John de Wit

Sexual risk behaviour relates to the virological and immunological improvements during highly active antiretroviral therapy in HIV-1 infection

ObjectivesTo evaluate the effect of highly active antiretroviral therapy (HAART) on the sexual behaviour of homosexual men, we conducted (i) an ecological study of time trends in sexual behaviour and sexually transmitted diseases; (ii) a HAART-effect study focused on the practice of unprotected anogenital sex. DesignSubjects were participants in the ongoing Amsterdam Cohort Studies (ACS) among homosexual men, initiated in 1984. Data for (i) represented all ACS visits by HIV-1-positive and -negative participants who entered ACS at or below 30 years of age and were followed until 35 years (n = 1062). Data for (ii) represented all ACS visits of HIV-1-positive men from 1992 to 2000 (n = 365), of whom 84 were HAART recipients with at least 2 months of behavioural follow-up. Results(i) After HAART became generally available in July 1996, unprotected sex was practised more frequently and the incidence of gonorrhoea was higher compared to March 1992–June 1996 among HIV-1-negative and -positive men, respectively. (ii) Among HIV-1-positive men, a higher level of unprotected sex with casual partners was observed after HIV-1 RNA became undetectable and CD4 cell counts increased with the use of HAART. Notably, in individuals who did not receive HAART, high HIV-1-RNA levels (above 105 copies/ml) were likewise related to unprotected sex with casual partners. ConclusionData support the need for the reinforcement of safe sex prevention messages among HIV-1-negative men, and our data also provide a lead for redirecting and tailoring current prevention strategies to the needs of HIV-1-positive men.

The Impact of Vulnerability to and Severity of a Health Risk on Processing and Acceptance of Fear-Arousing Communications: A Meta-Analysis

This meta-analysis of studies of the persuasive impact of fear appeals evaluated the contribution of our stage model of the processing of fear-arousing communications relative to other fear appeal theories. In contrast to other theories, our stage model (a) specifies the cognitive processes underlying persuasion through fear-arousing communications, (b) proposes that threat-induced defensive processing does not interfere with the effectiveness of fear-arousing communications but actually contributes to it, and (c) predicts that vulnerability and severity manipulations have differential effects on measures of attitude as compared with intention and behavior. To evaluate these predictions, the authors expanded on previous meta-analyses by assessing the independent as well as joint effects of vulnerability to and severity of a risk, both on information processing and on measures of persuasion (attitude, intention, behavior). Overall, findings were consistent with the stage model. The theoretical and practical implications of these findings are discussed.

Assessing sexual risk behaviour of young gay men in primary relationships: the incorporation of negotiated safety and negotiated safety compliance

ObjectivesTo establish the actual rate of risky unprotected anal intercourse (UAI) among young gay men in steady relationships by correcting for negotiated safety (NS) and NS compliance. In addition, to examine whether the rate of UAI with steady partners, after correction for NS and NS compliance, is higher than the rate of UAI during sexual contacts with casual partners. MethodsA total of 435 young gay men completed questionnaires regarding relationship status, HIV status, NS agreements, and sexual behaviour with steady and casual partners in the preceding 6 months. ResultsTwelve per cent of the participants in a relationship practised NS. The non-compliance rate with NS agreements reached 10%. The rate of UAI with steady partners stood at 54%. After correction for NS and NS compliance, the actual risky UAI rate with steady partners dropped to 39%. Chi square tests showed that even after correction for NS and NS compliance, the rates of UAI with steady partners remained significantly higher than the rates of UAI with casual partners. ConclusionIt is imperative to correct the rates of UAI with steady partners for NS and NS compliance in order to estimate accurately the rates of risky UAI. The higher rates of risky UAI found with steady partners, even after correcting for NS, support the assumption that steady relationships provide a context that facilitates sexual risk-taking behaviour. We should therefore specifically target primary relationships as a source of risk for HIV transmission, and take into consideration non-compliance with NS agreements.

Finding the Critical Cue: Implementation Intentions to Change One's Diet Work Best When Tailored to Personally Relevant Reasons for Unhealthy Eating

Implementation intentions promote acting on ones good intentions. But does specifying where and when to act also suffice when goals involve complex change that requires not merely initiating a behavior but rather substituting a habit with a new response? In a pilot study and two experiments, the authors investigated the efficacy of implementation intentions to replace unhealthy snacks with healthy snacks by linking different types of cues for unhealthy snacking (if-part) to healthy snacking (then-part). The pilot study identified cues for unhealthy snacking, differentiating between situational (where/when) and motivational (why) cues. Studies 1 and 2 tested the efficacy of implementation intentions that specified either situational or motivational cues in altering snacking habits. Results showed that implementation intentions specifying motivational cues decreased unhealthy snack consumption whereas the classic specification of where and when did not. Extending previous research, for complex behavior change “why” seems more important than “where and when.”

Self-Regulation in Health Behavior

Self-regulation in health behavior , Self-regulation in health behavior , کتابخانه دیجیتال جندی شاپور اهواز

The contribution of steady and casual partnerships to the incidence of HIV infection among homosexual men in Amsterdam

Objective: To assess the relative contribution of steady and casual partnerships to the incidence of HIV infection among homosexual men in Amsterdam, and to determine the effect of increasing sexually risky behaviours among both types of partners in the era of highly active antiretroviral therapy (HAART). Methods: A mathematical model was developed for the spread of HIV infection among young homosexual men in Amsterdam after the introduction of HAART. The model describes the formation of both steady and casual partnerships. Behavioural parameters were estimated separately for steady and casual partners from the Amsterdam Cohort Study among young homosexual men. HIV incidence and the fraction of new infections attributed to casual contacts were calculated from the model, allowing for uncertainty in the increases in risky behaviour, the effect of HAART, and levels of HIV testing and HAART administration. Results: Currently, 86% (range 74–90%) of new HIV infections occur within steady partnerships. A reduction of 75–99% in infectivity caused by HAART will be counterbalanced by increases of 50% (range 30–80%) in risky behaviour with steady partners, but not by increases of up to 100% with casual partners. If HIV testing is increased from 42 to 80% and HAART administration from 70 to 85%, then even an increase of 100% in risk-taking with steady partners will not outweigh the effect of HAART. Conclusion: Most new HIV infections among homosexual men in Amsterdam occur within steady relationships. Prevention measures should address risky behaviour, specifically with steady partners, and the promotion of HIV testing.

The Impact of Fear Appeals on Processing and Acceptance of Action Recommendations

A stage model of processing of fear-arousing communications was tested in an experiment that examined the impact of vulnerability to a severe health risk, the quality of the arguments supporting a protective action recommendation, and the source to which the recommendation was attributed, on processing and acceptance of the recommendation. Argument quality influenced attitudes toward the recommendation (but not intention to act), and this effect was mediated by negative thoughts about the recommendation. Vulnerability influenced intention to act (but not attitudes), and this effect was mediated by perceived threat and positive thoughts about the recommendation. The pattern of findings suggests that although vulnerability to a severe health risk induces biased processing of the recommendation, biased processing is restricted to intentions and does not compromise the evaluation of the recommendation. The theoretical and practical implications of these findings are discussed.

Primary HIV infection as source of HIV transmission within steady and casual partnerships among homosexual men

Objective: To assess the contribution of primary or acute HIV infection to the transmission of HIV among homosexual men in Amsterdam and to investigate how the initiation of treatment during primary HIV infection (PHI) can affect the incidence of HIV infection. Methods: A mathematical model describing HIV transmission among homosexual men was developed. In the model, men are involved in both steady and casual partnerships. Infectivity is higher during PHI than during chronic HIV infection. Highly active antiretroviral therapy reduces infectivity and increases the time to the development of AIDS. Its effect is enhanced if treatment is initiated during PHI. HIV incidence and the fraction of transmission attributed to PHI were calculated for different levels of treatment efficacy. Results: Primary infections account for 35% of HIV transmissions from casual partners and 6% of transmissions from steady partners. Among all new infections, only 11% occurs during PHI. Therefore, the effect of treatment during PHI on the incidence of HIV is limited. However, in a community with higher risky behaviour among casual partners, the fraction of transmission attributed to PHI increases to 25%. Conclusion: Primary infections play a more important role in transmission from casual partners than in transmission from steady partners. Therefore, in communities in which steady partners account for the majority of new infections and the epidemic is at an advanced phase, the contribution of PHI to the transmission of HIV is rather small and the effect of early treatment on the incidence of HIV is limited.

Increase in the share of steady partners as a source of HIV infection: a 17-year study of seroconversion among gay men

ObjectivesTo examine the share of steady versus casual partners as the source of HIV infection in gay male seroconversions between 1984 and 2000 and the effect of age at seroconversion on the source of HIV transmission. MethodsThe sample consisted of 144 seroconverstors from the Amsterdam Cohort Study among Homosexual Men. Questionnaires and post-seroconversion interviews were used to determine the source of HIV transmission. ResultsAnalysis revealed an interaction effect between calendar year and age at seroconversion (P < 0.05). Younger seroconverters had higher odds ratios [odds ratio, 11.33; 95% confidence interval, 1.77–72.13] to be infected by their steady partner late in the AIDS epidemic: 15% (three of 20) between 1984 and 1987 versus 67% (six of nine) between 1994 and 2000. No such time effect was present for older seroconverters who were consistently more likely to be infected by a casual partner: 79% (37 of 47) between 1984 and 1987, and 83% (15 of 18) between 1994 and 2000. ConclusionsYoung gay seroconverters today are more likely to have contracted HIV from a steady partner than from a casual partner, compared with early in the AIDS epidemic and compared also with older gay seroconverters. There is a pressing need for preventive measures addressing sexual risk behaviour within steady relationships among younger gay men.

Breaking Habits With Implementation Intentions: A Test of Underlying Processes

Implementation intentions specifying the replacement of a habitual response with an alternative response in a critical situation can overrule habits. In three experiments the cognitive effects of such counterhabitual implementation intentions were investigated. Results showed that implementation intentions eliminated the cognitive advantage of the habitual means in the “horse race” with the alternative response. That is, in the control condition, the habitual means was more accessible than the alternative means on encountering the critical situation, but this was no longer the case when implementation intentions were formulated. However, the cognitive advantage of the habitual means was not immediately replaced by an automatic activation of the alternative means. This suggests that formulating counterhabitual implementation intentions increases individuals’ flexibility to choose which behavior to perform in the critical situation but that actual behavior will depart from their habits only to the extent that individuals have strong alternative goal intentions.