Mapping hypofrontality during letter fluency task in schizophrenia: a multi-channel near-infrared spectroscopy study

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Schizophrenia is characterized by cognitive impairment and frontal lobe dysfunction.
• The letter fluency test (LFT) is a sensitive measure of this cognitive dysfunction.
• The precise nature and location of hypofrontality in schizophrenia require further elucidation.

Purpose of the Study:

• To investigate prefrontal cortex activation during LFT performance in schizophrenia patients using near-infrared spectroscopy (NIRS).
• To determine the topography and characteristics of hypofrontality in schizophrenia.

Main Methods:

• Utilized multi-channel near-infrared spectroscopy (NIRS), a noninvasive functional imaging technique.
• Measured oxygenated hemoglobin concentration changes in the prefrontal cortices of 31 schizophrenia patients and 26 healthy controls during LFT.
• Controlled for medication effects in the analysis.

Main Results:

• Schizophrenia patients exhibited significantly reduced prefrontal cortex activation compared to healthy controls during the LFT.
• Hypofrontality was most pronounced in the bilateral prefrontal ventrolateral subregion.
• Reduced activation was characterized by both lower magnitude and lesser fluctuation of oxygenated hemoglobin changes, independent of symptoms.

Conclusions:

• NIRS during LFT effectively detects prefrontal lobe dysfunction in schizophrenia.
• This method may serve as a novel tool for monitoring schizophrenia treatment and disease progression.
• Findings highlight the utility of NIRS in characterizing neurobiological underpinnings of cognitive deficits in schizophrenia.