A study presented Monday at the International AIDS Society Conference on Pathogenesis and Treatment in Paris showed that HIV-positive patients experiencing side effects from their anti-HIV drugs reported a significant lessening of the adverse effects, including depression, after switching to a regimen that includes Abbott Laboratories' protease inhibitor Kaletra. The eight-week study of 588 adults in 14 countries examined the impact that switching either another protease inhibitor or a nonnucleoside reverse transcriptase inhibitor for Kaletra had on moderate drug-related side effects, including depression. Patients switching to Kaletra were only about half as likely to report significant symptoms of depression as were those taking on other anti-HIV drug regimens. "Research shows that depression can decrease a patient's energy and may even contribute to the progression of HIV/AIDS," said researcher Jurgen Rockstroh. "It is important to consider HIV drug regimens that help keep the virus undetectable and help minimize the barriers to treatment success that depression can create." The study also showed that Kaletra performed as well or better than other protease inhibitors or NNRTI drugs in suppressing HIV viral levels in the study subjects.