Cognitive reserve masks neurobehavioral expression of human immunodeficiency virus-associated neurological disorder in older patients

April D Thames^1,3, Jessica M Foley², Stella E Panos^1,3, Elyse J Singer¹, Suzie El-Saden^1,3, Charles H Hinkin^1,3
1University of California, Los Angeles School of Medicine, Los Angeles, CA; ²Boston VA Healthcare System/Harvard Medical School, Boston, MA; ³VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA

Background: Cognitive reserve theory may help to explain why some individuals are better able to withstand greater neurological insult before neurobehavioral manifestations occur. The present study provides a direct test of the cognitive reserve hypothesis in a sample particularly predisposed to cognitive impairment, ie, older human immunodeficiency virus (HIV)-positive adults.
Methods: Eighteen older HIV-positive adults, of mean (standard deviation) age 53.25 ± 4.2 years, with 13.5 ± 2.0 years of education, underwent magnetic resonance imaging and neuropsychological assessment. Regions of interest in the basal ganglia were extracted from T1 weighted scans and volumetric measurements were acquired. Cognitive reserve capacity was measured using premorbid intelligence quotient estimates and years of education. Participants were matched based on global neuropsychological performance.
Results: Individuals with higher levels of cognitive reserve demonstrated greater atrophy in the basal ganglia compared with individuals with lower levels of reserve, despite consistent cognitive function.
Conclusion: Older HIV-positive patients with higher levels of cognitive reserve may appear cognitively healthier than their striatal integrity would suggest.

Keywords: cognitive reserve, human immunodeficiency virus, magnetic resonance imaging, aging, basal ganglia