Tuesday, June 17, 2008

ADHD is genetic

ABOUT one in 20 children (those under 18) have a group of symptoms that has come to be known as attention-deficit hyperactivity disorder (ADHD). About 60% of them carry those symptoms into adulthood. For what is, at root, a genetic phenomenon, that is a lot-yet many studies have shown that ADHD is indeed genetic and not, as was once suspected, the result of poor parenting. It is associated with particular variants of receptor molecules for neurotransmitters in the brain. A neurotransmitter is a chemical that carries messages between nerve cells and, in the case of ADHD, that chemical is often dopamine, which controls feelings of reward and pleasure. The suggestion is that people with ADHD are receiving positive neurological feedback for inappropriate behaviour. The surprise is that the variant receptors are still there. Natural selection might have been expected to purge them from the population unless they have some compensating benefit.

Of course, this analysis turns on the definition of "inappropriate". The main symptom of ADHD is impulsiveness. Sufferers have trouble concentrating on any task unless they receive constant feedback, stimulation and reward. They thus tend to flit from activity to activity. Adults with ADHD tend to perform poorly in modern society and are prone to addictive and compulsive behaviour. But might such people do well in different circumstances?

One hypothesis is that the behaviour associated with ADHD helps people, such as hunter-gatherers and pastoral nomads, who lead a peripatetic life. Since today's sedentary city dwellers are recently descended from such people, natural selection may not have had time to purge the genes that cause it.

Dan Eisenberg, of Northwestern University in Illinois, and his colleagues decided to test this by studying the Ariaal, a group of pastoral nomads who live in Kenya. The receptor Mr Eisenberg looked at was the 7R variant of a protein called DRD4. Previous work has shown that this variant is associated with novelty-seeking, food- and drug-cravings, and ADHD.

The team looked for 7R in two groups of Ariaal. One was still pastoral and nomadic. The other had recently settled down. As they report in this week's BMC Evolutionary Biology, they found that about a fifth of the population of both groups had the 7R version of DRD4. However, the consequences of this were very different. Among the nomads, who wander around northern Kenya herding cattle, camels, sheep and goats, those with 7R were better nourished than those without. The opposite was true of their settled relations: those with 7R were worse nourished than those without it.

How 7R causes this is not yet known. It may stem from behavioural differences or it may be that different versions of DRD4 have different effects on the way the body processes food. Nevertheless, this discovery fits past findings that 7R and a set of similar variants of DRD4, known collectively as "long alleles", are more common in migratory populations.

One suggestion is that long-distance migration selects for long alleles (see chart) because they reward exploratory behaviour. This might be an advantage in migratory societies because it encourages people to hunt down resources when they constantly move through unfamiliar surroundings.

As for the Ariaal, there remains the question of why 7R-although it is apparently beneficial to a nomadic way of life-is found in only a fifth of the population. One possibility is that its effects are beneficial only when they are not universal, and some sort of equilibrium between variants emerges. A second is that the advantage is gained when 7R exists along with another version of DRD4 (the genes for the two variants having come from different parents). Unfortunately, the way Mr Eisenberg collected the data does not allow these hypotheses to be tested.

Either way, his research raises the question of whether people suffering from ADHD and conditions related to it, such as addiction, are misfits coping with a genetic legacy that was useful in the evolutionary past, but is now damaging. As society continues to diverge from that evolutionary past, the economic and social consequences of being such a misfit may become increasingly important.


The nanny state has spoken on binge-drinking. But who’s listening?

By Australian columnist Janet Albrechtsen

The nanny state has apparently spoken. I went to bed last night feeling happy after a night out with friends. I wake up in the morning to news that I am a binge drinker because I indulged in more than three glasses of wine.

If you had four middies of beer last night, join the club. You are a binge drinker. That is according to the boffins at the National Health and Medical Research Council who have reportedly drafted new guidelines on safe drinking for Australians. While the Council is refusing to confirm reports in the Fairfax media until the release of its final report next month, perhaps the Council could do with some community feedback on their apparent eagerness to label so many of us binge-drinkers.

Yes, binge-drinking is a problem. Yes, alcohol driven violence is a problem. But surely that means addressing these real problems rather than conflating the issue of alcohol abuse by setting consumption limits at ridiculous levels. Health bureaucrats, whatever their well-intentioned beef, be it setting down eating and drinking guidelines for pregnant women or these latest drinking rules for the rest of us, always seem to frame their rules for the lowest common denominator brain. They treat us all like a bunch of feather-brained numskulls incapable of making sensible decisions about just about anything to do with our lifestyle. Now, we apparently have to endure being labelled a “binge-drinker” if we exceed 4 drinks during a pleasant evening out with friends.

There is another label that comes to mind. It applies to this kind of bureaucratic overreach. It’s called infantilisation. Reducing us to the status of children, they set down rules that end up neutering our ability to take personal responsibility for our actions. Like moves to ban the advertising of fast food, this is just another step by Big Brother to interfere in our choices by applying scary labels of binge-drinking to behavior that many of us would regard as normal.

Former federal health minister Tony Abbott is right to describe these new guidelines as fostering a “moral panic, which is taking over the land.” There is, says Abbott, “no doubt that binge drinking is a problem, but it is no worse than in the past. I am in favour of people improving society but you have to be reasonable about it. Usually these debates are more about establishing the virtue of the people leading the way. In the end what an individual does is his or her responsibility particularly with something that is legal.”

The medical boffins so keen to mould their own vision of utopia should keep in mind that this kind of dogmatic overreach comes with its own risks. When health guidelines are set at patently unreasonable levels, it might just mean people stop listening to these bodies about anything they have to say. It might undermine what is an important educative function if they start laying down rules that seem so preposterous to the social drinker. As Lenore Taylor said on the ABC’s Insiders today in response to claims that the delightful Belinda Neal MP had been the victim of sexism, we need to be careful about devaluing the currency by flinging about inappropriate labels. Likewise, binge drinking should be reserved for real alcohol abuse.

Before the chaps who are so keen to impose new nanny state drinking rules on us conclude their final report next month, they need to get out more. Perhaps have a drink or two with a few social drinkers who take umbrage at this new Puritanism. Labelling us all as binge-drinkers will do nothing to address the real problem of alcohol abuse.



Anonymous said...

You quoted: "Either way, his research raises the question of whether people suffering from ADHD and conditions related to it, such as addiction, are misfits coping with a genetic legacy that was useful in the evolutionary past, but is now damaging. As society continues to diverge from that evolutionary past, the economic and social consequences of being such a misfit may become increasingly important."

My word, you failed to comment on why ADHD is *still* selected for, which is that the vast majority of people who create companies from scratch have mild to severe ADHD!

[Bill Gates even has Asperger's Syndrome ("highly functioning autism") which is often misdiagnosed as ADHD, meaning it has some symptoms in common. Video of his Justice Department trial on monopoly charges shows him answering questions clearly while clearly rocking back and forth in highly autistic manner.

Steve Jobs, while developing the new line of Macs, after he was re-hired by Apple, was asked what he thought of the leading candidate for president. He replied: "who?".]

This is also why so many small companies that begin to grow must hire a management team since ADHD founders cannot stand ROUTINE of any sort. I speak from experience. I one designed dozens of lighting sculptures. Two were were so successful that I started making 90% of my profit from them, and I eventually got so overwhelmed that I made the mistake of concentrating on just one and sold it as an upscale "lamp", thus locking myself into a gilded jail.

The building of a business is a massive challenge, as is scaling up production, learning to hire, fire and manage assistants effectively, finding new clients, tweaking a designs price and internal simplicity.

But then paperwork and routine factory-like labor and repetitive marketing set in, and the suffering this sort of routine creates in a hyper (and thus hyper creative and hyper multi-tasking and risk-taking) person is simply ruinous. ADHD is mainly linked to routine tasks, but actually is much more complex, except in truly dysfunctional cases, and indeed matches the qualities of a good hunter, meaning it includes EXTREME pleasure being associated with tight, patient concentration on non-routine matters (such as invention by trial and error over months of time, or in the case of most ADHD children, free time being used to play extremely quick paced and unpredictable computer games).

If you move up to Darwinian group/group selection, in which a lack of either hunters, soldiers, or inventors are lacking becomes a major disadvantage, then it becomes no surprise that this "deficit disorder" has much selection pressure to remain being at an optimal minority temperamental type in societies, including modern ones.

Finally, there are five distinct types of ADHD, and lucky for me, mine is the more rare. In most cases, only part of the brain is over-active. In mine, the whole thing is lit up, thus its subtype being given the term "Ring of Fire." This means that normal ADHD drugs (which act in the ironic manner of being stimulants which activate the INHIBITORY frontal lobes) do *not* calm me down, but nor was I a problem as a child except for extreme creativity in pulling pranks on authority.

I once had an oddly realistic dream, two decades ago, for which the Statute of Limitations has long past: I made a master key for my entire grade school building two hours after I thought of the possibility. Carving multiple choice answers with a razor blade into the side of a yellow pencils after finding the answer books in teacher's offices was merely an exercise in learning to keep my small group of friends quiet about it, and to sternly warn them to not get 100% grades on tests. Good classes, of course, did not use standardized, state-sponsored textbooks that included teacher's kits of multiple-choice tests, and I was finally highly attracted to science, mainly chemistry. It was one biology teacher that communicated the thrill of science, unlike our alcoholic physics teacher, psychotic witch math lady, zero computer training, and a chemistry teacher we tormented with sheets of paper dipped in nitrogen triiodide, which explodes more or less randomly. His locked storeroom of hundreds of chemicals was my playground. Making smoke bombs was not, back then, considered even worth investigation for delinquency like it is now. Alas, being ADHD, suburbia was indeed otherwise rather boring, which is why I now live in NYC whose noise and rivers of people actually make me feel peaceful instead of restless.

Eventually I got a Ph.D. in very non-routine synthetic chemistry from Columbia, graduating with TOP student honors, which helped me land postdoctoral work at Harvard where I did very inventive benchtop ("poor man's") microfabrication work. Then I switched to art, then lamps and am now inventing new ways to make jewelry. Does this sort of biography sound normal?! Of course not. Does this sort of biography sound stimulatory to the economy as well as the culture? Duh.

I functioned so well at the OBSESSIVE problem-solving aspect of ADHD that I would be much better at inventive type of "work" than my peers, while too often moving onto new things as older projects were shelved instead of perfected (or published as a scientific paper).

As an aside, meeting women in public, successfully, is analogous to hunting. You wait and wait, very patiently, as you watch beast after beast walk by, giving you a nastly look and turning tail before you can even get close enough to say hi (spear her), but a few times a day, a very healthy, well developed sample accidently strays into your sights and the chase is on. And you wonder why ADHD might be preserved in the gene pool?! It being men who approach women most of the time in human beings as a species, an ADHD tempered man has something of an advantage in the hunt for a good mate followed the the uncontrollable impulsiveness to approach the most desirable ones, prey which average hunters fear wasting time on, since unlike an ADHD man, they are to slow (in creatively teasing wit) to trap them.


John A said...

Binge docs - is there any overlap with the doctors who proposed laws keeping knives out of the kitchen (i.e., only doctors should have sharp pointy things)/

Oh, that was the UK. Where, yes, "binge" drinking has been addressed in this same manner. As well as changing the legal age of buying alcohol from 21 to 18 - in shops, presumably to be imbibed at home, but leave the age at 18 in pubs and restaurants for those who want to drive home after instead of before drinking.