State Estimates of Substance Use and Mental Health from the
2005-2006 National Surveys on Drug Use and Health

National data State level data Metropolitan and other subState area data

2. Illicit Drug Use

The National Survey on Drug Use and Health (NSDUH) obtains information on nine different categories of illicit drug use: marijuana, cocaine, heroin, hallucinogens, inhalants, and nonmedical use of prescription-type pain relievers, tranquilizers, stimulants, and sedatives. Estimates of illicit drug use reflect any of the nine categories listed above. In 2004-2005, 8.0 percent of the U.S. population aged 12 or older had used an illicit drug in the past month, and the percentage was similar in 2005-2006 (8.2 percent) (Table C.1). Marijuana, the most commonly used illicit drug, was used by 6.0 percent of the population in 2005-2006 during the past month (Table B.3).

2.1 Illicit Drugs

Estimates of past month use of illicit drugs ranged from a low of 5.7 percent in North Dakota to a high of 11.2 percent in Rhode Island for all persons aged 12 or older (Table B.1). See Section 1.2 for a discussion of the proper use of the prediction intervals [PIs]. Montana, Rhode Island, and Vermont were in the highest fifth for all persons aged 12 or older and for each of the age subgroups: 12 to 17, 18 to 25, and 26 or older (Figures 2.1 to 2.4).

Two States showed significant changes from 2004-2005 to 2005-2006 (at the 5 percent level of significance) in the percentage of all persons aged 12 or older who used an illicit drug in the past month: Kentucky decreased from 8.4 to 7.0 percent, and Washington increased from 8.5 to 10.0 percent (Table C.1). At the national level, the use of illicit drugs among youths aged 12 to 17 declined from 10.3 percent in 2004-2005 to 9.8 percent in 2005-2006 (approximately a 1.0 percent change between 2004 and 2006).⁶ In spite of having a significant decrease of past month use of illicit drugs at the national level among youths, no States showed significant declines in the percentage of youths using illicit drugs in the past month (Table C.1).

2.2 Marijuana

Because marijuana is the predominant drug used among those using an illicit drug, States that had high prevalence rates for illicit drug use also had high prevalence rates for past month use of marijuana. All of the 10 States in the top fifth for past month use of an illicit drug among persons aged 12 or older also were ranked in the top fifth for past month use of marijuana. Four States were common to the top fifth for past month marijuana use in all three age groups, 12 to 17, 18 to 25, and 26 or older, and among persons 12 or older: Maine, Montana, Rhode Island, and Vermont (Figures 2.1 and 2.9 to 2.12). Utah had the lowest rate of past month use of marijuana in 2005-2006 (4.3 percent) in the 12 or older population, and Vermont had the highest rate (9.7 percent). Vermont also had the highest rate of past month marijuana use among young adults aged 18 to 25 (28.3 percent), and Utah had the lowest rate in that age group (9.6 percent) (Table B.3).

Nationally in 2005-2006, 10.4 percent of all persons aged 12 or older reported marijuana use in the past year (Table B.2). Young adults aged 18 to 25 reported the highest rate of past year use of marijuana, 28.0 percent. North Dakota had the lowest rate (7.5 percent) of past year use of marijuana among persons aged 12 or older. Vermont had the highest rate of past year marijuana use in that age group (15.5 percent). Vermont also had the highest rate of past year marijuana use in the Nation in the 18 to 25 age group (41.9 percent), and Utah had the lowest rate in this age group (18.9 percent).

Only one State showed a significant decrease in the past year use of marijuana among all persons aged 12 or older between 2004-2005 and 2005-2006: North Dakota (from 8.5 to 7.5 percent) (Table C.2). Nationally, there was a significant decrease in the past month use of marijuana among youths aged 12 to 17 from 7.2 to 6.7 percent, and past year use of marijuana among youths also decreased from 13.9 to 13.3 percent over the same period (Table s C.2 and C.3).

2.3 Perceptions of Risk of Marijuana Use

An individual's perception of the risks of substance use has been shown to be inversely related to whether he or she actually uses the substance (e.g., Bachman, Johnston, & O'Malley, 1998). At the State level, 8 of the 10 States that ranked in the lowest fifth of perceived great risk of using marijuana once a month were also among the States that ranked in the highest fifth for past month use of marijuana in 2005-2006 for persons aged 12 or older (Figures 2.9 and 2.13).

Slightly over one quarter (27.1 percent) of all persons aged 12 or older in New Hampshire reported that using marijuana occasionally (once a month) was a great risk (Table B.4). However, in Mississippi slightly more than half (52.0 percent) of all persons aged 12 or older indicated that occasional use of marijuana was a great risk. Although Mississippi (5.1 percent) did not have the lowest rate for past month use of marijuana among persons aged 12 or older, it ranked in the lowest fifth for that measure (Table B.3 and Figure 2.9).

The national percentage of persons aged 12 or older perceiving a great risk of using marijuana once a month remained relatively unchanged between 2004-2005 (39.0 percent) and 2005-2006 (38.9 percent) (Table C.4). Two States showed a decrease in perceived risk of using marijuana once a month among persons 12 or older: Montana (from 36.0 to 32.0 percent) and Rhode Island (from 35.4 to 31.0 percent).

2.4 Incidence of Marijuana Use

Related to the prevalence of marijuana use is the number of persons in a period of time who used marijuana for the first time ever. When the number of first-time users of a substance increases for a number of consecutive years, the prevalence rate for the substance tends to increase also. The average annual incidence of marijuana for this report is estimated somewhat differently than in the national report (OAS, 2007).⁷ The estimate for a single year is averaged over the 2 most recent years and expressed as a rate per 100 person years of exposure. For the combined years 2005-2006, the national marijuana incidence rate for all persons aged 12 or older was 1.6 percent (Table B.5). Vermont had the highest rate, 2.4 percent, and West Virginia had the lowest rate, 1.2 percent.

Seven States that were ranked in the top fifth for marijuana incidence in the 12 or older age group also ranked in the top fifth for past month marijuana use (Alaska, District of Columbia, Maine, Montana, Oregon, Rhode Island, and Vermont) (Figures 2.9 and 2.17). Because most initiation of marijuana takes place at age 25 or earlier (Gfroerer, Wu, & Penne, 2002), the rates of initiation in the 26 or older age group were much lower than those in the 18 to 25 and 12 to 17 age groups: The national rates were 0.2, 6.0, and 5.6 percent, respectively (Table B.5). Vermont had the highest rate among youths aged 12 to 17 (7.8 percent) and among young adults aged 18 to 25 (10.6 percent). Utah had the lowest rate among youths aged 12 to 17 (4.1 percent), and among young adults aged 18 to 25 (4.2 percent).

Nationally, rates of first use of marijuana declined significantly among youths aged 12 to 17 between 2004-2005 and 2005-2006 (from 5.8 to 5.6 percent) and in the overall population aged 12 or older (from 1.7 to 1.6 percent) (Table C.5). Three States (Alaska, Montana, and Wisconsin) had significant declines among youths aged 12 to 17. However, only one State showed a significant decrease in marijuana incidence among persons 12 or older: North Dakota (from 1.6 to 1.4 percent). There were no significant increases in marijuana incidence in any age group between 2004-2005 and 2005-2006.

2.5 Illicit Drugs Other Than Marijuana

Illicit drugs other than marijuana include cocaine, heroin, hallucinogens, inhalants, and the nonmedical use of prescription-type pain relievers, tranquilizers, stimulants, and sedatives. The national estimate of past month use of illicit drugs other than marijuana among persons aged 12 or older was 3.8 percent for 2005-2006 combined (Table B.6). North Dakota had the lowest rate (2.5 percent) of past month use of an illicit drug other than marijuana among persons 12 or older, and Tennessee had the highest rate (4.7 percent). Four States that were in the top fifth for past month use of an illicit drug among those aged 12 or older also were ranked in the top fifth for past month use of an illicit drug other than marijuana: Alaska, District of Columbia, Massachusetts, and Rhode Island (Figures 2.1 and 2.20).

The rate of past month use of illicit drugs other than marijuana increased between 2004-2005 and 2005-2006 among all persons aged 12 or older (from 3.6 to 3.8 percent) (Table C.6). It also increased among young adults aged 18 to 25 (from 8.5 to 8.8 percent) and among persons aged 26 or older (from 2.5 to 2.8 percent). Although some States showed significant increases in the rates among persons 12 or older (Arizona changed from 3.5 to 4.5 percent, Michigan increased from 3.7 to 4.2 percent, and Tennessee increased from 3.9 to 4.7 percent), no States showed any significant decreases.

2.6 Cocaine

The 2005-2006 national prevalence rate for the use of cocaine in the past year among all persons aged 12 or older was 2.4 percent (Table B.7). Because cocaine is one of the substances included in the "illicit drug use other than marijuana" category, it is useful to compare the rankings of States with respect to these two measures. In 2005-2006, five States (Arizona, District of Columbia, Massachusetts, Rhode Island, and Tennessee) ranked in the highest fifth for both past month use of an illicit drug other than marijuana (aged 12 or older) and past year use of cocaine (aged 12 or older) (Figures 2.20 and 2.24). The District of Columbia had the highest rate of past year cocaine use (4.9 percent) among persons aged 12 or older; North Dakota had the lowest rate (1.6 percent) in that population (Table B.7). Colorado was the only State that ranked in the top fifth for past year cocaine use among all three age groups (12 to 17, 18 to 25, and 26 or older) and among persons 12 or older (Figures 2.24 to 2.27).

The District of Columbia (from 3.4 to 4.9 percent) and Ohio (from 2.0 to 2.4 percent) showed significant increases in past year cocaine use among persons aged 12 or older between 2004-2005 and 2005-2006 (Table C.7). No States showed any significant changes in cocaine use among youths aged 12 to 17, but two States (Ohio and Pennsylvania) showed changes among young adults aged 18 to 25 and the District of Columbia showed an increase in cocaine use among persons 26 or older.

2.7 Pain Relievers (Nonmedical Use)

In 2005-2006, 5.0 percent of all persons aged 12 or older reported having used pain relievers nonmedically in the past year, a percentage that reflected an increase from 2004-2005 (4.8 percent) (Table C.8). In 2005-2006, Oklahoma had the highest percentage (6.7 percent) of persons aged 12 or older using pain relievers for nonmedical purposes in the past year. Hawaii, New Jersey, and South Dakota had the lowest rate in the Nation—3.9 percent (Table B.8). Arkansas, Nevada, and Tennessee ranked in the top fifth of States for this measure in each of the three age groups (12 to 17, 18 to 25, and 26 or older) and for the total population aged 12 or older (Figures 2.28 to 2.31).

A national increase in the nonmedical use of pain relievers among the 26 or older population (from 3.2 percent in 2004-2005 to 3.4 percent in 2005-2006) seems to have been triggered by an increase in the use of pain relievers in the Midwest and the South in the same age group (3.0 to 3.3 percent and 3.2 to 3.5 percent, respectively) (Table C.8). Because this population constitutes a large portion of the 12 or older population, a similar trend was observed in that age group as well. The only significant decrease in the nonmedical use of pain relievers was seen among the young adults aged 18 to 25 in Pennsylvania (from 12.6 to 11.1 percent).