Type I and Type II Alcoholism: An Update.

A commonly cited alcoholism typology, the type I-type II typology, was developed from the findings of a study of Swedish adoptees and their biological and adoptive parents. Type I alcoholism affects both men and women, requires the presence of a genetic as well as an environmental predisposition, commences later in life after years of heavy drinking, and can take on either a mild or severe form. Type II alcoholism, in contrast, affects mainly sons of male alcoholics, is influenced only weakly by environmental factors, often begins during adolescence or early adulthood, is characterized by moderate severity, and usually is associated with criminal behavior. Additional studies have demonstrated that type I and type II alcoholics also differ in characteristic personality traits (e.g., harm avoidance and novelty seeking) as well as in certain neurophysiological markers. A replication study with a second group of Swedish adoptees has confirmed many of the findings of the original adoption study.