HIV-associated neurocognitive disorder in Australia: a case of a high-functioning and optimally treated cohort and implications for international neuroHIV research

Abstract

The Australian HIV-infected (HIV+) population is largely comprised of high-functioning men who have sex with men (MSM). Like other English-speaking countries, Australia mostly relies on US neuropsychological normative standards to detect and determine the prevalence of neurological disorders. Whether the US neuropsychological (NP) normative standards are appropriate in Australian HIV+ MSM has not been established. Ninety virally suppressed HIV+ and 49 HIV-uninfected (HIV−) men (respectively 86 and 85 % self-reported MSM; mean age 54 and 56 years, mean premorbid verbal IQ estimate 110 and 111) undertook standard NP testing. The raw neuropsychological data were transformed using the following: (1) US standards as uncorrected scaled scores and demographically corrected T scores (US norms); and (2) z scores (without demographic corrections) derived from Australian comparison group scaled scores (local norms). To determine HIV-associated neurocognitive disorder prevalence, we used a standard definition of impairment based upon a battery-wide summary score: the global deficit score (GDS). Impairment classification (GDS≥0.5) based on the local norms was best at discriminating between the two groups (HIV−=14.3 % vs. HIV+ = 53.3 %; p<0.0001). This definition was significantly associated with age. Impairment classification based on the US norms yielded much lower impairment rate regardless of the HIV status (HIV−=4.1 % vs. HIV+=14.7 %; p= 0.05), but was associated with historical AIDS, and not age. Both types of summary scores were associated with reduced independence in activities of daily living (p≤ 0.03). Accurate neuropsychological classifications of high (or low) functioning individuals may need country-specific norms that correct for performance-based (e.g., reading) estimates of premorbid cognition in addition to the traditional demographic factors.

Evolving clinical phenotypes in HIV-associated neurocognitive disorders

“…Dramatic downward shifts in the incidence of HAD were evident, although increased longevity led to an overall increased prevalence of this more severe form of HAND (8). Recently published results on cohorts continue to find increased neurocognitive impairment prevalence rates in those on cART and suppressed systemic viral load as previously found in 2007 (9),(10). In the CHARTER baseline study (11), approximately 30% continue to have neurocognitive impairment in those who were suppressed with CD4+ counts > 200, and without substantial comorbidities.…”

Validation of the International HIV Dementia Scale as a Screening Tool for HIV-Associated Neurocognitive Disorders in a German-Speaking HIV Outpatient Clinic

“…Several reasons explain this fluctuation: Population differences existing between the different study groups -age, gender, educational level, comorbidities and viral control- play a determinant role [9]. In other cases, the wide use of standardised norms in populations being falsely considered equal has brought upon misclassification of patients, thereby altering the proportions of affected individuals and the global prevalence in the cohort, as a study by Cysique et al shows, comparing US and Australian populations [40]. This supports the idea of developing local normative standards for tests and screenings that apply to specific linguistic, social and cultural groups of people.…”

Cognitive change trajectories in virally suppressed HIV-infected individuals indicate high prevalence of disease activity

“…Details on methods and the sample characteristics used to develop local norms have been published [21]. The standard Global Deficit Score (GDS) method [27,28] was used to classify impairment.…”