It's been awhile since I talked about my attention deficit disorder, maybe because the topic overwhelms me and the meds don't work like they used to, and I have a side of me — the side that thinks I could be "bipolar" too — that thinks ADHD is a scam cooked up by Big Pharma to sell decongestants that had been ruled unsafe as weight loss drugs, because it totally was, and yet on the really bad days it's kind of nice to think, no, I spent nine hours a night on my fifth-grade homework and dropped out of school and I lose everything — seriously, the other day on the way to getting reamed out by the Passport agency for having lost nine still-valid passports I managed to lose my three-week-old phone — because I am sick. I have a disease, a disease so hysterically crippling to my efforts to survive in society it's a wonder I made it past natural selection…Well, guess what?
I'm no longer wondering! Because today I learned, along with the fact that "natural" cures are totally worthless that ADHD is linked to some protein blah blah allele something that also cause alcoholism and eating disorders and shit but turns out to be somehow useful to nomadic tribesmen in Africa.
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.
So now we know why Amazonian shamans don't have some magical natural cure for us in the rainforests? Because they'd be too busy competing with us for food? Well… How nice for modern civilization that I am in no danger of passing on these alleles!
Patient Voices: ADHD [NY Times]