Most of the time, doctors can diagnose a child or adult with attention deficit hyperactivity disorder (ADHD) simply by observing his behavior in the office, and asking parents or spouses to describe his attention or behavior problems — when they started, where they occur, and so on.
But sometimes doctors have trouble making a definitive ADHD diagnosis. Maybe the symptoms don't precisely fit the profile of ADHD. Maybe mood swings and anxiety muddy the picture. Or perhaps the patient has been taking ADHD medication for a while and things have gotten worse instead of better. What now?
When the diagnosis is iffy, the usual approach is to order one or more additional standard diagnostic tests (see Diagnosing Difficult Cases). But, in part because these tests have their own limitations, a handful of ADHD docs have begun offering high-tech (and high-cost) diagnostic tests — notably a technique known as single photon emission computed tomography (SPECT) and quantitative electroencephalography (qEEG), which measures brain wave activity.
Can these tests really pinpoint the cause of a patient's behavioral and emotional problems, as their proponents claim? Can the tests predict the most effective treatment? Or are they, as many mainstream ADHD docs insist, a useful tool for research, but unproven as a means of diagnosing individual cases of ADHD?
SPECT and speculation
The neuroimaging technique that has aroused the most interest among those suspected of having ADHD is SPECT. This 20-minute test measures blood flow within the brain; it shows which brain regions are metabolically active ("hot") and which are quiescent ("cold") when an individual completes various tasks.
The procedure entails an injection of a radioactive isotope that is then picked up by the brain. This means exposure to a small amount of radiation — about the equivalent of an X ray. The patient lies motionless as a camera rotates around his head. Several scans may be required, at a cost that can top $1,000.
SPECT has an outspoken advocate in psychiatrist Daniel Amen, M.D., of Newport Beach, California. Dr. Amen heads a group of four clinics, which, he says, have performed a total of 31,000 SPECT scans of people with various psychiatric problems.
"Neuroimaging doesn't give you a diagnosis," says Dr. Amen. "It's one part of a full evaluation that you have to put in the context of what goes on in a patient's life." Low activity in the prefrontal cortex is typical of ADHD, he says, but it can also occur with schizophrenia, dementia, and head injury. "You can't read these things blindly."
By providing information that is impossible to obtain from a simple clinical examination, Dr. Amen claims, "SPECT adds to the richness of the diagnosis and helps target treatment." The images are useful in a range of psychiatric and neurological disorders, not just ADHD, he says.
"No one with a simple problem comes to see us," Dr. Amen says. His average ADHD patient carries at least three other diagnoses — usually anxiety, bipolar disorder, conduct disorder, or depression. "Head trauma is much more common than people think. Forty percent of my patients have some sort of injury."