Metabolic alterations of the lenticular nuclei in acute and euthymic patients with bipolar disorder: a proton magnetic resonance spectroscopy study

Abstract

Objective To identify the possible alteration of brain functioning metabolism levels of the lenticular nuclei in basal ganglia in patients with bipolar depressive episode and euthymic state using proton magnetic resonance spectroscopy (1H-MRS). Methods The N-acetylaspartate(NAA), choline(Cho), and creatine(Cr) of the lenticular nucleus in basal ganglia were studied in 29 bipolar disorder (BD) patients during acute depressive episode, 22 euthymic BD patients and 24 age-, sex-, and educational-matched right-handed healthy controls. The ratios of NAA/Cr and Cho/Cr were calculated. Pearson's correlation analyses were used to determine whether clinical variables correlated to the brain biochemical metabolite ratios in both acute and euthymic patients with BD. Results On the comparison of biochemical changes, both acute (1.5±0.2, 1.5±0.1) and euthymic (1.5±0.1, 1.5±0.1) BD patients showed significantly lower NAA/Cr ratios in bilateral lenticular nucleus when compared to the healthy controls (1.7±0.3, 1.7±0.2; F=5.614, P=0.005; F=7.811, P=0.001). There were no significant differences among 3 experimental groups for Cho/Cr ratiain in bilaterdl lenticular nucleus. On the comparison of correlation of brain biochemical changes and six clinical variables, there was no significant correlation between two metaboliteratios and age, duration of illness number of episodes. 24-item HAMD and YMRS scores. Conclusions These findings suggest that biochemical abnormalities in the lenticular nucleus may occur both in acute and euthymic BD patients. Metabolic decline in bilateral lenticular nucleus likely are markers of endophenotypes of BD. Key words: Bipolar disorder; Magnetic resonance spectroscopy; Putamen