title: Similarities of biochemical abnormalities between major depressive disorder and bipolar depression: a proton magnetic resonance spectroscopy study.
abstract: BACKGROUND
  Depression in the context of bipolar disorder (BD) is often misdiagnosed as major depressive disorder (MDD), leading to mistreatments and poor clinical outcomes for many bipolar patients. Previous neuroimaging studies found mixed results on brain structure, and biochemical metabolism of the two disorders. To eliminate the compounding effects of medication, and aging, this study sought to investigate the brain biochemical changes of treatment-naïve, non-late-life patients with MDD and BD in white matter in prefrontal (WMP) lobe, anterior cingulate cortex (ACC) and hippocampus by using proton magnetic resonance spectroscopy ((1)H-MRS).
  
  
  METHODS
  Three groups of participants were recruited: 26 MDD patients, 20 depressed BD patients, and 13 healthy controls. The multi-voxel (1)H-MRS [repetition time (TR)=1000ms; echo-time (TE)=144ms] was used for the measurement of N-acetylaspartate(NAA), choline containg compounds (Cho), and creatine (Cr) in three brain locations: white matter in prefrontal (WMP) lobe, anterior cingulate cortex (ACC), and hippocampus. Two ratios of NAA/Cr and Cho/Cr as a measure of brain biochemical changes were compared among three experimental groups.
  
  
  RESULTS
  On the comparison of brain biochemical changes, both MDD patients and BD patients showed many similarities compared to the controls. They both had a significantly lower NAA/Cr ratio in the left WMP lobe. There were no significant differences among three experimental groups for Cho/Cr ratio in the WMP lobe, and for the ratios of NAA/Cr and Cho/Cr in the bilateral ACC and hippocampus. The only difference between MDD and BD patients existed for the NAA/Cr ratio in the right WMP lobe. While MDD patients had a significantly lower NAA/Cr ratio than controls, BD patients showed no such differences. On the comparison of correlation of medical variables and brain biochemical changes, all participants demonstrated no significant correlations.
  
  
  CONCLUSIONS
  Reduced NAA/Cr ratio at the left WMP lobe indicated the dysfunction of neuronal viability in deep white matter, in both MDD and BD patients who shared similarities of brain biochemical abnormalities, which might imply an overlap in neuropathology of depression.
authors.affiliation: Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou 510630, China.
authors.forename: Shuming
authors.initials: S
authors.lastname: Zhong
authors.affiliation: Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Science and Education, Guangdong Emergency Hospital, Guangzhou 510316, China.
authors.forename: Guoxiang
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Institute of Biomedicine, Jinan University, Guangzhou 510630, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Xiang
authors.affiliation: Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China.
authors.forename: Xueying
authors.initials: X
authors.lastname: Ling
authors.affiliation: Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China.
authors.forename: Sirun
authors.initials: S
authors.lastname: Liu
authors.affiliation: Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China. Electronic address: cjr.huangli@vip.163.com.
authors.forename: Li
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou 510630, China. Electronic address: Yanbinjia2006@163.com.
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Jia
mesh_terms: D000293:Adolescent; D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001714:Bipolar Disorder / Q000175:diagnosis / Q000378:metabolism*; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D055815:Young Adult
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline
keywords: Bipolar disorder; Magnetic resonance spectroscopy; Major depressive disorder