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Continued Decline in Youth Substance Abuse

Current illicit drug use among teens is continuing to decline, according to a new report by the U.S. Substance Abuse and Mental Health Services Administration (SAMHSA) released today. The study also shows positive signs that teens are seeing the dangers of abusing prescription drugs and methamphetamine and are pushing back. Among youth ages 12-17, the 2007 National Survey on Drug Use and Health (NSDUH), the Nation's largest substance use survey, shows that the significant decline in overall past month illicit drug use that began in 2002 continued through 2007, from 11.6 percent to 9.5 percent.

The survey, released at the start of the 19th Annual National Alcohol and Drug Addiction Recovery Month, shows that the reductions in youth drug use occurred for nearly every type of illicit drug including marijuana, cocaine, hallucinogens, LSD, and Ecstasy. The survey also shows dramatic declines in meth use, down by 67 percent (from 0.3% to 0.1%) and prescription drug abuse among teens, which declined overall by 18 percent, from 4 percent to 3.3 percent between 2002-2007.

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Columns - Research to Practice

Saturday, 30 September 2000

Editor's note: This article is part 8 in a series written by Dr. Michael J. Taleff to help clinicians, prevention specialists, supervisors and administrators use and understand research. Parts 1-7 of the series, which addressed experimental designs and introduced threats to internal and external validity, were published in NAADAC's The Counselor and are now available online at Counselor Magazine Online

There can be many explanations for a treatment effect. For example, does the maturity level of the clients under study have a major impact on substance-use disorder outcome? Or is it the regression effects (the tendency to return to some level of normality) that have the major impact? Or is it the passing of time itself that mostly affects outcome? Or does the effect of simply taking repeated tests, or the test instrument being used, have an impact on outcome?

One way to reduce the number of alternative explanations is to reduce the internal threats that might be mistaken for treatment effects (Kazdin, 1986). An internal threat to validity is a competing explanation for a research outcome — and competition may be good for the economy, but not for a research project!

The following six threats are less common than those discussed in Part 7. All are from Heppner, Kivlighan and Wampold (1999).

Six examples

You may find that, following an experiment; there are clear differences in an outcome between one group and another. You feel pleased and confident you have come across an intervention that seems to produce a difference. But what if the differences existed before the experiment? That would be an internal threat to your outcome called selection. Differences in groups before we divide them into control and experimental groups do exist. An important way around this possibility is to make sure your subjects were randomly assigned to a control and an experimental group.

Next, suppose you make this observation: As you share some of your personal history during a session, there seems to be more progress in treatment. This seems to be a logical assumption on your part. However, how can you be sure that a client's progress is not causing more disclosures from you? This threat to validity is called ambiguity about the direction of a causal influence. Until the direction is established, all you have is a correlation, not a causal factor. In our example, one way to check on the direction is to stop disclosing and see what happens to the progress of treatment.

Suppose you are conducting an experiment to test the effectiveness of a new form of treatment you developed. You must have two groups, give one group (the experimental group) the treatment and withhold the treatment from the other group (the control group). You know that one group is not going to receive your new treatment, yet the thought of withholding a treatment that might benefit clients does not sit well with you. So you indirectly (or directly) provide some additional service to the control group to make up for not giving them the new treatment.

When you give that extra service to the control group, you contaminate the outcome of your research. This threat to validity is called compensatory equalization of treatments. In science, we often must withhold treatment from a group to find out whether the treatment works better than nothing at all. That doesn't mean you have to withhold a new treatment forever. If the experiment demonstrates that the treatment works, you can then apply it to the control group.

Similar to the deliberate compensation of services to a control group is the unwitting spread of treatment to that group.

This is most likely to happen if the treatment involves providing information. The information might be about how to reduce the spread of HIV, for example, and the objective is to measure whether the information changes attitudes. If that special set of information unintentionally spreads to a control group, the outcome will be compromised. This threat to validity is called diffusion or imitation of treatments. The way to avoid such a situation is to give the information to the experimental group only.

Staying with the experimental group and the control group experiment, suppose you remain firm in your conviction to science and do not apply any parts of your new treatment to the control group.

Now suppose that individuals in the control group find out that they are not receiving some new form of treatment. They could decide to show you they can do as well as the experimental group; that is, the control group acts differently than it usually would. That would certainly confound the results of your experiment. This threat to validity is called compensating rivalry by participants receiving less desirable treatments. Again, the simple way to avoid this situation is to secure what you are doing to only the experimental group.

In the same situation suppose that the control group, instead of trying to compensate and acting in a positive way, becomes demoralized and acts differently, but negatively. Again, this would affect your results. This threat to validity is called resentful demoralization of participants receiving less desirable treatments.

Internal threats to validity apply to the various forms of experimental designs discussed in Parts 1 through 6 of this series. It is in your best interest to keep these threats to a minimum in any research you conduct and keep these threats in mind as you attempt to make sense of daily treatments you institute. Knowledge of internal threats to research validity may enable you to reach more accurate conclusions about the difference between effective strategies and guesswork.

Next: External threats to validity.

Michael J. Taleff, PhD, CAC, MAC, is assistant
professor in the Counselor Education Department and
project director of Chemical Dependency Programs at
Pennsylvania State University. He is also a member
of the NAADAC Research Committee.

References
Heppner, P.P., Kivlighan, D.M., & Wampold, B.E. (1999). Research design in counseling, (2nd ed.).Belmont, CA: Wadsworth.
Kazdin, A.E. (1986). The evaluation of psychotherapy: Research design and methodology. In S.L. Garfield & A.E. Bergin (Eds.). Handbook of psychotherapy and behavior change (3rd ed., pp. 23-68). New York: John Wiley and Sons.
Michael J. Taleff, PhD, CAC, MAC, is assistant professor in the Counselor Education Department and project director of Chemical Dependency Programs at Pennsylvania State University. He is also a member of the NAADAC Research Committee and welcomes comments on this series.