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.