The purpose of this R01 study is to evaluate the association between neuropsychological executive dysfunction and HIV infection among young injection and non-injection drug users. A longitudinal study will be conducted in which the cohort of seronegative drug users completing a baseline neuropsychological battery are re-assessed on three subsequent occasions, roughly six months apart. The primary aim of the longitudinal study is to estimate the magnitude of the suspected causal relationship between executive dysfunction and HIV-risk behaviors while adjusting for time-invariant (e.g. sex, ethnicity) and time-varying (e.g. degree of drug abuse) covariates. We also seek to evaluate: (1) the degree to which specific executive dysfunctions predispose heroin and cocaine users to high-risk injection practices or sex behaviors, and (2) whether observed relationship between executive dysfunction and HIV-risk behaviors can be understood independent of levels of drug -taking frequency, or whether the observed data are more consistent with complex patterns of interdependency between executive dysfunction, drug-taking frequency, and HIV-risk-behaviors. If successful, this project will shed new light on significant and potentially malleable HIV-risk factors in injection and non-injection drug users. This will be important evidence because injection drug abuse continues to account for a large proportion of HIV seroconversions particularly among young women and minorities. As such, this RO1 research project serves as an important initial step in a line of innovative investigations about suspected causal associations between neuropsychological deficits and HIV-risk behaviors in drug users. Ultimately, this line of investigation should lead to changes in public and clinical practices designed to prevent HIV infection.

Inclusion Criteria:

• Drug users aged 15 to 50 years old.

Exclusion Criteria:

• Acute psychotic, suicidal, homicidal ideation.

In total, we seek to recruit 150 HIV positive and 800 HIV negative drug users who are between the ages of 15 and 50 years and who have used illicit drugs within the previous five years of enrollment.