Answering the Skeptics:
the "Risk-AIDS" or "Behavioral" Hypothesis

Skeptics of the role of HIV in AIDS have espoused a "risk-AIDS" or a
"drug-AIDS" hypothesis (Duesberg, 1987-1994), asserting at different times
that factors such as promiscuous homosexual activity; repeated venereal
infections and antibiotic treatments; the use of recreational drugs such as
nitrite inhalants, cocaine and heroin; immunosuppressive medical procedures;
and treatment with the drug AZT are responsible for the epidemic of AIDS.
Such arguments have been repeatedly contradicted. Compelling evidence
against the risk-AIDS hypothesis has come from cohort studies of high-risk
groups in which all individuals with AIDS-related conditions are
HIV-antibody positive, while matched, HIV-antibody negative controls do not
develop AIDS or immunosuppression, despite engaging in high-risk behaviors.

In a prospectively studied cohort in Vancouver (Schechter et al., 1993a),
715 homosexual men were followed for a median of 8.6 years. Among 365
HIV-positive individuals, 136 developed AIDS. No AIDS-defining illnesses
occurred among 350 HIV-negative men despite the fact that these men reported
appreciable levels of nitrite use, other recreational drug use, and frequent
receptive anal intercourse. The average rate of CD4+ T cell decline was 50
cells/mm3 per year in the HIV-positive men, while the HIV-negative men
showed no decline. Significantly, the decline of CD4+ T cell counts in
HIV-positive men and the stability of CD4+ T cell counts in HIV-negative men
were apparent whether or not nitrite inhalants were used. There were 101
AIDS-related deaths among the HIV-seropositive men, including six unrelated
to HIV infection. In the seronegative group, only two deaths occurred: one
heart attack and one suicide. In this study, lifetime prevalences of risk
behaviors were similar in the 136 HIV-seropositive men who developed AIDS
and in the 226 HIV-seropositive men who did not develop AIDS: use of nitrite
inhalants, 88 percent in both groups; use of other illicit drugs, 75 percent
and 80 percent, respectively; more than 25 percent of sexual encounters
involving receptive anal intercourse, 78 percent and 82 percent,
respectively. Among HIV-seronegative men (none of whom developed AIDS), the
lifetime prevalences of these behaviors were somewhat lower, but
substantial: 56 percent, 74 percent and 58 percent, respectively.

Similar results were reported from the San Francisco Men's Health Study, a
cohort of single men recruited in San Francisco in 1984 without regard to
sexual preference, lifestyle or serostatus (Ascher et al., 1993a). During 96
months of follow-up, 215 cases of AIDS had occurred among 445 HIV-antibody
positive homosexual men, 174 of whom had died. Among 367 antibody-negative
homosexual men and 214 antibody-negative heterosexual men, no AIDS cases and
eight deaths unrelated to AIDS-defining conditions were observed. The
authors found no overall effect of drug consumption, including nitrites, on
the development of Kaposi's sarcoma or other AIDS-defining conditions, nor
an effect of the extent of the participants' drug use on these conditions. A
consistent loss of CD4+ T cells was limited to HIV-positive subjects, among
whom there was no discernible difference in CD4+ T cell counts related to
drug-taking behavior. Among HIV-seronegative men, moderate or heavy drug
users had higher CD4+ T cell counts than non-users.
Observational studies of HIV-infected individuals have found that drug use
does not accelerate progression to AIDS (Kaslow et al., 1989; Coates et al.,
1990; Lifson et al., 1990; Robertson et al., 1990). In a Dutch cohort of
HIV-seropositive homosexual men, no significant differences in sexual
behavior or use of cannabis, alcohol, tobacco, nitrite inhalants, LSD or
amphetamines were found between men who remained asymptomatic for long
periods and those who progressed to AIDS (Keet et al., 1994). Another study,
of five cohorts of homosexual men for whom dates of seroconversion were
well-documented, found no association between HIV disease progression and
history of sexually transmitted diseases, number of sexual partners, use of
AZT, alcohol, tobacco or recreational drugs (Veugelers et al., 1994).

Similarly, in the San Francisco City Clinic Cohort, recruited in the late
1970s and early 1980s in conjunction with hepatitis B studies, no consistent
differences in exposure to recreational drugs or sexually transmitted
diseases were seen between HIV-infected men who progressed to AIDS and those
who remained healthy (Buchbinder et al., 1994).

Because many children with AIDS are born to mothers who abuse recreational
drugs (Novick and Rubinstein, 1987; European Collaborative Study, 1991), it
has been postulated that the mothers' drug consumption is responsible for
children developing AIDS (Duesberg, 1987-1994). This theory is contradicted
by numerous reports of infants with AIDS born to women infected with HIV
through heterosexual contact or transfusions who do not use drugs (CDC,
1995a). As noted above, the only factor that predicts whether a child will
develop AIDS is whether he or she is infected with HIV, not maternal drug
use.