Abstract
In this study, hyperpolarized (13) C MRI (HP-(13) C MRI) was used to investigate changes in the uptake and metabolism of pyruvate with age. Hyperpolarized (13) C-pyruvate was administered to healthy aging individuals (N = 35, ages 21-77) and whole-brain spatial distributions of (13) C-lactate and (13) C-bicarbonate production were measured. Linear mixed-effects regressions were performed to compute the regional percentage change per decade, showing a significant reduction in both normalized (13) C-lactate and normalized (13) C-bicarbonate production with age: - 7% ± 2% per decade for (13) C-lactate and - 9% ± 4% per decade for (13) C-bicarbonate. Certain regions, such as the right medial precentral gyrus, showed greater rates of change while the left caudate nucleus had a flat (13) C-lactate versus age and a slightly increasing (13) C-bicarbonate versus age. The results show that both the production of lactate (visible as (13) C-lactate signal) as well as the consumption of monocarboxylates to make acetyl-CoA (visible as (13) C-bicarbonate signal) decrease with age and that the rate of change varies by brain region.