Altered Brain Function During Memory Test Related to Increased Schizophrenia Risk

Functional impairment captured in two brain regions during a simple memory task may serve as a biomarker for schizophrenia, according to a study published online January 1, 2014, in JAMA Psychiatry.

For their study, Roberta Rasetti, MD, PhD, and researchers at the National Institutes of Health (NIH) in Maryland observed 62 schizophrenia patients, 65 healthy siblings, and 181 control subjects. From there, “functional magnetic resonance imaging (MRI) was used with a simple visual declarative memory paradigm to test for differences in neural activation” across the 3 participant groups. During this test, the investigators analyzed “differences in hippocampus and parahippocampus activation and coupling across groups and correlations with accuracy.”

According to the researchers, the intention of the study was to “define whether the impairment in declarative memory and in the underlying related network is a trait or a state feature of schizophrenia.” Though the study mainly focused on genetics, the investigators explained that “it is preferable to study siblings rather than parents because age is a state factor that affects memory and brain physiology.”

The authors found that “both patients with schizophrenia and their healthy siblings showed reduced parahippocampal activation and hippocampal-parietal coupling during the encoding of novel stimuli when compared with normal control participants.” In addition, “there was a significant positive correlation between parahippocampal activation during encoding and the visual-memory score,” the researchers noted.

The results suggests that “hippocampal-parahippocampal dysfunction in schizophrenia is a familial, likely heritable, trait,” the authors wrote. ”We found that activation of the parahippocampus and hippocampal coupling with inferior parietal lobule (IPL) during the incidental encoding phase of the simple declarative memory task are impaired both in patients with schizophrenia and their healthy siblings.”

In light of those results, the investigators said neuroimaging to measure hippocampal-parahippocampal function “could prove useful in identifying neural system mechanisms for genetic susceptibility and as a potential biomarker for intervention” in schizophrenia.