My understanding is that people with ADHD have different brain structure to people without.

If this is the case, why isn't the difference of brain structure used to diagnose ADHD, rather than a series of questions relating to behavioral symptoms?

  • $\begingroup$ Unfortunately, your question appears absolutely unclear to me. First, the title is not fully comprehensible. Second, the question is incoherent in itself: if one could state that ADHD "is caused by a brain structure" it would appear to me the most obvious diagnostic strategy to check for that structure (or difference in structure). Third, behavioural symptoms are THE way of diagnosing ADHD and many other (neuro-)psychiatric disorders. Yet, other methods apart of rating behavioural variables might be used. Please clarify your question so that it can be answered. $\endgroup$
    – bunsenbaer
    Commented Aug 10, 2015 at 21:43
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    $\begingroup$ Furthermore, it cannot be stated for virtually any such disorder that it can be explained by the malfunction of any single brain structure. The brain is a highly complex system with its many different parts dynamically affecting many others directly or indirectly from molecular up to the systems level. $\endgroup$
    – bunsenbaer
    Commented Aug 10, 2015 at 21:48
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    $\begingroup$ Could you give a source that claimed ADHD is caused or correlated with abnormal brain structure? $\endgroup$
    – Seanny123
    Commented Aug 10, 2015 at 22:03

2 Answers 2


ADHD is not 'caused' by a brain structure. However, there are observable differences in the brains of ADHD sufferers compared to non-ADHD sufferers.

For example, ADHD sufferers have a disproportionately greater decrease in volume in the left side of the prefrontal cortex, as well as the posterior parietal cortex.

In addition, there is typically a reduction in the number of dopamine receptors, as well as a sensitivity to neurotransmitter activity. Thus, stimulants and cognitive enhancements are often used to treat ADHD.

This paper does a good, in-depth job of mapping networks and brain connectivity to ADHD. If you were to read it, you might notice a problem -- it isn't the case that there is one 'brain structure' that ADHD sufferers have that non-sufferers do not have, nor is it just one brain structure that is affected. The way that ADHD seems to 'work' in the brain is very complex, and there is still much to be learned about the brain before we can go about diagnosing people based on MRI data.

Furthermore, the line between ADHD and other mental disorders is not clearly drawn. Inattentiveness could stem from depression, trauma, or insomnia, for example. Mania and/or hyperactivity could stem from bipolar disorder or histrionic personality disorder. We are so far from figuring the brain out that we can only rely on context at this point in time.

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    $\begingroup$ Not to mention that diagnostic tools for "brain structure" are not exactly cheap or convenient compared to standard diagnostics. $\endgroup$
    – Arnon Weinberg
    Commented Aug 11, 2015 at 1:41
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    $\begingroup$ Do you think you could expand on your answer to make explicit why/how behavioral symptoms are best for making the diagnosis? $\endgroup$
    – dwjohnston
    Commented Aug 20, 2015 at 22:53
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    $\begingroup$ @dwjohnston behavioral symptoms and subjective data are among the only resources we have for diagnosing ADHD in this point in time. It may or may not be the 'best' way; however, it /is/ the most accurate way right now, for the reasons outlined above. Using the brain to diagnose ADHD is about as reliable as using the brain to prove that someone is a 'kind-hearted person'; there are so many varying definitions and perspectives on the term, that it is almost impossible to create an all-encompassing definition. The /only/ somewhat reliable measure we have is behavioral data. $\endgroup$ Commented Aug 21, 2015 at 0:06

The latest research in ADHD scan studies show a lack on activity in the left side of the pre-frontal cortex. As far as your question goes not everyone can afford these scans to come up with an accurate diagnosis. Also a SPECT scan could show two different patterns in activity if the scan was done more than once. It would have to take numerous scans over time to come up with an accurate diagnosis. That is why it is much easier to be honest about symptoms with a psychiatrist you trust.

David Lopez Blass

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    $\begingroup$ Adding references to strong claims is important to allow folks to read more on the backgrounds of your answer. -1 $\endgroup$
    – AliceD
    Commented Aug 14, 2015 at 1:17
  • $\begingroup$ As far as I know the predictive power of SPECT and other brain scans is still too low for ADHD or any other major psychiatric disorder. $\endgroup$ Commented Nov 20, 2017 at 15:51

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