title: Diagnosis and body mass index effects on hippocampal volumes and neurochemistry in bipolar disorder.
abstract: We previously reported that higher body mass index (BMI) was associated with greater hippocampal glutamate+glutamine in people with bipolar disorder (BD), but not in non-BD healthy comparator subjects (HSs). In the current report, we extend these findings by examining the impact of BD diagnosis and BMI on hippocampal volumes and the concentrations of several additional neurochemicals in 57 early-stage BD patients and 31 HSs. Using 3-T magnetic resonance imaging and magnetic resonance spectroscopy, we measured bilateral hippocampal volumes and the hippocampal concentrations of four neurochemicals relevant to BD: N-acetylaspartate+N-acteylaspartylglutamate (tNAA), creatine+phosphocreatine (Cre), myoinositol (Ins) and glycerophosphocholine+phosphatidylcholine (Cho). We used multivariate factorial analysis of covariance to investigate the impact of diagnosis (patient vs HS) and BMI category (normal weight vs overweight/obese) on these variables. We found a main effect of diagnosis on hippocampal volumes, with patients having smaller hippocampi than HSs. There was no association between BMI and hippocampal volumes. We found diagnosis and BMI effects on hippocampal neurochemistry, with patients having lower Cre, Ins and Cho, and overweight/obese subjects having higher levels of these chemicals. In patient-only models that controlled for clinical and treatment variables, we detected an additional association between higher BMI and lower tNAA that was absent in HSs. To our knowledge, this was the first study to investigate the relative contributions of BD diagnosis and BMI to hippocampal volumes, and only the second to investigate their contributions to hippocampal chemistry. It provides further evidence that diagnosis and elevated BMI both impact limbic brain areas relevant to BD.
authors.affiliation: Mood Disorders Centre, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.|Department of Psychiatry, University of Minnesota Medical School, Minneapolis, MN, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Bond
authors.affiliation: Mood Disorders Centre, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.|Laboratory of Molecular Psychiatry, Centro de Pesquisas Experimentais, Hospital de Clínicas de Porto Alegre and INCT for Translational Medicine, Porto Alegre, Brazil.
authors.forename: L E
authors.initials: LE
authors.lastname: Silveira
authors.affiliation: Department of Medicine (Neurology), University of British Columbia, Vancouver, BC, Canada.
authors.forename: E L
authors.initials: EL
authors.lastname: MacMillan
authors.affiliation: Mood Disorders Centre, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.
authors.forename: I J
authors.initials: IJ
authors.lastname: Torres
authors.affiliation: Department of Radiology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: D J
authors.initials: DJ
authors.lastname: Lang
authors.affiliation: Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.
authors.forename: W
authors.initials: W
authors.lastname: Su
authors.affiliation: Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.
authors.forename: W G
authors.initials: WG
authors.lastname: Honer
authors.affiliation: Mood Disorders Centre, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.
authors.forename: R W
authors.initials: RW
authors.lastname: Lam
authors.affiliation: Mood Disorders Centre, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada.
authors.forename: L N
authors.initials: LN
authors.lastname: Yatham
mesh_terms: D000293:Adolescent; D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001714:Bipolar Disorder / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism; D015992:Body Mass Index; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D016022:Case-Control Studies; D003401:Creatine / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007294:Inositol / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009765:Obesity / Q000150:complications; D009929:Organ Size; D050177:Overweight / Q000150:complications; D010713:Phosphatidylcholines / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D055815:Young Adult
chemical_list: D004151:Dipeptides; D010713:Phosphatidylcholines; D010725:Phosphocreatine; C027172:isospaglumic acid; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine