The purpose of the study was to identify risk factors underlying cognitive functioning among adults with HIV. Determining such correlates may be beneficial in detecting precursors to future cognitive impairments and target areas for interventions. The present study suggests that HIV chronicity, medical problems, social support network, and degree of hardiness were not predictive of cognitive performance. While SES was not uniquely predictive of performance on any measure, educational quality as measured by WRAT-3 Reading score was predictive of performance on several measures, suggesting that quality of education may have attenuated the combined effect of income and educational level. Other predictive factors were found, including age, gender, CD4+ lymphocyte cell count, HIV medication usage, mood disturbance score, and psychoactive drug use.
The individual hierarchical regression models for each measure explained 8 – 48% of the variability in cognitive performance; some of which explained a high degree of variance. Predictors of the speed of processing domain included age, WRAT-3 Reading score, and mood disturbance score. Similarly, predictors of reasoning reflected those of speed of processing, but also included CD4+ lymphocyte cell count, along with whether or not they were using HIV medication. Attention and working memory had the fewest predictors, with only the demographics of age and WRAT-3 Reading score being significant predictors. Executive functioning predictors included age, gender, WRAT-3 Reading score, and CD4+ lymphocyte cell count. Finally, psychomotor speed and visuomotor coordination measures had the largest number of predictors, which included age, gender, WRAT-3 Reading score, mood disturbance score, psychoactive drug use composite score, and whether or not they were using HIV medication.
Several factors were consistently predictive of performance across many of the cognitive domains. Age and WRAT-3 Reading score were the most consistent demographic predictors across all five cognitive domains. Of the other factors included, only CD4+ lymphocyte cell count, HIV medication usage, and mood disturbance score emerged as predictors, but were not as consistently predictive across domains. One possible explanation for this finding is the high percentage of the sample that was using HIV medication; HIV medication has been shown in previous studies to be neuroprotective (Vance & Burrage, 2006
). In addition, a majority of the sample had a CD4+ lymphocyte cell count of 200 and above. Similarly, psychoactive drug use was only predictive in one cognitive domain (psychomotor speed and visuomotor coordination). One explanation for this finding is the fact that participants were not recruited based on having a history of substance use, thus making it difficult to determine the correlation between psychoactive drug use and cognitive performance. A second explanation is that the psychoactive drug use composite measure used may not be sensitive enough to detect the contribution of psychoactive drug use on differences in cognitive performance.
Surprisingly, there was no significant relationship between HIV chronicity and cognitive performance. Vance, Woodley, and Burrage (2007)
found years living with HIV to be predictive of performance on several measures, with those being diagnosed longer exhibiting better cognitive performance, possibly as a result of a greater degree of hardiness (e.g., better coping strategies) throughout the course of the disease. Although this study did not find a positive correlation between HIV chronicity and cognitive performance, the fact that a negative correlation (longer diagnosis predictive of poorer performance) was not detected is promising because it suggests that those living longer with HIV may not necessarily be subject to cognitive decline as a function of chronicity. Instead, age and HIV severity as indicated by CD4+ lymphocyte cell count may serve as more significant predictors.
Strengths and Limitations
Several strengths may be noted about this study. First, this study is one of a few that required that participants be diagnosed for at least 1 year with HIV; this was done to control for the effect of reactive depression of being diagnosed with HIV on cognition. Second, this study used standardized and acceptable measures. Third, this study used a variety of unique psychosocial predictors (i.e., hardiness) to examine their effects on cognition.
All studies have limitations and this one is not without exception. One limitation of this study is the restricted age range of our sample. Although the range was 24 – 67 years, there was not a large portion of participants over age 65, making it difficult to examine the effect of much older age on performance. As a result, the magnitude of age as a predictor was small in comparison to other studies (Hardy & Vance, 2009
); however, with statistical findings about advancing age still being observed in this sample, this may attest to the concern that HIV may be a form of accelerated aging (Vance et al., 2009
). Another limitation is that self-report of one’s most recent CD4+ lymphocyte cell count is used. This could potentially lead to reporting bias in that those with more memory problems may not be able to recall their most recent CD4+ lymphocyte cell count. Another limitation is that a measure of medication adherence was not included; so there is no way to discern the consistent use of HIV mediation usage on cognitive performance. A final limitation is that the psychoactive drug score is based on self-report; because of the illicit nature associated with this variable, participants may have under reported psychoactive drug use based on social desirability (Polit & Beck, 2008
Implications for Nursing Practice and Research
Given their proxy to patients, nurses are in a key position to observe cognitive changes and problems in their patients with HIV. From their assessment of these changes, nurses and nurse practitioners can act promptly on the patient’s behalf to address and treat these adverse effects. This study has shown that those patients who are older, engage in psychoactive drug use, experience more negative affect, do not use HIV medications, have a lower CD4+ lymphocyte cell count, and have a poorer quality education may exhibit problems on several cognitive tests. By attenuating to health outcomes such as limiting psychoactive drug use, maintaining a steady medication schedule in order to improve CD4+ lymphocyte cell count, and reducing depression, nurses can provide interventions that cognitively benefit patients.
Vance and Burrage (2006)
posited several ways nurses can improve cognitive functioning in adults with HIV. Focusing on HIV treatment to avoid any further immunological and neurological decline is the first step. This requires educating patients about the importance of medication adherence and the perils of viral mutation on not just immunological health, but on neurological health as well. The second step is to promote general health and well-being through physical exercise, mood stabilization, good sleep hygiene, proper nutrition, and avoiding or curbing substance use. These approaches have been shown in the literature to be neuroprotective. In addition, nurses can educate patients on the possible interactions between recreational drugs, psychotropic medications, and antiretroviral medications, which may require adjustments in current dosages. Furthermore, nurses can discuss dietary restrictions which may affect drug absorption. Finally, nurses can encourage positive neuroplasticity in patients. Positive neuroplasticity refers to the brain’s ability to form new connects between neurons. Improving such connects occurs in response to challenging and novel stimuli (Vance & Burrage, 2006
). Therefore, activities that promote learning something new should be encouraged.
Nurse researchers have a unique opportunity to study cognitive aging in this clinical population. With the aging of the population and the increased lifespan of those with HIV, there will be increased opportunity to examine the complex interaction between older age and HIV on cognition. The results of this study indicate a need for studies explicitly recruiting much older adult samples whose declines may be more sensitive to cognitive measures. In addition, future studies should utilize a longitudinal design in order to examine the effects of HIV and aging over time. Likewise, studies investigating strategies to prevent or intervene in lieu of such cognitive changes with HIV should be employed. In an on-going study, Vance, Marceaux, Fazeli, McKie-Bell, and Ball (2009)
have used specially designed computer exercises, referred to as speed of processing training that is similar to gaming technology, to improve the Useful Field of View of adults with HIV. This approach is important because other studies show that declines in Useful Field of View are related to at-fault crashes and instrumental activities of daily living (Ball, Edwards, & Ross, 2007
). Other cognitive remediation techniques may also prove to be important in improving everyday functioning in adults with HIV.
Neurological insults due to HIV can produce subtle cognitive declines in patients. There is much concern that this may get worse with age. Therefore, it is important to maintain adequate CD4+ lymphocyte cell counts, which may be done through the use of HIV medications, to prevent more neurological insults. Nurses should be frank with their patients about the possibility of slow, but progressive, cognitive decline that can occur. Likewise, they should also stress the factors that may accelerate such declines, such as psychoactive drug use and poor mood.