[Cerebral imaging and depressive disorder]

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Cerebral imaging has been explored since the 1980s to identify organic or functional anomalies in depressive syndromes.
• Fewer studies exist for depression compared to schizophrenia.

Purpose of the Study:

• To review the findings of various cerebral imaging techniques in depressive states.
• To assess the utility of techniques like CT, scintiscan, PET, and EEG mapping in diagnosing depression and ruling out other conditions.

Main Methods:

• Review of studies utilizing computed tomography (CT), scintiscan, positron emission tomography (PET), and electroencephalography (EEG) mapping.
• Comparative case-control studies and functional imaging techniques (e.g., Xenon 133 test for cerebral blood flow, PET for glucose consumption).

Main Results:

• CT scans generally show no cerebral defects in depressed patients, except for some subtypes (aged, delusional/hallucinatory) exhibiting cortico-subcortical atrophy.
• Scintiscan and PET scans indicate decreased cerebral blood flow and, under specific conditions, reduced glucose consumption in depressed subjects.
• EEG mapping has primarily identified abnormalities in organic brain syndromes, particularly dementia, which requires exclusion in depression diagnosis.

Conclusions:

• Cerebral imaging, particularly PET and scintiscan, suggests functional alterations like reduced blood flow and glucose metabolism in depression.
• CT is less conclusive, though atrophy may be seen in specific patient groups.
• EEG mapping is crucial for differentiating depression from dementia, especially in involutional depression.