The current study used bivariate longitudinal models to address an important gap in the literature regarding the longitudinal relationships between mental health and both substance use and sexual behavior; past literature in this area has been primarily cross-sectional. Our findings on baseline relationships were consistent with previous cross-sectional studies. Mental health symptoms were common among the PLH, similar to other researchers’ findings using cross-sectional data (Bing et al., 2001
; Lyketsos, Hanson, Fishman, McHugh, & Treisman, 1994
; McClure, Catz, Prejean, Brantley, & Jones, 1996
; Remien et al., 2006
). At baseline, 40% of PLH showed clinically significant levels of depression, and 36% had anxiety symptoms that were clinically significant. Twenty-five percent reported symptoms of both depression and anxiety. These high rates of mental health symptoms among PLH who were continuing to engage in substance use and unsafe sex highlight the need to understand how patterns of mental health symptoms relate to the transmission of HIV over time, to the uninfected population.
We did not find strong evidence that the relationship between mental health symptoms and HIV-transmission risk acts varied by intervention condition. Some findings were significant in one intervention condition but not the other. However, we did not find consistent patterns as to how PLH may have differed across intervention conditions in their relationships between mental health symptoms and HIV-transmission risk acts. Furthermore, we did not find any instances where significant relationships were in opposite directions across intervention conditions.
Relationships we found between elevated levels of mental health symptoms and substance use at baseline and from assessment to assessment corroborated findings from previous cross-sectional studies (Bing et al., 2001
; Chander, Himelhoch, & Moore, 2006
; Lightfoot et al., 2005
; Rotheram-Borus et al., 1999
). Longitudinal findings on the relationship between an increasing positive state of mind and decreasing alcohol / marijuana use over time was a natural extension of findings from cross-sectional studies.
Elevated levels of mental health symptoms at baseline were related to decreasing substance use over time; relationships between baseline levels of substance use and mental health time trends were not found. These findings suggest that mental symptoms precede a decrease in substance use and are counterintuitive and inconsistent with theories about using drugs to self-medicate for symptoms of depression or anxiety, e.g. the Tension-Reduction theory. A possible explanation follows, at least for findings related to alcohol / marijuana use. Among hard drug users, limiting substance use to alcohol and marijuana is often perceived as a significant reduction in risk (Luna, 1997
). Perhaps alcohol and marijuana are seen as less harmful drugs in our cohort of PLH, over half of whom reported using hard drugs at baseline. Alcohol and marijuana may be used more recreationally rather than as an escape or coping resource; an improved mood may lead to increasing use over time. Another possible explanation is a ceiling effect. PLH with lower levels of mental health symptoms at baseline may develop mental health symptoms and increase substance use over the course of the study, whereas PLH with elevated mental health symptoms at baseline may be more likely to decrease or maintain the same level of mental health symptoms and substance use over time. In order to test for ceiling effects, we conducted post-hoc comparisons in which PLH in the entire sample were split into two groups based off the clinical threshold at baseline. Among PLH above and below the clinical cutoff for depressive symptoms, relationships between baseline levels of depressive symptoms and substance use time trends remained in the same direction compared to relationships in the entire sample; relationships tended to lose significance in the depressed and nondepressed subsamples. We were unable to fit models to subsamples of PLH with and without clinically relevant anxiety symptoms. Post-hoc comparisons were inconclusive as to whether or not a ceiling effect was present.
Relationships between mental health symptoms and risky sexual behavior reflected cross-sectional findings in the literature where significant results were found (Kalichman, 2000
). Relationships between elevated levels of mental health symptoms and elevated risky sexual behavior were found at baseline; inverse relationships that we found from assessment to assessment contradicted mainstream findings, though these relationships were quite small.
Relationships that emerged between mental health symptoms and sexual behavior occurred in tandem, as significant relationships between baseline and time trends were lacking. Both increasing PSOM scores in the intervention condition and increasing depressive symptoms in the lagged condition were related to decreasing numbers of HIV negative sexual partners over time. These findings are consistent with cross-sectional studies that have found both positive and negative moods to be associated with risky sexual behavior (Kalichman, 2000
). For example, PLH may experience positive moods at the time of unsafe sex and experience regret and negative moods later. A limitation in exploring sexual behavior in our study is that we used measures that were assessed from the perspective of the PLH and aggregated partner-level information. However, sexual risk always emerges in a partnership: the patterns of risk within a partnership get established early and are typically maintained over time. There are really qualitatively different types of sexual relationships: some PLH engage with a relatively small number of partners and within each partnership these patterns of risk are stable over time. Those with more partners do not establish stable patterns within the partnership, especially when there is only one encounter. In these types of sexual partnerships, risk is reflective of the type of relationship, rather than the mental health status of the PLH.
In addition to the assessment of partner-level behavior, future research may also benefit by including measures of psychiatric diagnoses or measures to cover a greater number of symptom clusters. For example, it would have been desirable to assess mania and transmission-related acts over time. It would have also been desirable to have biological markers of substance use and sexual risk. We did examine rates of sexually transmitted diseases among the sample at the baseline interview, but the rate was far too low (2–3%) to allow us to use biological markers of STD as indications of transmission risk.
It is important to recognize the subpopulation of PLH the current study represents. Despite high follow-up rates, one potentially important selection effect may be the loss of PLH exhibiting more depressive symptoms after the baseline assessment. There may have been relationships between depressive symptoms and transmission acts that were attenuated in the sample we retained over time.
Our sample is representative of the subpopulation of PLH who continue to engage in sexual risk acts after learning they are HIV positive, approximately 34% to 50% of PLH (Crepaz and Marks, 2002
). We recruited PLH engaging in sexual behaviors that could transmit HIV to HIV-negative sex partners because the behavioral intervention targeted risky sexual behavior. Though this is not a representative sample of the population of PLH, the demographic profile of the sample matches the profile of PLH in the statistics of the Centers for Disease Control and Prevention (2007)
. The sample is predominantly of ethnic minority heritage and has substantial numbers of women, MSM, and heterosexual males, both injecting drug users and those likely to have acquired HIV through sexual transmission. Furthermore, PLH seeking HIV prevention services who continue to practice unprotected sex are the subpopulation of PLH where cross-sectional relationships between negative emotions and sexual risk have emerged (Kalichman, 2000
); we expect longitudinal relationships between mental health symptoms and HIV-transmission risk behaviors to be at least as pronounced if not more so in this subpopulation.
Given these limitations, our findings provide a first step in disentangling the complex temporal relationship between mental health and HIV-transmission risk. More longitudinal studies are needed, especially longitudinal studies designed to facilitate mediational analyses. The challenge remains to establish causality and identify common factors of mental health and HIV-transmission risk. New data capture methods are also needed. Longitudinal studies, including ours, are wedded to retrospective reports. The assessment of moods can be confounded by even a short window of time, e.g. PLH may experience positive moods prior to substance use and negative moods afterwards. Daily diaries are a step in the right direction by providing more frequent assessments compared to retrospective reports, and in turn, less recall bias. A few studies have used daily diaries to assess mental health and substance use with limited success. See for example, Tournier et al. (2003)
. However, diaries still rely on pen and paper as the data capture tool and may be perceived as both inconvenient and intrusive by a study participant. Emerging technologies, e.g. smart mobile phones, enable real-time data capture through devices that participants are already using in their daily lives. Future longitudinal studies employing both improved analytic tools and data capture methods will provide a stronger basis to establish causality between mental health and HIV-transmission risk.