A large proportion of antiretroviral-treated HIV patients exhibit imminent neuronal damage, which is revealed through cerebral FDG-PET scanning abnormalities and elevated TNF alpha and IL-6 levels, according to a study published in Feb. 14 in the Journal of Neuroinflammation.

The study population consisted of 1,300 HIV-positive patients known to be infected for more than five years and on antiretroviral (ARV) treatment for a minimum of three years with no history of virological failure, a CD4 count above 200 × 10⁶ cells/l and no other co-morbidities.

Åse Bengård Andersen, MD, of the department of infectious diseases at University of Copenhagen in Denmark, and colleagues analyzed circulating levels of brain derived neurotrophic factor (BDNF), tumour necrosis factor (TNF) alpha, interleukin (IL) 6, and soluble urokinase plasminogen activator receptor (suPAR) by enzyme-linked immunosorbent assay. Anderson and colleagues correlated these levels with potential signs of neurodegenerative processes.

The distribution of the regional cerebral metabolic rate of glucose metabolism was measured using F18 FDG-PET scanning. The PET scans were evaluated for individual pathology using Neurostat software and for group pathology using statistical parametric mapping.

“More than half (55 percent) of the patients exhibited varying severities of mesial frontal reduction in the relative metabolic rate of glucose. Compared to healthy subjects, the patients with abnormal FDG-PET scanning results had a shorter history of known HIV infection, fewer years on antiretroviral therapy and higher levels of circulating TNF alpha and IL-6,” wrote Andersen and colleagues.

According to Andersen and colleagues, the abnormalities described by FDG-PET scanning are probably only a very early sign of suffering neurons, and overt cell damage may not necessarily have occurred.

Andersen and colleagues speculated that a substantial fraction of optimally treated HIV patients have suffered longer brain exposure to high HIV loads than those without abnormalities, which may represent imminent neuronal damage.

“The potential neuroprotective effect of early ARV treatment should be considered but further studies and prospective follow-up studies, including detailed neuropsychological testing, are needed to evaluate the clinical implications of these results,” the researchers concluded.