SPECT imaging of odor identification in schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Olfactory identification deficits occur in neuropsychiatric disorders like schizophrenia.
• These deficits persist despite normal odor perception.
• The neural underpinnings of these olfactory impairments are not fully understood.

Purpose of the Study:

• To investigate differences in regional cerebral blood flow (rCBF) between schizophrenia patients and controls during odor identification.
• To identify brain regions associated with odor identification impairments in schizophrenia.

Main Methods:

• Used SPECT scans with 99mTc-HMPAO to measure rCBF during a baseline (picture matching) and an activation (odor identification) task.
• Compared rCBF between six schizophrenia patients and seven controls using statistical parametric mapping (SPM).

Main Results:

• Schizophrenia patients exhibited hypometabolism in right-sided cortical regions, including Broca's area, superior temporal lobe, and supramarginal/angular gyri during odor identification.
• Controls showed increased rCBF in the inferior temporal fusiform gyrus, hippocampi, and visual association areas during odor identification.
• Schizophrenia patients failed to show these increases in rCBF, indicating impaired activation in these memory and visual processing areas.

Conclusions:

• Schizophrenia is associated with significant hypometabolism in specific cortical areas during odor identification.
• Patients with schizophrenia do not engage hippocampal and visual association areas for odor identification as controls do.
• These findings suggest potential roles for these brain regions in olfactory identification deficits and memory retrieval in schizophrenia.