In a fascinating study published in 1998 in the Archives of General Psychiatry, William Vega, an American public health researcher at Rutgers University, showed just how psychologically corrosive American culture can become for those who drop into it from the outside.

Vega focussed on recent immigrants from Mexico. When they first arrived in the US, he found, they were much healthier than the Americans they settled among, with half the incidence of psychological dysfunction. But the longer they stayed, the sicker they got. During the first 13 years, their chance of developing a disorder in their lifetime was 18 percent. After 13 years, whatever cul-tural protection their Mexican heritage offered them had worn off, and their rates of depression, anxiety and drug problems had risen to the same level as the general population’s (32 percent).

Among Mexican-Americans born in the US, meanwhile, the rate of those afflictions soared to 49 percent. Mexican men born in the US were five times as likely as recent immigrants to experience a "major depressive episode." Drug misuse among Mexican women born in the US was seven times as high as that of recent immigrants.

Could it be that Mexicans are somehow uniquely vulnerable to this particular American cultural virus? Apparently not. Other studies have both replicated William Vega’s findings and extended them to other ethnic groups and problems, such as domestic violence. Acknowledging that "components of Mexican culture are protective against mental health problems," Vega concludes that "socialization into American culture and society [will] increase susceptibility to psychiatric disorders."

The findings present a puzzle. The Mexican immigrants Vega studied were better adjusted psychologically, even though they fall far below the US average in education and income. But that’s just the point. Income and education lose their meaning in a world of rising mental expectations and reduced life satisfaction. The former are rooted in our consumerist, media-saturated society, while the latter emerge out of the loss of collective family and community life in the face of American individualism. The real puzzle is how a problem so big can draw almost no attention at all.