fMRI & ADD/ADHD

HOME
PHYSICS BASICS
MRI BASICS
 fMRI BASICS
REFERENCES




                This page contains information with respect to the application of fMRI as a tool for making a clinical diagnosis of ADD and ADHD. 

Click on the links below to be directed to any of these topics.

CHALLENGE FOR CLINICIANS AND SCHOOLS
CURRENT DIAGNOSTIC PROTOCOLS
fMRI

CHALLENGE FOR CLINICIANS AND SCHOOLS

      
Approximately 5% of school aged children in the United States currently diagnosed with ADD or ADHD.  As a school teacher at an affluent prep school it would seem at first glance that in my community this number is much higher.  My own personal, non-scientific estimation would be more on the order of 10-15% of the population.  This a staggering number.  This presents a challenge for psychological clinicians and schools alike.  For the clinicians, the challenge arises out of the lack of a definitive clinical test for ADD and ADHD.  Currently the disorder is diagnosed by what some would argue is a relatively non-specific evaluation of a child's (or adult's) ability to maintain attention and complete tasks in an age appropriate fashion.  Many of the behaviors associated with ADD could easily be attributed to simply being a child, for example "fidgets or plays with ones hands."  A large determinant in the diagnosis is the comments of parents, teachers, and the patient themselves on questionnaires which attempt to determine if the patient has "appropriate" levels of attention and focus.  Obviously, much of this information is subjective and allows for a multitude of interpretations.  This poses a concern for schools in particular because under the Americans with Disabilities Act (ADA), these students are entitled to certain educational accommodations as a result of their having an educational disability.  These educational accommodations include everything from extra time on tests, to alternative versions of tests, note-takers, access to computers, etc.  Some of these accommodations could easily translate to advantages for students who do not truly need them and hence fraud is a significant concern. 

Return to top

CURRENT DIAGNOSTIC PROTOCOLS

      
Currently ADD is diagnosed predominantly through the use of rating scales and survey methods as well as through the use of particular psycho-educational tests. 
Return to top

fMRI

      
Functional MRI, fMRI, provides new opportunities for a more definitive diagnosis of ADD and ADHD.  The most common treatment for ADD and ADHD is the prescription of stimulant medications such as Methylphenidate, MPH, (Ritalin) or Amphetam (Adderall). ADD patients tend to see a significant decrease in symptoms with the use of these medications.  Unfortunately, the medications only provide a temporary fix.  However, the success of these medications in treating ADD symptoms has provided some of the strongest evidence for the hypothesis that ADD and ADHD are caused by dopaminergic dysfunction in the frontal lobes and striatal structures (basal ganglia.)  Stimulant medications prevent reuptake of catecholamines, particularly dopamine.  Dopamine is particularly important in the frontal and striatal regions.  There is also some evidence of genetic links between variations in the dopamine transporter and D-4 genes and the presence of ADD.  PET scans have shown decreased metabolism in frontal and striatal regions in ADD.  Structural MRI has shown reduced volumes in frontal and striatal regions in ADD.

          In a very important study performed at Stanford, researchers investigated 2 key questions?

1. Does frontal-striatal function differ in ADHD and control children?
2. Does MPH modulate frontal-striatal function differently in ADD children than in control children?

They performed this investigation by subjecting children, both ADD and non-ADD, to a set of Go/No-Go tasks both on and off MPH.  The organization of the test is shown below.

Go No Go Test

For the off MPH scans, ADD subjects went off medication for 36 hours prior to the scan and for MPH scans, ADD patients took their regular dose (7.5 - 30 mg) of MPH 2.0-2.5 hr before the scan and control subjects were given 10 mg doses of MPH in the same time frame.  Scans were performed on the frontal lobes and two striatal structures, the head of the caudate nucleus and the anterior portion of the putamen. 

The results of the study are summarized below.   As one can

Result Table 1


Results Table 2

Results Table 3

Results Table 4

Results fMRI Film

    As one can clearly see from the data and scans, there are observable differences between ADD and non-ADD subjects. Of particular note is the increase in brain activation for the ADD subjects on the medication and the seeming decrease in brain activation for non-ADD subjects on the medication.  This suggests that non-ADD persons might actually suffer from the use of stimulant medications. 

    Obviously much more research is need but this study certainly shows promise for the use of fMRI in diagnosing ADD and ADHD.


Return to top