Depending on the circumstances, missing N-acetylaspartate (NAA) in the brain may indicate Alzheimer’s disease, ischemic stroke, a brain tumor, or traumatic injury. And, as doctors soon learned with the AIDS epidemic, NAA levels drop in tandem with the neurological deterioration that further cripples people with HIV.
Yet Gilberto Gonzalez was unprepared for the precipitous fall and resurgence of this marker of neuronal injury in macaques with simian immunodeficiency virus (SIV) over the course of their AIDS-like disease, before and after they were treated with a potent antiretroviral cocktail.
“We expected a decline, but we saw a whopping decline,” said Gonzalez, Harvard Medical School professor of radiology and chief of neuroradiology at Massachusetts General Hospital. “When we treated them, we expected the decline to stabilize, but the rebound was as stunning as the decline. I’ve never seen anything like it.”
The observations suggest that neuronal injury in AIDS – and perhaps other neurodegenerative diseases – may be reversible and that treating monocytes in the blood may ameliorate or prevent the brain damage, Gonzalez and his colleagues reported in the September 2005 Journal of Clinical Investigation.