THE WINNOWING

Are East Asians for genetic reasons more likely to become Internet addicts?   The suggestion is more plausible than it might seem.  Indeed, modern life, with all its entertaining stimuli, might even be exerting Darwinian selection pressures against more addiction-prone ethnic groups.

Enter an Internet café in mainland Asia these days, and you might have the sense of being in an unusually well organized crack house.  In dim light, rows of young men sit and stare, and seem as immersed in their cybernautic adventures as any drug addict ever was in his inner trip.  The sight reminds you that human bliss can manifest not in oohs and ahhs but in a look of somber intent.

American researchers still argue over the idea that a mere video can whack the brain’s learning and motivation centers hard enough to cause a genuine addiction.  The definition of addiction itself is fuzzy; where do you draw the line past which a behavior starts to intrude on normal life and responsibilities?

But Asian researchers are less conflicted.  “We know addiction when we see it,” they’ve been saying – and they’ve been seeing a lot of it.  Recent studies of high school and college students in Korea, Japan, Taiwan and China suggest an Internet-addiction prevalence of at least a few percent.  Some Chinese researchers believe that there at least ten million addicts in that country.  In response, clinics and “boot camps” have been set up to treat them.

Internet use of the potentially addictive kind tends to occur in the privacy of homes in the US, and there is perhaps more stigma attached to it.  That makes it a bit more difficult to study, and in any case the data so far on American Internet addiction prevalence seems soft.  But there is at least the suggestion, from the evidence out there, that Internet addiction is a significantly greater problem in East Asia than it is here.

Such a difference could be at least partly explained by cultural factors, e.g., a greater tendency to follow the herd, and maybe a greater need in those societies for fulsome forms of escape.

There could be genetic factors too.  We know that there are genetically based susceptibilities to other forms of addiction.  And we know that some ethnic groups differ broadly in genes relevant to addiction.  So it is entirely plausible that some populations have inherited – on average – significantly greater addiction-susceptibility than others.  And although we like to think of modern society as rather soft and post-Darwinian, the increasingly stimulus-strewn environment of modern life may even be in the process – however subtle – of winnowing susceptible populations from the global gene pool.

I remember a couple of years ago listening to a lecture by Alan Leshner, former director of the National Institute on Drug Abuse, who asked at one point “Where are all the heroin addicts from thirty years ago?” before answering his own question sombrely:  “Well, fifty percent of them are dead.”

Such an increased mortality among addicts, or even decreased fertility, would be expected to have evolutionary consequences if their addictions are even partly driven by their genes.  The genes — or rather, genetic variations — that drive an addiction would matter less if people who carry them tended to become addicted only in their older, post-childbearing years, i.e., after they have already successfully passed on their genes.  However, people are more likely to become addicted in their youthful and otherwise fertile years.  The pleasure and motivation circuits in younger brains are juicier with endogenous opioids and dopamine, and thus can be hijacked more powerfully.  Young people also tend to have less developed inhibitory and self-awareness circuitry (in the prefrontal cortex, the last brain area to develop) so their defenses against addiction also are lower.

Why would genetic variations affecting addiction susceptibility exist between whole populations, i.e., distinct ethnic groups?  Simply because separate populations by definition exist in separate environments, both natural and social.  Different environments subject their populations to different selection pressures, which force these populations to diverge genetically.

A classic, tragic example of genetic divergence concerns the susceptibility to infection.  The disappearance of most Native American populations over the last five centuries appears to have been due largely to diseases introduced by Europeans – who had incubated these pathogens in their more crowded societies but presumably had developed some resistance to them as the more vulnerable members of their population died off over the centuries.

Native Americans also appeared to have a greater susceptibility to European-introduced alcohol.  Prior to the Europeans’ arrival, they had their own recreational/social drugs, such as peyote; but apparently these indigenous drugs worked differently enough that they failed, over the generations, to confer any protection against alcohol.  The whisky-addled Indian became a stereotyped figure of the 19th century American West, and even now, Native Americans have extremely high rates of alcoholism (and other drug abuse).  Though much of their increased susceptibility might be due to non-genetic factors – an understandable cultural depression, for example – prominent addiction researchers suspect that at least some of their increased susceptibility is indeed genetic.

But some of the best evidence for ethnic differences in addiction-proneness comes from studies of Far East Asians (Chinese, Koreans, Japanese).  This population, on average, appears to be less susceptible to alcoholism than Europeans.  That is not because their societies have used alcohol for a longer time; apparently it is because they are more likely to carry gene variants that make consuming alcohol a more unhealthy experience.  The genes in question code for the aldehyde dehydrogenase (ALDH) enzymes, which break down a relatively toxic metabolite of alcohol (acetylaldehyde) in the liver.  Variants of those genes that are relatively common in East Asia make faulty versions of those enzymes.  Thus, blood levels of acetylaldehyde spike after alcohol consumption, with side effects that include facial flushing.

I can’t help noticing that it is this same broad group of East Asians that seems unusually addicted to Internet role-playing games and other electronic media content.  It might simply be a coincidence.  But I can think of another possible explanation for the connection:  East Asians, having had less exposure to alcohol for genetic reasons, might have had less need – evolutionarily speaking – to develop other defenses against addiction generally.  Thus they could become addicted more easily to novel diverting behaviors, provided that they are not alcohol-related.

One complication here is that in the 1800s the Chinese went through a period of heavy addiction to opium – an addiction more or less forced on them by the British, who wanted to balance their trade with China and needed to sell them something to make up for all the tea they were importing.  However, before and after that period, Chinese governments were able to protect the population somewhat by controlling or cutting off the opium trade.  Moreover, during the time of maximum exposure the Chinese apparently showed a great susceptibility to the drug – as if their systems, in an evolutionary sense, had never experienced anything like it.  Yet their experience might have been too short to allow protective genetic influences to increase in the population.

Even so, my hypothesis may seem too much of a stretch, particularly since we don’t yet have solid comparative data on addiction rates among different ethnic populations.  It is also likely to be a touchy area – which helps to explain why there is so little useful data.

But one could test this hypothesis by looking for differences – between Internet addicts and non-addicts, and between East Asians and other populations – on behavioral tests that predict addiction proneness (tests of impulsivity, ability to self-monitor and inhibit impulses, etc.) as well as in genes that regulate mesolimbic and prefrontal circuitry.

The point of all this wouldn’t be to denigrate East Asians, but to understand better where human vulnerabilities lie, so that we can better address them.  Surely East Asian governments would like to know if their populations are more vulnerable to media content and other stimuli that are virtually ubiquitous in modern life.  These societies, by the way, don’t fully embrace the Western idea that people have “free will,” i.e., the miraculous autonomy that allows them to consume information without being adversely affected by it.  Even if they never articulate it this way, Asian societies are more likely to believe that greater freedom brings greater vulnerability – not just to addiction but to any selfish, subversive agent that can infest the human mind.

THE WINNOWING