A new research found low levels of the protein amyloid beta in the spinal fluid as common in both, the people with HIV-related cognitive deficits and Alzheimer's-related dementia.
The findings may be able to help doctors distinguish patients with HIV-related memory loss and those with early Alzheimer's.
Many HIV patients experience memory problems as they get older, but the reasons why are not well understood.
Study's lead author David Clifford of Washington and colleagues tpo ook at the spinal fluid of 49 HIV patients with cognitive impairments, 21 HIV patients with normal cognitive function, 68 patients with mild Alzheimer's and 50 normal, healthy "controls."
The Alzheimer's patients were older (average age 74) than the controls (average age 50), impaired HIV patients (average age 48) and cognitively normal HIV patients (average age 43).
They tested the spinal fluid for the presence of amyloid beta - the protein that folds and accumulates in the brains of Alzheimer's patients and is thought to play a key role in driving the brain damage that characterizes the disease.
They also looked at other biomarkers associated with Alzheimer's, including tau, a protein found in tangled nerve fibers in Alzheimer's patients.
When amyloid beta accumulates in the brains of Alzheimer's patients, levels decrease in the spinal fluid, and the researchers expected to find low levels of the protein in samples of the Alzheimer's patients they studied.
But they were surprised to find the same low levels in the spinal fluid of HIV patients with cognitive dysfunction. Both groups of patients had significantly lower amyloid beta levels than HIV patients without cognitive impairments and the normal controls.
The lower levels are an indicator that amyloid beta in the brain alters the normal turnover of the protein in the body.
The study appears in the journal Neurology.