http://www.sciencedaily.com/releases/2012/07/120730094822.ht...
http://www.nami.org/Template.cfm?Section=ADHD&Template=/Cont...
They appear to be about the same research program. They share the same author, Philip Shaw. From the first "We measured the thickness of the cortex across thousands of points in the brain in .. (466) children - half of whom had ADHD and half of whom did not" and from the second "They recruited 234 children with ADHD and 231 typically developing children ... they were able to map the trajectories of surface area development at over 80,000 points across the brain."
Even though they appear to be different efforts (the number of children involved are different and the years are different), there might still be some spurious correlations solely because the same people, with the same expectations and analysis technique, are involved.
Unfortunately, I am unable to read the primary literature. The first links to a paywalled journal article ($31.50), the second doesn't have a journal citation. I found http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3342014/ by the same author, and published a couple of months after the article in the first link. Unfortunately, which it says there are distinguishable features, along with two reference comparisons, it doesn't give enough information to judge if those differences are truly diagnostic.
I did find http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3440402/ which comments "The ADHD diagnosis rests only on these symptoms because no biological markers (e.g. genetic tests, brain imaging) have been validated [11]", but that reference [11] is from 2006, and older than the two links you gave.
A 2007 metaanalysis (so again, older than the two references you gave) at http://www.ncbi.nlm.nih.gov/pubmed/16950217 points out that at that time "Although there are many structural neuroimaging studies of attention-deficit/hyperactivity disorder (ADHD) in children, there are inconsistencies across studies and no consensus regarding which brain regions show the most robust area or volumetric reductions relative to control subjects."
To highlight the intent behind those last two previous paragraph, they are saying that there are many studies like the ones you pointed out, which show a correlation between some physical measurement and ADHD. Unfortunately, they don't seem to be consistent. Because of the well-known publication bias problem, it's likely that false positives are over-reported. It takes additional followup work to determine if those signals are really true, and if they are distinguishable enough to be used diagnostically.
This all tells me that there is no "large structural brain difference", and especially not one which has been validated as a diagnostic tool. There might be a small structural brain difference, but again, I find no evidence that identification of this difference is available as a diagnostic tool at all, even if the price were disregarded.
Again, I might be focusing on the wrong thing, but perhaps you may be misinformed? If most of your research is through the popular literature, then my earlier reference to http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3440402/ ("Why Most Biomedical Findings Echoed by Newspapers Turn Out to be False: The Case of Attention Deficit Hyperactivity Disorder") may be useful:
> Because newspapers preferentially echo initial ADHD findings appearing in prominent journals, they report on uncertain findings that are often refuted or attenuated by subsequent studies. If this media reporting bias generalizes to health sciences, it represents a major cause of distortion in health science communication.
What this means is that you get a lot of studies that have conclusions such as "well this drug worked for 70% of the test subjects but danged if we know why the other 30% were unresponsive, after all, they have been diagnosed with ADHD!"
If you really want to dive deep, I suggest this talk by Russell Barkley, https://www.youtube.com/watch?v=q3d1SwUXMc0, it does an excellent job of covering why the hell the current literature on ADHD is such a mess.
He also provides lots of compelling evidence for ADHD, but also discusses various symptom (and treatment!) clusters that defy explanation if you think of just "ADHD". There is also discussion different causes of ADHD, suffice to say the symptom rate for children born to mothers who drink during pregnancy is, to say the least, way above the norm, with ADHD in those cases being co-morbid with other disorders[0]. Finally there is some slides about genetics as well.
On a related note, it is funny, the term ADHD-PI is being used by some people to basically describe an entirely different disorder with a completely different treatment mechanism. Stimulants do nothing, but there are treatment programs that do help. On ADHD support forums, those of us who are regular contributors try to do our best to educate ourselves about ways to help people who both have "ADHD" and also "ADHD-PI".
As for the entire "ADHD isn't real" crowd, well, those of us who have it get rather pissed off. I have been reduced to tears because I wanted to do something with every fiber of my being but was unable to focus on it for more than seconds at a time.
Even with a well tweaked treatment regimen, ADHD is still a daily struggle. It is a literal fight to maintain control of myself, from pushing back against a constant all consuming addiction to anything that resembles a dopamine reward cycle[1] to having a reserve of will power[2] that resembles a water pump sitting out in the dry desert heat.
One thing people without ADHD don't realize is that for those with ADHD, the drugs work very differently. Someone without ADHD can take ADHD stimulants and stay up for 2 days straight and have razor focus. Someone with ADHD who takes the same meds, well, going back to my previous metaphor, it is like priming the pump, even with drugs it still takes a slew of self control techniques learned through years of therapy to maintain control over my life.
To live my daily life, I carry an organizer around wherever I go that I write everything down in. I then have calendar events for everything I need to do. On top of that I have my life carefully arranged such that everything I need to do is within instant quick reach, because if I have to spend even a modicum of effort to achieve what I want to do, I will get distracted on my way and forget what the hell I am after.
Thankfully little details help establish some sort of normality. My keys, wallet, laptop, badge, glasses, notebook, all sit next to each other stacked in a nice pile that I can put into/on my pockets/back/face within seconds. If I get interrupted, I will forget one of those.
Side effects of this? I pretty much have to live close to work because I'll forget my laptop at home roughly 60% of the time. (I don't carry my laptop home every day so I do not have the same years of routine built up that allow me to remember the other things I need.)
Heck yesterday I went to a friend's house to make waffles and I forgot the bloody waffle mix. (Sorta the one thing required to make waffles.)
Any one set of these symptoms in of itself is not unusual. Some people have a poor memory, meh. Some people are easily distracted, sure. But when a cluster of symptoms all comes together and has a serious negative impact on the quality of someone's life, then there is a real problem that needs investigation and help.
I guess what it comes down to is, I've both struggled with ADHD myself, and seen undiagnosed, untreated, ADHD completely destroy people's lives.
Finally, there are a variety of diagnostic criteria that can be used for testing ADHD. A full suite of psychological evaluation tests will include sections on attention and focus. People with ADHD will basically fail bomb those parts of the test. (Said tests tend to take multiple days and cost thousands of dollars to administer...)
[0]ADHD's co-morbidity with bi-polar disorder is tragically high. Thankfully this is a topic which has recently gotten a lot more awareness in the medical community, so patients are finally being properly diagnosed. Of course there is a huge stigma around bi-polar disorder, much more so than ADHD, so a lot of people who are willing to admit that they have ADHD may very well turn away or refuse to believe a diagnose of bi-polar. This typically doesn't end well...
[1]I avoid MMOs and mobile gaming like the plague. I've gotten almost addicted to MMOs a couple of times, thankfully both times I was able to write a bot to play for me and then lost interest.
As I pointed out in my earlier response, science journalism does a poor job of communicating science. Even the primary journals are subject to publication bias and other factors, which has lead to articles like "Why Most Published Research Findings Are False" http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1182327/ . If your information comes primarily filtered through science journalism and an occasional primary reference, then you may have an overly skewed view of the research results.
Based in what you've just written, you confirm by implication that there aren't large brain differences. If there were large differences, then ADHD would have a well characterized physical diagnosis. As you point out, it doesn't. It depends on psychological tests. You mention those tests take "multiple days and cost thousands of dollars to administer." But NMR or MRI scans do not take that much time nor cost that much, and would pick out "large structural brain differences", which tells me that there are no large structural brain differences that can be used as a diagnostic test for ADHD.
Then you mention 'the entire "ADHD isn't real" crowd'. I empathize with your frustrations, but that is a different topic. I am not a member of that crowd, nor was the primary reference which started this HN discussion saying that ADHD isn't real. Its argument is that ADHD is very likely overdiagnosed:
> Only one significant study has ever been done to try to determine how many kids have been misdiagnosed with ADHD, and it was done more than twenty years ago. It was led by Peter Jensen, now the vice-chair for psychiatry and psychology research at the Mayo Clinic, but at the time a researcher for the National Institute of Mental Health. After a study of 1,285 children, Jensen estimated that even way back then—...—between 20 and 25 percent were misdiagnosed. They had been told they had the disorder when in fact they did not.
It agrees with your statement that there are "variety of diagnostic criteria", and emphatically agrees with your earlier statement that "a 30 minute patient interview should not be the sole determining factor." It's horrible if someone isn't diagnosed as ADHD who would do better under ADHD treatment. It point is that it's also horrible if someone is misdiagnosed as ADHD and gets ADHD treatment even if it that treatment doesn't help, likely makes things worse by not getting the right treatment.
BTW, I looked for information about your [0]. See http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3028268/ , "Bipolar and ADHD Comorbidity: Both Artifact and Outgrowth of Shared Mechanisms" (2010).
> Published rates of comorbidity between pediatric bipolar disorder (PBD) and attention-deficit/hyperactivity disorder (ADHD) have been higher than would be expected if they were independent conditions, but also dramatically different across different studies. This review examines processes that could artificially create the appearance of comorbidity or substantially bias estimates of the ADHD-BPD comorbidity rate ...
(The point is that if there are dramatically different results, then that may be because of artificial biases, rather than real ones.)
See also http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3201827/ , "Pediatric bipolar spectrum disorder and ADHD: comparison and comorbidity in the LAMS clinical sample" (2012)
> "Of 707 children, 538 had ADHD, 162 had BPSD, 117 had both ADHD and BPSD, and 124 had neither. Comorbidity (16.5%) was slightly less than expected by chance (17.5%). ... The high rate of BPSD in ADHD reported by some authors may be better explained as a high rate of both disorders in child outpatient settings rather than ADHD being a risk factor for BPSD." (italics are mine)
The limited search I did of the primary literature does not seem to give the same conclusion as what you have stated. While I don't know the literature, nor the field, I will be so bold as to suggest that things you believe to be true about ADHD are actually not so well understood as you believe them to be.
