title: Altered intracortical myelin staining in the dorsolateral prefrontal cortex in severe mental illness.
abstract: Imaging and postmortem studies into the severe mental illnesses of major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SZ) have revealed deficiencies in the myelination of deep white matter tracts of the brain. Recent studies have further suggested that deficits could extend to myelinated fibers running through the cortex in those illnesses. Disruptions in this intracortical myelin may underlie functional symptomology in MDD, BD, and SZ; thus, in this study, we hypothesized that individuals with these illnesses may have reduced myelin staining relative to controls in the cerebral cortex. We stained 60 sections of dorsolateral prefrontal cortex for myelin with Luxol®fast blue in four groups: 15 BD, 15 MDD, 15 SZ, and 15 controls with no psychiatric illness. We digitally measured optical tissue attenuation reflecting the amount of myelin staining across six cortical depths in the middle frontal gyrus (MFG), in superficial white matter in the crown of the MFG, and in deep white matter. We found that a diagnosis of MDD or SZ meant that optical tissue attenuation was significantly reduced in the shallowest depths of the cortex. Furthermore, there was a trend toward reduced optical tissue attenuation in all illnesses across all myelinated regions we studied. These results encourage future studies into potential reductions in intracortical myelin in severe mental illness.
authors.affiliation: Imaging Research, Sunnybrook Research Institute, Toronto, ON, Canada.
authors.forename: Evelyn M R
authors.initials: EMR
authors.lastname: Lake
authors.affiliation: Department of Psychology, Neuroscience and Behaviour, McMaster University, Psychology Complex, Room 304, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Steffler
authors.affiliation: Department of Psychology, Neuroscience and Behaviour, McMaster University, Psychology Complex, Room 304, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Rowley
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada.
authors.forename: Manpreet
authors.initials: M
authors.lastname: Sehmbi
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada.
authors.forename: Luciano
authors.initials: L
authors.lastname: Minuzzi
authors.affiliation: Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada.
authors.forename: Benicio N
authors.initials: BN
authors.lastname: Frey
authors.affiliation: Department of Psychology, Neuroscience and Behaviour, McMaster University, Psychology Complex, Room 304, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada. bockn@mcmaster.ca.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Bock
mesh_terms: D000328:Adult; D000578:Amidines / Q000378:metabolism; D001714:Bipolar Disorder / Q000473:pathology*; D003865:Major Depressive Disorder / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009186:Myelin Sheath / Q000378:metabolism / Q000473:pathology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D017397:Prefrontal Cortex / Q000473:pathology*; D012559:Schizophrenia / Q000473:pathology*
chemical_list: D000578:Amidines; C031455:diamidino compound 253-50
keywords: Bipolar disorder; Cerebral cortex; Major depressive disorder; Myelin; Schizophrenia