Hypofrontal vs. hypo-Sylvian blood flow in schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Psychology

Background:

• Hypofrontality is inconsistently found in schizophrenia regional cerebral blood flow studies.
• Subject and state variables (age, education, task, anxiety) influencing blood flow are not fully examined in psychiatric populations.

Purpose of the Study:

• To investigate regional cerebral blood flow (rCBF) patterns in schizophrenia, bipolar, and unipolar depressive disorders.
• To identify unique neural correlates of schizophrenia, particularly language-related deficits during memory tasks.

Main Methods:

• Regional cerebral blood flow (rCBF) was measured in normal controls, schizophrenic, bipolar, and unipolar depressive subjects.
• Subjects performed narrative prose recall and a verbal recognition memory task across repeated trials.
• Statistical analyses controlled for age, education, gender, state anxiety, and verbal memory performance.

Main Results:

• Narrative prose memory deficit distinguished schizophrenic and bipolar subjects from controls.
• Left hemisphere hypofrontality correlated with narrative memory in the early learning stage, independent of diagnosis.
• State anxiety linked to left hypofrontality, and right hypofrontality to narrative memory in the late learning stage.
• Schizophrenia uniquely showed focal suppression of left peri-Sylvian activation (Broca's and Wernicke's areas).

Conclusions:

• Narrative memory deficits are present in both schizophrenia and bipolar disorder.
• Left peri-Sylvian activation suppression during memory tasks is a unique focal deficit in schizophrenia.
• This deficit is language-related and specific to schizophrenia, independent of other variables.