E-Mail WASHINGTON (Feb. 22, 2021) --- People living with the human immunodeficiency virus (HIV) who have a history of severe immunosuppression and at least one copy of the Alzheimer's disease-related gene variant APOE4, might see a compounded adverse effect on the circuitry that impacts memory. This could eventually lead to an increased risk for dementia after age 65, according to Georgetown University Medical Center investigators and colleagues. The researchers used MRI scans to examine the brain, with a focus on two regions - the hippocampus, which is critical for memory and is often affected in Alzheimer's disease, and the caudate nucleus, which sits deep in the center of the brain and is often affected in people with HIV. Based on the MRI images, they found that connectivity between the two regions was affected by APOE4 in people with HIV. A history of severe immunosuppression further exacerbated the impact of APOE4.