Linda M. Skalski

Independent effects of HIV infection and cocaine dependence on neurocognitive impairment in a community sample living in the southern United States

BACKGROUND Prior studies have established that methamphetamine and HIV can have additive deleterious effects on neurocognitive functioning, but there has been relatively little research on other stimulants like cocaine. This study investigated the effects of cocaine and HIV on neurocognitive impairment in a large, well-characterized sample. METHODS The sample included 193 adults across four groups: HIV-positive cocaine users (n = 48), HIV-negative cocaine users (n = 53), HIV-positive non-drug users (n = 60), and HIV-negative non-drug users (n = 32). Cocaine users met criteria for lifetime dependence and had past-month cocaine use. A comprehensive battery assessed substance abuse and neurocognitive functioning. RESULTS Participants were mostly male (66%) and African-American (85%), with a mean age of 46.09 years. The rate of global impairment was 33%, with no significant main effects across groups on likelihood of impairment. There were main effects for cocaine on processing speed and executive functioning, with cocaine users having greater impairment (F = 9.33 and F = 4.22, respectively), and for HIV on attention, with HIV-infected persons having greater impairment (F = 5.55). There was an interaction effect for executive functioning, with the three patient groups having greater impairment than controls (F = 5.05). Nonparametric analyses revealed significant additive impairment in the presence of both HIV and cocaine for processing speed. CONCLUSIONS While cocaine does not appear to increase vulnerability to global HIV-associated neurocognitive impairment, it does have independent adverse effects on executive functioning and processing speed. Given prior evidence that domain-specific deficits predict real-world impairments, our results may help explain the poorer behavioral and functional outcomes observed in HIV-infected cocaine users.

Coping Styles and Illicit Drug Use in Older Adults with HIV/AIDS

The prevalence of HIV infection in older adults is increasing; by 2015, over half of adults living with HIV/AIDS in the United States will be over 50. This study describes the prevalence of drug use and examines psychosocial predictors of drug use in a sample of HIV-infected adults aged 50 and older. Participants were 301 HIV-positive older adults enrolled in a clinical trial of a coping intervention aimed to reduce their depressive symptoms. One-quarter used illicit drugs in the past 60 days (48% any cocaine, 48% weekly marijuana, 44% any other drugs) with an average of 36 days for marijuana and 15 days for cocaine. After controlling for demographics, self-destructive avoidance was positively associated and spiritual coping was negatively associated with drug use. These findings suggest that assessment of drug abuse should be a routine part of care for older patients in HIV clinics. Furthermore, interventions designed to increase spiritual coping and decrease self-destructive avoidance may be particularly efficacious for HIV-infected older adults.

Memory Impairment in HIV-Infected Individuals with Early and Late Initiation of Regular Marijuana Use

Marijuana use is disproportionately prevalent among HIV-infected individuals. The strongest neurocognitive effect of marijuana use is impairment in the domain of memory. Memory impairment is also high among HIV-infected persons. The present study examined 69 HIV-infected individuals who were stratified by age of regular marijuana initiation to investigate how marijuana use impacts neurocognitive functioning. A comprehensive battery assessed substance use and neurocognitive functioning. Findings indicated early onset marijuana users (regular use prior to age 18), compared to non-marijuana users and late onset marijuana users (regular use at age 18 or later), were over 8 times more likely to have learning impairment and nearly 4 times more likely to have memory impairment. A similar pattern of early onset marijuana users performing worse in learning emerged when examining domain deficit scores. The potential for early onset of regular marijuana use to exacerbate already high levels of memory impairment among HIV-infected persons has important clinical implications, including increased potential for medication non-adherence and difficulty with independent living.

Expectancy of impairment attenuates marijuana-induced risk taking

BACKGROUND Marijuana use has been associated with increased risk-taking and impulsive behavior. While pharmacologic effects of marijuana can lead to inhibitory impairment, expectancy of potential impairment may result in compensatory behavioral response by decreasing impulsive decisions and risky behaviors. With the increases in marijuana use and related problems, a better understanding of the individual characteristics associated with marijuana intoxication and risky behavior is needed. This study examined the role of impairment expectancies in marijuanas acute effects on behavioral measures of impulsivity and risk-taking. METHODS Participants (N=136) were regular marijuana users. A balanced placebo design (BPD) was used crossing marijuana administration (i.e., 0% Tetrahydrocannabinol (THC) vs. 2.8% THC) with stimulus expectancy (i.e., Told Placebo vs. Told THC). Marijuana outcome expectancies were measured by self-report and dependent measures included a number of behavioral impulsivity tasks and the balloon analogue risk task (BART). RESULTS Among participants who received THC, higher expectancies for cognitive-behavioral impairment (CBI) were related to lower risk-taking on the BART. Among those who received placebo, there was no association between CBI expectancies and BART performance. CBI expectancies did not moderate the stimulus expectancy effect on the BART nor drug or stimulus expectancy effects on impulsivity measures. CONCLUSIONS Results provide initial evidence that expectancies of greater impairment are associated with compensatory behavior on a risk-taking task under acute marijuana intoxication. Future studies should examine the role of impairment expectancies on risk behaviors of substantial public health concern, such as driving while under the influence of marijuana.

Sex-related marijuana expectancies as predictors of sexual risk behavior following smoked marijuana challenge

Marijuana use has been associated with sexual risk behavior, but the mechanisms that underlie this relationship are not well understood. The present study examined whether marijuana acutely increased sexual risk on a behavioral decision-making task and whether sex-related marijuana outcome expectancies influenced sexual risk decisions after marijuana administration. Participants were heterosexual marijuana users (n = 126) who were randomly assigned to 1 of 4 study conditions using a 2 × 2 factorial design crossing drug administration (received 2.8% delta-9-tetrahydrocannabinol [THC] or 0% THC) with instructional set (told THC or told placebo). Participants completed a self-report measure of sex-related marijuana outcome expectancies at baseline and estimated likelihood of using condoms with a new and a steady partner in an interactive sexual role-play task (SRT) after smoking. In gender-specific analyses, there was a significant interaction of drug administration by sex-related outcome expectancies, such that for men in the received-placebo conditions, more salient sex-related marijuana outcome expectancies were associated with increased likelihood for sex without a condom with a new partner. Among women, there was no interaction or main effect of drug administration but more salient sex-related marijuana outcome expectancies were associated with increased likelihood of sex without a condom with a steady but not new partner. Findings suggest marijuana does not acutely increase risk for engaging in sexual risk behaviors. By contrast, sex-related marijuana outcome expectancies may play a more significant role in sexual decision-making process among marijuana users.