A new study found an increase in alcohol dependence possibly due to American teenagers drinking at earlier ages. In particular, this increase in alcohol dependence seemed to be explained by women drinking at increasingly younger ages throughout time. While researchers saw an increase in earlier drinking and alcohol dependence in men, the changes were much more dramatic among women.

The study took a look at drinking habits among Americans born between 1934 and 1983, based on data from nearly 40,000 men and women who responded to 2 large national surveys — one conducted between 1991 and 1992, the other between 2001 and 2002. It’s findings were published in the journal Alcoholism: Clinical & Experimental Research.

The study showed women born between 1934 and 1943 began drinking at the average age of 22, while those born after 1963 typically started drinking when they were 17. While only 9% of women born between 1934 and 1943 had been alcohol dependent at some point in their lives, the percentage jumps to roughly 22% of women born after 1963. The increase in early drinking seemed to explain the higher incidence of alcohol dependence.

While the findings don’t necessarily prove that early drinking causes alcohol dependence, it does suggest that social factors may be contributing rather than just a genetic vulnerability. Women’s average age at first alcohol use and their rate of alcohol dependence both shifted significantly in a matter of decades. “Genes don’t change in that amount of time,” explained lead researcher Dr. Richard A. Grucza, of Washington University School of Medicine in St. Louis. Certainly, women gaining more independence, working outside the home and furthering their educations throughout time have helped.

Read about the study in this Reuters Health article, Early drinking may raise risk of alcoholism