Emory Report

December 7, 1998

 Volume 51, No. 14

Medical researchers present findings on HIV, ADHD

Health sciences researchers have uncovered alarming findings regarding sexual behavior of people taking protease inhibitors for HIV and discovered that the drug Ritalin does create positive brain changes in people with hyperactivity disorder.

Patients treated with protease inhibitors more likely to resume risky sex

Patients living with HIV treated with protease inhibitors may be less concerned about practicing safe sex than those not being treated with the drugs, according to a new collaborative study. Researchers at the Rollins School, the University of Alabama at Birmingham and the Centers for Disease Control and Prevention studied sexually active persons living with HIV and found those treated with protease inhibitors were more likely to report inconsistent condom use.

The study included a cross section of HIV-infected patients attending six public clinics in non-urban Alabama communities. Within the study group, sexually active patients being treated with protease inhibitors were about 2.5 times more likely to engage in risky sex (using condoms less than half the time while having sex) compared to patients not being treated with protease inhibitors.

Even more alarming, said Ralph DiClemente, professor of behavioral sciences and health education, was the finding that patients using protease inhibitors were also more likely to report "never" using condoms during sexual intercourse. Even after controlling for factors such as age, race, education and other AIDS-defining conditions, patients taking protease inhibitors were significantly more likely to report engaging in risky sex. There were significant differences, however, by sexual preference.

Within the study group, homosexual men treated with protease inhibitors were 3.8 times more likely to report using condoms fewer than half the times they engaged in sexual intercourse compared to homosexual men not being treated with the drugs. The study also found that homosexual men using protease inhibitors were 5.4 times more likely to report "never" using condoms during sexual intercourse. Similar findings were not observed for heterosexual men or women.

"Given that many HIV-infected individuals will be treated with protease inhibitors, these unanticipated consequences are disturbing and suggest a need for further in-depth study," said DiClemente.

Brain scans provide clues as to how Ritalin enhances memory

The first study to evaluate the role of the drug Ritalin on working memory in people with attention deficit/hyperactivity disorder (ADHD) found brain activity in adults with the disorder are significantly different from scans of adults without it. Yet few differences are noted between scans of these two groups once the ADHD patients begin to take the Ritalin, Emory researchers found.

Brain activity was first recorded using positron emission tomography (PET) in 13 nonmedicated adults with ADHD and nine without. Participants performed a challenging auditory arithmetic assignment known as the PASAT, or paced auditory serial addition task. As expected, the patients with ADHD had more difficulty performing the task unmedicated. Researchers noted from their brain scans that cerebral blood flow was dysfunctional-overactive in some areas of the brain and underactive in others.

Task-related neural activity among men with ADHD was not noted in the frontal region-an area traditionally associated with working memory-as it was in the control subjects, but rather appeared in the PET images to be most concentrated in the brain's cerebellum and basal ganglia, areas associated more with basic motor functioning and attention.

But when researchers repeated the test on the same group of adults with ADHD while they were treated with Ritalin (methylphenidate) and compared PET scans to those of the nonpatients, the brain images were remarkably similar, with the exception of the absence of frontal activations in the ADHD group.

Ritalin may improve working memory by "decreasing activation in competing regions that are unnecessary for task demands and by recruiting new compensatory regions," explained Julie Schweitzer, assistant professor of psychiatry and behavioral sciences at the School of Medicine.

Working memory is a fairly new term that replaces and expands upon the concept of short-term memory. Researchers have theorized that working memory serves not only as temporary storage for new information but also actively manipulates new data. Part of the active process may involve forgetting certain knowledge.

Disruption of working memory may explain many of the everyday difficulties individuals with ADHD encounter, from coping with laborious reading to never remembering to complete one of multiple unfinished tasks, Schweitzer said.

--Holly Korschun

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