Functional imaging, affective disorder and dementia.

Perfusion imaging has had modest success thus far in mood disorder. The most consistent findings in both primary major depression and in secondary depression have been reductions in inferior frontal cortex, adjacent cingulate cortex, temporal cortex and basal nuclei. They are compatible with a primary network for the integration of emotional experience in inferior frontal cortex, striatum and amygdala which is partially supported by the findings from relevant lesions and activation studies in normal controls. There are additional findings implicating dorso-lateral prefrontal and adjacent medial/limbic cortex in some patient groups. In elderly men particularly, reductions in prefrontal cortex appear to correlate with cognitive impairment. In dementia, perfusion imaging with single photon emission tomography (SPET) is becoming established as an important clinical tool ancillary to neuropsychological testing. Quantitation and statistical definitions of regional abnormality will be worthwhile innovations as camera systems become more technically advanced.