be stored as episodic fragments and sensory impressions. EMDR, he concluded, somehow allows the frontal lobes to act as a filter, stripping the memories of their "emotional valence."

A Real Breakthrough?
EMDR boosters say it doesn't really matter how it works, but that it does. The technique has been used on thousands of patients, from Vietnam War veterans to disaster victims, including survivors of earthquakes in Mexico and Turkey, the Oklahoma City bombing, the Columbine High School shootings, and families of TWA flight 800 passengers. Many adult and child victims of rape, molestation, assault, and car and plane crashes have also been treated with EMDR.

Fewer than two dozen studies of EMDR's effectiveness have been done, yielding mixed results. Some show a majority of patients treated with EMDR experience a significant, lasting reduction in PTSD symptoms compared to patients who receive no treatment. But EMDR-treated patients rarely seem to fare much better when compared with patients who receive other kinds of therapy, leading Shapiro's many critics to say all she's done is to add sleight of hand to an amalgam of old therapies. In 1997, clinical psychologists Gerald Rosen and Jeffrey Lohr wrote, "What appears to have happened is that Shapiro took existing elements from cognitive-behavior therapies, added the unnecessary ingredient of finger waving, and then took the new technique on the road before science could catch up."