AIDS dementia complex: brain high-energy phosphate metabolite deficits

To test whether compromised high-energy phosphate metabolism is implicated in the neurologic impairment of acquired immunodeficiency syndrome dementia complex (ADC), brain phosphate metabolite concentrations and ratios were measured noninvasively in 12 patients with mild to moderate ADC and 29 healthy volunteers by use of localized phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy and proton (hydrogen-1) magnetic resonance (MR) imaging. In patients, brain phosphocreatine (PCr) and nucleoside triphosphate (NTP) concentrations in sections through the centrum semiovale that were seen with NMR spectroscopy were reduced significantly from normal values of 4.92 mmol/kg wet weight +/- .13 (standard error of the mean) and 2.79 mmol/kg +/- .11, respectively, to 3.33 mmol/kg +/- .26 and 1.99 mmol/kg +/- .13 (P less than .0001). The ratios of metabolites detectable with P-31 NMR spectroscopy did not differ significantly from those of control subjects. The magnitude of the PCr and NTP deficits in ADC was not explicable by focal abnormalities or cerebral atrophy quantified in images of the same regions. These results are consistent with the hypothesis of a generalized virus-associated toxic process affecting brain cell function in ADC. Noninvasive measurement of metabolite concentrations with NMR spectroscopy provides new functional information that may help quantify disease progression and response to therapy.