HIV and hepatitis B, C co-infection and correlates of HIV infection among men who have sex with men in Rwanda, 2021: a respondent-driven sampling, cross-sectional study

BACKGROUND

Men who have sex with men (MSM) are a key population group disproportionately affected by HIV and other sexually transmitted infections (STIs) worldwide. In Rwanda, the HIV epidemic remains a significant public health concern, and understanding the burden of HIV and hepatitis B and C coinfections among MSM is crucial for designing effective prevention and control strategies. This study aims to determine the prevalence of HIV, hepatitis B, and hepatitis C infections among MSM in Rwanda and identify correlates associated with HIV infection within this population.

METHODS

We used respondent-driven sampling (RDS) to recruit participants between November and December 2021. A face-to-face, structured questionnaire was administered. Testing for HIV infection followed the national algorithm using two rapid tests: Alere Combo and STAT PAK as the first and second screening tests, respectively. Hepatitis B surface antigen (HBsAg) and anti-HCV tests were performed. All statistics were adjusted for RDS design, and a multivariable logistic regression model was constructed to identify factors associated with HIV infection.

RESULTS

The prevalence of HIV among MSM was 6·9% (95% CI: 5·5-8·6), and among HIV-positive MSM, 12·9% (95% CI: 5·5-27·3) were recently infected. The prevalence of hepatitis B and C was 4·2% (95% CI: 3·0-5·7) and 0·7% (95% CI: 0·4-1·2), respectively. HIV and hepatitis B virus coinfection was 0·5% (95% CI: 0·2-1·1), whereas HIV and hepatitis C coinfection was 0·1% (95% CI: 0·0-0·5), and no coinfection for all three viruses was observed. MSM groups with an increased risk of HIV infection included those who ever suffered violence or abuse because of having sex with other men (AOR: 3·42; 95% CI: 1·87-6·25), those who refused to answer the question asking about 'ever been paid money, goods, or services for sex' (AOR: 10·4; 95% CI: 3·30-32·84), and those not consistently using condoms (AOR: 3·15; 95% CI: 1·31-7·60).

CONCLUSION

The findings suggest more targeted prevention and treatment approaches and underscore the importance of addressing structural and behavioral factors contributing to HIV vulnerability, setting interventions to reduce violence and abuse against MSM, promoting safe and consensual sexual practices, and expanding access to HIV prevention tools such as condoms and preexposure prophylaxis (PrEP).

Primacy and recency effects in hierarchical renewal in rats

Previous studies on hierarchical resurgence produced mixed results regarding the order and magnitude of recurrence of responses trained initially (primacy effect) or more recently (recency effect). Although changes in contextual stimuli could explain such differences, in resurgence procedures contextual stimuli are not commonly presented, thus their effects on multiple operants trained sequentially remain unclear. Renewal procedures, in contrast, have been useful to determine the effects of exteroceptive contextual stimuli on response recurrence. Thus, primacy and recency effects were studied using a renewal procedure in which three contexts were presented sequentially. Lever presses by rats were reinforced on a different lever under each training context and were then exposed to extinction in a different context. Presses on a fourth lever were never reinforced. During renewal testing, the three training contexts were presented in the same or inverse order relative to training. A strong primacy effect was found in rats exposed to the original training order. Both primacy and recency effects were found when the rats were exposed to contexts in inverse order. These results suggest that the magnitude of renewal of hierarchically trained responses is affected by training order and order of presentation of contextual stimuli during testing.

Less motor (re-)planning requires fewer working memory resources

In the current study, we asked if less motor re-planning requires fewer resources in working memory (WM). To this end, participants executed a spatial WM task in parallel to different sequential motor tasks: (1) a randomised task with a high amount of motor re-planning and (2) an ordered task with a lower amount of motor re-planning. Recall performance in the spatial WM task was measured as the dependent variable. Hand posture was used to calculate the percentage of motor re-planning and, thus, to validate the experimental manipulation. The percentage of motor re-planning was lower in the ordered task, while spatial WM performance was higher. This indicates that WM resources depleted by the motor task scale with the amount of motor re-planning. Results further showed a significant recency effect (i.e. better recall of late items) in the spatial WM task. As previous studies found that recency effects in a verbal WM task are disrupted by a concurrent motor task, the presence of recency in the current study indicates a differential interference of a concurrent motor task on verbal vs. spatial recall, which has important implications for several current models of WM.

Counterfactual thinking and recency effects in causal judgment

People tend to judge more recent events, relative to earlier ones, as the cause of some particular outcome. For instance, people are more inclined to judge that the last basket, rather than the first, caused the team to win the basketball game. This recency effect, however, reverses in cases of overdetermination: people judge that earlier events, rather than more recent ones, caused the outcome when the event is individually sufficient but not individually necessary for the outcome. In five experiments (N = 5507), we find evidence for the recency effect and the primacy effect for causal judgment. Traditionally, these effects have been a problem for counterfactual views of causal judgment. However, we argue that an extension of a recent counterfactual model of causal judgment explains both the recency and the primacy effect. In line with the predictions of our extended counterfactual model, we also find that, regardless of causal structure, people tend to imagine the counterfactual alternative to the more recent event rather than to the earlier one. Moreover, manipulating this tendency affects causal judgments in the ways predicted by this extended model: asking participants to imagine the counterfactual alternative to the earlier event weakens the interaction between recency and causal structure, and asking participants to imagine the counterfactual alternative to the more recent event strengthens the interaction between recency and causal structure. We discuss these results in relation to work on counterfactual thinking, causal modeling, and late-preemption.

Predicting Early Mild Cognitive Impairment With Free Recall: The Primacy of Primacy

OBJECTIVES

Serial position effects have been found to discriminate between normal and pathological aging, and to predict conversion from Mild Cognitive Impairment (MCI) to Alzheimer's disease (AD). Different scoring methods have been used to estimate the accuracy of these predictions. In the current study, we investigated delayed primacy as predictor of progression to early MCI over established diagnostic memory methods. We also compared three serial position methods (regional, standard and delayed scores) to determine which measure is the most sensitive in differentiating between individuals who develop early MCI from a baseline of cognitively intact older adults.

METHOD

Data were analyzed with binary logistic regression and with receiver-operating characteristic (ROC). Baseline serial position scores were collected using the Rey's Auditory Verbal Learning Test and used to predict conversion to early MCI. The diagnosis of early MCI was obtained through statistical algorithm and consequent consensus conference. One hundred and ninety-one participants were included in the analyses. All participants were aged 60 or above and cognitively intact at baseline.

RESULTS

The binary logistic regression showed that delayed primacy was the only predictor of conversion to early MCI, when compared to total and delayed recall. ROC curves showed that delayed primacy was still the most sensitive predictor of progression to early MCI when compared to other serial position measures.

CONCLUSIONS

These findings are consistent with previous studies and support the hypothesis that delayed primacy may be a useful cognitive marker of early detection of neurodegeneration.

Characteristics of Persons Who Inject Drugs with Recent HIV Infection in the United States: National HIV Behavioral Surveillance, 2012

We evaluated characteristics associated with recent HIV infection among persons who inject drugs (PWID) from 19 U.S. cities who participated in 2012 National HIV Behavioral Surveillance. Recent infection was defined as having a reactive HIV test, a Bio-Rad Avidity index cutoff ≤ 30%, no reported HIV diagnosis ≥ 12 months before interview, and no evidence of viral suppression. Of 8667 PWID, 50 (0.6%) were recently HIV infected. Having a greater number of sex partners (≥ 2 partners vs. 0) [prevalence ratio (PR) 4.7, 95% confidence interval (CI) 1.3-17.8], injecting heroin and other drugs (PR 3.0, 95% CI 1.3-6.6) or exclusively non-heroin drugs (PR 5.9, 95% CI 1.7-20.7) compared to injecting only heroin, and having male-male sex in the past year (PR 7.1, 95% CI 3.0-16.6) were associated with recent infection. Promoting not only safe injection practices but also safe sex practices will be key to preventing new HIV infections.

Recency memory effects in Macaques during sequential delayed match-to-sample task with visual noise

Visual object recognition requires both visual sensory information and memory, and its mechanisms are often studied using old-world monkeys. Wittig et al. (2014, 2016) reported that Rhesus monkeys and humans seem to adopt different strategies in a short-term visual memory task. The Rhesus monkeys seemed to rely on recency of stimulus repetition, whereas humans relied on specific memorization. We conducted experiments using a sequential delayed match-to-sample task with random dot visual noise using Rhesus and Japanese monkeys and found that recency effect was observed in both species. There were differences in the noise effect on behavioral performances across species.

Individual differences in children's comprehension of temporal relations: Dissociable contributions of working memory capacity and working memory updating

In two experiments, we examined 9- to 12-year-old children's comprehension and processing of two-clause sentences with a temporal connective (before or after) in the sentence-medial or sentence-initial position. We obtained measures of individual differences in working memory (WM) capacity and WM updating to test their contributions to comprehension. We measured the accuracy of children's responses to the questions "What happened first?" (Experiment 1; N = 74) and "What happened last?" (Experiment 2; N = 50) as well as their sentence reading times. Together, these experiments show continued development of comprehension of temporal relations in children in upper elementary school and suggest that children's comprehension difficulties (i.e., more comprehension errors and longer reading times) were influenced by clause salience and recency effects rather than sentence chronology or the familiarity of the connective. Our findings are consistent with a memory resource-limited account and suggest that individual differences in WM updating and WM capacity make dissociable contributions to processing and comprehension of sentences with temporal order information.

Discrimination between recent and non-recent HIV infections using routine diagnostic serological assays

The suitability of routine diagnostic HIV assays to accurately discriminate between recent and non-recent HIV infections has not been fully investigated. The aim of this study was to compare an established HIV recency assay, the Sedia limiting antigen HIV avidity assay (LAg), with the diagnostic assays; Abbott ARCHITECT HIV Ag/Ab Combo and INNO-LIA HIV line assays. Samples from all new HIV diagnoses in Ireland from January to December 2016 (n = 455) were tested. An extended logistic regression model, the Spiegelhalter-Knill-Jones method, was utilised to establish a scoring system to predict recency of HIV infection. As proof of concept, 50 well-characterised samples were obtained from the CEPHIA repository whose stage of infection was blinded to the authors, which were tested and analysed. The proportion of samples that were determined as recent was 18.1% for LAg, 6.4% with the ARCHITECT, and 14.5% in the INNO-LIA assay. There was a significant correlation between the ARCHITECT S/CO values and the LAg results, r = 0.717, p < 0.001. ROC analysis revealed that an ARCHITECT S/CO < 250 had a sensitivity and specificity of 90.32% and 89.83%, respectively. Combining the Abbott ARCHITECT HIV Ag/Ab Combo assay and INNO-LIA HIV assays resulted in an observed risk of being recent of 100%. Analysis of the CEPHIA samples revealed a strong agreement between the LAg assay and the combination of routine assays (κ = 0.908, p < 0.001). Our findings provide evidence that assays routinely employed to diagnose and confirm HIV infection may be utilised to determine the recency of HIV infection.

Two distinct mechanisms of selection in working memory: Additive last-item and retro-cue benefits

In working memory research, individual items are sometimes said to be in the "focus of attention". According to one view, this occurs for the last item in a sequentially presented list (last-item benefit). According to a second view, this occurs when items are externally cued during the retention interval (retro-cue benefit). We investigated both phenomena at the same time to determine whether both result from the same cognitive mechanisms. If that were the case, retro-cue benefits should be reduced when the retro-cue is directed to the item that already benefits from being presented last. We measured speed-accuracy-tradeoff functions with the response-deadline paradigm to measure retrieval dynamics in a short-term recognition task. Across three experiments, we found that retro-cues benefited the last item and other items to the same extent. The additivity of the last-item benefit and the retro-cue benefit points towards the co-existence of at least two distinct forms of attentional prioritization in working memory.

Frontotemporal function]al connectivity and executive functions contribute to episodic memory performance

The contributions of hemispheric-specific electrophysiology (electroencephalogram or EEG) and independent executive functions (inhibitory control, working memory, cognitive flexibility) to episodic memory performance were examined using abstract paintings. Right hemisphere frontotemporal functional connectivity during encoding and retrieval, measured via EEG alpha coherence, statistically predicted performance on recency but not recognition judgments for the abstract paintings. Theta coherence, however, did not predict performance. Likewise, cognitive flexibility statistically predicted performance on recency judgments, but not recognition. These findings suggest that recognition and recency operate via separate electrophysiological and executive mechanisms.

Serial-position effects on a free-recall task in bilinguals

In this study, we examined mechanisms that underlie free-recall performance in bilinguals' first language (L1) and second language (L2) through the prism of serial-position effects. On free-recall tasks, a typical pattern of performance follows a U-shaped serial-position curve, where items from the beginning of the list (the primacy effect) and items from the end of the list (the recency effect) are recalled with higher accuracy than items from the middle of the list. The present study contrasted serial-position effects on the free-recall task in Korean-English bilinguals' L1 vs. L2 and examined the relationship between an independent working memory (WM) measure and serial-position effects in bilinguals' two languages. Results revealed stronger pre-recency (primacy and middle) effects in L1 than in L2, but similar recency effects in the two languages. A close association was observed between WM and recall performance in the pre-recency region in the L1 but not in the L2. Together, these findings suggest that linguistic knowledge constrains free-recall performance in bilinguals, but only in the pre-recency region.