The American Psychiatric Association's Diagnostic and Statistical Manual-IV Text Revision (DSM-IV-TR) estimates that Attention Deficit Hyperactivity Disorder (ADHD) affects 3% to 7% of children in the U.S. and can last through teenage years and into adulthood. The accuracy of such statistics is as difficult to determine as the neurobehavioral disorder is to diagnose. (See “Sample attention state analyses” and “Sample motion results.”)

ADHD affects the way an individual functions in different settings, such as school or home environments, but it manifests itself as extreme forms of commonly occurring types of behavior. Assessment involves the observation of three core symptom areas: inattention (the difficulty in staying focused and on task), hyperactivity (the inability to control movement and sit still while working), and impulsivity (the inability to inhibit inappropriate responses). In order to diagnose an individual with ADHD, he or she must exhibit symptoms at abnormal levels for his or her stage of development that interfere with normal daily activities.

Doctors and psychologists traditionally diagnosed ADHD by relying on standard guidelines from the American Academy of Pediatrics and the American Academy of Child and Adolescent Psychiatry. Clinicians arrived at diagnoses based on how a child's behavior compared with that of other children the same age. These tests based on verbal communication and observation often yield inconsistent or questionable results. As ADHD awareness became more prevalent, so too was the need for an objective, scientific test based on stimulation and motion detection.

Such a system was recently developed by BioBehavioral Diagnostics (BioBDx), Cambridge, MA, (biobdx.com). The Quotient ADHD System is a 15- to 20- minute test that monitors an individual's movement while he or she attempts to focus on changing visual stimuli. The first system of its kind to receive FDA approval, it measures levels of inattention, hyperactivity, and impulsivity and provides an objective, simple report within the privacy of a healthcare provider's office.

Engineers at Farm Design of Hollis, NH, (farmdesigninc.com) and Worcester, MA-based Coghlin Companies (coghlincompanies.com) subsidiary, DCI Engineering, created the system, which captures a patient's movement (within less than 1 mm) in real-time (50 times/second). For patients between the ages of 6 and 12, the device uses one reflector to capture movement of the forehead. However, for patients 13 years of age or older, shin movement was found to have clinical significance in diagnosing ADHD. For these patients, the device captures movement of both the forehead and shins using three reflectors.

The engineering challenge was creating a device that could simultaneously measure motion and capture response time to changing visual stimuli. This measurement combination provides a comprehensive picture of symptoms in a clinician report. The final design required a device that could withstand heavy use and continually report the highest quality, objective measurements.

During the Quotient ADHD System testing process, the patient watches a screen and responds to stimulus images using coded keyboard keys. The testing device must measure the patient's movement with no impact from the spurious vibrations caused by the keyboard or by patient hyperactivity. These exact measures of movement, and the patterns of motion, provide useful information.

In the early design stages, engineers evaluated each concept for the Quotient ADHD System according to its ability to meet the design criteria — particularly durability, isolation of motion, mobility, and suitability for clinical use. Ultimately, design engineers developed a sturdy kiosk design that would not only allow clinicians to move the device from room to room, but would also remain stable and immobile during testing. The motion tracking sensors (MTS) were mechanically isolated from the main part of the kiosk in order to minimize possible distortion of test results caused by extraneous vibrations.

Design engineers built several full-scale models for review and alterations in the testing phase. The goal was to incorporate shapes that would adapt well to the thermoforming process. Engineers used standard parts wherever possible to guarantee that any required service to a unit in the field could be conducted by a single person without specialized tools. Additionally, the device's modular design provides flexibility to adapt to changes as electronic components evolve with new technology, or as the system expands with additional capabilities in the future.

There were several engineering challenges. During the validation build performed by Coghlin Companies subsidiary, Cogmedix Inc., for example, engineers discovered several inconsistencies in mating major components. Further research of the solid model confirmed tolerance build-up was creating an inconsistent fit issue along with other mechanical issues. Research yielded intermittent observations of these numerous problems. BioBDx and DCI Engineering worked with the commercial parts suppliers and modified engineering details of custom fabrications as necessary to eliminate the tolerance stack-up conflicts, ultimately resolving the issues.

The kiosk design replicates environmental attributes present in daily life, such as a desk at school or work. This is consistent with the DSM-IV's guidance to make patients feel comfortable and relaxed during the assessment of ADHD. In addition, the kiosk's unobtrusive design blends with the office environment of a pediatrician, psychiatrist, psychologist, or neurologist.

By housing all elements of the system (even the stool) in a single, moveable unit, the system is literally plug and play. Clinicians can move it to a desired testing room, lock it in place to eliminate the possibility of vibration, and immediately put it to use.

From the onset of the project, development teams worked closely with DCI Engineering and Cogmedix Tier 1 suppliers to ensure the unit could be manufactured and scaled reliably in quantities as needed.

Currently there are 100 Quotient ADHD systems in use throughout the United States with installations in Europe expected soon.