A team of Danish and American researchers has discovered that men whose wives outearn them are more likely to have erectile dysfunction than men in more-traditional dad-as-breadwinner families. This was true even in families where the difference between the two salaries was fairly small, but when the woman earned about $20,000 per year more than the man, the chance that he’d need Viagra or other drugs for ED doubled.

They made this discovery by studying salary and prescription data on more than 200,000 married couples. What’s especially noteworthy is that men whose wife had always out earned them seemed to be no more prone to ED than the average man. It was only when he was earning more at the beginning of the relationship but the roles gradually flip-flopped.

ED drugs are only the beginning of the pharmacological fallout from trend for women to earning more than their male partners. The men in these couples were also more likely to be taking anti-depressants (other studies have found that since the economic downturn started in 2007 and 2008, the suicide rate for men 25-54 has risen dramatically, further demonstrating what happens when men feel displaced from their role as primary breadwinner). Meanwhile, the women were more likely than “traditional” women to have been prescribed medication for anxiety and insomnia.

The inescapable conclusion is that gender roles are a lot more deeply ingrained than we’d imagined. As a society, we still tend to rate men based on their salary and professional status, and women based on their status as primary nurturer. And the psychological pressure we put on both groups to live out those stereotypes takes a heavy toll.

Having their provider-protector role usurped could be “potentially causing men to suffer reduced sexual desire or dysfunction,” write the researchers. At the same time, “if social norms against female breadwinners continue to be strong, increasing female income will produce real costs in marriage, including the anxiety, insomnia and erectile dysfunction identified here.”

The study was published in the journal Personality and Social Psychology Bulletin.