This study investigates the neuronal features associated with of cognitive ability in middle-aged and older men with well-controlled HIV infection. The study used high-density EEG during a cognitive task and structural MRI to examine the relationships between task-evoked EEG responses, cognitive ability, and HIV severity. The results showed that EEG activity was associated with cognitive ability at later stages of both tasks, and only the oddball task was reliably associated with HIV severity. The study also found that thalamus volume correlated with oddball task EEG activity, while globus pallidus volume was related to EEG activity in both tasks. These findings suggest potential brain mechanisms and biomarkers for individual differences in cognition in HIV.
This study used converging methods to examine the neural substrates of cognitive ability in middle-aged and older men with well-controlled HIV infection.
Seventy-six HIV+ men on antiretroviral treatment completed an auditory oddball task and an inhibitory control (Simon) task while time-locked high-density EEG was acquired; 66 had usable EEG data from one or both tasks; structural MRI was available for 43. We investigated relationships between task-evoked EEG responses, cognitive ability and immunocompromise. We also explored the structural correlates of these EEG markers in the sub-sample with complete EEG and MRI data (N = 27).
EEG activity was associated with cognitive ability at later (P300) but not earlier stages of both tasks. Only the oddball task P300 was reliably associated with HIV severity (nadir CD4). Source localization confirmed that the tasks engaged partially distinct circuits. Thalamus volume correlated with oddball task P300 amplitude, while globus pallidus volume was related to the P300 in both tasks.
This is the first study to use task-evoked EEG to identify neural correlates of individual differences in cognition in men living with well-controlled HIV infection, and to explore the structural basis of the EEG markers. We found that EEG responses evoked by the oddball task are more reliably related to cognitive performance than those evoked by the Simon task. We also provide preliminary evidence for a subcortical contribution to the effects of HIV infection severity on P300 amplitudes. These results suggest brain mechanisms and candidate biomarkers for individual differences in cognition in HIV.