“…For example, we reported recently that 15% of a sample of English 11-16year-olds regularly used drugs in combination with alcohol, whereas fewer than 1% of the sample used drugs but not alcohol (Sutherland & Willner, 1998). However, the nature of this relationship remains unclear (De-Piano & Van-Hasselt, 1994). A number of studies have advanced the concept that alcohol serves as a 'gateway' to illicit drugs, based on observations of a temporal progression from alcohol to drug use (Kandel, 1975;Yamaguchi & Kandel, 1984;Welte & Barnes, 1985;Kandel et al, 1992;Kandel & Yamaguchi, 1999).…”