Magnetic resonance spectroscopy in prefrontal white matter of bipolar II disorder and its relation with executive function

Abstract

Objective To explore the magnetic resonance spectroscopy characteristics of prefrontal white matter in bipolar Ⅱ disorder and its relation with executive function. Methods Thirty bipolar Ⅱ disorder patients and twenty healthy controls were evaluated with Multi-Voxel proton magnetic resonance spectroscopy(1H-MRS)scans on prefrontal white matter to assess the N-acetyl-aspartate (NAA), Choline (Cho), Creatine (Cr) and myo-inositol (MI), and then the ratios of NAA/Cr, Cho/Cr, MI/Cr, NAA/Cho and NAA/Cho+ Cr were calculated.All subjects were assessed for executive function using the Wisconsin Card Sorting Test (WCST). Results NAA/Cr in right prefrontal white matter(1.43±0.26) and NAA/Cr, NAA/Cho, NAA/Cho+ Cr in left prefrontal white matter(separately1.40±0.29, 1.13(1.53, 0.24), 0.62±0.12) were lower than healthy controls(separately 1.58±0.18, 1.59, 0.23, 1.30(0.53±0.29), 0.71±0.08)(P<0.05). The correct trials and the number of categories of WCST in Bipolar Ⅱ disorder (separately 26.97±8.97, 3(6, 3)) were less than in healthy controls(separately 36.35±4.85, 5(3, 2)), and perseverative errors and random errors were more in patients(separately 12.77±5.73, 7(21, 5)) than healthy controls(separately 7.35±3.01, 4(13, 2)). NAA/Cho and NAA/Cho+ Cr in left prefrontal white matter were positively correlated with correct trials, number of categories, and negatively related with perseverative errors(P<0.05). Conclusions Bilateral prefrontal white matter fiber damage occurs to bipolar Ⅱ disorder. And left prefrontal white matter fiber damage in bipolar Ⅱ disorder may lead to executive impairment. Key words: Bipolar Ⅱ disorder; Magnetic resonance spectroscopy; Executive function; Frontal lobe