The challenges of diagnosing ADHD
Testing for attention deficit hyperactivity disorder (ADHD) isn’t as straightforward as a blood test or throat swab. To diagnose ADHD, a doctor will ask you and your child’s teachers to complete a survey or checklist about your child. The checklist covers behavioral situations such as trouble concentrating or impulsivity. Some kids may also take verbal or written tests.
ADHD can show up differently in each child affected, which makes it harder to determine the diagnosis. Some kids don’t have the typical behaviors like inattention. Others may have different symptoms, like moodiness or obsessive- compulsive tendencies.
Some doctors have started using new methods to diagnose ADHD. Since ADHD is a neurodevelopmental disorder, high-tech brain scans based on blood flow and brain wave activity may help give insight into this condition.
But do these scans really work? Read on to see what current research and science says about brain scans and ADHD.
Looking inside the brain
Some researchers believe that clinical ratings and measures are unreliable. Results can often vary based on clinicians, cultures, and countries. Looking at images of brain waves and patterns is a more objective way of evaluating ADHD.
A functional magnetic resonance image (fMRI) can help scientists compare the brain function of people with and without ADHD. Just as an electrocardiogram (EKG) shows the heart’s electrical activity, a functional MRI shows the brain in action. Since ADHD is a neurodevelopmental disorder, it makes sense to look at brain activity. Abnormalities in the structural and functional connectivity of the brain’s networks are consistently linked to ADHD.
But there aren’t many studies looking at brain activity and ADHD. Scientists are still trying to figure out the best activity or pattern to look for in these scans.
What brain scans show
There are many different brain scan machines and methods that researchers use to study brains with ADHD. Some of these include:
- single-photon emission computed tomography (SPECT)
- positron emission tomography (PET)
- functional magnetic resonance imaging (fMRI)
One pilot study compared the brain MRIs of adolescents with ADHD to those without. The patterns from grey matter accurately classified about 79.3 percent of the participants who had been previously diagnosed with ADHD.
Looking at brain functions and activity
The National Institute of Mental Health found that the certain sections of the brain in people with ADHD mature slower than those without ADHD. This delay occurs mostly in the frontal lobe, the part of the brain that is responsible for impulse control, concentration, attention, and planning.
Even though certain sections of the brain are associated with ADHD behaviors, how the parts of the brain communicate with each another may also be important in people with this condition. Someone with ADHD might show impairments related to cognitive, behavioral, and motivational functioning. This means that not only looking at brain structure but also at brain activity during a task may provide clues as to the causes of ADHD.
But many clinicians do not rely on brain imaging scans for an ADHD diagnosis. In fact, many of these tests are not reliable, valid, or approved.
What brain imaging is available now?
The Food and Drug Administration (FDA) approved one biological test to help diagnose ADHD in children from 6 to 17 years old. It’s called the Neuropsychiatric EEG-Based Assessment Aid (NEBA) System. It records the type and number of brain waves that nerve cells give off each second. It is shown that people with ADHD tend to have a higher brain wave ratio between the two common brain waves — theta and beta — compared to people without ADHD. But this test isn’t meant to replace clinical evaluations. The results are meant to be used alongside a patient’s medical history and physical assessment.
If the NEBA test does not indicate a likelihood of ADHD, it can lead the clinician to evaluate the patient for other conditions such as head injuries, substance abuse, and auditory processing disorders. These conditions can also cause ADHD-like symptoms including impaired functioning and low attention span. So when it’s unclear if symptoms are due to ADHD or another condition, a clinician can use the information provided by NEBA scans.
The controversy behind SPECT
SPECT is when your child receives an injection of a radioactive substance. A doctor observes the substance to measure blood flow and brain activity, often while the child is performing a task. But there are no reported studies on the effectiveness of SPECT.
In fact, SPECT scans are not FDA-approved for diagnostics. They are controversial because they only have a 54 percent sensitivity, meaning they’re only accurate half the time. While some people in the medical community may use SPECT, there is no scientific evidence that it’s reliable or accurate.
What are the limitations of brain scans?
Brain imaging scans may be appealing because they appear to offer a firm diagnosis. However, these tests are still new in regards to their use in ADHD, and they have many limitations. These tests are also expensive and can potentially expose children to radiation.
Lack of sensitivity: Brain imaging scans aren’t sensitive enough to provide clinicians accurate data for just one individual. Most of the accuracy data for brain scans and ADHD comes from group analysis. This means that on a case-by- case basis, the accuracy of a brain scan may drop. For ADHD, a diagnosis applies to the individual, not groups.
Lack of specificity: Most brain imaging tests look at the brain of someone with ADHD and someone without. These tests can’t provide a differential diagnosis or help identify other conditions. Few imaging studies compare the brain activity of multiple disorders.
Lack of standardization: Brain scans aren’t ready for widespread clinical use. At the moment, there’s no one way to conduct a brain test, which means lab results can differ. Study results are incomplete without information on what people were asked to do during the brain scan.
Currently, brain scans are more useful for research purposes than for making clinical diagnoses.
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