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Comment by rdtsc | Hacker News Reader

Another anecedotal (and probably wrong) idea related to this is the explanation of prevalence of ADHD in US relative to EU, for example.

The genetic selection idea goes something like this -- individuals who ended up migrating here, self selected for being bolder, ready to take on more risk, being less content staying in one place. On one side that is a postive trait, but on the other side manifests as ADHD.

There is a study from 2003 showing that it is not true and that it is due to how diagnosis is handled:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1525089/

Other places claim a strong genetic factor is there:

"ADHD often runs in families. Researchers have found that much of the risk of having ADHD has to do with genes"

http://www.nimh.nih.gov/health/publications/attention-defici...

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Been a couple of years since I've closely tracked the literature on some of these questions. Regarding diagnosis and prevalence of ADHD in children and adults, the population rates are similar internationally (Germany, Brazil, US) provided that the same diagnostic criteria are used. The new standard criteria given in DSM5 and ICD10 may reduce regional differences in the the criteria that are applied.

ADHD is one of the most studied conditions in terms of genetic predisposition. Across many studies the overall heritability is 0.75-0.80, denoting that 75% of the variability between affected and non-affected individuals is accounted for by genetic factors. IIRC the genetic risk of a child having ADHD if one parent has it is about 55-60%.

The migration theories don't hold up well to closer scrutiny, for one thing only some ADHD sufferers are prototypical restless risk-takers. At least an equal proportion are quite risk-avoidant, and would be less inclined to pick up and move.

Nonetheless ADHD may have evolutionary persistence because it confers reproductive advantage, though such advantages are hard to pin down. Perhaps energetic risky behavior is attractive or sexual impulsivity predisposes to having more children, but that's just speculation.

You would think that any bold/risky phenotypes would balance itself out: - On one side, maybe ADHD-types reproduce more or are better disposed to make sure their offsprings get to a reproductive stage (e.g. wealthy, due to a bold move which payed out). - On the other side, their are also more likely to have taken a risky move, which end up costing them a lot, including their life, so no offspring or no additional support to support kin-selection.

It's true that ADHD adults have higher mortality from auto accidents, more health problems, higher divorce rates, greater unemployment, lower educational achievement than non-ADHD peers.

Despite all their disadvantages, rate of ADHD occurrence in the population has been stable as far as can be determined. The inference is reproduction is not impeded, and may exceed the population mean in light of anticipated losses as you describe. I haven't specifically looked into this, not recently anyway, but data may well be out there.

Anecdotally it's a common pattern to see ADHD adults having had numerous partnerships which are not sustained beyond a few years. Not surprisingly, an ADHD parent can wind up with children from these several partners as a result, leading to the hypothesis that instances of high birthrate offset the fraction of ADHD adults with low birthrate.

Obviously, even a small positive offset in birthrate of all ADHD vs. controls would be sufficient to keep incidence of ADHD constant.

Anecdotally, I have heard French people say that it is practically impossible to get a adult psychiatric diagnosis of ADD in France, regardless of how clear and debilitating your symptoms are. It may be that the apparent low rates in the EU are actually systemic diagnostic failures.

(Similarly, I have read that in [I think] Japan, it is actually illegal to begin a course of ADD medication after 18--if you were diagnosed as a child, you're fine, but if your parents never took you to a psych, you're screwed forever. Even in the US I've had a general-practice doctor tell me that they thought ADD just went away after a certain age. There's a lot of denial about adult ADD.)

Interesting. Wonder if it is cultural, and if there is any element of antagonism against US practices -- i.e. "we know US is pretty liberal with this diagnosis, we think it is rather wrong, so we'll just go the other way and deliberately shy away from diagnosing it as much as possible".

Even as a teen in France doctors basically brushed off the entire possibility of me having ADHD and just prescribed me a thing for drowsiness... despite having been treated for ADHD all through middle school with positive results.

I have yet to succeed getting medication that works for me in Japan (crappy laws mean no Adderall for me), but there are adult ADHD support groups that list doctors willing to work with adults despite no prehistory.

ADHD has been in my field of practice for quite a long time. It's true that many countries have greater restrictions on treatment, and medications available in the US are not approved elsewhere. Cultural biases against recognizing the condition are common, but is greater in some countries than others.

In this respect the US has been way ahead of most other places in terms of recognizing ADHD in adults and treating the condition. Even in the US, it still remains highly under-diagnosed and -treated, as its estimated only about 20% of cases ever come to clinical attention, and only a small proportion of those cases get proper and persistent treatment.

Over the last decade or so the stigma against diagnosis and treatment of adult ADHD has diminished, but remains a huge barrier for care of people with the difficulty. It's not a minor condition, in fact research shows ADHD has poor outcomes in all domains of functioning. IOW ADHD is frequently associated with lifetime disability which is usually reduced with appropriate treatment.

Just to point out, there is no conflict between the claims (1) "ADHD is diagnosed more often in the US than in the EU because the US has looser diagnostic standards"; and (2) "ADHD is genetically determined".

In modern societies, kids tend to get little quality time with their parents. In addition, they tend not to grow up in a relaxed carefree environment.

I see kids today with mobile phones, playing addictive games and being unable to focus on a single thing for more than a few moments.

It is tough to make multiyear controlled experiments on such things. I would discount heredity for now.

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