Drug Abuse & Mental Disorders: Comorbidity Is Reality

A quarter century of basic and clinical research has provided us with a substantial number of scientifically developed and tested pharmacological and behavioral techniques for treating drug abuse and addiction. A main thrust of NIDA's current research is to discover which combinations of treatments and services work best for individual patients with particular constellations of problems. The goal is to customize treatment for every patient, including those with coexisting problems such as multiple drug abuse, drug abuse-related infectious diseases, histories of sexual abuse, or homelessness.

Drug abusers who have concurrent, or comorbid, mental health problems are at the top of the list of those who will benefit from this research, for two reasons. First, they are numerous. Recent epidemiologic studies have shown that between 30 percent and 60 percent of drug abusers have concurrent mental health diagnoses including personality disorders, major depression, schizophrenia, and bipolar disorder. Second, drug abusers with mental illness comorbidity are more likely to engage in behaviors that increase risk for HIV/AIDS. For example, two studies of injecting drug abusers have found that antisocial personality disorder (APD) is associated with a higher frequency of needle sharing.

In order to direct treatment and services research to where it is most needed, NIDA supports epidemiologic studies of mental health comorbidities. The results to date suggest that the most common are personality disorders including APD and borderline personality disorder; anxiety disorders including post-traumatic stress disorder (PTSD); and depression. Some evidence suggests that men who use drugs are more likely to have APD, while women and minorities are more likely to have depression or PTSD. While people with schizophrenia do not constitute a large portion of the drug-abusing population, an extraordinarily high percentage of people with this disease abuse drugs. A concurrent mental disorder can complicate drug abuse treatment in a multitude of ways. For example, research suggests that clinically depressed individuals have an exceptionally hard time resisting environmental cues to relapse, that is, urges to resume drug taking that commonly occur when abstinent addicts encounter people, places, or things associated with their previous drug use. In some cases, treatment for mental disorders must be adjusted because of concurrent drug abuse. For example, opiate users with anxiety disorders are considered poor candidates for standard therapy with anti-anxiety drugs of the benzodiazepine class because these drugs can cause a second addiction.

NIDA-supported researchers have identified effective ways to tailor treatment for some patients with dual diagnoses. In one study, opiate addicts with APD responded better when standard contingency management therapy was modified. In the standard type of this therapy, patients receive small rewards for abstinence that become progressively greater the longer abstinence is maintained. In the modified version, treatment professionals gave more frequent rewards for desirable behaviors, such as attending scheduled counseling sessions and testing clean for drugs. In another study, drug craving was reduced among teenage cocaine abusers with bipolar disorder who receive lithium, and in depressed heroin abusers who were treated with imipramine. In this issue of NIDA NOTES, we report on promising results with methylphenidate and antidepressants in children with attention-deficit/ hyperactivity disorder (ADHD) and with methylphenidate in adult cocaine abusers with ADHD.

Just as the co-occurrence of drug abuse and mental health problems presents special problems for treatment, so does it also for research. The problems arise in part because drug abuse and other mental health disorders can intertwine in several ways. For example, successful treatment of cocaine addiction often also dispels concurrent depression, while nicotine addicts' depression commonly persists after successful smoking cessation treatment. Such variations make it difficult to generalize treatment research findings across large patient groups.

As a result, progress has been made in relatively small increments. Another problem facing researchers is that a study population that is ostensibly uniform because all individuals have the same drug abuse and mental health disorders may actually be nonuniform. The reason is that the relationship between the two disorders may vary in different patients. For example, some people with a mental disorder may initiate drug use as an inappropriate form of self-medication, some people who take drugs may develop mental disorders as a consequence of their drug use, and a third group may simply have the two disorders at the same time. If an intervention is evaluated in a study population where some patients have drug abuse as a primary disorder and others as a secondary disorder, the treatment may appear to be ineffective even though it works well for one of these subgroups.

A structural difficulty that complicates research on drug abuse and mental illness comorbidity is that few drug abuse treatment programs treat enough patients with a particular mental health disorder to easily generate the preliminary data necessary to justify a full-scale study of a treatment for the disorder. To overcome this difficulty and accelerate the pace of discovery, NIDA's Behavioral Therapy Development Program places special emphasis on pilot studies in drug abuse and mental illness comorbidity. The program represents a kind of research "venture capital," making possible the rapid initial testing of many ideas, the best of which will then proceed rapidly to further, more definitive testing. Starting next year, NIDA's Clinical Trials Network will accelerate this wider testing by facilitating the recruitment of large numbers of patients with the drug abuse and comorbidity characteristics that treatments are designed to address.

Drug abuse and mental health professionals both confront the difficulty of providing effective care to patients whose problems overlap two health care specialties that share much, but are also in many ways very distinct. In response to this situation, NIDA and the National Institute of Mental Health have been actively collaborating on epidemiologic and treatment research on comorbidity. For example, the two Institutes are examining the problem of treating the relatively small population of patients who abuse drugs and also have severe mental disorders, such as schizophrenia or bipolar disorder. These patients require integrated specialty treatments.

In drug abuse as in other areas of health care, isolated disorders are simplest to study and treat, but comorbidity is reality for many individuals. NIDA research has laid the foundation for successful investigations of these complex realities.

Fact Sheet courtesy of:
National Institute on Drug Abuse (NIDA)
6001 Executive Blvd Bethesda, MD. 20892
www.nida.nih.gov/

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