1997 National Household Survey on Drug Abuse
Trends by Age Group for the Most Commonly Used Substances (Tables 2.5 to 2.8)
The only significant changes in age group-specific lifetime prevalence rates from 1996 to 1997 were an increase in lifetime cocaine use among youths aged 12 to 17 (from 2% to 3%) and a decrease among middle adults aged 26 to 34 (from 21% to 18%). These specific differences were, however, part of a larger and more general pattern of changes in lifetime use of marijuana, cocaine, and the category of "any illicit drug" use over the past several years. For example, the rates of lifetime use of any illicit drug, marijuana, and cocaine among middle adults decreased significantly in 1997 from their levels in the early 1990s and exhibited a generally declining trend throughout the decade. This pattern reflects the aging of a cohort of persons who were young adults and thus more likely to use drugs than other age groups during the peak years of illicit drug use in the late 1970s and early 1980s. Over the past several years of the survey, this cohort has been aging out of the middle adult age group and into the older adult age group. Consequently, the high levels of illicit drug use that were characteristic of the early 1980s were responsible for the recent escalations in lifetime use among older adults, and the simultaneous decrease in use among middle adults, and to a lesser extent young adults.
Rates of any illicit drug use, as well as marijuana and cocaine use, among youths exhibited substantial increases in lifetime use over the past several years of the survey. Unlike the increases in lifetime use among older adults, however, these increases were not due to the carryover effects of prior drug use in this particular cohort. Rather, they reflect increasing rates of illicit drug use within this age group primarily since 1991. Estimates of the incidence of first-time marijuana use among youths aged 12 to 17 jumped from 37 new users per 1,000 person-years of exposure in 1991 to 83 new users in 1996; corresponding rates for new users of cocaine were 4 in 1991 and 11 in 1996 (OAS, 1998c, Tables 38 and 39). Not only were more 12 to 17 year olds using illicit drugs in 1997 than in any previous year in the past decade, but the mean age of first use of marijuana among all users declined from 17.5 in 1991 to 16.4 in 1996. Corresponding mean ages of first use for cocaine were 21.4 and 18.7, respectively (OAS, 1998c, Tables 38 and 39).
For alcohol, rates of lifetime use among persons aged 18 or older changed little in the past few years for which estimates are available. But for youths aged 12 to 17, lifetime alcohol use (which is relatively recent first use for this age group) declined from 71% in 1979 to 40% in 1997, although most of the reduction occurred between 1979 and 1991. As for lifetime use of cigarettes, rates did not differ significantly across most of the survey years for persons aged 18 to 25 and 35 or older each year, although the pattern across the years was for the rates for these age groups to decrease slightly. Among adults aged 26 to 34, the prevalence of lifetime cigarette use in 1997 (73%) was significantly lower than it was in 1995 (76%) and in most earlier years. The pattern of lifetime cigarette use among youths aged 12 to 17 showed reductions in the rates since 1985's high rate of 51%; however, in the period from 1991 to 1996, none of the rates differed significantly from the 1997 rate of 39%.
Past Year Use (Table 2.6). Over the period from 1979 to 1997, past year use of any illicit drug, marijuana, and cocaine among adults of all age groups was generally lower than it was for the same-aged persons in 1979 and the early 1980s. In recent years of the NHSDA (i.e., since 1991), there was little change over time in these rates. Very different patterns, however, were observed for youths aged 12 to 17. Adolescents reported higher rates of use of these three categories of illicit drugs in 1997 than did the same-aged youths in any year since 1985. Although a few of the annual rates of past year use of these three drugs werenot significantly different from the rate of past year use by youths aged 12 to 17 in 1997 (e.g., any illicit drug use in 1995 and 1996, marijuana use in 1995, cocaine use in 1995), the 1997 rate of past year use among the 12 to 17 year olds was higher than the corresponding rate in every previous year since 1985 (with the exception of cocaine in 1988). Indeed, the prevalences of use of these three categories of illicit drugs among youths aged 12 to 17 in 1997 did not differ significantly from those prevalences reported by youths in 1979 (except for cocaine), 1982, and 1985, years when rates of drug use were the highest ever measured in the NHSDA.
Past year use of alcohol and past year use of cigarettes by all age groups in 1997 were about the same as they had been for most of the 1990s, although most of the rates of past year use of these two substances were lower, a few significantly so, than they were in the 1980s. In particular, the past year rate of use of alcohol by youths aged 12 to 17 was substantially lower in 1997 (34%) than it was in the period from 1979 (56%) through 1991 (41%). The rate of past year use of alcohol by other age groups also was lower in 1997 than it was in 1979 and the 1980s, but not significantly so. The pattern of increased rates of past year use of cigarettes by youths aged 12 to 17 since 1992 (when the rate of 21% was at its lowest among this age group) continued in 1997 to 26%. The 1997 data show that the rate of cigarette smoking among young adults aged 18 to 25 was significantly higher in 1997 than in 1994 (46% vs. 41%, respectively).
Past Month Use (Tables 2.7 and 2.8). Past month use of any illicit drug and marijuana was about the same in 1997 as it was in 1996 and most of the 1990s for the older three of the four age groups (Table 2.7). Past month cocaine use by both young adults and middle adults was significantly lower in 1997 than it was in 1996 and also just as low or lower (although not always significantly so) than in any year since 1979. But young adults aged 18 to 25 continued to be the age group with the highest rates of use of all three of the categories of drugs listed in Table 2.7.
Past month use of all three categories of drugs increased among youths aged 12 to 17, and the 1997 rates of past month use of any illicit drug (11%) and marijuana (9%) were significantly higher than the 1996 rates of use by this age group (9% and 7%, respectively). Furthermore, the prevalence in 1997 of past month use of all three of these categories of illicit drugs by youths was significantly higher in 1997 than at any time during the 4 years between 1991 and 1994. The recent increases in past year marijuana use among youths appeared to be pervasive across such demographic characteristics as age (as measured using 2-year age groupings), gender, race/ethnicity, metropolitan size, and region. The same was true for past month cocaine use except with respect to race/ethnicity. The rates from 1994 to 1997 rose substantially for white youths and remained at a constant low level for black youths (data not shown in Table 2.7 or 2.8; see OAS, 1996a; OAS, 1997; OAS, 1998a; and Tables 3.3 and 4.3 of this report).
Past month use of alcohol in any manner or amount by all four age groups was about the same in 1997 as in 1996 (Table 2.8). The only exception was that fewer young adults aged 18 to 25 engaged in "binge" drinking in 1997 than in 1996 (28% vs. 32%). The prevalence of any current alcohol use continued in 1997 to be significantly lower for those aged 12 to 34 than it was in 1979 and the early 1980s. Among youths aged 12 to 17 in 1997, only about one in five used any alcohol in the past month compared with half of the youths who were 12 to 17 years old in 1979 and 27% of those aged 12 to 17 in 1991.
Current cigarette smoking was about as prevalent in 1997 as it was in 1996 for all age groups. The rate of current cigarette use among young adults aged 18 to 25 in 1997 was the highest that it had been for this age group since 1992, although the difference from the 1997 rate of current cigarette smoking (41%) was statistically significant only for the 1994 and 1995 rates (both 35%). Rates of current cigarette use among other age groups has remained relatively stable since the early 1990s.
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