Highlights of Recently Published NIDA-Supported Studies

Combined Treatments Improve Dual Abstinence

Two anti-addiction medications are better than one for people who abuse both cocaine and alcohol, according to a new NIDA-funded study. Researchers randomly assigned 208 men and women to one of four protocols for an 11-week trial: disulfiram and naltrexone; disulfiram with placebo; naltrexone with placebo; or a double placebo. Among the dual-medication participants, 35 percent attained 3 consecutive weeks of abstinence from both cocaine and alcohol, compared with 17 percent of those taking either naltrexone or disulfiram and 15 percent of those receiving the double placebo, report Drs. Helen Pettinati, Kyle Kampman, Charles O'Brien, and colleagues at the University of Pennsylvania.

The patients who attained 3 weeks of abstinence during treatment had double the rates of abstinence at a 6-month followup than those who did not attain that standard. The combination treatment may meet a widespread need; an estimated 50 percent of cocaine abusers are also addicted to alcohol.
Addictive Behaviors 33(5):651-667, 2008. [Abstract]

Drug Cues Outside Awareness Rapidly Trigger Brain's Emotion Centers

Even when a cocaine abuser is not aware of briefly seeing a drug-related image, such a picture can instantaneously activate the emotion and reward circuits in the brain. Quick views of sexual images also activate many of the same brain areas. That pattern of activity may be "the brain's primordial signature for desire," according to Drs. Anna Rose Childress and Charles O'Brien and colleagues at the University of Pennsylvania.

In a study with 22 men seeking treatment for cocaine abuse, the researchers demonstrated that the participants' brains responded to images outside their conscious awareness. The researchers used a technique in which a target picture, which featured either sexual or drug-related imagery, was flashed for 33 milliseconds, followed by a gray screen and then a 467-millisecond presentation of a neutral picture.

Participants reported remembering the neutral pictures, but not the target pictures. Nevertheless, activity in their neural circuits increased in response to the target images.

The researchers did not determine whether participants felt a surge in craving after viewing the subliminal pictures. Cocaine abusers' rapid neural response to reward cues outside awareness may signify vulnerability to relapse, the researchers suggest.
JPLoS ONE 30;3(1):e1506, 2008. [Full Text]

Sensory Aspects of Smoking May Counter Bad Mood, Craving

The act of smoking—apart from actual or expected nicotine delivery—may soothe a smoker's negative mood. Dr. Kenneth A. Perkins and colleagues at the University of Pittsburgh showed 200 smokers combinations of images and music, some pleasant and others disturbing, to induce a good or bad mood. The study participants began smoking sooner and smoked more after the disturbing presentations than after the pleasant ones.

The participants reported that smoking alleviated their negative feelings, offset symptoms of nicotine withdrawal, and relieved cigarette craving. As in past research, their responses were similar whether they were given regular nicotine cigarettes or cigarettes with only trace amounts of nicotine. Strikingly, however, their responses were also similar when they recognized that the cigarettes contained almost no nicotine.

The team repeated the procedure with 20 smokers, this time giving them unlit cigarettes to handle and pretend to puff. These smokers reported no alleviation of their negative moods or craving.

Taken together, the two studies suggest that the sensory experience of smoke inhalation, but not nicotine, is critical to the acute emotional benefits of smoking experienced by chronic smokers and that these benefits accrue even when the smokers know they are getting almost no nicotine.
Journal of Abnormal Psychology 117(1):79-93, 2008. [Abstract]

Methamphetamine Abuse Alters Response to Facial Cues

Methamphetamine abusers may have more difficulty than nonabusers in responding with empathy and self-control to people who are experiencing intense emotions, according to Dr. Edythe London and colleagues at the University of California, Los Angeles. Using functional magnetic resonance imaging, the researchers compared the brain patterns of 12 recently abstinent methamphetamine abusers and 12 nonabusers while they viewed images of fearful or angry faces. Compared with the nonabusers, the abusers showed less activity in brain areas related to important socioemotional processes such as interpreting facial expressions, controlling aggressive impulses, and building a concept of another person. The abusers showed greater activity than the others, however, in a region involved in pain processing and social distress. The deficit in socioemotional processing combined with the heightened signaling of negative feelings may contribute to socially inappropriate behaviors among methamphetamine abusers, the researchers say.
Drug and Alcohol Dependence 93(1-2):93-102, 2008. [Abstract]

Volume 22, Number 4 (October 2009)