Underlying Neural Mechanisms of Cognitive Improvement in Fronto-striatal Response Inhibition in People Living with HIV Switching Off Efavirenz: A Randomized Controlled BOLD fMRI Trial.

INTRODUCTION: It is unclear whether neurotoxicity due to the antiretroviral drug efavirenz (EFV) results in neurocognitive impairment in people living with HIV (PLWH). Previously, we found that discontinuing EFV was associated with improved processing speed and attention on neuropsychological assessment. In this imaging study, we investigate potential neural mechanisms underlying this cognitive improvement using a BOLD fMRI task assessing cortical and subcortical functioning. METHODS: Asymptomatic adult PLWH stable on emtricitabine/tenofovirdisoproxil/efavirenz were randomly (1:2) assigned to continue their regimen (n = 12) or to switch to emtricitabine/tenofovirdisoproxil/rilpivirine (n = 28). At baseline and after 12 weeks, both groups performed the Stop-Signal Anticipation Task, which tests reactive and proactive inhibition (indicative of subcortical and cortical functioning, respectively), involving executive functioning, working memory, and attention. Behavior and BOLD fMRI activation levels related to processing speed and attention Z-scores were assessed in 17 pre-defined brain regions. RESULTS: Both groups had comparable patient and clinical characteristics. Reactive inhibition behavioral responses improved for both groups on week 12, with other responses unchanged. Between-group activation did not differ significantly. For reactive inhibition, positive Pearson coefficients were observed for the change in BOLD fMRI activation levels and change in processing speed and attention Z-scores in all 17 regions in participants switched to emtricitabine/tenofovir disoproxil/rilpivirine, whereas in the control group, negative correlation coefficients were observed in 10/17 and 13/17 regions, respectively. No differential pattern was observed for proactive inhibition. CONCLUSION: Potential neural mechanisms underlying cognitive improvement after discontinuing EFV in PLWH were found in subcortical functioning, with our findings suggesting that EFV's effect on attention and processing speed is, at least partially, mediated by reactive inhibition. TRIAL REGISTRATION: Clinicaltrials.gov identifier [NCT02308332].

The Effect of Efavirenz on Reward Processing in Asymptomatic People Living with HIV: A Randomized Controlled Trial.

Functional magnetic resonance imaging (fMRI) studies have demonstrated that HIV-infection affects the fronto-striatal network. It has not been examined what impact efavirenz (EFV), an antiretroviral drug notorious for its neurocognitive effects, has on the reward system: a key subcomponent involved in depressive and apathy symptoms. Therefore, this study aims to investigate the effect of EFV on reward processing using a monetary incentive delay (MID) task. In this multicenter randomized controlled trial, asymptomatic adult participants stable on emtricitabine/tenofovirdisoproxil fumarate (FTC/TDF)/EFV were randomly assigned in a 2:1 ratio to switch to FTC/TDF/rilpivirine (RPV) (n = 30) or continue taking FTC/TDF/EFV (n = 13). At baseline and 12 weeks after therapy switch, both groups performed an MID task. Behavior and functional brain activity related to reward anticipation and reward outcome were assessed with blood-oxygen-level-dependent fMRI. Both groups were matched for age, education level, and time since HIV diagnosis and on EFV. At the behavioral level, both groups had faster response times and better response accuracy during rewarding versus nonrewarding trials, with no improvement resulting from switching FTC/TDF/EFV to FTC/TDF/RPV. No significant change in activation related to reward anticipation in the ventral striatum was found after switching therapy. Both groups had significantly higher activation levels over time, consistent with a potential learning effect. Similar activity related to reward outcome in the orbitofrontal cortex was found. Discontinuing FTC/TDF/EFV was not found to improve activity related to reward anticipation in asymptomatic people living with HIV, with similar cortical functioning during reward outcome processing. It is therefore likely that EFV does not affect motivational control. Further research is needed to determine whether EFV affects motivational control in HIV populations with different characteristics.

High efavirenz levels but not neurofilament light plasma levels are associated with poor neurocognitive functioning in asymptomatic HIV patients.

The aim of this study is to assess the effect of efavirenz exposure on neurocognitive functioning and investigate plasma neurofilament light (Nfl) as a biomarker for neurocognitive damage. Sub-analysis of the ESCAPE-study, a randomised controlled trial where virologically suppressed, cognitively asymptomatic HIV patients were randomised (2:1) to switch to rilpivirine or continue on efavirenz. At baseline and week 12, patients underwent an extensive neuropsychological assessment (NPA), and serum efavirenz concentration and plasma Nfl levels were measured. Subgroups of elevated (≥ 4.0 mg/L) and therapeutic (0.74 to< 4.0 mg/L) baseline efavirenz concentration were made. Differences between these groups in baseline NPA Z-scores and in delta scores after efavirenz discontinuation were assessed. Nfl level was measured using an ELISA analysis using single molecule array (Simoa) technology. Correlation of plasma NFL with NPA Z-scores was evaluated using a linear mixed model. The elevated group consisted of 6 patients and the therapeutic group of 48. At baseline, the elevated group showed lower composite Z-scores (median - 1.03; IQR 0.87 versus 0.27; 0.79. p 0.02). This effect was also seen on the subdomains verbal (p 0.01), executive functioning (p 0.02), attention (p < 0.01) and speed (p 0.01). In the switch group, the elevated group improved more on composite scores after discontinuing efavirenz (mean 0.58; SD 0.32 versus 0.22; 0.54, p 0.15). No association between plasma Nfl and composite Z-score was found. High efavirenz exposure is associated with worse cognitive functioning compared with patients with therapeutic concentrations. Plasma Nfl is not a suitable biomarker to measure cognitive damage in this group.

Objective and Subjective Improvement of Cognition After Discontinuing Efavirenz in Asymptomatic Patients: A Randomized Controlled Trial.

BACKGROUND: Efavirenz is well known for its clinical cognitive side effects. Even asymptomatic patients who switch for other reasons than neurocognitive complaints have reported a subjective improvement in cognitive functioning after discontinuing efavirenz. The aim of this study was to assess the effect on cognition of switching Atripla (TDF/FTC/EFV) to Eviplera (TDF/FTC/RPV), hypothesizing an improvement when discontinuing efavirenz. SETTING: A randomized controlled design with a highly comparable comparator drug was used to minimize bias and to differentiate drug versus learning effects. An extensive sensitive neuropsychological assessment (NPA) was used to detect subtle changes. METHODS: Virologically suppressed, cognitively asymptomatic male HIV-infected patients on Atripla were included and randomized (2:1) to switch to Eviplera (switch group) or continue on Atripla (control group) for 12 weeks. At baseline and week 12, patients underwent an extensive NPA. RESULTS: Fourteen control and 34 switch subjects completed the study. There were no differences at baseline. Group analysis demonstrated a significantly better improvement for the switch group on the domains attention (P = 0.041) and speed of information processing (P = 0.014). Normative comparison analyses showed that 5 of the 34 patients who switched (15%) improved on NPA score as compared to the control group. Interestingly, subjective improvement after discontinuing efavirenz made 74% of the switch group chose for a regime without efavirenz after study completion. CONCLUSIONS: Switching from Atripla to Eviplera resulted in objective cognitive improvement on the group level in cognitively asymptomatic patients. Discrepancies in objective and subjective cognitive complaints make it challenging to identify patients who would benefit from discontinuing efavirenz.

HIV and Cognitive Impairment in Clinical Practice: The Evaluation of a Stepwise Screening Protocol in Relation to Clinical Outcomes and Management.

Neurocognitive impairment (NCI) is an increasingly important comorbidity in an ageing HIV+ population. Despite the lack of available treatment modalities, screening for NCI is recommended. In the UMC Utrecht, yearly NCI screening is done using the Montreal Cognitive Assessment (MoCA) tool and the HIV Dementia Scale (HDS). The aim of this study was to evaluate this screening protocol in relation to clinical outcomes and management. A retrospective cohort study was performed in suppressed adult HIV+ patients. Apart from the MoCa and the HDS, the Utrecht Scale for Evaluation of Rehabilitation-Participation (USER-P) and the Hospital Anxiety and Depression Scale (HADS) were performed. Patients scoring below average on cognitive screening tests or with subjective cognitive complaints were further evaluated using a standardized protocol, including optimizing cART and checking for somatic disorders. In patients with cognitive complaints and participation restrictions, cognitive rehabilitation was proposed. Two hundred eighty-six patients were screened. The vast majority were MSM with an average age of 49 years. One hundred forty-four out of 286 patients (50%) had an abnormal test score and/or had subjective cognitive complaints. Restrictions in participation were present in 23% of patients. Six patients on Efavirenz switched their regimes, as this drug is known for its potential central nervous system (CNS) side effects. A depressive component was present in 58 patients (40%). Five patients had a clinical relevant laboratory abnormality. Moreover, six patients were referred for cognitive rehabilitation, which resulted in a 100% success rate in set goals in the five evaluable patients. Although the protocol was not fully adhered to in all patients, it did result in detectable underlying causes of NCI in 59% of patients, and 21% was referred for further treatment. Moreover, cognitive rehabilitation appears to be a very successful intervention for patients with NCI who experience subjective complaints and participation restrictions.