Cerebral metabolic abnormalities in COPD patients detected by localized proton magnetic resonance spectroscopy

Study objectives: To investigate changes in the cerebral metabolism of patients with COPD, using localized in vivo proton magnetic resonance spectroscopy (H-1 MRS), and to evaluate the clinical significance of cerebral metabolic abnormalities in COPD patients. Patients and methods: Seventeen symptomatic COPD patients and 21 age-matched healthy volunteers participated in this study. All subjects underwent H-1 MRS, and neuropsychological tests (Wechsler memory scale-revised [WMS-R], color trail test, and grooved pegboard test) were performed by COPD patients. Magnetic resonance spectra were obtained from localized regions of parietal white matter (PWM) and occipital gray matter (OGM). Absolute levels of N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), and myo-inositol (ml) were calculated. Results: In COPD patients, the mean (+/- SD) FEV1 was 38 +/- 10% predicted, the PaCo2 was 39 +/-7 mm Hg, and the Pao(2) was 89 +/- 18 mm Hg, and these values did not exhibit statistical correlation with the levels of cerebral metabolites. NAA, Cr, and Cho levels in PWM were all significantly lower in COPD patients than in control subjects (p<0.0125 [Bonferroni adjusted]). Neuropsychological parameters were lower in COPD patients compared with standardized values. However, they were not correlated with the levels of cerebral metabolites except for a positive correlation between the Cho level in PWM and the general memory quotient of WMS-R (r=0.52; p<0.05). Conclusions: Our results demonstrate that the cerebral metabolism is significantly altered in symptomatic COPD patients. The relationship between decreased Cho levels and memory dysfunction, and the clinical significance of other cerebral metabolic changes in COPD patients need to be further investigated.