CTNPT 026: Neuroimaging as a biomarker for cognitive training in HAND

About The Study

This study aimed to answer three questions. Which magnetic resonance imaging (MRI) techniques:

1. are most effective at showing the difference between HIV+ people with high and low cognitive ability?
2. are most effective at predicting the response to an 8-week computerized cognitive training program? (MRI scan at the start of the program)
3. are most effective at showing the difference between those with a positive response to this program and those whose cognitive ability does not improve? (MRI scan at the end of the program)

Background

Poor brain health (cognitive impairment) is a relatively common health concern in those living with HIV. It is now clear that the impact of HIV as a chronic illness can have negative effects on cognition and mental health, even with excellent viral control.

Modern neuroimaging provides us with powerful new ways of analyzing the possible causes of cognitive and mental health changes. This could potentially allow us to predict the risk of mental decline and how effective certain strategies (like computerized cognitive training) are in improving or preserving mental function.

But neuroimaging is a fast-moving field, with new methods and strategies being developed from month to month. The possibilities this creates are exciting, but also make for some challenges: what measures are most suitable? What are some of the effects and how will we predict them? How can we minimize the cost and burden on participants while maximizing what can be learned about brain measures?

Study Approach

The neuroimaging measures were acquired in two samples taken from an on-going study of brain health in HIV (CTN 273). A total of 80 subjects were selected from those enrolled in the main cohort. Participants were enrolled in an 8-week Web-based cognitive training program focused on improving attention and executive function (mental skills helping you with getting tasks done). This intervention was offered to a randomly selected group with cognitive symptoms and evidence of lower cognitive ability during testing. Some participants began this cognitive training immediately while others began their training after a waiting period but within 8 weeks of starting the study.

To achieve the first aim of this study, another twenty subjects without cognitive complaints and with higher cognitive ability during testing were recruited from the main group of participants. All subjects had two MRI sessions, about three months apart.

Results

CTNPT 026 compared two imaging techniques to determine which was most effective at showing changes in the brain associated with cognitive ability in people living with HIV. Resting state electroencephalogram (EEG) imaging shows the brain’s electrical activity, while structural MRI shows the shape, size, and integrity of the brain. The researchers determined the EEG was more sensitive than MRI when it comes to assessing the brain changes related to cognitive ability among people living with HIV.

To better understand HIV-related changes in people with different cognitive abilities (from normal to mild cognitive impairment), CTNPT 026 assigned participants two cognitive tasks. While they completed the tasks, data about their brain activity were gathered using EEG imaging, and measured against the severity of their HIV infection, as measured by CD4 count. EEG imaging revealed that the brain responses seen while completing the tasks could be good indicators of cognitive ability in people with normal to mild cognitive impairment. The findings also indicate that the severity of HIV infection was related to brain function and subsequent cognitive ability. These results suggest that measuring brain activity via EEG while completing specific tasks could be a useful way to target or monitor treatment or rehabilitation approaches for cognitive impairment among people living with HIV.