Individuals living with HIV may experience cognitive difficulties or marked declines known as HIV-Associated Neurocognitive Disorder (HAND). Cognitive difficulties have been associated with worse outcomes for people living with HIV, therefore, accurate cognitive screening and identification is critical. One potentially sensitive marker of cognitive impairment which has been underutilized, is intra-individual variability (IIV). Cognitive IIV is the dispersion of scores across tasks in neuropsychological assessment. In individuals living with HIV, greater cognitive IIV has been associated with cortical atrophy, poorer cognitive functioning, with more rapid declines, and greater difficulties in daily functioning. Studies examining the use of IIV in clinical neuropsychological testing are limited, and few have examined IIV in the context of a single neuropsychological battery designed for culturally diverse or at-risk populations. To address these gaps, this study aimed to examine IIV profiles of individuals living with HIV and who inject drugs, utilizing the Neuropsi, a standardized neuropsychological instrument for Spanish speaking populations.

Spanish speaking adults residing in Puerto Rico (n=90) who are HIV positive and who inject drugs (HIV+I), HIV negative and who inject drugs (HIV-I), HIV positive who do not inject drugs (HIV+), or healthy controls (HC) completed the Neuropsi battery as part of a larger research protocol. The Neuropsi produces 3 index scores representing cognitive domains of memory, attention/memory, and attention/executive functioning. Total battery and within index IIV were calculated by dividing the standard deviation of T-scores by mean performance, resulting in a coefficient of variance (CoV). Group differences on overall test battery mean CoV (OTBMCoV) were investigated. To examine unique profiles of index specific IIV, a cluster analysis was performed for each group.

Results of a one-way ANOVA indicated significant between group differences on OTBMCoV (F[3,86]=6.54, p<.001). Post-hoc analyses revealed that HIV+I (M=.55, SE=.07, p=.003), HIV-I (M=.50, SE=.03, p=.001), and HIV+ (M=.48, SE=.02, p=.002) had greater OTBMCoV than the HC group (M=.30, SE=.02). To better understand sources of IIV within each group, cluster analysis of index specific IIV was conducted. For the HIV+ group, 3 distinct clusters were extracted: 1. High IIV in attention/memory and attention/executive functioning (n=3, 8%); 2. Elevated memory IIV (n=21, 52%); 3. Low IIV across all indices (n=16, 40%). For the HIV-I group, 2 distinct clusters were extracted: 1. High IIV across all 3 indices (n=7, 24%) and 2. Low IIV across all 3 indices (n=22, 76%). For the HC group, 3 distinct clusters were extracted: 1. Very low IIV across all 3 indices (n=5, 36%); 2. Elevated memory IIV (n=6, 43%); 3. Elevated attention/executive functioning IIV with very low attention/memory and memory IIV (n=3, 21%). Sample size of the HIV+I group was insufficient to extract clusters.

Current findings support IIV in the Neuropsi test battery as clinically sensitive marker for cognitive impairment in Spanish speaking individuals living with HIV or who inject drugs. Furthermore, the distinct IIV cluster types identified between groups can help to better understand specific sources of variability. Implications for clinical assessment in prognosis and etiological considerations are discussed.

Injection drug use is a significant public health crisis with adverse health outcomes, including increased risk of human immunodeficiency virus (HIV) infection. Comorbidity of HIV and injection drug use is highly prevalent in the United States and disproportionately elevated in surrounding territories such as Puerto Rico. While both HIV status and injection drug use are independently known to be associated with cognitive deficits, the interaction of these effects remains largely unknown. The aim of this study was to determine how HIV status and injection drug use are related to cognitive functioning in a group of Puerto Rican participants. Additionally, we investigated the degree to which type and frequency of substance use predict cognitive abilities.

96 Puerto Rican adults completed the Neuropsi Attention and Memory-3rd Edition battery for Spanish-speaking participants. Injection substance use over the previous 12 months was also obtained via clinical interview. Participants were categorized into four groups based on HIV status and injection substance use in the last 30 days (HIV+/injector, HIV+/non-injector, HIV/injector, HIV-/non-injector). One-way analysis of variance (ANOVA) was conducted to determine differences between groups on each index of the Neuropsi battery (Attention and Executive Function; Memory; Attention and Memory). Multiple linear regression was used to determine whether type and frequency of substance use predicted performance on these indices while considering HIV status.

The one-way ANOVAs revealed significant differences (p’s < 0.01) between the healthy control group and all other groups across all indices. No significant differences were observed between the other groups. Injection drug use, regardless of the substance, was associated with lower combined attention and memory performance compared to those who inject less than monthly (Monthly: p = 0.04; 2-3x daily: p < 0.01; 4-7x daily: p = 0.02; 8+ times daily: p < 0.01). Both minimal and heavy daily use predicted poorer memory performance (p = 0.02 and p = 0.01, respectively). Heavy heroin use predicted poorer attention and executive functioning (p = 0.04). Heroin use also predicted lower performance on tests of memory when used monthly (p = 0.049), and daily or almost daily (2-6x weekly: p = 0.04; 4-7x daily: p = 0.04). Finally, moderate injection of heroin predicted lower scores on attention and memory (Weekly: p = 0.04; 2-6x weekly: p = 0.048). Heavy combined heroin and cocaine use predicted worse memory performance (p = 0.03) and combined attention and memory (p = 0.046). HIV status was not a moderating factor in any circumstance.

As predicted, residents of Puerto Rico who do not inject substances and are HIVnegative performed better in domains of memory, attention, and executive function than those living with HIV and/or inject substances. There was no significant difference among the affected groups in cognitive ability. As expected, daily injection of substances predicted worse performance on tasks of memory. Heavy heroin use predicted worse performance on executive function and memory tasks, while heroin-only and combined heroin and cocaine use predicted worse memory performance. Overall, the type and frequency of substance is more predictive of cognitive functioning than HIV status.