Device aims to perfect diagnoses of ADHD
Motion sensors used to detect movements
BELMONT — The tiny red eye of the Quotient diagnostic device can’t see a child’s face. It can’t see him fidget in class. It doesn’t know what his grades are. But it can see even the subtle moves a child makes, down to the millimeter.
According to the company that manufactures the device and the McLean Hospital psychiatrist who invented it, the Quotient’s motion tracker can help a doctor determine whether a child has attention deficit hyperactivity disorder, or ADHD.
The makers call it the first objective test for ADHD. But BioBehavioral Diagnostics must overcome skepticism among many doctors, who have seen other diagnostic tests for ADHD flop.
The absence of a reliable test, combined with the wide use of behavior-modifying drugs, has made ADHD a controversial disorder. Often, parents are left unsure about what to do when their child is one of the 5 to 10 percent of children diagnosed with ADHD, which is characterized by hyperactivity, inattention, and impulsivity.
“These diagnoses are based on behavioral descriptors, or subjective states of being,’’ said Judith Warner, author of “We’ve Got Issues: Children and Parents in the Age of Medication.’’ “That makes it suspect in the eyes of people who don’t understand it.’’
BioBehavioral Diagnostics, of Westford and Philadelphia, says its device can change that, by distinguishing between the restlessness and jitters of a child with ADHD and the movements of one who does not have the disorder.
“The idea is, if you have objective measures for this disorder, it should give people a lot more confidence about the diagnosis,’’ said executive chairman Byron Hewett.
Some clinicians, however, said the Quotient looked similar to an older type of test, called a continuous performance test, or CPT, that has been mostly abandoned. In a CPT, the patient works at a task and the number and type of mistakes the patient makes are recorded and quantified.
“The problem with those tests is that . . . they have not been shown to be useful,’’ said Dr. William Barbaresi, an ADHD researcher at Children’s Hospital Boston. “They don’t correlate accurately to the presence of ADHD, and that makes me skeptical about the ability of this [new] instrument.’’
Dr. Ari Tuckman, vice president of the ADD Association, a national advocacy group, had the same impression. “This is basically just a CPT test that adds a motion sensor to it,’’ he said.
But the motion sensor is what makes the Quotient different and better than the older tests, said Dr. Martin Teicher, the Harvard Medical School associate professor who invented the device at McLean. “The [CPT] tests aren’t very good, I totally agree,’’ he said. But when a motion-sensitive camera is added, he said, the picture changes.
Here’s how the Quotient works: The test-taker sits at a computer, playing a simple game. Black stars flash against a white screen, and the patient has to hit the space bar as they appear. The task measures concentration and impulsivity.
But the computer game isn’t as important as the infrared cameras watching the test-taker’s every move.
Three cameras record the position of reflective dots strapped to the forehead and shins, taking frames at 50 times per second. It’s the same technology used in motion-capture animation for movies like “Avatar’’ and “Watchmen.’’
The result is a detailed, quantifiable record of how the patient moves during a boring, challenging attention task. It doesn’t matter so much what the task is, but how patients behave while they complete it, Teicher said.
When Teicher examined the data, he said, he found a marked difference between people with and without ADHD — something that’s easy to see on paper.
The reflective dot on the foreheads of a person with ADHD traces a tangled snarl, like a child’s scribble. A person without ADHD moves much less, producing a jittery dot.
But it’s not just that people with ADHD move more, Teicher said — they also move differently.
People without ADHD move more erratically, he said, while people with ADHD have simpler, swaying movements. “We didn’t expect it to be so clear-cut,’’ he said.
In a study of 29 children, published in the Journal of the American Academy of Child and Adolescent Psychiatry in 1996, Teicher reported that the device accurately identified 16 of the 18 children who had been previously diagnosed with ADHD, and all 11 who did not have the disorder.
Teicher said he initially developed the technology for his research. It was only later that he realized motion-capture could be as useful in a doctor’s office as in a lab.
BioBehavioral Diagnostics approached McLean to develop Teicher’s work into a marketable diagnostic tool in 2004. The company has licensed the technology from McLean. Teicher said he is a paid consultant for the company and “has the potential’’ to receive royalties for use of the technology. He declined to say how much the company pays him, but said the arrangement complies with Harvard’s conflict of interest policies.
The test has been approved by the Food and Drug Administration, and there are about 60 Quotient kiosks in use across the country, Hewett said. The device costs clinicians $19,500; the company then charges $50 per child and $55 for adults for providing a computer-generated report for each patient. Hewett said the company hopes to break even this year.
Warner said she hopes the Quotient works as advertised.
“There’s been so much doubt — not within the medical community, but the public at large — about whether ADHD is real,’’ she said. “People are desperate for certainties.’’