Deficits in olfactory identification, despite normal odor perception,
are found in some neuropsychiatric disorders, including schizophrenia.
We examined if regional cerebral blood flow (rCBF) differed between s
chizophrenia patients and controls during odor identification, hypothe
sizing that these brain regions could be relevant to odor identificati
on impairments. Eight schizophrenia and eight comparison subjects prov
ided a baseline (picture identity matching) and activation (odor ident
ification) SPECT scan, obtained using Tc-99m-HMPAO in a low dose/high
dose design. Six patients and seven controls had analyzable data. MEDX
data saved in ANALYZE format for SPM 95 generated paired t-test stati
stical data for display in Talairach space, with rCBF changes given as
Z-scores. There was no schizophrenia vs. control group difference in
rCBF for the baseline picture-matching test. For odor identification,
schizophrenia patients had a hypometabolic right-sided cortical region
that included the frontal lobe Broca's area, superior temporal lobe,
and supramarginal and angular gyri. Post hoc within-group contrasts of
picture-matching vs. odor identification showed that the controls sig
nificantly increased rCRF in the right-sided inferior temporal fusifor
m gyrus, and bilateral hippocampi and visual association areas for the
odor test. The schizophrenia group showed no rCBF differences for pic
ture-matching compared to odor identification. Patients showed signifi
cant hypometabolism in right-sided cortical areas for odor identificat
ion. They also failed to show increased rCBF in the hippocampus and vi
sual association area, as seen in controls for odor identification com
pared to picture-matching. These regions may be unique to schizophreni
a or have broader implications for olfactory memory retrieval. (C) 199
8 Elsevier Science Ireland Ltd.