phosphocreatine and Dementia

It is unclear whether alterations in cerebral pH underlie Alzheimer's disease (AD) and other dementias. We performed proton spectroscopy after oral administration of histidine in healthy young and elderly persons and in patients with mild cognitive impairment and dementia (total N = 147). We measured cerebral tissue pH and ratios of common brain metabolites in relation to phosphocreatine and creatine (Cr) in spectra acquired from the hippocampus, the white matter (WM) of the centrum semiovale, and the cerebellum. Hippocampal pH was inversely associated with age in healthy participants but did not differ between patients and controls. WM pH was low in AD and, to a lesser extent, mild cognitive impairment but not in frontotemporal dementia spectrum disorders and pure vascular dementia. Furthermore, WM pH provided incremental diagnostic value in addition to N-acetylaspartate to Cr ratio. Our study suggests that in vivo assessment of pH may be a useful marker for the differentiation between AD and other types of dementia.

Topics: Adult; Aged; Aged, 80 and over; Aging; Alzheimer Disease; Brain; Cognitive Dysfunction; Creatine; Dementia; Female; Hippocampus; Histidine; Humans; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Male; Middle Aged; Phosphocreatine; Young Adult

To determine whether the proton spectra from patients with clinically diagnosed Parkinson disease differ from the spectra of age-matched healthy subjects with respect to the major cerebral metabolite resonances as well as lactate.. Fourteen patients with Parkinson disease (38 to 81 years of age) and 13 healthy control subjects (37 to 81 years of age) were studied using image-guided, single-voxel (27-cm3 volume) proton MR spectroscopy of the occipital lobe.. The peak area ratios of N-acetyl aspartate to creatine and N-acetyl aspartate to choline for Parkinson patients did not show a statistically significant difference from the corresponding ratios for control subjects. There was a very significant increase in the ratio of lactate to N-acetyl aspartate for patients with Parkinson disease, with the greatest increase (threefold) manifested by the subgroup (n = 4) with dementia. The difference in N-acetyl aspartate to choline between women (n = 7) with Parkinson disease and healthy women (n = 9) approached significance. No dependence of the peak ratios on age, duration of Parkinson disease, or medication (L-dopa) regimen was found.. Preliminary results indicating an increase in cerebral lactate in patients with Parkinson disease support the hypothesis that Parkinson disease is a systemic disorder characterized by an impairment of oxidative energy metabolism. The larger increases for Parkinson patients with dementia may be diagnostically useful in assessing clinical course and in differentiating Parkinson disease from other causes of dementia. Additional studies are needed, though, to quantitate lactate changes and identify potential contributions from lipid resonances better.

Topics: Adult; Aged; Aged, 80 and over; Aspartic Acid; Brain; Choline; Creatine; Dementia; Energy Metabolism; Female; Humans; Lactates; Levodopa; Magnetic Resonance Spectroscopy; Male; Middle Aged; Occipital Lobe; Oxidation-Reduction; Parkinson Disease; Phosphocreatine; Protons