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Functional MRI, memory processing measure accurately identify deficits in patients with schizophrenia

Results from a multisite functional MRI study of episodic memory encoding and retrieval indicate that the Relational and Item-Specific Encoding paradigm successfully detects functionally and neuroanatomically specific deficits in relational memory processes among patients with schizophrenia.

“The Relational and Item-Specific Encoding (RiSE) paradigm was created through the Cognitive Neuroscience Test Reliability and Clinical Applications for Schizophrenia Consortium. The original paradigm, developed in healthy undergraduate students, was optimized to provide a valid and reliable measure of episodic long-term memory in schizophrenia, dissociate specific encoding and retrieval processes, and assist with identification of corresponding brain regions to facilitate translational research aimed at improving cognition as well as clinical and functional outcomes,” J. Daniel Ragland, PhD, of the University of California, Davis, in Sacramento, and colleagues wrote.

J. Daniel Ragland

To determine if schizophrenia disproportionately affects medial temporal lobe and prefrontal cortex subregions during relational coding and retrieval relative to item-specific memory processes, researchers conducted functional MRI in 52 outpatients with clinically stable schizophrenia and 57 demographically matched healthy controls.

Following relational encoding, patients with schizophrenia had disproportionately impaired item recognition compared with healthy controls (P = .03). This deficit was accompanied by reduced dorsolateral prefrontal cortex activation during relational encoding among patients with schizophrenia (P < .05).

Retrieval success, defined by researchers as more hits than misses, was associated with hippocampal activation among healthy patients during relational item recognition and associative recognition conditions. Hippocampal activation was reduced among patients with schizophrenia during recognition of relational information, but not item-specific information (P < .05).

“As alluded to by Ragland et al, relational memory deficits are becoming recognized as a reliable cognitive marker of schizophrenia and neuronal activity abnormalities as a potential biomarker of such an impairment,” Martin Lepage, PhD, of McGill University in Montreal, and colleagues wrote in an accompanying editorial. “A point to consider from our laboratory’s study of specialized cognitive remediation is the presence of individual differences of relational memory deficits among individuals with schizophrenia. Therefore, to better understand these individual differences, it is vital to determine the onset of this deficit among populations at risk and with early psychosis.” – by Amanda Oldt

Disclosure: Ragland reports receiving research grants from Brain and Behavior Research Foundation, ELJB Foundation, NIH and Robert Wood Johnson Foundation. Lepage and colleagues report no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.