Little is known about the effects of aging on mood and cognitive abilities on people with HIV/AIDS. There is some basis for concern that older HIV+ people may have elevated rates of distress and disorder. Older people in general have fewer sources of social or institutional support, fewer surviving peers, and fewer family members to provide emotional and material support. For older adults who are HIV+, additional sources of strain include illness management, often-complex medication regimens, and psychosocial challenges such as the likelihood that their non-HIV+ peers may consider HIV infection more stigmatizing than do younger people. Comorbid medical conditions are more common, which themselves may be associated with depression and cognitive problems. Cognitive disorders associated with aging also may be present. These factors must be considered in light of the repeated (and counterintuitive) epidemiological finding that, in general population surveys, older people have lower rates of lifetime and current depressive disorders, substance use disorders, and anxiety disorders than do younger respondents (Kessler et al, 2005).
In this brief review, we examine the available research evidence regarding prevalence of distress and depression in older HIV+ adults. We compare these findings where possible with prevalence rates for two comparison groups: younger HIV+ adults and older HIV- adults. These groups are intended to control for the influence of age and HIV status, although we have found no large-scale studies that include both control groups.
Effects of Study Design on Rates of Disorder
Before citing rates of distress and disorder, it is important to note the many reasons why different studies have found widely discrepant findings. Inevitably, there is a trade-off between diagnostic precision and the time, cost, and staff training required to assess disorders. Smaller studies in general use much more extensive and lengthy face-to-face diagnostic procedures while large studies tend to use diagnostic "screens," which are briefer less precise and tend to overestimate distress rates. Depressive symptoms overlap with medical symptoms such as fatigue, insomnia, and weight loss; self-rating scales that include such somatic symptoms (and most do) may show misleadingly high rates of "depressive" symptoms.
Choice of respondents also influences results. For example, rates of mood disorders are much higher in substance-using samples independent of HIV status, and in samples recruited from medical clinics compared to community respondents. HIV symptom severity also may influence depression rates. Overall, the more disorders assessed, the higher the overall prevalence rate. These can contribute to the differences in reported rates of distress and disorder. With respect to substance use disorders, inclusion of cannabis (marijuana) use elevates the overall rates, as marijuana is used medicinally in HIV+ patients to enhance appetite and relieve neuropathic pain as well as being used recreationally. The more diagnoses included, the higher the rate.
Distress and Depressive Disorders
Formal diagnostic studies of the prevalence of psychiatric disorders in HIV+ samples have been conducted over the past 20 years. Earlier studies of gay men with and without HIV infection using psychiatric diagnostic interviews tended to find lower overall rates of current major depression, in the range of 5% to 10%, with few differences attributable to HIV status (Rabkin, 1996). Later studies, with larger and more heterogeneous samples including women and injection-drug users, have reported elevated rates of depressive symptoms, in the range of 30%-60%; many but not all relied on diagnostic "screens" or self-report symptom checklists (Treisman et al, 2001; Bing et al, 2001).
In summary, rates of depressive disorders and substance use disorders among HIV+ respondents may or may not be elevated compared with those of HIV- respondents from the same community (e.g. gay men, substance-using respondents), but they are clearly elevated compared to rates for the general population. The available evidence does not show increasing rates of psychopathology with declining CD4 counts, although somatic symptoms are indeed correlated with depression. It is noteworthy that most respondents with lifetime or current depressive disorders report an onset that preceded knowledge of HIV status and most likely preceded infection. Finally, we wish to emphasize that most HIV+ adults are not depressed most of the time, and many show a resiliency surprising in the face of the daunting medical and psychosocial issues they confront.
Age, Distress, and Depression
In all major population studies, rates of both depressive disorders and substance use decrease substantially by age and birth cohort. For example, in a nationally representative population study of 9,000 respondents, 12-month and lifetime prevalence rates for the youngest cohort (ages 18-29) were about double the rates of the oldest cohort (aged 60+) (Kessler et al, 2003). In another recent face-to-face survey of 43,000 adults (Hasin, 2005), current rates of major depression were 6.4% for respondents aged 18-29 and 2.7% for those over age 65; lifetime rates similarly declined from 12% to 8% in these age groups. Overall, the decline with age is dramatic, not subtle, in community samples.
Because HIV/AIDS has until recently been a disease of youth and middle age, few of the earlier prevalence studies of psychopathology included enough older HIV+ respondents to analyze their data separately, and even today, "older" is defined as "over age 49" in most HIV studies. The limited available evidence has found that while younger and older HIV+ people do show some differences regarding psychological adjustment, "more striking is the large number of similarities between the two groups" (Heckman TG et al, 2002). In two similar studies, age was not a predictor of depressive symptoms.
A recently completed survey of 914 HIV+ community residents age 50 or older used a self-report rating scale, the CES-D, to assess depressive symptoms (Karpiak & Shippy, 2006). Over 80% of respondents were nonwhite, and 45% reported a history of incarceration. In this sample, 26% of respondents reported symptoms consistent with a diagnosis of depressive disorder.
The single largest database to address the relation between age and depression in the context of HIV infection probably is the combined Veterans Aging 3 Site Study (VACS 3), with 881 HIV+ subjects, and the HIV Cost and Service Utilization Study (HCSUS), which included 2,864 HIV+ subjects (Zigmond et al, 2003). Of these, 286 in the HCSUS sample and 370 of the VACS sample were aged 50+. Elicitation of depressive symptoms was by self-report. They found that older age was associated with a lower likelihood of reporting depressed mood.
In cohort studies conducted in the 1990s of gay men with HIV/AIDS, we used the Structured Clinical Interview for DSM-IV (SCID) to diagnose major depression in 308 men, of whom 42 were aged over 50 years, and 134 HIV- men of whom 20 were over age 50 (Rabkin et al, 2004). This is the only data set we know of that included controls for both age and serostatus, and used the gold standard method of diagnosis rather than self-report rating scales. In both groups, the mean age was 55. Current major depression rates were 6% for HIV+ men under 50 and 5% for those over 50, and 6% for HIV- men under 50 and zero for those over 50. In these comparisons, older HIV-negative men had lower rates, as expected according to general population surveys, but HIV+ men over 50 did not show this decline.
Similar findings have been reported from the Veterans Aging Cohort 5-Site Study: Depressive symptoms declined with age among HIV-negative but not HIV+ veterans (Justice et al, 2004). Perhaps the available literature can be summarized by these findings: It is not that older HIV+ people have elevated rates compared to younger HIV+ people, but their rate of depression does not decline with age as it does in the general population. Future research needs to include both younger HIV+ and older HIV-negative comparison groups, with "older" being defined as at least age 60, controlling for variables including education, medication history, and HIV stage.
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