Where is the evidence to support ‘ADHD expert’ Prof Kohn’s claim that amphetamines aid brain development?

Open letter to Professor Michael Kohn

Dear Professor Michael Kohn,

Despite significant longstanding evidence to the contrary a recent article in the Daily Telegraph stated:

“Westmead Hospital pediatrician Professor Michael Kohn, who has patients under the age of six, said… more evidence had recently come to light which confirmed that children with ADHD had brains that developed slower. Stimulant medication like Ritalin helped brain growth. “Children with ADHD have a lower rate of brain growth and development and they do not reach the same peak of brain growth that children without ADHD do,” Prof Kohn said. “When we give them stimulant medication, scans show a more normal pattern of brain development than would otherwise have occurred.[1]

This letter seeks evidence supporting your claim that giving ‘ADHD’ children stimulants, amphetamines (dexamphetamine) and amphetamine-like drugs (Ritalin, Concerta) aids in ‘brain development’. I am very surprised by this claim as numerous studies have long established that the use of psycho-stimulants by children has regularly resulted in gross malfunctions in the brain, and ‘can cause shrinkage (atrophy) or other permanent physical abnormalities.[2] As this is the opposite of what you are claiming, I would like to have access to any contradictory new evidence and if it is valid help to publicise it. If, however, there is not adequate supporting evidence I would welcome an explanation of why you made this surprising claim.

I would also like to have access to the evidence supporting your claim that ‘children with ADHD have a lower rate of brain growth and development and they do not reach the same peak of brain growth that children without ADHD do’. I am aware of previous similar discredited claims in studies which purported to show differences in brain growth in ADHD and non-ADHD brains.  Amongst numerous methodological flaws these studies compared ‘non ADHD brains’ that have never been medicated, to ‘ADHD brains’ that have been atrophied by previous exposure to psycho-stimulants.  In the past this important point has not been highlighted in arguments used to justify giving children ADHD amphetamines.[3] If you have new valid evidence I would appreciate access to it. If not, I wonder what efforts you are going to make to correct the record with Daily Telegraph readers.

Some readers of the Daily Telegraph article may also have been left with the impression that you prescribe Ritalin to children 5 and younger. Obviously I presume you never prescribe any methylphenidate product (including Ritalin) to your patients ‘under the age of six’ as you are undoubtedly aware methylphenidate is NOT APPROVED for use in children under 6 years of age. This is because methylphenidates’ safety and efficacy in this age group has not been established.[4] It might also be helpful to clarify this with Daily Telegraph readers.

I would welcome your early reply and offer you the opportunity to post it unedited on my website.

Yours sincerely

Martin Whitely MLA

21 June 2011

Update: 3 October 2012 Still no answer from Professor Kohn 

[1]     Janet Fife-Yeomans, ‘Rising rate of ADHD drugs for kids like Ritalin’, The Daily Telegraph, 13 June 2011.  Available at http://www.dailytelegraph.com.au/news/rising-rate-of-adhd-drugs-for-kids-like-ritalin/story-e6freuy9-1226073934249
[2] Peter R. Breggin, M.D., Talking Back to Ritalin: What Doctors Aren’t Telling You about Stimulants for Children, Common Courage Press, Monroe, 1998, p. 358.[3] Jonathan Leo & David Cohen, ‘Broken Brains or Flawed Studies?  A Critical Review of ADHD Neuroimaging Research’, the Journal of Mind and Behaviour, Winter 2003, Vol 24, 1: p29 http://psychrights.org/research/Digest/NLPs/criticalreviewofadhd.pdfaccessed 21 June 2011[4] Medication Guide: Ritalin-SR.  Available at  http://www.dailytelegraph.com.au/news/rising-rate-of-adhd-drugs-for-kids-like-ritalin/story-e6freuy9-1226073934249

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  1. Dr Joe’s avatar

    It is time that self proclaimed” experts” were held to account for both their words and actions


  2. Dr. Mark Foster’s avatar

    As a family practice physician in the US, I encounter daily parents of rambunctious or distracted children who have read articles similar to the one in which Professor Kohn was quoted. These well-intended parents have been persuaded that their children have a disease that requires treatment with potentially harmful and expensive medications.

    I applaud your letter to Professor Kohn and eagerly await his clarifications. After all, if the science and the truth is on his side, then this will be news indeed, and he should welcome the opportunity to share his sources with your readers.


  3. bj2circeleb’s avatar

    Absolutely brilliant letter and I hope that you were also able to get it published in The Daily Telegraph to at least try and allow parents some other second opinion.

    I totally agree that is time that these self proclaimed experts were asked to show “evidence” for what they claim to have discovered, and to verify the accuracy of such claims.

    Above all else it is time that ethics committees that give permission of such dubious studies to take place and those that fund them give a serious look at the methodology of such research BEFORE they ever allow them to go ahead. The amount of useless research that is being generated about so called “brain disorders” just never ceases to amaze me. If a student attempted to submit 99% of it for an honours or PhD thesis they would be failed outright and yet highly creditialled experts are able to, and no one questions what they say and in fact believe them as though they were ‘god”.


  4. bj2circeleb’s avatar

    He was on “A Current Affair” tonight Wednesday the 6th of July, claiming that they have indisputable evidence via brain scans that prove that ADHD does exist and that these drugs SAVE people’s and especially children’s lives!! He said that without them they were likely to commit murder, be in hit and run accidents and have all manner of criminal convictions. And of course for good measure they had a patient of his, and this now obedient 11 year old said that he used to try to be good, but he could not be, and now he could do all that was asked of him at school, he could play the guitar and play with the children. Shame they were not willing to give an example of what happens when the drugs fail, the side effects of them, how they do not benefit children long term and the like. All things that have been shown over and over again and that were detailed extensively and brilliantly in Robert Whitakers book “Anatomy of an Epidemic”. Any body with any common sense would not trust anything on that show, but the sad part is those the are the most gullible and going to believe it all. Why he needs to be seen on a show as poor as that, is beyond me, if he really had the evidence he would be willing to have it properly analysed and debated on something like Four Corners, but its much easier to get a heap of patients and gullible parents this way.


  5. Martin Whitely’s avatar

    I saw Professor Kohn’s performance on ‘A Current Affair’ tonight. If he makes the extraordinary claims he made with cameras running I wonder what he tells niaive, trusting parents when nobody else is there to hear.


  6. Gayle D’s avatar


    Is this the same Professor Michael Kohn appearing as one of the experts on this documentary? Certainly seems very eager to medicate.


    1. Martin Whitely’s avatar

      It certainly is the same Professor Kohn. Thankfully there aren’t two of him.



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