A study of individuals born between 1934 and 1983 found that more Americans began drinking alcohol at an early age over the decades, especially women, and that those who did drink at a younger age were more likely to be alcohol-dependent as adults.

Reuters reported June 9 that researcher Richard A. Grucza of the Washington University School of Medicine and colleagues said that the study doesn't prove that early drinking leads to dependence, "but what [it] does show is that early drinking does not simply reflect a genetic vulnerability to alcohol dependence."

Earlier onset of drinking and increased alcohol dependence in adulthood was true for both men and women, but the changes were more significant in women. Women who were born between 1934 and 1943 began drinking at age 22, on average, while those who were born after 1963 started drinking at an average age of 17. The rate of lifetime alcohol dependence was 9 percent among women born between 1934 and 1943 but rose to 22 percent among those born after 1963.

Grucza noted that while the study found that the decrease in women's average age of first alcohol use and rise in alcohol dependence occurred over the course of a few decades, human "genes don't change in that amount of time."

The study will be published in the August 2008 issue of the journal Alcoholism: Clinical & Experimental Research.