Though needle drug abusers often change their practices when told of the risks of AIDS, many still suffer immune system damage that may make it difficult to ward off the disease, a study suggests. Researchers also confirmed Friday that one's state of mind affects the immune system, and suggested it may make a difference with AIDS. The work was presented at the annual meeting of the American Psychological Association. The change in drug practices is significant because drug users are often thought not responsive to health warnings, said researcher John Watters. His study, done in San Francisco, found users cut back on the sharing of hypodermic needles, which can spread the AIDS virus, cleaned their needles more and increased their use of condoms during sex when told of the dangers. ``We found dramatic changes'' after a program to educate drug users began in 1986, said Watters, of the Urban Health Study in San Francisco. Intravenous drug abuse is blamed for about 19 percent of the nation's cumulative total of some 70,000 cases of acquired immune deficiency syndrome. Workers in the San Francisco program told drug abusers about AIDS prevention measures, distributed condoms and gave out bleach to disinfect needles. Researchers studied drug and condom practices of 386 drug users interviewed in 1986 before the program began, and 545 users interviewed in early 1987 some eight months after the start of the program. An additional 534 were sampled later in 1987, and 553 in early 1988. Use of ``safe needle hygiene'' rose from 13 percent of the time drugs were used before the outreach program to 63 percent afterward. Safe hygiene was defined as using bleach, alcohol, hydrogen peroxide or boiling water to disinfect needles, or not sharing needles. The follow-up surveys found hygiene used 70 percent of the time in late 1987 and 71 percent in early 1988. The estimated number of sharing partners dropped from an average of 11 before the outreach program to eight in early 1987, with nine and five reported in the following two surveys. Condom use rose from 3 percent of the time before the outreach program to 16 percent afterwards, with 23 percent in each of the follow-up surveys. Blood tests found that the rate of users exposed to the AIDS virus jumped from 6 percent in early 1986 to 13 percent in early 1987, with 9 percent and 11 percent in the following two surveys. James Sorensen of the University of California, San Francisco, who has studied AIDS prevention among drug users in treatment, said Watters' results on behavioral change ring true. But, he warned, `` We need to work very hard to reach people who haven't been reached.'' The study of drug users in treatment focused on 30 outpatients in a long-term methadone program. None had been infected with the AIDS virus, said Nancy Klimas of the University of Miami School of Medicine and the Veterans Administration Medical Center in Miami. But they showed significant deficiencies in the functioning of their disease-fighting immune system, she said. For example, the functioning of their ``natural killer cells'' was about half of normal, she said. Poor nutrition, non-AIDS infections, prior drug abuse or perhaps the methadone may be responsible, but no cause has yet been found, she said. Don Des Jarlais of the New York State Division of Substance Abuse Services said previous research has shown that immune abnormalities in drug users can take years to disappear once they enter methadone treatment. Klimas' study also found that immune system function was better by several measures in abusers who showed greater ``hardiness,'' defined as commitment to life, a feeling of control and a tendency to see stresses as challenges. Loneliness and confusion were associated with poorer immune system performance, she said. But no cause-and-effect conclusion can be drawn from any of the psychological data, she cautioned. Another study released Friday found that for homosexual men soon after AIDS infection, immune system functioning was better in men determined to get on with life, who focused on and expressed their emotions, and who had a feeling of psychological robustness. Again, no cause-and-effect conclusions can yet be drawn, said Nancy Blaney of the University of Miami School of Medicine.