Relative glucose metabolic rate higher in white matter in patients with schizophrenia.
OBJECTIVE
There is increasing evidence demonstrating that circuits involving the frontal lobe, striatum, temporal lobe, and cerebellum are abnormal in individuals with schizophrenia, which suggests that metabolic activity in the white matter connecting these areas should be investigated.


METHODS
The authors obtained [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET) and matching T1-weighted magnetic resonance imaging (MRI) on 170 subjects. Participants were 103 normal volunteers and 67 unmedicated patients with schizophrenia (N=61) or schizoaffective disorder (N=6). The images were coregistered and warped to standard space for significance probability mapping.


RESULTS
Compared with normal volunteers, patients showed higher relative metabolic rates in the frontal white matter, corpus callosum, superior longitudinal fasciculus, and white matter core of the temporal lobe. Elevated activity in white matter was most pronounced in the center of large white matter tracts, especially the frontal parts of the brain and the internal capsule. The white matter elevation did not appear to be entirely related to changes in gray matter/white matter brain proportions, whole brain metabolic rate bias, or excess head motion in patients, but this cannot be ruled out without absolute glucose determinations. Patients also showed significantly lower relative glucose metabolism in the frontal and temporal lobes, caudate nucleus, cingulate gyrus, and mediodorsal nucleus of the thalamus relative to normal volunteers, which is consistent with earlier studies.


CONCLUSIONS
In comparisons of unmedicated schizophrenia patients with normal volunteers, relative metabolic increases are apparent in white matter in patients with schizophrenia as well as decreases in gray matter. Inefficiency in brain circuitry, defects in white matter leading to enhanced energy need, white matter damage, and alterations in axon packing density are among the possible explanations for these schizophrenia-related findings of relatively increased metabolism in white matter.
Buchsbaum
Monte S
MS
Department of Psychiatry, Radiology and Neuroscience, Mount Sinai School of Medicine, Mount Sinai Medical Center, New York, NY 10029-6574, USA. monte.buchsbaum@mssm.edu
Buchsbaum
Bradley R
BR
Hazlett
Erin A
EA
Haznedar
M Mehmet
MM
Newmark
Randall
R
Tang
Cheuk Y
CY
Hof
Patrick R
PR
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001479:Basal Ganglia / Q000000981:diagnostic imaging / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography; D011618:Psychotic Disorders / Q000175:diagnosis / Q000378:metabolism; D012559:Schizophrenia / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000378:metabolism*; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism; D014018:Tissue Distribution
D019788:Fluorodeoxyglucose F18; D005947:Glucose