4 HIV Status and Cannabis Use: A Rigorous Examination of Between Group Differences in Neurocognitive Functioning

Abstract

Objective:

A recent review called for a more robust assessment of cannabis use (CU), including amount and timing of recent use to assess neurocognitive effects of CU among people living with HIV (PWH) (Ellis et al., 2021). The current study addresses some issues raised by investigating between group neurocognitive differences among healthy controls and PWH who differ on their cannabis use histories, using strict inclusion criteria, robust classification of CU, and administration of an established neurocognitive test battery.

Participants and Methods:

Among this community sample of adults (N=309), 58 were classified as CU+/HIV+ group (84.5% Male), 76 as CU-/HIV+ (57.9% M), 86 as CU+/HIV- (58.1% M), and 89 as CU-/HIV- (53.9% M). Exclusion criteria included history of past 12-month dependence and extensive lifetime dependence or significant use of illicit substances other than cannabis, severe or current mood or thought disorder, and other medical conditions that adversely impact neurocognitive functioning. Inclusion criteria for CU+ groups included <30-days since last CU, >10 times of CU in last month, 3 times of CU per month in last 12 months, > 1 year of CU, and > 500 times used in lifetime. CU parameters did not statistically differ between HIV+/CU+ and HIV-/CU+. CU- groups’ inclusion criteria required no CU in last 6 months, 196 lifetime number of times used, and no history of CU dependance. Lifetime CU did not statistically differ between CU-/HIV+ and CU-/HIV- groups. HIV+ groups did not differ significantly on HIV viral load in plasma or nadir CD4+ counts. Significant between group differences included age, sex, years of education, and amount of alcohol and nicotine use within 12 months. The aforementioned sociodemographic and substance use variables that differed between groups were covariates in analyses. A battery of 10 neurocognitive measures, two measures per each domain of learning, memory, motor, executive functioning, and processing speed. Global composite summary scores for overall neurocognitive performance were calculated by averaging M T-scores for each neurocognitive domain. Data transformations were used to address any violations of statistical assumptions.

Results:

To facilitate data reduction, neurocognitive task scores were standardized to T-scores using the M and SD of the CU-/HIV-group. An omnibus model of between-group comparisons on global neurocognitive task performance revealed no significant differences, F(3) = .16, p = .923. Subsequent Tukey’s post hoc test revealed no significant differences among the four groups. Results also revealed nonsignificant differences between groups in neurocognitive performance within each domain. However, the CU-/HIV- group performed significantly worse than the CU-/HIV+ group on the Executive Functioning domain, based on Tukey’s post hoc test.

Conclusions:

We found no significant global neurocognitive differences among groups; however, there was some evidence for domain-specific neurocognitive differences in executive functioning. This contrasts somewhat with existing literature on HIV and cannabis-associated neurocognitive deficits. Several factors may have contributed to this, including our relatively healthy PWH sample. Future analyses will examine interactive effects of HIV severity and severity of CU on neurocognition. This analysis will better determine who, among PWH, are most at-risk for cannabis-associated neurocognitive effects and what factors may exacerbate them.